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04-26-2010, 10:45 AM - 1 Like   #121
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QuoteOriginally posted by Marc Sabatella Quote
I think my DA15 is probably my sharpest lens overall, followed by my DA70. While I have the DA40 and M50/1.7 and see them getting a lot of votes, I don't think mine quite compare to the 15 or 70. But like most here, I've never really done any sort of controlled test - I'm going mostly by the results I get in typical use and how they tend to strike me. It's images from the the 15 and 70 that are most likely to take me aback.
I've been thinking about this and looking at more images, and I'm going to amend this a bit. What impresses me most about the DA70 is the sharpness it can get at relatively large apertures, and this feeling ends up being enhanced by the shallow DOF I get from those apertures at that focal length. I think that's the source of much of the "wow" I get from this lens.

But stopped down to f/5.6 or f/8, the DA40 really does do at least as well. Unfortunately, my images from the M50/1.7 don't report aperture, but I know I tended to use it mostly for low light, so very few of the images I have from it would be at f/8. My A50/1.7 does report aperture, but I haven't used it nearly as much because I got it around the same time as my DA40, which I definitely prefer overall (just for the focal length, and of course size, AF, etc), so it's hard for me to include the 50/1.7 in the comparison.

I've found it interesting to search for all portraits & candids done with these lenses, find examples shot in good enough light to give me fast shutter speeds at low ISO, with the face filling the frame in roughly the same way, then examine them at 100%. Obviously, I'm shooting from different distances with different lenses in order to do this, but I'm pretty sure that's how you'd want to compare sharpness: with a subject the same size in the frame (that's how resolution tests are done, isn't it?). It is of course difficult to judge corners using portraits, but it's the one subject where I can easily find at least some reasonably comparable images from each lens. One thing that surprised me is finding the M28/2.8 noticeable sharper at f/8 than either the M100/2.8 or M135/3.5. Maybe it shouldn't have - I guess it's normal for wider lenses to have better resolutions scores than telephoto lenses.

And in fact, the more I look the more I'm convinced the DA15 really is my sharpest lens overall. Again, it's tough to judge corners by looking at portraits, but at the center, the DA15 is pretty equally amazing anywhere in the f/4 to f/8 range. Photozone's MTF scores show it actually doing better in the center at f/4 than f/8, and I can't dispute that. And it supposedly peaks at f/5.6, which now makes me want to shoot that aperture more than I otherwise would.

But of course as most people know, the DA15 has a reputation for much softer borders until f/8. I still haven't done any real controlled testing to see how much of this perception is just field curvature & DOF issues (photozone acknowledges it is an issue in their own measurements). But one thing I have noticed is that when I do happen to get something at the edge of the frame in focus at f/4, sharpness is really much better in the *middles* of the borders (ie, the 12:00, 3:00, 6:00, and 9:00 positions) than some sample images would lead you to believe. It's actually only the extreme corners where it seems to require more stopping down to get the kind of results one might want.

Anyhow, just some random thoughts.

04-26-2010, 11:30 AM   #122
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Thanks Marc for your assessment above. As I indicated in my previous post, I wish my 15 was sharper (as well as the 21). But now I realize while reading your post that I have to revisit the issue for myself. I always found the 15 "quite soft" at any aperture (on both the K7 and K2) in the corners and edges, and "softer than expected" in the center. But I really have to do is to check for "overall subjective sharpness", which involves contrast caracteristics as well.
If you have a chance, please tell me what sort of subject you would use for this purpose. as you indicated, portrat would not give you a fair idea of edge sharpness.
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04-26-2010, 11:56 AM   #123
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This is going to sound crazy but I'd have to give the nod to my Pentax-K 55mm f2.0, a relatively inexpensive and underrated lens.

