Updates:

• February 15, 2019: Updated to include Tamron 28-75 f2.8 XR Di LD Aspherical (IF) Autofocus, Pentax D-FA 28-105 HD f3.5-5.6 SDM WR and Pentax D FA 15-30 f2.8 ED SDM WR .
• July 4, 2016: Updated to include SMC K 24mm f3.5.
• February 13, 2015: Updated to include the following lenses: A 28 f2.8, DA 40mm f2.8 XS, D-FA 50mm f2.8 macro, Tamron SP 90mm f2.8 macro, D FA 17-70 f4, SMC A 35-105 f3.5, FA 80-200 f4-5.6
• February 13, 2015: Updated to note if impression is based upon use with film, APS-C DSLR, or both.
• July 4, 2012: Updated to include Sigma 135 - 400 f4.5 - 5.6 APO
• September 19, 2007: Updated to include D FA 100mm f2.8 macro. Added note re D FA lenses to lens types.
• April 14, 2007: Updated to include the DA 16-45 f4.
• April 14, 2007: Unpadded to include note about Ricoh lens compatibility.
• January 7, 2007: Updated to include Pentax DA 18-55.
• June 6, 2006: Updated to include teleconverters.

Note: These are my personal and subjective impressions of these lenses. I am not affiliated with Ricoh, Pentax, or any other camera or lens manufacturer.

I’ll never forget when I bought my first SLR camera. I was working on a project making digital collages, and found that I needed to go out and take some photos to use as source material in the collages. I knew nothing about photography, but I did a little reading and wandered into the local camera shop, intending to buy an APS film camera, which (based on my reading) seemed to be the obvious future of photography...

By chance I wandered over to the used equipment counter, and before all was said and done I had blown my budget and was walking out of the store with a Pentax Pz-70 camera, and a pair of Takumar-F zooms. I was elated – I was certain that I would never need to buy another piece of camera gear again...

The decision to go Pentax was purely accidental, but for me it was a happy coincidence. The basic Pentax K mount is virtually an open source design, and Pentax’s commitment to backwards compatibility remains strong. Pentax A, F, FA, D-FA and DA lenses can be used on any current (2015) Pentax DSLR. (These lens designations are explained below.) Most DSLR's can use older pre-1980's / pre-A lenses but require stop down metering. DSLR bodies that support these lenses can be configured to do this at the press of a button.

If you are planning on buying a Pentax camera, check out Ricoh's website for current information about lens compatibility and how to configure new bodies to meter with pre-A lenses.

The purpose of this essay is to share a few subjective impressions of the K Mount lenses I have personally used. Over the last few years, as I have bought and sold a variety of K-Mount lenses, I've often wished for more info regarding available lenses. So here are my thoughts regarding the lenses that I have owned and used.

As noted in the title, the following observations are primarily my subjective impressions about the lenses. From time to time I do run formal tests of my lenses, but that is usually to determine the relative quality of two or more comparable pieces. I never run formal resolution tests that determine line per millimeter data or some other objective data. There are sites that have this data - and such information can be a useful factor in evaluating lenses. But ultimately, this essay is simply my own perceptions about various lenses.

This essay covers a wide variety of both Pentax and third party lenses. In all cases I own(ed) the lens and used it enough to evaluate it. However, most of my work is done with a small number of lenses at any given time. Currently (in 2015) the A* 200mm f4 macro, D-FA 100mm f2.8 macro, D-FA 50mm f2.8 macro, DA 16-45 f4 and DA 17-70 f4 make up the bulk of my digital shooting. I still shoot quite a bit of film and use the FA 28-105 f4-5.6 and Tamron 90mm f2.8 macro on 35mm film cameras.

In the impressions below, I have indicated if my observations are based on using the lens with film, a DSLR or both.

Terminology

The terminology below should be familiar to anyone experienced with Pentax K mount lenses. For those who are not, here is a quick guide:

SMC: Super multi-coated. Pentax's patented 7 layer multi coating process. Almost all of the K Mount lenses were SMC, the Takumar-F and Bayonet Takumar series being the main exception. Recently, the HD designation has begun to supplant the SMC designation, with the newer HD designation presented as an improvement over the SMC process.

Takumar: Probably the most confusing term in the Pentax lexicon. Originally, Takumar lenses referred to Pentax screw mount lenses. With the introduction of the super multi coating process, SMC-Takumar lenses appeared and were considered top of the line screw mount lenses. With the subsequent introduction of the bayonet K Mount, the Takumar label was applied to budget lenses that lacked the SMC coatings. This persisted for several years with K-mount lenses, so for example there are Takumar-F auto focus lenses that were contemporary with SMC-F autofocus lenses. However, the Takumar models were the budget line that, while coated, lacked Super Mult Coating (SMC). In general, K mount lenses with the Takumar designation are considered lower end lenses than K mount lenses with the SMC designation.

K Series Lenses: The earliest manual focus K mount lenses bore no series designation. They simply bore the "SMC Pentax" and "Ashai Optical Co., Japan" designation. For the sake of clarity, I have used the designation SMC-K in describing these lenses.

M Series Lenses: In the early 1980's, Pentax introduced a series of compact, manual focus, lenses designed to accompany the popular ME, ME Super, and MX cameras. These lenses bear the designation "SMC Pentax-M" along with "Ashai Optical Co., Japan."

