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05-07-2016, 01:45 PM - 1 Like   #1
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FF mode - DA15 - crop factors & crop sizes

One interesting thing is to optimize the usage of DA lenses within the FF image circle.

Just did some crop tests with DA15 in FF mode and get better results as expected:

1 : 1 - 4500 x 4500 px
5 : 4 - 4912 x 3930 px
4 : 3 - 4912 x 3684 px
16 : 9 - 5600 x 3150 px

Maybe this is interesting for you too.

I stored the settings as styles in Capture One Pro. Now I can simply select the crop-style I'd like to use for a DA15 image. The only thing to do is to move the crop frame on the full frame image to get a position without vignetting.

For the test shot I didn't use the build in hood but an external "Lego hood":

To get "in front" of the build in lens hood rim of DA15 I used an uv filter 49mm, then step-up 49-62mm - step-up 62-82mm - metal lens hood 82mm - 105mm - looks funny. I don't know if this is necessary but it works. It doesn't clip the DA15 image circle.

05-09-2016, 01:57 AM   #2
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any samples to share? Just hope Ricoh add these crop modes in coming firmware

BTW, full size image should be 7360 X 4912?
05-09-2016, 09:45 AM - 1 Like   #3
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QuoteOriginally posted by yipchunyu Quote
any samples to share? Just hope Ricoh add these crop modes in coming firmware

BTW, full size image should be 7360 X 4912?
I captured my lightbox in FF mode so you can recognize the image circle of the DA15. For this capture I set the distance to infinite and aperture f4. These settings show the smallest image circle for this lens. I also added 2 frames to each image. The red one shows the APSC-frame that measures 4800 x 3200 px. The green one shows the frame with specific ratio and dimensions in px.

I really put the dimensions to the limit. The price for this is some vignetting in the corners that widely can be eliminated in post processing. To get rid of this I also think about creating LCC-profiles for a set of apertures. So it may be possible to automate the process.

What you'll also see is that you can get a wider angle of view than on APSC cameras like K-3 - very nice.

For all crops I created a Capture One style. One klick on a crop style menu item and immediately I get the centered crop I wished - just perfect IMO.




FF 7360x4912 DA15 4500x4500px


FF 7360x4912 DA15 5x4 4912x3930px


FF 7360x4912 DA15 4x3 4912x3684px


FF 7360x4912 DA15 16x9 5600x3150px



FF 7360x4912 DA15 2x1 5600x2800px



05-09-2016, 12:14 PM - 4 Likes   #4
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Crop modes in action ...
  • capture: FF mode, HD DA15, iso1000, f11, 1/50, DNG
  • raw processing: Capture One Pro
  • no work on vignetting
  • scaled down to 600px width



FF 7360x4912 DA15 uncropped - 36,15 MP


FF 7360x4912 DA15 1:1 4500x4500px - 20,25 MP


FF 7360x4912 DA15 5:4 4912x3930px - 19,30 MP


FF 7360x4912 DA15 4:3 4912x3684px - 18,10 MP


FF 7360x4912 DA15 3:2 4800x3200 APSC-crop - 15,36 MP


FF 7360x4912 DA15 16:9 5600x3150px - 17,64 MP


FF 7360x4912 DA15 2:1 5600x2800px - 15,68 MP




Please let me know if these infos were kind of helpful for someone - thanks in advance!



Last edited by acoufap; 05-09-2016 at 12:48 PM. Reason: image references corrected, megapixel added
05-09-2016, 05:09 PM   #5
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Should we expected to see some images on your post?
05-09-2016, 05:41 PM   #6
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QuoteOriginally posted by yipchunyu Quote
Should we expected to see some images on your post?
I see images. They are located on pentaxforums.com server, so they should be globally visible.

The URL looks like this for the last flower image:
Code:
https://www.pentaxforums.com/forums/members/34716-acoufap/albums/9062-technic/picture99184.jpg
05-09-2016, 05:52 PM   #7
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Thx. Saw the images now
The image size will be smaller than the one from k3ii, right?