It's consistently sharper at f2 than my slew of other 50mm lenses which include:
A50 f1.4
A50 f2.0
M50 f1.4
M50 f1.7
M50 f2.0
SMC Takumar 50 f1.4 (sharpest 50mm lens in a well conducted test, second only to a stopped down A50 1.2)
Super Takumar 55mm f1.8
Super Takumar 55mm f2.0

I haven't pit it against my Vivitar S1 90mm f2.5 yet as that's on the DL, but I'm almost positive the 55mm is sharper. I'm curious as to the sharpness of the K55 1.8. I have no idea why this lens is the sharpest of the bunch although it could be because the K series is sharper than the M/A/takumars or because of its long focusing throw (270 degrees I believe) or that this is just an exceptionally good copy of the lens.

I have the Super Takumar 50mm f1.4 arriving in a few days so I'll put that lens through the paces.
04-26-2010, 01:06 PM   #124
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QuoteOriginally posted by hangu Quote
This is going to sound crazy but I'd have to give the nod to my Pentax-K 55mm f2.0, a relatively inexpensive and underrated lens.

It's consistently sharper at f2 than my slew of other 50mm lenses which include:
A50 f1.4
A50 f2.0
M50 f1.4
M50 f1.7
M50 f2.0
SMC Takumar 50 f1.4 (sharpest 50mm lens in a well conducted test, second only to a stopped down A50 1.2)
Super Takumar 55mm f1.8
Super Takumar 55mm f2.0

I haven't pit it against my Vivitar S1 90mm f2.5 yet as that's on the DL, but I'm almost positive the 55mm is sharper. I'm curious as to the sharpness of the K55 1.8. I have no idea why this lens is the sharpest of the bunch although it could be because the K series is sharper than the M/A/takumars or because of its long focusing throw (270 degrees I believe) or that this is just an exceptionally good copy of the lens.

I have the Super Takumar 50mm f1.4 arriving in a few days so I'll put that lens through the paces.
some people say that the 1.8 and f2 K's are the same, the only difference is only the 1/3 aperture speed, but this slight advantage in aperture works well with bokeh rendering. honestly, I prefer it's bokeh better than the 1.4 and 1.7.

as to why it maybe sharper is possibly due to a much longer and precise focus control adjustment and the SMC coating of the K as well.

I haven't tried my Vivitar S1 yet, so I cannot verify which one has more sharpness and has a much preferred bokeh.

04-26-2010, 01:28 PM   #125
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QuoteOriginally posted by Pentaxor Quote
some people say that the 1.8 and f2 K's are the same, the only difference is only the 1/3 aperture speed, but this slight advantage in aperture works well with bokeh rendering. honestly, I prefer it's bokeh better than the 1.4 and 1.7.

as to why it maybe sharper is possibly due to a much longer and precise focus control adjustment and the SMC coating of the K as well.

I haven't tried my Vivitar S1 yet, so I cannot verify which one has more sharpness and has a much preferred bokeh.

Now that I've thought about it a bit more, I don't think it's because of the SMC, as its main competitiors (SMC Takumar 1.4, SMC-A 1.4, SMC-M 1.4) all have SMC. Furthermore, tests were done in my room, which gets almost no sunlight.

I also don't think it's the long throw, as I have a big enough of a sample to tell that the sharpest f1.4/f1.7 photos I have are not as sharp as the 55mm f2.0.
04-26-2010, 01:53 PM   #126
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QuoteOriginally posted by hangu Quote
Now that I've thought about it a bit more, I don't think it's because of the SMC, as its main competitiors (SMC Takumar 1.4, SMC-A 1.4, SMC-M 1.4) all have SMC. Furthermore, tests were done in my room, which gets almost no sunlight.

I also don't think it's the long throw, as I have a big enough of a sample to tell that the sharpest f1.4/f1.7 photos I have are not as sharp as the 55mm f2.0.
Taks have SMC but don't mean they may contain the same type of coat. as far as long throw is concerned, this is in reference with macro lenses which have longer throws are considered sharper than the usual sharp primes. the minimal adjustment that can be made with a longer throw can spell the difference between a sharp and a sharper image.
04-26-2010, 02:38 PM   #127
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QuoteOriginally posted by Pentaxor Quote
Taks have SMC but don't mean they may contain the same type of coat. as far as long throw is concerned, this is in reference with macro lenses which have longer throws are considered sharper than the usual sharp primes. the minimal adjustment that can be made with a longer throw can spell the difference between a sharp and a sharper image.
So you're saying the K series have superior coating to even the later M and A series? Also, I might be wrong, but I don't think SMC plays that big of a role in sharpness indoors.