A Series Lenses: These manual focus lenses have the contacts and aperture ring setting to support program modes - like auto exposure mode or shutter priority. When set to the "A" setting the camera body can control the aperture setting. These lenes also support evaluative metering in modern camera bodies. (The K and M series lenses allow only center weighted or spot metering.) The “A” lenses retain full compatibility with all Pentax Cameras, including the most modern digital SLR's. The prior K and M lenses are not compatible with some newer bodies.

F and FA Autofocus Lenses: Pentax has produced two series of film era autofocus lenses - the F and FA lines. In many cases, the differences between these two series are primarily cosmetic, with some differences in internal electronics. While some FA zooms support the power zoom function, newer FA zooms do not.

D-FA Autofocus Lenses: These are optically optimized for digital photography – with lens design and coatings intended to reduce chromatic aberration and otherwise work well with digital SLR’s. However, the image circle covers the full 35mm frame. Some D-FA lenses have aperture rings, some do not.

DA Autofocus Lenses: Like the D-FA lenses these are designed for Pentax DSLR. They are genrally designed to cover APS-C sensors.

Star "*" Lenses: Pentax designates their highest quality lenses with a green star - usually transcribed with the asterisk. M*, A*, F*, FA*, DA* etx.

In the essay below I describe non Pentax third party K Mount lenses as follows:

K-compatible: Manual focus K mount lenses that do not support auto exposure features. These would be similar to Pentax K or M lenses.

A-compatible: Manual focus K mount lenses with auto exposure support, similar to Pentax A lenses.

Autofocus: Third party lenses comparable to Pentax F, FA, D-FA or DA lenses.

In body shake reduction and manual focus lenses: One addition compatibility issue exists with manual focus lenses and Pentax DSLR's with in body shake reduction (SR). The SR function is optimized to the lens' focal length. Autofocus lenses, starting with the F series, communicate the focal length to the camera which automatically optimizes the SR. Pre-F lenses do not communicate the focal length to the camera body. With prime lenses this is a minor issue - when the lens is attached or when the camera is powered up, a prompt appears asking the user to enter the focal length. Once entered SR has the data it needs. But with a manual focus zoom lens only one focal length can be entered. The user picks either the average of the zoom range or the focal length expected to be used the most. This does not render SR useless, but it is not optimized as the different focal lengths of the zoom lens are used.

Note about Ricoh lens compatibility:

In 2011 Pentax was acquired by Ricoh Imaging Company. However, years before this, Rocoh made a line of film based SLRs that utilized the K mount found in Pentax and other cameras. Later, Ricoh introduced program bodies that used a modified K mount. In this article, references to "Ricoh lenses" refer to the older K mount lenses or Ricoh program lenses.

Ricoh program lenses are not compatible with Pentax Auto-Focus bodies. You can identify Ricoh program lenses by a “P” on the aperture ring – when the ring is rotated into the “P” (Program) position, the ring locks in place and you have to depress a small button to get the it to move again.

The Ricoh program lenses have a small ball bearing contact on the rear flange of the lens that will slide into the hole that holds the AF cam on Pentax autofocus bodies. The result will be that the lens gets locked tight on the body, only halfway mounted. I learned this the hard way trying to mount a Ricoh lens on my Pz-1p! It took a trip to the repair shop to get the lens off the camera.

The Ricoh program lenses will work fine on manual focus Pentax bodies – no AF cam or hole to get stuck on. With my Ricoh 50mm f 1.7 I just removed the back flange from the lens and took out the ball bearing contact. With the modification it no longer works as a program lens on Ricoh bodies (not that I have any Ricoh program bodies) but can now be mounted on and removed from Pentax AF bodies.

Older, non program Ricoh lenses do not have the program contact or this problem

All Ricoh lenses are basically like SMC-K or M lenses in their aperture operation. That is, they do not support program modes on Pentax bodies so you can shoot in either manual or aperture priority only and must set the aperture using the ring on the lens.

With the exception of the 50mm f1.7 mentioned above, all of the Ricoh lenses reviewed here are the older, non-program models that fit without problem on all Pentax bodies, both manual and autofocus. However, anyone experimenting with older Ricoh lenses is well advised to be sure the lens is not a Ricoh program lens before attempting to mount it on a Pentax autofocus camera.

And with that - here are the lens summaries:

Prime Lenses

Sigma 14mm f3.5 (A-Compatible) (Used with film and APS-C digital): In brief - very wide, flawlessly rectilinear, and reasonably priced. This is not a lens that I use very often, but when I do the results are usually good. The ultra wide angle of view opens up many interesting creative opportunities. The lens is very sharp, suffers from light fall off at aperture below f8, and does have a problem with flare / reflections when bright light sources hit the front element. These are not uncommon problems for lenses of this focal length. For me, this is a nice optic in a focal length that I don’t use very often, and was available at a reasonable price. I have the manual focus version of this lens, and keep it in my bag, despite infrequent use. This lens was replaced by Sigma's 14mm f2.8 EX. It should be noted that on APS-C DSLRs this lens is comparable to a 21mm angle of view.

SMC-K 24mm f2.8 (Used with film): Much sought after and often pricey, I used this lens only a few times before selling it. The few shots I took with it looked very good, but the FA 20-35 f4 looked just as good, so I decided to hang onto the zoom and sell off the prime.