Last edited by yipchunyu; 05-10-2016 at 05:44 AM.
05-10-2018, 01:35 AM   #8
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QuoteOriginally posted by acoufap Quote
Crop modes in action ...
  • capture: FF mode, HD DA15, iso1000, f11, 1/50, DNG
  • raw processing: Capture One Pro
  • no work on vignetting
  • scaled down to 600px width



FF 7360x4912 DA15 uncropped - 36,15 MP


FF 7360x4912 DA15 1:1 4500x4500px - 20,25 MP


FF 7360x4912 DA15 5:4 4912x3930px - 19,30 MP


FF 7360x4912 DA15 4:3 4912x3684px - 18,10 MP


FF 7360x4912 DA15 3:2 4800x3200 APSC-crop - 15,36 MP


FF 7360x4912 DA15 16:9 5600x3150px - 17,64 MP


FF 7360x4912 DA15 2:1 5600x2800px - 15,68 MP




Please let me know if these infos were kind of helpful for someone - thanks in advance!
Many thanks acoufap - excellent information clearly explained with photos. My K1 is on the way and I have a DA 15 that I want to use. Your post certainly helps till I figure out a better wide angle alternative (other than the Pentax 15-35).

Thanks.
Arvind

05-10-2018, 01:44 AM   #9
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Although I love the DA15, it is already notorious for marginal image quality in the corners of the APS-C frame.

Even ignoring the vignetting, pushing its image circle yet further seems unlikely to improve that situation.
05-10-2018, 03:10 AM   #10
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QuoteOriginally posted by VAV Quote
Many thanks acoufap - excellent information clearly explained with photos. My K1 is on the way and I have a DA 15 that I want to use. Your post certainly helps till I figure out a better wide angle alternative (other than the Pentax 15-35).

Thanks.
Arvind
Thank you for your reply! When I get new equipment I always stress it's boundaries and I like to share results of my investigation.

In practice I used the DA15 sometimes in FF Square Mode - a kind of trade-off. With a little cropping it gave me some nice pictures that are not possible with an APSC camera/sensor. But I feel it's a little sad that you always have to crop - even in Square mode that I like very much. And of course what @Sandy Hancock says is right. The more you crop near to the image circle, even within the APSC area, the weaker areas you get. So it depends very much on the scenery where usage makes sense.

I'm looking for a little better alternative on FF. But my demand is not full FF compatibility. My demands: not shorter than 15mm, not too heavy, flexible, WR and price also has an impact on my decision but isn't the most important point.

DFA15-30 drops out for me - weight and cost are too extreme. DA12-24 is not WR and haptic/build is not good enough for a nearly 1000,- IMO. Irix 15 is an alternative, but a bit more flexibility would be nice. So I wait and see what the DA*11-18 will deliver. It has a 82mm filter thread. So my hope is that it will be full frame compatible at 18mm - should be sufficient for me. I guess it will be no problem to use it in K-1 Square mode where cropping shouldn't be necessary. Unfortunately there is no new FF compatible Pentax 18-35 or 20-40 in sight.
05-10-2018, 04:08 AM   #11
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QuoteOriginally posted by acoufap Quote
DFA15-30 drops out for me - weight and cost are too extreme.
The DFA15-30 really is very good. A set of Lee 150 filters can be made to fit just about any other lens. That saves quite a bit of money
05-10-2018, 04:35 AM   #12
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15-30 is good between 15 and 21mm or thereabouts. Better (as in pleasing image) results can be had by using Leitaxed 15mm Distagon and 21/2.8 ZK. Filter holders for bulbous front element lenses have all very nasty issues thanks to small particles on the filter glass being amplified by stopping down to shooting aperture. The filters are simply located too far from the front element surface. Zeiss lenses may feel costly but in the end you will end up with mental issues by using those large glass plates. With Zeiss option circular polarizer is all that is needed and Pentax takes care of the rest (multiexposure shooting for skipping the ND filter).
05-10-2018, 05:31 AM   #13
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Let me get this straight; you're suggesting I get two expensive manual focus Zeiss primes, pay to have them adapted to K-mount, and purchase circular filters which lack the functionality of the Lee system with respect to graduated ND's, rather than using a high quality, weather resistant, autofocus zoom?

Dream on.
05-10-2018, 05:39 AM   #14
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Yes. 15-30 costs here about 1700 euros. Put 1000€ on top of that for filter holder and proper filters. At that cost you get two used Zeiss lenses and with a bit of luck the other one is straight K-mount lens. Very simple and far more rewarding if photographs are what counts. Autofocus is the real gimmick on any lens and even more on wide angles.
05-10-2018, 06:05 AM   #15
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QuoteOriginally posted by MJKoski Quote
Autofocus is the real gimmick on any lens and even more on wide angles.
Wow. Obviously the last twenty years have been a complete waste of time. My bad.
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