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Showing all 10 reviews by rdenney

Review of: HD Pentax-DA 645 28-45mm F4.5 ED AW SR by rdenney on Mon December 10, 2018 | Rating: 10 View more reviews 

Views: 33956
Reviews: 7
I purchased a pre-owned lens from Adorama at a good price, and the lens turned out to be a problem performer. It was fine at some angles, but when level on the tripod, aimed at my test scene, it did not match the performance of either the 35mm prime or the 45mm end of the 45-85 zoom, and it missed by a mile. My suspicion is that something that is supposed to not be loose was, and fell out of alignment under certain conditions and into alignment at other times. Adorama took it back without a hiccup, and I sent that money to Australia to a forum member who offered me his lens instead. The beast was proving physically unmanageable for him, and I can understand that. It is indeed a beast, as all who have reviewed it will confirm. But compared to my Sinar P, it's light as a feather. And compared to a Zeiss Jena 180mm f/2.8 Sonnar (or, Heaven forbit, the 300), it's not particularly beastly. Put that Sonnar on a Kiev 60, and carry that around for a bit. Or a Pentax 67 with a 300mm lens and TTL finder. You'll never complain about the 645z again. But I do consider carrying it around as part of my workout regimen. I warm up using my dumbbells, usually in the range of 35-50 pounds each, as a warm up for the big lift of carrying this puppy. Okay, it's not that bad, but it will still be favored by those who work out in the gym. Today I made new test photos with the replacement lens, and conditions were a bit more like my original test in terms of lighting. It was a gray day just as it was in the late spring when I tested the other lenses in this series. But unlike that prior occasion, it never made it above freezing here so the camera got a bit of a cold-weather workout. The winter conditions also mean that the bushes and trees at Chez Denney are more leafless than in prior photos. Here's a general view at 28mm: As before, these are straight out of the camera, processed in DxO Photolab with the driest possible settings. 28mm Here's a 100% crop from the middle of the image, at f/4.5. Remember that these 1:1 crops, when displayed on a typical monitor at 100 pixel/inch, are part of an image seven feet wide. One of the tests of a zoom is whether it's better to carry a range of primes. The only good prime that competes at this end of the zoom range is the DA or DFA 25mm lens, which is of course no longer in production. The only lens I have in my collection that hopes to compete at this focal length is an Arsat 30mm Fisheye. So, what the heck, let's show the center crop from that lens (which is itself also a beast). Here is the image made at f/11, so we are comparing the best aperture of that lens with the wide-open aperture of the 28-45. The Arsat doesn't stand a chance. But if you need a fisheye, and only a fisheye will do, then the Arsat is one. But the real test of a wide-angle lens is in the corners. Is there field curvature? Does the sharpness hold up in the corners? Let's look. Here's the lower right corner: This isn't curvature--it's just loss of sharpness in the extreme corner at f/4.5. But this IS just the very corner--compare this with the full image above. We're talk the four or five inches from the corner on that seven-foot print. This loss of sharpness in the corner nearly completely cleans up at f/5.6, and we'll look at f/8 further down and see that the effect is completely resolved once we've stopped down a bit. What about curvature: Here's the upper left corner: The branches you see are about in the focus plane, and they are sharp. The loss of sharpness that would correspond to the lower right corner is suffused into the bit of house that is quite out of focus. I don't see evidence of curvature here. And here's the lower left corner, which was generally sharp with the FA35 (which is known for curvature). The field looks acceptably flat at 28mm. While we are at 28mm, let's look at several apertures and see if we can determine the ideal aperture. Here's the center again at f/5.6: f/8: f/11: f/16: And f/22: There is no practical difference between f/4.5, 5.6, 8, and 11 in the center of the image and in the focus plane. F/16 starts to degrade slightly, though I may be imagining it, but not enough to keep me from using it even for a large print. F/22, though, would allow only a more subdued print size. But insufficient depth of field trumps diffraction. Before moving away from 28mm, here's the lower right corner at f/8: At f/8, it's sharp right to the corner. 35mm I'll spend less time at longer focal lengths now that we know the basic behavior of the lens. Questions for 35mm: Does it out-perform the FA35mm prime lens? Are the corners better than at 28? Here's the center at f/4.5: F/5.6: And at f/8: Here is the FA 35/3.5 at f/11: This makes me want to check that f/8 exposure, which is very slightly softer than the f/4.5 image. F/5.6 is the clear winner of all of these, but the 35 may be diffracting a touch at f/11. The 35mm prime is very good in the center, but it's not better than the zoom. It is a LOT cheaper, though. Here is the upper left corner at f/8: Again, no sign of field curvature. The branches and dead leaves are close to the focal plane. The wood at left is only five feet from the lens, and the background pines are three times as far as the focus plane. There is a touch of movement blur here--shutter speed was 1/13 second. The camera was, of course, mounted on a tripod, but that river birch tree will move in not much breeze. 45mm Center of the image at 1:1, F/4.5: Here's the 45-85 zoom at 45 and f/4.5: The 45-85 is stunningly good, especially at the short end. The 28-45 is a bit better. Here's the same comparison at f/8: Again, the 45-85 is outstanding, and the 28-45 is a bit better. Finally, a word about focus accuracy. This lens front-focused very slightly, and I set the focus adjustmentment for this one to -3. In conclusion, a good example of the 28-45 is an amazing performer. I tested the failed lens for details about shake reduction, but I did not test again here. I find that shake reduction is good for about a stop, but I did not use it in the above images that were made on a tripod using mirror pre-release. But these lenses are not bullet-proof. If you buy one pre-owned, test it. Rick "just about thawed out" Denney