SMC-K 24mm f3.5 (Used with APS-C digital): In 2015 I experimented with stack focused macro shots and started looking for a shorter focal length lens to use on extension for high magnification images. I stumbled into a used copy of this lens, available at a reasonable price, and grabbed it. I've only used it reverse mounted for snowflake photos and stacked macros in, but it has worked very well. Some sample images - 1, 2, 3.

Ricoh XR Rikenon 24mm f 2.8 (K Compatible) (Used with film): Adequately sharp but somewhat weak in flare control, this lens nonetheless is very reasonably priced, features an outstanding build quality, and is an excellent way to get into a prime at this focal length. As with the 24mm SMC-K, I sold it off in favor of the FA 20-35 f4.

Ricoh XR Rikenon 28mm f2.8 (K Compatible) (Used with film and APS-C digital): This is one manual focus lens I still use. It's a standard for my infrared film shooting. I’m very satisfied with the results of this lens. Not a common lens, it can be had at a reasonable price when you do find it. On an APS-C DSLR this has the equivalent angle of view of a 42mm lens on a 35mm camera, and I enjoy the relaxed normal perspective.

SMC-A 28mm f2.8 (Used with APS-C digital): I purchased this in 2014 for use with DSLR's. It has supplanted the Ricoh lens described directly above. Very good in sharpness and flare control at f 5.6 or smaller. While I have used it only on digital bodies it is of course a film era lens and totally compatible with film bodies.

SMC-A 35mm f2.8 (Used with film): The most disappointing Pentax lens I ever tried. Unsharp at any aperture, this lens just never produced good results. Maybe I had a bad sample. Not recommended.

SMC-K 35mm f3.5 (Used with film): I bought this as a replacement for the SMC-A 35mm f2.8 and was happy with the results. Again – sold it off when I got the FA 20-35.

SMC-M 40mm f2.8 Pancake (Used with film): Many people find the diminutive size and nearly perfectly "normal" focal length to be very compelling, and this lens regularly sells for a pretty high price on eBay and other venues. Personally, I'm not enthralled by this piece. Granted, the 40mm focal length is great - the perspective is more relaxed than 50mm and does not have quite the wide angle feel of a 35mm. But this small size makes this lens a pain to work with, the optical quality is good but not outstanding, and the price is ridiculously inflated. If you like small things or if you can get this lens at a discount, it just may be right for you, otherwise you can get better optical performance and a fraction of the price from an SMC-M or A 50mm f1.7. While the 50mm is over twice the size of the 40mm, it still is only about 1 CM longer - so with a little ingenuity you can probably still be able to carry the more bulky 50mm setup.

DA 40mm f2.8 XS (Used with APS-C digital and film.): This came as the kit lens on a Pentax K-01. It is very small - little larger than a body cap - and is impressively sharp throughout its range. In 2016 I started using this with a Pentax Mz-S film body with good result - sample image.

SMC-FA 43mm f1.8 Limited (Used with film and APS-C digital): A really outstanding lens - exceptional build quality and style, with really impressive optics. The price is a bit daunting though. As much as I liked this lens, I ultimately sold it off. The most compelling reason for me to use this lens was the focal length, but as I moved to APS-C digital with its 1.5x focal length factor, the 43mm focal length was not as useful. It is one lens that I do regret selling.

SMC-A 50mm f1.4 (Used with film and APS-C digital): A fine normal focal length lens, very sharp, great flare control, and excellent color rendition and contrast. When I bought my sample it was a leader in the "bang for the buck" category - a truly great optic typically available used for under $100. I tested this lens against the Ricoh Rikenon 50mm f1.4 and very rare Rikenon 55mm f1.2 - and it outperformed both.

Ricoh Rikenon 50mm f1.4 (K Compatible) (Used with film): Not particularly sharp and with pretty poor flare control, this lens does have some interesting characteristics. I shot quite a bit with this for a while, but it was supplanted by better 50mm lenses. While it makes pleasing images with a nice bokeh, there are better choices in the 50mm range.

SMC-M 50mm f1.7 / SMC-FA 50mm f1.7 (Used with film and APC-C digital): I'm lumping these together since they are virtually identical optically (the most notable exception being in the lens coatings.) These lenses are very sharp, even wide open, with excellent flare control. I have used these lenses to photograph snowflakes and find that the quality is comparable to many 50mm macro lenses used. The "M" version of this lens is often available at very affordable prices. The FA version is always in my lens bag.

Ricoh Rikenon 50mm f1.7 (K Compatible)(Used with film): I bought a newer version of this lens on sale, and used it on a camera that I kept under the car seat for a few years. The all plastic construction of the newer lens is a bit disappointing, the optical performance is very good but not on par with the Pentax 1.7.

SMC-M 50mm f2: I use a pair of these lenses as loupes for examine slides, but have never put them on a camera to test them out.

Ricoh XR Rikenon 50mm f2: Like the SMC-M 50mm f2 I mostly use this as a loupe. I have tested this on a K mount adapter with the Pentax Q, and found it is remarkably sharp on that digital body. The Q's small sensor with extremely dense pixel pitch, is very demanding. A sample image of this lens on the Pentax Q is in the post found here (note that several other lenses are tested there as well.)

