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05-19-2016, 04:02 AM   #1
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DA* 55mm 1.4 on K-1 good extreme corner sharpness?

Hi there, by any chance someone tested the DA* 55mm 1.4 on the K-1 in FF mode and can comment on the sharpness of the extreme corners?

I am in need of an WR lens for the K-1 and considering the 28-105 and the DA* 55mm, the 24-70mm is out of my budget.
I tried both in a store, but it was hard to inspect the extreme corner sharpness there. What I found was that the DA* 55mm seems to be sharper in general, the question is if this holds also true for the corners / extreme corners.

I also learned to be careful with wide apertures at the DA* 55mm, with the wrong background the bokeh can get reall ugly. Stopping down helps here though, so I guess it is a learning curve one needs to master.
At the moment I am leaning towards the DA* 55mm because of center sharpness and much better bokeh balls. Also I am a little wary on "WR" zoom lenses, since my 3 year old 18-55mm WR lens got fungus behind the front element.

Can anybody already comment on the border to border sharpness of the DA* 55mm on the K-1 in FF mode?
Some samples would be great.

05-19-2016, 04:09 AM - 1 Like   #2
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A quick check on the forum and found this thread. Hope it is useful.


https://www.pentaxforums.com/forums/169-pentax-full-frame/319864-any-test-sho...105-a.html#top
05-19-2016, 04:14 AM   #3
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QuoteOriginally posted by Snakeisthestuff Quote
extreme corners.
what is an extreme corner???
05-19-2016, 05:27 AM   #4
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QuoteOriginally posted by pjv Quote
A quick check on the forum and found this thread. Hope it is useful.


https://www.pentaxforums.com/forums/169-pentax-full-frame/319864-any-test-sho...105-a.html#top
Thanks but the few samples linked there do not show the corner performance of the lens.

05-19-2016, 07:29 AM   #5
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Shoot loose, crop later, and your corners will always be sharp. That's one of the advantage of owning a 36MP camera.
05-19-2016, 07:40 AM - 1 Like   #6
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Extreme corners at infinity are smeared and stay smeared even if you stop to f8. At f11 it almost catches up with fa50 1.4 but is still worse. The rest of the frame has actually very good sharpness.
There might be significant copy variation as I guess these were only tested on APS-C before leaving the factory.

Last edited by npc; 05-19-2016 at 08:20 AM.
05-19-2016, 08:22 AM - 1 Like   #7
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Here are the corners at 100% of DA* 55 1.4 vs FA 50 1.4 at f8 (just a quick handheld snapshots):

On a side note I've noticed K-1 would randomly pick higher iso than really necessary if you leave that to auto as you can see on these two, but there's no real difference in noise between iso 100 and 200 ...
Attached Images
 

Last edited by npc; 05-19-2016 at 08:28 AM.
05-19-2016, 09:08 AM - 1 Like   #8
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I have a couple of DA *55 shots at f1.4 on my Flickr account.

This is one, uncropped.



It is really going to be tough to evaluate extreme corners on this lens at f1.4, because odds are they aren't going to be in focus. I guess you could shoot a brick wall, but i don't usually do that. To me, corners are OK, but dark and require some adjustment with vignette control to fix (but they are fixable).

05-19-2016, 05:14 PM   #9
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Big thanks @npc and @Rondec, that clears things up. Looks like the performance of my DA 35mm ltd. Macro without the heavy vignetting.

Thats probably the reason why they did not state this lens as FF compatible. So looks like the D FA 28-105 should be better for corner to corner sharpness then.
05-19-2016, 05:41 PM   #10
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I love it on the K-1, Snakeisthestuff. F2 is the sweetspot.

For corner to corner, the D FA 50mm f2.8 Macro is great, but it's certainly not WR, and doesn't have the DA*55's nine rounded blades.
05-19-2016, 07:15 PM   #11
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QuoteOriginally posted by clackers Quote
I love it on the K-1, Snakeisthestuff. F2 is the sweetspot.

For corner to corner, the D FA 50mm f2.8 Macro is great, but it's certainly not WR, and doesn't have the DA*55's nine rounded blades.
Oh man I was almost convinced to buy the 28-105mm xD.
The 55mm is also about 20% cheaper here... hard decision.

The samples of the 28-105mm I saw so far are also not that good in the borders often, seams like it has a curved field curvature or something...
05-19-2016, 07:27 PM   #12
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QuoteOriginally posted by Snakeisthestuff Quote
Oh man I was almost convinced to buy the 28-105mm xD.
The 55mm is also about 20% cheaper here... hard decision.

The samples of the 28-105mm I saw so far are also not that good in the borders often, seams like it has a curved field curvature or something...
I agree with Clackers. At f2 it is really nice and the corners are a lot better there.
05-19-2016, 07:48 PM   #13
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QuoteOriginally posted by Rondec Quote
I agree with Clackers. At f2 it is really nice and the corners are a lot better there.
The comparison shots posted above were taken at f/8. Are you saying the lens would sharpen up in the corners at f/2 rather than f/8...?
05-19-2016, 07:54 PM   #14
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QuoteOriginally posted by kp0c Quote
The comparison shots posted above were taken at f/8. Are you saying the lens would sharpen up in the corners at f/2 rather than f/8...?
I am pretty sure Rondec is referring to his post, so compared to F/1.4
05-20-2016, 03:04 AM   #15
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QuoteOriginally posted by kp0c Quote
The comparison shots posted above were taken at f/8. Are you saying the lens would sharpen up in the corners at f/2 rather than f/8...?
I was talking mainly about vignetting. I'll try to upload a shot or two from my copy and they are pretty decent. As I said before, the problem at wide apertures is that it is hard to have the corners in focus due to depth of field issues. I guess the only way to know for sure when they sharpen up is to shoot a wall of some kind. I just haven't done that.
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