Review of: SMC Pentax-A 645 80-160mm F4.5 by rdenney on Sat June 30, 2018 | Rating: 8 View more reviews 

Views: 44954
Reviews: 7
The 645 A 80-160 zoom lens has a reputation for being very good, particularly at the short end of the zoom range. Given no change in optical design between the A version and the FA version, and the probability that this would be a secondary lens to primes, I opted for the A version. And it was cheap at $75 on ebay. Like the 45-85, reasonable sharpness from this lens is available, but only by f/8. I would not, however, heitate to use this lens if I needed flexibility in this range and could bring only one lens. It might limit print size a bit, though. As with the 45-85, I looked at three focal lengths: 80, 120, and 160. I only show the performance wide open and at f/8, but I explore a couple of other aspects, too. And I'll compare it to primes. 80mm Here's the full image at 80mm: And the 1:1 center crop, at f/4.5: This is pretty soft. The bokeh is decent, but at f/4.5, it's hard to really paint the background with a wide, smooth brush. Let's compare it to the 75 leaf shutter lens at f/5.6: At maximum aperture for the zoom, the prime wins handily. What about the 45-85 at 85, wide open? Here it is: So, the 80-160 is better wide open on the short end than is the 45-85 wide open at the long end. Buf if you want a wide aperture, use a prime. As with the shorter zoom, the 80-160 sharpens up very well at f/8: It's still not as good as primes, or as the FA 45-85 at f/8, but this is a snip from the middle of what would be a seven-foot print at the usual monitor resolution of 100 pixels/inch. This is quite usable. 120mm Full image at f/8: 1:1 center crop at f/4.5: Not too sharp. But let's look at it at f/8: At 120mm, it's still getting sharper at f/8, but let's compare it to the 645 A 120 Macro, at f/8: Again, the prime is better. 160mm Full image at f/8: 1:1 Center crop at f/4.5: A little soft, but no worse than at shorter focal lengths. In fact, I think it's rather better than the short focal lengths. So much for the conventional wisdom. 1:1 center crop at f/8: As with 120mm, it takes until f/8 to get all the way sharp, and that's the only weakness at the long end that I can see. Wide open, it has a soft-focus effect and reasonable bokeh, with a similar effect to the 165/2.8 Pentax 67 lens. So, how does it play at the edges, wide open? Here's the lower right corner at 1:1 and f/4.5, and 160mm. The grasses are near the focal plane, so a severe curvature would show them softer than they are. The field is pretty flat. I see some coma, where the safittal performance is perhaps not quite as good as the tangential performance. This would sharpen up pretty nicely with some unsharp masking. I don't see any lateral color, either, or longitudinal color, though the contrast might not be high enough here to reveal it. Now, let's explore a different application. Usually, lenses of this length are thought of as portrait lenses, where we will often use selective focus to bring attention to the subject. But let's say our real objective is a landscape, where we want everything sharp. We are often most afraid of diffraction, but this is an unreasonable fear. Diffraction takes the edge off the stuff right in the focus plane, but it adds sharpness to the foreground and background, and can therefore often make an image look sharper. Here's that center crop again at f/22: The center is fractionally less sharp than at f/8, but everything else in the photo is sharper. Nothing is ever fully sharp if it isn't in the focal plane, but make a big print (let alone a small print) of the above and those background leaves will seem sharp. Continuing the examination of f/22, let's look at the upper left corner, which shows foreground material, and the upper right corner, which reveals background material. Upper left corner at 1:1 and f/22: The leaves, which are close to the focal plane, are sharp. The bark isn't sharp at this magnification, but in a moderate print at normal viewing distance it will seem sharp enough, perhaps, and some judicious sharpening will also help. Here's the upper right corner, with pine trees in the distant background: Out of focus is out of focus, even at f/22, but this magnification is pretty unforgiving. Of couse 160mm is long--too long for f/22. But it illustrates the point that being out of focus is a LOT worse than diffraction. So, when people say a zoom is as sharp as a prime, well, no. In this focal range, I'll stick with primes, though this lens will serve if I have room for only one that has to cover this range. Rick "it probably looked pretty good on film for those who didn't own a microscope or an enlarger with a drop bed" Denney

