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05-31-2010, 07:54 PM   #31
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QuoteOriginally posted by JHD Quote
Looking at the Photo Zone tests, is there anything for Pentax that measures higher in center sharpness than the Sigma 30 1.4?
The Zeiss 18mm T* Distagon f3.5 is available in k-mount. Direct comparisons can't be made between the tests because the Sigma was tested on a K20d and the Zeiss 18 was tested on a full frame Canon. However, I suspect it would be even better on aps-c regarding the edges.





Edit: While we are at it, here is the Zeiss 21mm also on full frame EOS.



05-31-2010, 07:55 PM   #32
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QuoteOriginally posted by ManuH Quote
The FA 43mm Ltd comes so close that the sensor resolution is probably the limiting factor as this point. It would be nice if Photozone was updated for the K20D/K-7 sensors.
You guys are migrating to a 'Normal' field of view. The reason they stick with a 'bench mark' as long as possible, ie, the K10d is to not have to redo major tests. These are simple brick wall analyses they are doing. At some point I agree they need to start doing both for awhile.

Lets look at the Sigma compared to a Pentax ltd in the edges.



FA 31mm ltd



All the grafts in my posts have been from photozone.com

http://www.photozone.de/pentax/145-sigma-af-30mm-f14-ex-dc-pentax-k-review--test-report?start=1

http://www.photozone.de/pentax/122-pentax-smc-fa-31mm-f18-al-limited-review-...report?start=1

Last edited by Blue; 05-31-2010 at 08:07 PM.
05-31-2010, 08:11 PM   #33
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QuoteOriginally posted by Blue Quote
Lets look at the Sigma compared to a Pentax ltd in the edges.
Two questions...

How close to the edge is does one have to get before those numbers become meaningful?

How much more does the Zeiss 18mm T* Distagon f3.5 cost than the Sigma 30 1.4?
05-31-2010, 08:20 PM   #34
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QuoteOriginally posted by JHD Quote
Two questions...

How close to the edge is does one have to get before those numbers become meaningful?

How much more does the Zeiss 18mm T* Distagon f3.5 cost than the Sigma 30 1.4?
The price of the Sigma is in DA 15 & 21mm ltd range and isn't even close in ltd build quality. I don't pixel peep in the edges a lot. However, the 30 is too close to being a 'Normal' field of view on aps-c bodies. However, it one is on a budget and the ~ 30mm is acceptable, the FA 35mm is something to consider or even the F 28mm. However, when someone is looking in the teens and says they want the sharpest wide angle lens available for a Pentax, the Zeiss has to be mentioned. It costs as much at present as I have in my DA 21, DA 35 and FA 77mm. Granted I got the 1st 2 before the price jump.

Edit: My god, look at the center numbers for that T* 18mm.

05-31-2010, 08:58 PM   #35
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I have a DA15, but even if there was no difference in focal length, the Sigma is still 3 stops faster. You're right about the build quality though, the limiteds are top notch in that regard; however Sigma backs their lenses with a much longer warranty. That's another reason why I don't shy away from Sigma. I don't know why Pentax doesn't express more confidence in the quality of their lens with a longer warranty. I'd be less hesitant buy more Pentax glass if they did.

Last edited by JHD; 06-01-2010 at 12:53 AM.
06-01-2010, 07:11 AM   #36
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QuoteOriginally posted by JHD Quote
I don't know why Pentax doesn't express more confidence in the quality of their lens with a longer warranty. I'd be less hesitant buy more Pentax glass if they did.
I agree on this one. Given the price of the Limited and their build, they should offer 5 years instead of 1 (2 in Canada). This would be an even further differentiator between the Ltd and regular lenses.
06-01-2010, 07:54 AM   #37
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QuoteOriginally posted by ManuH Quote
I agree on this one. Given the price of the Limited and their build, they should offer 5 years instead of 1 (2 in Canada). This would be an even further differentiator between the Ltd and regular lenses.