Sigma EX 50mm f2.8 macro (Autofocus compatible) (Used with film and APS-C Digital): Pretty big and bulky for a 50mm, this lens focuses down to 1:1 without any additional extension or filters. I use this lens mostly for snow crystal shots, and it has performed admirably in that capacity. It has since been supplanted by the DFA 50mm f2.8 macro and SMC K 24mm f3.5 macro.

D-FA 50mm f2.8 macro (Used with APS-C Digital): A lightweight and compact (when not fully extended) 50mm macro that focuses down to 1:1 without any additional extension. I bought this in 2014 for use in photographing snowflakes and for stack focused macro photos of insects. Extremely sharp and with well managed flare. Definitely the sharpest 50mm lens I have ever used. This lens also has quick-shift focusing that lets the photographer move between auto focus and manual focus without changing settings on the lens or camera body - a real boon to macro shooting. Resversed mounted this is excellent for stacked macro work as well. Sample images: 1, 2, 3, 4.

SMC-M 50mm f4 macro (Used with film and APS-C digital): This lens only focuses down to half life sized - you need to added extension tubes or close-up filter to get additional magnification - and at f4 it is also rather slow. It's a nice lens and pretty inexpensive as macro's go, but if you want a macro lens for close focusing, one that focuses down to 1:1 would be much better. If macro focusing is not important, a faster, cheaper, smaller non-macro 50mm is a better choice. In the past I mostly use this for shooting snow crystals, where I reverse mount the lens on bellows. However, the slow f4 maximum aperture, combined with the light loss from extreme extension, make focusing with this lens challenging. I have hung onto my copy but it has mostly been supplanted by 50mm f2.8 macro lenses.

Ricoh XR Rikenon 55mm f1.2 (K Compatible) (Used with film): A big, fast lens that comes close to the Pentax SMC f1.4 and 1.7 50mm's in quality. I like the size and heft of this lens, and the mystique of a lens this fast is really appealing. But in my tests I found that the SMC 50mm f1.4 was sharper at f 1.4 though f4, at which point the performance of the two lenses seemed to be equivalent. This is a fine optic, but more of a collectable than a working lens, IMO – which is why I sold mine to a collector.

SMC-M 100mm f2.8 (Used with film): Great lens, Small, great optics, and available at a reasonable price. This is a nice lens for portrait work or general shooting - much smaller than a 100mm macro and with a focusing mechanism that allows you to fine tune distant subjects as opposed to close ones.

Tamron SP 90mm f2.8 macro (Used with film and APS-C Digital): This is the older, non-DI version of this lens. Optically, this is comparable to the D-FA 100 f2.8 macro - i.e. excellent. My only complaint about this lens is the awkward way it shifts between autofocus and manual focus - requiring both setting the focus mode on the lens itself and also on the camera body. The quick-shift focus mode on the D-FA 100 lens is a huge improvement over this, letter you shift seamlessly from manual to auto to manual focus as you will. I bought this lens used at a very reasonable price and leave it on a spare camera for quick grab shots in the garden - optically it is excellent and makes for a great extra / backup macro lens.

SMC D FA 100mm f2.8 (Used on APS-C Digital): As noted above, I upgraded to this lens, in part to get past the chromatic aberrations of the Kiron 105mm macro, but also to gain autofocus in a macro lens. This lens is much smaller and lighter than the Kiron, however it lacks the rugged metal construction of the older lens. Autofocus can be relatively fast – but the lens lacks a focus limiter so if the camera does decide to start hunting, the lens can annoying swing far out of focus. The manual focus ring is large, and the focusing mechanism is smooth. This lens also employs the clutch focusing mechanism, so you can manually focus at any time without disengaging autofocus on the body. The lens also features a focusing clamp, which will lock the focus position in place – handy when working in a studio environment.

This lens has a really huge hood, which attaches to the main body of the lens, and not the front element. This means that as the front element extends – and as you focus down to 1:1 it extends by a couple of inches – the hood does not move. However, at high magnifications the front of the lens is almost flush with the edge of the lens hood, making the hood essentially ineffective. Personally, I don’t like the design and have opted to just put a hard, 49mm threaded hood onto the front element (by chance I have a sturdy metal one that works very nicely.)

From my limited use of the lens thus far, image quality appears to be superb. I intentionally shot high contrast scenes, hoping to induce chromatic aberrations or fringing, but virtually none was to be found. Resolution, detail, edge definition are all excellent. Color saturation, contrast, and flare control are all excellent. Tested on a film body (Pentax Mz-S) the lens proved that it did indeed cover the full 35mm frame, even at 1:1 magnification, with no noticeable light falloff in the corners.

Kiron 105mm f2.8 macro (Used with film and APS-C Digital): A big macro lens that focuses down to 1:1, this was my main workhorse lens before I bought the SMC-A* 200 macro. There are a lot of macros in the 90-100 mm focal length, and many are very good. This is one of the best and is great if you can get it at a reasonable price. I use this on the digital *ist-D, also with good result. There is some very slight chromatic aberration apparent when using this on the digital, but nothing beyond the ability of Photoshop’s raw interpreter to correct. Update: Once I started using this lens on the K10D, I noticed pretty significant chromatic aberration, particularly at high magnification shots. It is still manageable in Photoshop, but prompted me to upgrade to the DA 100 f 2.8.