Review of: SMC Pentax 645 LS 75mm F2.8 by rdenney on Thu June 28, 2018 | Rating: 9 View more reviews 

Views: 49940
Reviews: 2
The FA75 and the A75 attract considerable favorable comment as being sharp and a good value. These were the standard normals for the 645 film cameras, having a focal length about the diameter of the full 645 frame. They are slightly long on the 33x44 frame of the 645D and 645Z, making it a good short portrait lens for use with studio lights and outside fill flash. I bought this for the latter use case, as part of my 645NII wedding kit. The lens came from KEH over a dozen years ago, when I paid a little over $400 for it. On the NII, this lens automatically sets the camera to LS mode, which automatically sets the shutter speed to 1/8. When using the leaf shutter, one had to meter manually (or use an automatic strobe), because the lens does not tell the camera what shutter speed is being used. Likewise, there is no A setting on the aperture ring. When using the focal-plane shutter in the camera, the leaf shutter is cocked and set to "o" for "open", at which point the lens operates with full wide-open metering and can use aperture-priority automatic exposure. Because there is no A setting on the aperture ring, shutter-priority automation is not available. The camera will automatically set the mode to Av even if the mode dial is pointing to some other setting, being M being the only allowable alternative. But I found that the 645Z provides the same LS display, but for some reason does not set the 1/8 shutter speed. The focal-plane shutter duration has to be long enough so that the stop-down lever 1.) stops down the lens, 2.) triggers the leaf shutter cycle, which 3.) closes the leaf shutter right before the focal-plane shutter opens (and this is just a matter of designed timing--there is no mechanical interlock), then 4.) opens and closes the leaf shutter right after the focal-plane shutter opens (again, just a matter of timing--there is no interlock). The leaf shutter stays closed after the exposure, which is disconcerting for many but not for me. My experience with a range of SLR's of ancient design has taught me that instant-return mirrors are a modern luxury, not a human right. If the camera doesn't force the focal plane shutter to 1/8, it will often set the shutter speed automatically and that is usually too fast to ensure that the focal plane shutter is open when the leaf shutter fires. When that happens, one gets an image that looks like this: I don't know why the 645Z does not operate the leaf shutter lenses as it should. The NII does it correctly, and it seems to me the 645Z firmware could do the same. Even though the camera reports "LS", the selected shutter speed is out of range--the EXIF reports "1/infinity s". It's nuts, but there it is. As has been reported here before, one must tape over the contacts on the lens (of which there are only a few) to prevent any electronic communication between the lens and the camera. Then, one must put the camera in M mode, and set the shutter speed to 1/8 second, at which point the leaf shutter will work as intended. To take a meter reading when using the leaf shutter, here's the process:
  1. Cock the shutter.
  2. Set the leaf shutter to "o", which opens the shutter for viewing.
  3. Set the focal plane shutter to the desired speed (which will be 60, 125, 250, or 500--the speeds provided by the leaf shutter).
  4. Adjust the ISO and aperture to center the metering display.
  5. Set the leaf shutter to the desired speed.
  6. Set the focal plane shutter in the camera to 1/8.