If Sigma can put a 10 year warranty on 10~20, then Pentax should be able to offer a 20 year warranty on the Limiteds and 10 years on everything else..........well maybe with the exception of SDM lenses; no warranty on SDM products would be better for profitability.
06-01-2010, 09:33 AM   #38
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QuoteOriginally posted by JHD Quote
How close to the edge is does one have to get before those numbers become meaningful?
Photozone Lens Test FAQ

06-01-2010, 10:33 AM   #39
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You asked for it

QuoteOriginally posted by Alex00 Quote
Can you post an untouched image with branches ageist bright sky as you mentioned above.
Here are a few shots. There is some CA but I feel it's pretty manageable




This is the worst of the bunch, and even here I find the CA to be manageable.


Don't get me wrong, if you WANT to get CA you can, but even here, where it's pretty bad, it's confined to the bokeh areas



I still haven't figured out how to get smugmug to import exif so here are the originals:http://saltwater.smugmug.com/Photography/LBA-Pentax-DA-12-24mm-F40/4238697_i...48007305_YcCi5


The shots have been cropped and resized, but thats all the "tinkering" I did to them.

NaCl(you asked for it)H2O

Last edited by NaClH2O; 06-01-2010 at 10:37 AM. Reason: fixed link
06-01-2010, 11:06 AM   #40
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QuoteOriginally posted by Marc Sabatella Quote
First, "center" doesn't mean just the absolute dead center. It really covers most of the frame - everything but maybe the 10% along the borders.
That doesn't appear to be what Photozone is calling center sharpness. In their Imatest explanation, they show a pink circle in the center of the frame where sharpness is measured, and it is right in the center. Green circles the denote border measurement sites, and blue is extreme edge. Points in between center and edge could be roughly interpolated.



Photozone Lens Test FAQ

Last edited by audiobomber; 06-01-2010 at 11:12 AM.
06-01-2010, 11:52 AM   #41
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recommend FA 20mm f/2.8, FA*24mm f/2, A 15mm f/3.5
06-01-2010, 12:02 PM   #42
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QuoteOriginally posted by NaClH2O Quote
Here are a few shots. There is some CA but I feel it's pretty manageable




This is the worst of the bunch, and even here I find the CA to be manageable.


Don't get me wrong, if you WANT to get CA you can, but even here, where it's pretty bad, it's confined to the bokeh areas



I still haven't figured out how to get smugmug to import exif so here are the originals:LBA: Pentax DA 12-24mm F4.0 - saltwater's Photos


The shots have been cropped and resized, but thats all the "tinkering" I did to them.

NaCl(you asked for it)H2O
This is not an untouched image. Post a full size untouched image which hasn't been processed by any program. You can't see CA by looking at small images. The image you have does not show branches against bright sky.
06-01-2010, 05:31 PM   #43
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QuoteOriginally posted by Alex00 Quote
This is not an untouched image. Post a full size untouched image which hasn't been processed by any program. You can't see CA by looking at small images. The image you have does not show branches against bright sky.
I'm sorry you can't accept what I've got. The images I posted DO show branches against bright sky. If you want the full sized images check the smugmug link I posted. I'm sorry but I don't feel like catering to your whims.

NaCl(a little courtesy goes a long ways)H2O
06-01-2010, 06:23 PM   #44
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QuoteOriginally posted by audiobomber Quote
That doesn't appear to be what Photozone is calling center sharpness. In their Imatest explanation, they show a pink circle in the center of the frame where sharpness is measured, and it is right in the center. Green circles the denote border measurement sites, and blue is extreme edge. Points in between center and edge could be roughly interpolated.
Interpolation might seem to make sense, but it doesn't on any lens I own. Performance is normally pretty even until you reach green circles.

That's certainly the case with the DA15. And even the green circle areas look good if you manage to get them in focus when shooting wide open (easier said than done!) As do the extreme borders at 12:00, 3:00, 6:00, and 9:00. It's only the blue circle areas that do indeed still look noticeably softer in the incredibly rare cases where they happen to be in focus. But only when shooting larger apertures than anyone in their right mind would be shooting when trying to get sharp corners.
06-01-2010, 06:51 PM   #45
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QuoteOriginally posted by Blue Quote
Edit: My god, look at the center numbers for that T* 18mm.
That's on full frame, right? So not comparable to APS-C.
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