Bayonet Takumar 135mm f2.5 (Used with film): Generally regarded as a dog, this lens lacks the Pentax SMC coatings. While the build quality is nice, the multi colored aperture markings make it look somewhat cheap. And this is a cheap lens - usually retailing below $50 US. But for all its faults, I always have fun with this lens. The finder is really bright for a telephoto, the shallow depth of field wide open is great, and while it's not the sharpest optic it does a decent job in most situations. If you find one priced cheap, grab it and join the fun.

Pentax SMC A* 200mm f2.8 (Used with film): A truly fine lens in every respect. Sharp, well build, fine Bokeh, impressive speed. Like many A* lenses it can be expensive, but is worth it. Ultimately, I sold mine off – at one point in time I had two zooms that covered 200mm and three prime lenses at this focal length. I whittled that down to the pair of zooms and the following lens:

Pentax SMC A* 200mm f4 macro (Used with film and APS-C digital): My most used lens - rock solid in build quality, exceptional optics and sharpness. This lens focuses down to 1:1, at which magnification the size of the image projected onto the film is the same as the size of the subject . I use this as my primary lens for both field and studio macros. This lens is compatible with the excellent 1.4x - L and 2x - L teleconverters - and in combination with those you can achieve some really high magnification images. This has continued to be my #1 most used lens for macro work with Pentax DSLRs, and the results are truly excellent. Highly recommended.

SMC M 200mm f4 (Used with film): Compact, well built, with very good optics. This is an affordable 200mm, not in the league of the A* lenses noted above, but also costing only a fraction as much. I use this lens with a 50mm reverse mounted in front as an easy way to get 4x life sized macros, and it does well in this application.

SMC A* 300mm f4 (Used with film and APS-C digital): Quite small and compact for a 300mm, excellent optics but not quite at the level of the A* 200's. My only complaint about this lens is the minimum focusing distance - just under 3 meters - which can limit its usefulness with small subjects. Despite this quibble, this is an excellent lens. This lens also works well on APS-C DSLR's where, due to the focal length factor, it is the equivalent of a 450mm f4 on a standard 35mm camera – a much more useful focal length for telephoto subjects. Despite this – it's one of the least used lenses in the bag.

SMC A* 400mm f2.8 (Used with film and APS-C digital): Big, fast, and heavy - I use this lens for birds, landscapes, and the occasional close up. I almost always use this lens with teleconverters - typically the 1.7 F autofocus adapter, but also with the 1.4x-L adapter and 2x adapter. With the 1.7x adapter, this lens becomes the equivalent of a 640mm f4.5 on a 35mm camera, and the equivalent of a 960mm f 4.5 on an APS-C DSLR. While the autofocus aspects of the adapter are limited with this lens, AF does kick in once the lens is pre-focused. Sharpness is on par with the best of the Pentax A* lenses. The only complaint I have with this lens is that the Bokeh can be harsh, particularly when used with the 2x-L teleconverter.

Tokina ATX 400mm f 5.6 (Used with film and APS-C digital): Like most Tokina lenses, this is a well build, solid piece. It's fairly small and compact for a lens of this focal length. With film, optical quality is acceptable at f5.6, much better at f 8 and 11, though it never rises to the level of the Pentax A* lenses. Surprisingly, on DSLR's, even the K3, the results are much better than on film and I find that it produces really excellent detail. On an APS-C DSLR his lens become the equivalent of a 600mm lens on a 35mm camera – making it very usable for birds etc My first sample of this lens became clouded with fungus and I replaced it when one came up on the used market.. Sample photos. Another here.

Takumar 500mm f4.5 (Used on film only): Often refered to as "Battle Ship Takumar," this lens is big, heavy, and all metal. My copy was the oldest, single coated screw mount version that was crudely modified to be a K-Mount lens by having a K mount adapter permanently affixed to it.. It was also make in a SMC screwmount version, and a K-Mount version. The K Mount version, which incorporated the same optical design, was manufactured through the late 1990's. With a manual aperture, physical size close to its focal length, and minimum focusing distance of 10 meters, this is definitely not a modern optic. But that does not prevent it from delivering great images - at least on film. In terms of sharpness, my tests show this lens to be on par with the Tokina 400mm f5.6 - very good but not outstanding. Where this lens is really outstanding is in it's saturation and contrast. Looking through this lens there is a visible 'pop' to colors that you can see in the finder - and that shows on the film as well. The screw mount version can found at very reasonable prices - mine cost $430 - and are probably the best way to get into some serious 'big glass' at a reasonable price. Though I sold my Takumar off before going digital, I suspect that the chromatic aberrations in this lens (even visible to some degree in film shots) would really impair its performance on a digital SLR. That’s speculation on my part but anyone considering this lens for use on a DSLR might want to research that point.

Zoom Lenses

Pentax D FA 15-30 f2.8 ED SDM WR (Used with APS-C and full frame digital): This is a big, heavy lens with bulbous front element. PROS: Superb image quality with outstanding sharpness and color from edge to edge, great close focusing ability, fast and silent autofocus, excellent build quality, weather sealing. It also produces very well corrected rectilinear images. CONS: Prone to flare due to the large semicircular front element, has no filter threads so standard filters cannot be mount in front of the lens without an adapter system, heavy (2.25 lbs / 1040 g). Though I bought this for use on the K1 full frame body, its actually seen a lot of use on an infrared converted APSC K-01 body. On APSC this lens is the equivalent of 23-46mm on a full frame body. On an infrared converted camera it produces great results with virtually no infrared hotspot, even when stopped down to f11 or f16. It is my go-to lens for infrared landscapes with the K-01 body.