  7. The idea was that one would not need to do this often, because one would only use the leaf shutter with flash, and the exposure would be dictated by the flash and not the meter. But when using fill flash, which is the primary use case, one must meter AND set the flash. I usually set the flash to expose a stop less than the ambient light (with an automatic flash, I set the ISO on the flash to twice that of the sensor, which will give it one stop less exposure), and then set the camera to ambient light. This requires metering the scene. Of course, one can also use an external meter. So, in practice, the leaf shutter is cumbersome to use. But it's not any worse than it used to be with most commercial cameras--my Mamiya C3 didn't have a meter at all, let alone a fully coupled one, and the leaf shutter was the only option with that camera. But the lens is fully usable with the focal plane shutter in the camera, with aperture-priority automatic exposure. This is not a spray-and-pray lens, but it works conveniently enough to serve as one's only 75mm prime, for those who have occasional use for synching a flash at speeds higher than 1/125. Note that the 645Z focal-plane shutter syncs with flash up to 1/125, so really only 1/250 and 1/500 leaf shutter speeds provide any real utility. The flash we are talking about is NOT a Pentax P-TTL speedlight like the AF-540FGz. The flash sync interface is through a PC connector on the side of the lens, not through the hot shoe. This lens works best with an old-fashioned automatic flash like a Vivitar 283 mounted on a bracket that doesn't touch the hot-shoe contacts, or with studio strobes. For set shots (such as outdoor portraits), I would often set up studio lights at the site (I still have that Speedotron 1600ws Brown Line power head with two mains and two fills). The flash power would be set to be compatible with ambient lighting. For those who never imagine themselves using the leaf shutter, get the A or FA 75mm lenses for the sake of convenience. It's a little like the old joke about the talking dog. A dog trainer comes to a talent agent, and says, "Book me at a circus, I have a talking dog." The talent agent says, "Okay, Fido, tell me what's over our heads." The dog says "woof!" The talent agent angrily kicks them out, and once outside, the dog looks at the trainer and says, "what was wong with that?" The trick is not that the dog speaks well, but that the dog speaks at all. The trick with this lens is not that the leaf shutter is easy to use, but that it's there at all on a camera fully optimized for a focal-plane shutter. So, are optics worth all this palaver? Pretty much. In short, the optics are quite good, even by normal-prime standards. Here's the full image, at f/11, using the 75mm LS: Here's a 1:1 crop of the center at f/2.8: It's sharp enough, but there's a bit of flare that reduces contrast and gives everything a bit of a glow. This is not a bug, but a feature. For a lens that is 1.3 times normal, and thus can serve as a short portrait lens (a useful use case for high-speed flash sync anyway), one wants a bit of softness at maximum aperture. Remember also that the 1:1 clip, when viewed at the 100 pixels/inch of typical monitors, is part of an image seven feet wide. The above is not bad. For comparison, here's the DFA 55 at 2.8: The 55 is a lens for making things sharp, not for making things soft, and it really doesn't do soft very well. The 75 can do both. By f/5.6, though, it's as sharp as anyone would want. Here's a 1:1 clip at f/5.6: Again, it's not as contrasty as the 55, but it's still quite sharp. Here it is at f/11: Which isn't really any sharper than f/5.6. And at f/22: Between f/5.6 and f/22, all that gets sharper is the out-of-focus foreground and background. Again, here's a comparison with the 55 at f/11: Differences are subtle, if we can barely see them at these magnifications. So, center performance is excellent by f/5.6, but how does it do in the corners? Upper right corner. 1:1 at f/2.8: The leaves that are mostly in focus are also in the focus plane, being about the same distance from the camera as the lamp. No lateral color, not longitudinal chromatic aberration, no appreciable field curvature. So, how does it compare with the 45-85 zoom, one lens that might keep me from needing this one on many occasions? Here's the 45-85 at 65, in the center at a good aperture: Hmmm. The 75 is good, but the zoom is just as sharp, and far more convenient. it's just not as fast. This one's on the bubble for an essential lens on a trip focusing on landscape photography, but for a gig that needs a lens that can do portraits that won't require a touch of softening in post, this one will do very well. Rick "special-purpose lenses often get left behind even when they are good" Denney