I've taken a large number of photos with my other 50mm's, especially the SMC A f1.4, I have a good idea of top sharpness with this lens. I've fiddled with it and tested it ad nauseum. I also rely on focus confirmation, which is really spot on for my K-x. There's no way the extra throw generates that much more sharpness.

I've only taken about 50-100 photos with the 55mm f2 and the sharpest photos are all sharper than my A50 f1.4.

I'm starting to think I either have an amazing copy or the K55 are all really that good. Can anyone else who owns a K55 chime in?
04-26-2010, 02:46 PM   #128
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Are you comparing F/2 shots vs. F/2 shots?

04-26-2010, 02:50 PM   #129
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Hah, of course. I also stop them down equally.
04-26-2010, 03:22 PM   #130
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QuoteOriginally posted by hangu Quote
There's no way the extra throw generates that much more sharpness.
I don't think this statement should be taken true entirely. this is how macro lenses got their bread and butter from. and macro lenses as you know, are the creme de la creme with regards to IQ sharpness at the tiniest level.


I don't think that you have an amazing copy since I haven't heard of anyone owning the lens to be saying that it is only a good lens, but rather it is a great lens (better than the 1.4 and 1.7, IMO basing from my use). you can check my review on it under the lens review section. I made a short comparison between it and the DA* 55/1.4 rendering.
04-26-2010, 03:27 PM   #131
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QuoteOriginally posted by Pentaxor Quote
some people say that the 1.8 and f2 K's are the same, the only difference is only the 1/3 aperture speed, but this slight advantage in aperture works well with bokeh rendering. honestly, I prefer it's bokeh better than the 1.4 and 1.7.
Anyone who says differently is welcome to their incorrect opinion.

The K55/2 might have superior bokeh wide open compared to the K55/1.8 set to exactly f2. I am too lazy at the moment to find out if my K55/1.8 has a click setting at exactly f2, so it might not be easy, but at that setting, the aperture opening is hexagonal. On the K55/2, it's round. I've had this comparison in mind to see if rounded aperture blades just sound good. Probably just a nice theory.
04-26-2010, 05:02 PM   #132
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QuoteOriginally posted by Just1MoreDave Quote
Anyone who says differently is welcome to their incorrect opinion.

The K55/2 might have superior bokeh wide open compared to the K55/1.8 set to exactly f2. I am too lazy at the moment to find out if my K55/1.8 has a click setting at exactly f2, so it might not be easy, but at that setting, the aperture opening is hexagonal. On the K55/2, it's round. I've had this comparison in mind to see if rounded aperture blades just sound good. Probably just a nice theory.
if OOF highlight shapes are concerned, then yes, the f2 would be better as far shape is concerned. bokeh blur of course, would be another thing.

as far as bokeh circles are concerned, I believe no one could rival the presets at all apertures. well maybe the circular blades a bit close around f5.6, but beyond that, the circular apertures begin to show their shortcomings.
04-27-2010, 03:32 AM   #133
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This is an intereting topic.
Is the "newspaper on the wall" a good test for comparing center to corner sharpness?
I'm thinking of tripod mounted camera as perpendicular as possible adjusting for a similar field of view as needed.
Would that be a good test?

Thanks,
04-27-2010, 08:05 AM   #134
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K55/1.8

Just got hold of this lens
I noticed it's mentioned quite a few times in this thread and so I took some pictures to decide for myself
Did it handheld in the morning at F1.8 and ISO 200. No PP, no nothing except resizing
I'm quite happy with the results
Really, it's tough trying to decide which is my sharpest lens. I love them all too much
I'll be posting more from it in the 'Post Your Photos!' section in just a minute
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04-27-2010, 09:55 AM   #135
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Sharpest lens......

Most likely the FA50 1.7 I got from VaughnA..........he probably wants it back. However the Sigma 10-20 has a degree of sharpness I really like as well.
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