Pentax SMC DA 16-45 ED AL f4 (Used on APS-C Digital): This lens is a step up from the 18-55mm kit zoom that comes with many Pentax DSLR's. The constant f4 aperture is nice. Overall sharpness is excellent, both in the center and the edges of the frame. There is no noticeable light fall off in the corners. The zoom range is very useful – corresponding to a 24-70mm lens in 35mm terms – though it would be nice if it were a little longer. Close focusing and maximum magnification are OK, but not as nice as the 18-55mm. Flare is very well controlled throughout the zoom range.

Physically, the lens is fairly large, but light and easy to carry. The accompanying hood is a nice accessory.

This is a fine general purpose zoom with the best image quality three DA zooms that I use. The only weakness that I would not is that the lens displays slight chromatic aberration in high contrast scenes – like tree branches against a light sky. Not enough to be a major problem.

I occasionally use an infrared converted Pentax DSLR and find that this lens does not perform well with it - there is an odd color shift between the center of the frame and the outer areas. This is specific only to using it with an infrared converted camera.

Pentax SMC DA 17-70 AL [IF] SDM f4 (Used with APS-C DSLR): I bought this lens in 2014 to use as a general purpose travel lens. The wider zoom range, especially at the long end of the range, makes it more versatile. This lens features SDM focusing via a hypersonic motor, and I find the focusing to fast, quiet and accurate. In terms of image quality - wide open at f4 the lens is acceptable but not razor sharp. It sharpens up significantly when stopped down even to just f5.6 and by f8 it is just short of the D FA 16-45, which I would consider to be an excellent performer. However the wider zoom range and excellent close focusing capability make this lens my choice for general walking around and travel use.

Regarding use on an IR converted DSLR - this lens is excellent in that capacity.

Pentax SMC-F 17-28 fisheye zoom (Used with film and APS-C digital): Now here's an odd duck. At the widest setting this lens has a pronounced fisheye effect, but as you zoom in the fisheye effect becomes less pronounced until it all but disappears. At the 28mm setting, this lens shows very little fisheye distortion, but shows a wider angle of view than a typical 28mm - approximately that of a 24mm. One drawback of this lens is that it cannot take front mounted filters due to a concave front element - there is a holder for gel filters on the rear of the lens.

This is a great lens that offers a lot of creative opportunity - and it's a lens unique to Pentax. Highly recommended for use with film cameras.. The situation changes somewhat with APS-C DSLRs. Because the digital sensor crops out the edges of the frame - where the fisheye effect is most pronounced - you don't get much of a fisheye feel to this lens on the digital SLR. Instead, you get what looks like a pretty poorly corrected, high distortion, wide angle. It is wide, and if you can correct the barrel distortion in Photoshop this lens may be a good wide angle alternative. I am hanging on to mine in hopes that it will shine on a full frame Pentax when and if I use one.

Pentax SMC DA 18-55mm f3.5-5.6 (Used with APS-C Digital): This is the kit lens / ‘normal zoom’ for Pentax digital SLR’s. For being such an inexpensive lens (mine came with a Pentax K10D kit for an added price of well under $100) this is a very good lens. It’s not up to the most rigorous standards – wide open it is soft in the corners of the frame, shows noticeable light falloff, and is subject to pretty noticeable chromatic aberration. The image quality improves notably when it is stopped down. It also focuses extremely close for a standard zoom – verging on macro lens magnifications – which is a real boon for those of us who like to get close. Note that there are several version of this lens - a "mark II" and WR / non-WR versions. My comments above apply to the original non-WR version.

Vivitar Series 1 19 - 35mm (A Compatible) (Used with film): A great lens at the price, this zoom is sharp and contrasty through its range. The one problem is flare. I used this on one trip - many indoor shots were great as were outdoor shots where the sun was behind me. But catch a few sun rays on the front element and you'd swear that Captain Kirk is beaming into your shot.

Pentax SMC-FA 20-35mm f4 (used with film and APS-C digital): This is one of my favorite lenses film use and still gets a lot of use in that capacity. On film results are sharp from corner to comer and the 20-35mm focal length is very useful. Images are sharp and contrasty, with minimal distortion. Like many ultra wide angles, this lens is prone to flare, though the accompanying hood is pretty good at helping to control it. I have used this on DSLR's but on an APS camera this focal length is not too appealing, at least to me. An excellent lens all around and one that I am looking forward to testing out on a full frame DSLR someday.

Pentax SMC FA 28-70mm f4 AL (used with film and APS-C digital): This is another standard lens, and one that I use frequently. Very good performance throughout the zoom range, and a good performer on both film and digital bodies. It should be noted that this is one lens that gets very mixed reviews – some people love it, others hate it. Maybe there is a lot of variation between individual lenses – I don’t know. In the past this lens was my first choice for general use on film cameras, but in the few times I have used it in recent years I've been unimpressed. The excellent build quality of new Pentax DFA zooms really puts the quality of this lens to shame - it feels very cheaply made.