Review of: SMC Pentax-A 645 120mm F4 Macro by rdenney on Tue June 12, 2018 | Rating: 10 View more reviews 

Views: 84089
Reviews: 17
I can't even believe this lens only cost me $139, on ebay. I've read it's not quite as good as the 90, and that it's not as good at distance. I don't have the 90 to compare it to, but my test was at distance, so at least I can explore that. There is already an excellent review of the autofocus FA version of this lens here, which praised it highly, so I won't attempt to test it in the macro range. But I wanted to know how it would do as a general-purpose lens. Here's my test scene at f/11: Even this image, most of which depends on the depth of field, looks sharp. The bark of the River Birch at left is quite sharp, and the background is reasonably sharp. This lens can definitely make a 16x20 that never undermines the illusion of endless detail. I had so much trouble trying to decide what the optimal aperture was, that I decided to show all of them. I'm only showing center crops, simply because I could tell the difference between the centers and the corners. Okay, I'll show one corner. Here's the lower right corner at f/11 and 1:1: There is some motion--this was a 1/3-second exposure. But the image is sharp. Remember, 1:1 at 100 pixels/inch of most monitors is part of a print seven feet wide. So, back to the center. Here's the center of the frame at 1:1, shot at f/4: Not too shabby, for sure. Sharper than the A* 300. The bokeh isn't much to write home about, though, so I'm not thinking this is a superlative portrait lens. At wide apertures, you'll be adding gaussian blur to the image to make it tolerable for a portrait of a sitter who will actually expect the image to be flattering, but even at wide apertures, the background will be distracting. But that's not what this lens is for. Here it is at f/5.6: In the focus plane, I'm not absolutely sure I can tell these apart. And at f/8: F/5.6 actually looks a bit better than f/8. Huh? F/11: Worse still. F/16: F/22: It's bee a long time since I looked at an SLR lens that was actually at its best wide open. In fact, I'm not sure I ever have. This may be the first truly diffraction-limited medium-format lens I've ever handled. With this lens, you use the widest aperture that provides the necessary depth of field. Let's look at that lower right corner again. Here's f/11 again: And here's the same corner at f/4: Yup, even the corner is sharpest wide open, as long as it's in focus. Simply amazing. Even the superb 55/2.8 got sharpened up enough down to f/11 to overcome diffraction. Oh, you can bet this one's going to Alaska. This will be one of my most used lenses. Now, I have to wonder if this lens with the 1.4 converter will be sharper than the 200/4, which, stopped down a bit, is no slouch. I'm going to have to adapt this lens to my Canon and put it up against my 70-200f/4L (which I think it will beat) and the 50mm Compact Macro, which is one of the sharpest lenses in the Canon line. Rick "this one's dangerously sharp" Denney

Review of: SMC Pentax-FA 645 45-85mm F4.5 by rdenney on Mon June 4, 2018 | Rating: 9 View more reviews 

Views: 79042
Reviews: 17
In short, this lens is simply stunning at f/8. My first project with this lens was a group photo at a motorhome rally. I knew this lens was sharp because I've owned it for 15 years--it's the lens I bought with my 645NII kit to use for weddings. The group photo included about 60 people standing in front of a row of classic GMC motorhomes, and the image was sharp enough to resolve the small print on in the nametags they were wearing. The 12x16" print I made for the host of the event is tack sharp, even when viewed through a loupe. I'm picky--this one is sharp, when it's stopped down. But wide open at the long end, it's nearly a soft-focus lens. In fact, it's rather perfect for portraits on the long end--one can dial in the sharpness needed. I've never had any issue using this lens--the focus and zoom controls are where my fingers expect them to be and I never find myself fighting the lens. I looked at three different focal lengths, because the lens has a reputation for not being quite as good at the long end. I'll just show the center crops at each focal length, wide open and at f/8. For the wide end, I showed a couple of corner shots, too. 45mm Here's the full image at 45mm: And the 1:1 center crop, at f/4.5: This is sharp enough, but it does improve at f/8 (essentially, I can't tell much difference between f/5.6 and f/16, except in depth of field): Here's the upper corner at 1:1 and f/8: Nope, no chromatic aberration. DXO Photolab has this lens in its database, but there's no lateral color at f/8 even without those corrections. Also, the leaves that are sharp are at the focus plane, near enough, so there's not much field curvature. Here's the lower corner, which is about half the distance to the focal plane: Depth of field is decent at f/8 and 45mm. Remember, these are 1:1 crops--parts of images that would be 7 feet wide at the 100 pixels/inch of most monitors. 65mm Full image at f/8: 1:1 center crop at f/4.5: Okay, this needs a smaller aperture. 1:1 center crop at f/8: At 65mm, it's still getting sharper at f/8, but by then it's as sharp as you could want. 85mm Full image at f/8: This lens really is soft at wide apertures and 85mm, so let's look at three apertures and watch it sharpen up by f/8: 1:1 Center crop at f/4.5: 1:1 center crop at f/5.6: 1:1 center crop at f/8: As with 65mm, it takes until f/8 to get all the way sharp, and that's the only weakness at the long end that I can see. Wide open, it's actually sort-of dreamy, with a soft-focus effect and very smooth bokeh. This would be a good portrait lens at the 85 end, though to be honest I've never used it at wider apertures. It has a similar effect to the 165/2.8 Pentax 67 lens. Just for grins, here's a reminder of the 55/2.8 at 2.8: So, when people say a zoom is as sharp as a prime, well, no. But it can be as sharp as a prime when used with care. Rick "Stop. It. Down." Denney

Review of: Rear Converter-A 645 1.4X by rdenney on Tue May 22, 2018 | Rating: 9 View more reviews 

Views: 23890
Reviews: 5
The real question is: Should one use a teleconverter, or merely crop the photo from the shorter lens? Here is a 1:1 center crop from an image made with a 645 A* 300/4, at f/11: And here is a crop from an image made with the 1.4 converter, downsampled to the same resolution as the image above: No question: Downsampling the longer lens combination is not better than using the shorter lens. But considering these crops (at least the first one) is part of a 7-foot-wide print viewed at 100 pixels/inch, they are both really good. I'd use the 1.4 when I needed all fifty million of my pixels, but otherwise the A* 300 just has nowhere to go but down. It didn't go very far down here, but the converter still degraded the image more than enlargment. Another question is whether a shorter lens plus a converter is better than carrying both the shorter and the longer lens. Here is a 1:1 crop made using the 400/5.6 ED(IF), at f/11: And here is a crop at 1:1 (without downsampling) from the 300+1.4 at f/11: Not much difference here, but I would say that the 400 looks a bit better. Clearly, the A* 300 is a (slightly) better lens, but the 400 is worth bringing if one needs to optimize for that focal length. So, the advice is: If you use the 1.4, start with a great lens. Stop it down a bit, and then don't worry about it. The converter has visible effects at high magnification, but it is still a very capable teleconverter. Rick "always room for a converter" Denney

Review of: SMC Pentax-FA 645 400mm F5.6 ED [IF] by rdenney on Mon May 21, 2018 | Rating: 9 View more reviews 

Views: 42096
Reviews: 8
Reasonably sharp even wide open. I will not hesitate to use this lens wide open, unless I need more depth of field. Bokeh shows some bright-line effect with busy backgrounds; not the best. Also not what this lens is for--I use it when trying to make distant things sharp, not when trying to make them smooth. Work just as well with the 1.4 converter. Mirror vibration is a factor with this lens. Even on a sturdy Gitzo tripod, I needed mirror lockup to avoid a vertical shake of the image. I saw the slightest bit of purple fringing around high-contrast highlights, but really it's too small to really notice. Full scene at f/5.6 1:1 at f/5.6, not much loss compared to f/11 1:1 at f/11 Rick "solid performer" Denney

Review of: SMC Pentax-FA 645 35mm F3.5 AL [IF] by rdenney on Tue May 15, 2018 | Rating: 10 View more reviews 