Tamron 28-75 f2.8 XR Di LD Aspherical (IF) Autofocus (Used with Film and Full Frame Digital): An excellent zoom that features a constant f2.8 aperture. I bought The Tamron 28-75 f2.8 well before acquiring a Pentax K1 and used it extensively on autofocus film bodies (Mz-S, Pz-1p and *ist). This lens uses the older screw drive autofocus and so it is fully compatible with older bodies that do not support SDM autofocus. It's probably the most affordable and available (in 2019) f2.8 zoom for 35mm film based Pentax cameras. And of course, it is fully compatible with even older manual focus bodies, since it has an aperture ring. Optically, it is an excellent performer on both film cameras and on the Pentax K1. PROS: f2.8 constant aperture, excellent optical performance throughout the zoom range on both film and digital bodies, excellent build quality, aperture ring, and for film SLR users - screw drive autofocus. CONS: color rendition is somewhat flat compared to Pentax lenses (which can be adjusted in post processing), not weather sealed, and for DSLR shooters - screw drive autofocus instead of faster/more quiet SDM autofocus. Sample images: 1, 2, 3, 4

Takumar F 28-80 (Used with film): The autofocus Takumar lenses were Pentax's 'budget' line when they first started offing cameras. They should not be confused with the older, screwmount Takumars, which were first rate lenses. This lens was one of the first lenses I bought, and frankly one of the worst. Soft, unsharp, prone to flare. It had a macro setting at the long end that did provide for fairly close focusing, but the sharpness was lacking. Not recommended.

Rikenon 28-100mm f4 (Used with film): An old style, manual focus, constant aperture zoom. Probably set a record for the lens I owned the shortest period of time. I bought one on eBay, tested it, sold it within a week. It was sharp enough, seemed prone to flare, but had terrible barrel and pincushion distortion at the different ends of the zoom range. When you can see the distortion in the finder – time to find a new lens.

Pentax D-FA 28-105 HD f3.5-5.6 SDM WR (Used with full frame digital):My go-to lens for general shooting, this zoom is remarkably sharp with excellent color reproduction while offering a very useful zoom range. It's light but well built and has fast and silent SDM autofocus. It does have some shortcomings, though. The maximum aperture setting s are slow which affects both low light shooting and the ability to obtain a narrow depth of field. It also has noticeable light falloff, though that can be easily corrected in post exposure processing. I've been extremely happy with this lens for use in landscape shooting and travel. Sample images: 1, 2, 3, 4

Pentax SMC FA 28-105mm f4-5.6 (Used with film and APS-C digital): This is the only power zoom lens that I have every used, The power zoom features were big in the Pz series of Pentax bodies, though I have never used them. The lens itself is very good and is my first choice when shooting with a film body. Optical quality is very good, but some distortion is apparent in larger prints shot at the wide angle end of the zoom. At f4-5.6 this lens is slow and due to the power zoom feature it is also rather heavy. Build quality and feel is better than the FA 28-70 but not as good as newer zooms.

Pentax SMC A 28-135mm f4 (Used with film): A real classic zoom that was no doubt a gem of a lens in its day. These can be hard to find and usually fetch a decent price. I found this to be a good sharp lens – not on par with the best primes or even the more modern zooms though. It’s solid as a rock (metal construction) and weighs about as much as a rock as well. It features a macro function on the short end – so you can focus close with the lens set to 28mm, not very logical IMO. I used mine on the trip through northern Michigan and got a lot of excellent photos with it – but sold it off shortly thereafter.

Pentax SMC A 35-105 f3.5 (Used with film and APS-C digital): This is known as the "stack o' primes" in some circles - suggesting that the quality throughout the zoom range is on par with prime lenses. I found one at a bargain price and bought it. It is sharp throughout its zoom range, but not as sharp as the best primes and no sharper than modern zooms. The 35-105mmzoom range is not ideal, in my opinion - not quite wide enough at the wide end. The macro feature lets you focus a little more closely at the long end, but it still does not focus very close. Build quality is excellent - all metal, silky smooth focusing and zooming action. However, the very narrow zoom ring takes some getting used to. It is a nice lens but nothing special.

Sigma EX 70-200mm f2.8 Used with film and APS-C digital): Not as sharp as the best prime lenses in this focal length (e.g. the A* 200 f4 macro or A* 200 f2.8) – but still very good. I use this with lighthouse photos, sports events, and various people shots. One quibble – it malfunctions at very cold temperatures (e.g. around 0 Fahrenheit) – the aperture opens up and does not shut. Note that I have the first version of this lens and there have been numerous updates since.

Pentax Takumar F 70-200 f4-5.6 (Used with film and APS-C digital): This is one of the first lenses I ever bought, and I sold it a few years later. In 2014 I purchased another copy (for less than $30). Despite being a budget lens both copies that I have used performed excellently. Razor sharp with outstanding resolution. The lens has weaknesses - it is very prone to flare, has poor close focusing distance and has a rotating front element. But for the price it makes a great lightweight telephoto..

Vivitar Series 1 70-210mm f3.5 macro zoom (Used with film): This lens was a bit revolutionary when it was introduced in the mid 1970’s. Apparently, it was one of the first third party lenses to be introduced that offered a quality that rivaled that of the major brand name optics. Several version of this lens were made – I had the first version, with the 67mm filter size. A lot of people rave about this lens, and it still enjoys a good reputation. Maybe I had a bad sample – you never know when you buy something used – but I found it to be lack luster in performance. Images were adequately sharp at f 8 and f 11, but were less sharp at more open apertures and downright soft wide open (aft f 3.5). The macro feature was intriguing – the lens snaps into a macro setting and focuses down to half life sized. On my lens, at least, the picture quality in macro mode was poor – about on par with using a single element close up filter. Again, maybe I had a bad sample – a lot of folks swear by this lens – and maybe it was quite the item 40 years ago. But personally, I would not recommend it.