Views: 45536
Reviews: 6
An excellent wide on the 645z. My testing views the raw file as corrected by DXO Photolab, but this lens is not in the database (unlike the D version). I see very slight lateral color in the corners wide open. It's gone by f/8. I also see a bit of softness in the corners at wide apertures, again gone by f/8. There may be a touch of curvature, but I don't usually photograph flat things and a bit of curvature often works to my advantage. There isn't enough here to be worth bothering with. At f/8, this lens is sensor-limited. This lens is every bit as good on the 645z as the legendary 45mm wide-angle lens on the 6x7. I'm spoiled by large-format Super Angulons, and this lens compares favorably at f/11 and f/16 (and those Super Angulons don't reach optimal until f/22). Even at f/8, depth of field is quite good viewed at 1:1 on my display (which is a 60" image width). At 400%, sharp edges consume one pixel at most, maybe a hair more in the corners. I will have no hesitation to use this lens for critical work, though other aspects of technique are still important. To get the most from this lens, one needs a good tripod. Another way to say that is that this lens will reward meticulous technique. Rick "who would need smaller pixels than on the 645z to find many flaws with this lens" Denney

Review of: SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW by rdenney on Tue May 15, 2018 | Rating: 10 View more reviews 

Views: 63088
Reviews: 12
Exceptionally good lens. I test images based on the default raw processing settings of DXO Photolab, and this lens is in their database, so distortion and lateral color are automatically corrected. I tested this on a 645z. My test scene is not flat, so field curvature may work to my advantage, as in the real world. My testing is nowhere as rigorous as doing star tests at f/2.8 in the corners. But I would be happy to make a 16x20 print from an image made at f/2.8, and I would have confidence that it would retain my required sense of endless detail at any viewing distance. 1:1 on the screen matches the full image quality of many smaller format lenses. A 60"-wide print would reveal pixels to the close-up viewer, but not lens faults. I bought this lens primarily to have a weather-resistant lens for my new 645z, but this lens really delivers and I will look for opportunities to use it even when it is not raining. Mine is a bit knocked about, and I bought it used in "V" condition from Adorama. Focused details are sharp to the pixel at any aperture down to f/16, after which diffraction has its effects. Bokeh is typical for double-gauss lenses. But it doesn't matter--like a really good plasmat on a 4x5 camera, this lens will want you to make the image sharp. Edit: Here are some images: Test scene, full frame, at f/11. Lighting was very flat, and I've done nothing to make these images look better. 1:1 center crop, f/2.8: 1:1 center crop at f/11: In those crops, the only thing that improved was the depth of field. Rick "seeing large-format-worthy results from this lens" Denney

Review of: SMC Pentax-FA 645 200mm F4 [IF] by rdenney on Tue May 15, 2018 | Rating: 9 View more reviews 

Views: 48733
Reviews: 12
Summary: Great little lens. My reviews are based on the default actions of DXO Photolab. Tested using 645z. It's at its sharpest at f/8 and f/11. At 400%, edges require two pixels. The 55/2.8 AW is slightly better. The 160 end of the 80-160 A zoom is slightly less sharp. In my "does this look good at 1:1 on my calibrated monitor" test, the 200 passes handily. The application of this lens is limited only by sensor resolution. The focus plane is slightly softer at f/22 (diffraction), but much sharper either side of the focus plane because of increased depth of field. I have no fear of using f/22 when I need DOF. F/5.6 is just behind f/8 in sharpness. F/4 is more noticeably softer. No obvious CA, though my test won't make it obvious. Bokeh is fairly neutral--a bit of double-line patterns at some textures, but no bright edge on out-of-focus highlights. This is a competent long portrait lens, and f/4 will avoid microscopic inspection of skin pores. The lens is small and light for a medium-format 200/4--compare with the 200/4 for the Pentax 67, which is noticeably bigger and heavier. The supplied bayonet shade is excellent and secure, and will mount reversed. Edit: Some corroborating images. Full frame of test scene at f/4: 1:1 center crop at f/4: 1:1 center crop at f/5.6: 1:1 center crop at f/11: Rick "a steal at current prices" Denney

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