Pentax SMC FA 80-200 f4-5.6 (Used with APS-C Digital): Compact and nicely built telephoto zoom. Optical performance is acceptable but not excellent. I bought this seeking a small lightweight telephoto zoom but the Takumar-F 70-200 has supplanted it.

Pentax SMC FA 80-320mm f4-5.6 (Used with film and APS-C Digital): This is one lens that I bought, never used much, but have not sold. I like it – very lightweight and with a good telephoto range. Performance from 80-200 is very good, more or less on par with the Sigma noted above, but of course a stop or more slower. Quality softens as you zoom out past 200mm or so.

Tokina ATX 100-300mm f4 (used with film): A massive, manual focus, constant aperture, ‘one touch’ zoom. Built like a rock – very solid. Optical performance is good, but not outstanding.

Sigma 135 - 400 f4.5 - 5.6 APO (Used with APS-C Digital): I bought a used sample of this lens when my Tokina 400mm f5.6 became clouded with fungus. These days, 400mm prime lenses for Pentax are quite scarce, and I figured I would never find a replacement for the Tokina. Amazingly, shortly after I bought the Sigma zoom, a Tokina came available and I snapped it up. Regarding the Sigma - I have the older, non-DG version. Image quality is very good, but not great. It never produces the fine detail that even the Tokina is able to do at f8, but it comes close. The Sigma is very good wide open which is a plus. The build quality is solid, but the lens zooms out to full extension very easily. Despite this, the zoom action is rather stiff, so you kind of get the worst of both worlds. I took this on an excursion to the St. Louis Zoo and found the zoom range to be very useful on my APS C sized SLR (Pentax K5). The K-5's in body IS worked really well with this, and I was able to get good image quality at low shutter speeds. Overall, sharpness of the lens is good even wide open and bokeh is nice. Sample shots in this post.

Teleconverters

Teleconverters fall into a unique category. Since they can only be used in combination with another lens, it's difficult to evaluate them on their merits. In my experience, a teleconverter that works well with one lens, may perform poorly on with another. Ultimately, using teleconverters is a bit hit and miss.

In theory, one way to avoid that kind of uncertainty is to use lenses and teleconverters that are designed to work together. Pentax makes several K Mount teleconverters that are specifically designed to work with certain lenses.

Among Pentax teleconverters, and the most pricey are the 2x-L, 1.4x-L, 2x-S, and 1.4x-S series. The “L” series stand for long lens, and are designed to work with longer optics. The “S” stands for short lens.

Despite these designations, some converters are designed to be used with specific lenses. For example, the “L” teleconverters are designed to be used with the A* 200mm macro, while the “S” converters are designed for use with the A* 200mm f 2.8 (non macro.) The “L” series converters are the least flexible in terms of use. They have an extension that reaches up into the lenses that they are paired to work with. This enables them to integrate into the lens nicely, but also make it impossible to mount them on any lenses other than those they are designed to work with.

Both the “S” and “L” teleconverters have the electrical contacts needed to preserve full auto exposure features with Pentax cameras. However, there is no linkage for the autofocus drive shaft, so while these converters can be used with autofocus lenses, autofocus functions are lost when using them.

A real odd duck in the Pentax teleconverter lineup is the 1.7x-AF converter. This converter links to the camera’s autofocus mechanism, and focuses by moving the elements in the teleconverter itself, as opposed to the lens.

When I bought an A* 400 f2.8 for birding, I also bought the matching 2x-L and 1.4x-L teleconverters. Here’s my impressions of those (and other) K mount teleconverters that I’ve used:

Pentax SMC 2x-L converter (used with film): This is a fairly large converter, and is compatible with several long focal length lenses. It's expensive, and to be honest I’ve never been very impressed by its performance. Images loose a fair degree of sharpness, contrast, and saturation, but even worse is the horrific bokeh that this teleconverter and the A* 400 can produce. I keep it as 'part of the set' for the A* 400 f2.8, but in my opinion the AF 1.7x produces a much better image at almost the same degree of magnification,.

Pentax SMC 1.4x-L converter (Used with film and APS-C Digital): In stark contrast to the 2x-L, I can hardly tell the difference between shots taken with this converter on and without it. It is particularly useful on the 200mm macro for getting 1.4x life-sized images, with virtually no degradation of image quality.

Pentax SMC 1.7x AF converter (used with film and APS-C digital): Like I said, this is truly a unique offering from Pentax. The optical quality is excellent – this is more or less permanently affixed to my A* 400 f.2.8 for birding (resulting in an effective 680mm f 4.5 lens for 35mm film, and a comparable 1020 mm on APS-C DSLRs, due to the digital 'crop factor.'). The autofocus, functionality is surprisingly good – best with fast, shorter focal length lenses (e.g. a 50mm f 1.4). The effective range of the AF is limited with longer lenses, but is accurate and effective still.

Kiron MC 7 2x Teleconverter (Used with film): Very good third party converter, works very well with the Kiron 105mm macro, but also as a general purpose converter. I had both the K Mount version (no electrical contacts) and the A compatible version, which supports full contacts. Both worked very well.