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04-21-2016, 09:22 AM   #1
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Quality of APS-C lenses on K-1?

Question: I've been using the K-5 for years. I'm going to upgrade to the K-1.

If you use a non full-frame lens on a full frame camera, does it lose lots of quality in the picture you get (ultimately defeating the purpose of the full-frame camera)? Mainly asking just in regards to one of my lenses.

Thanks

04-21-2016, 09:41 AM   #2
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Depends on what you mean by 'quality'.

You have two different issues here:
1) The image circle. A designed for APS-C lens such as the 18-135 or the DA 15mm will not cover the full frame image circle so you only get an image in the center with lots of vignetting on the sides. Sort of looking through a paper tube. The lens can be used on the K-1 in "crop mode" and will work fine delivering an image sized about the same as your K-5. Or you can shoot in FF mode and crop off the dark edges. Some DA lenses seem to work just fine.

2) The actual image quality. There is no reason a designed for APS-C lens will do any better or worse (in general) on the K-1 than it did on the K-5. Except for the image circle issue as noted above the quality of the image should be relatively unchanged. It might actually look better depending on the lens.

More reading here: PENTAX K-1 Laboratory | PENTAX K-1 Special site | RICOH IMAGING

And here: https://www.pentaxforums.com/forums/54-pentax-lens-articles/31629-da-lenses-f...ts-thread.html
04-21-2016, 09:48 AM   #3
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QuoteOriginally posted by jatrax Quote
depends on what you mean by 'quality'.

You have two different issues here:
1) the image circle. A designed for aps-c lens such as the 18-135 or the da 15mm will not cover the full frame image circle so you only get an image in the center with lots of vignetting on the sides. Sort of looking through a paper tube. The lens can be used on the k-1 in "crop mode" and will work fine delivering an image sized about the same as your k-5. Or you can shoot in ff mode and crop off the dark edges. Some da lenses seem to work just fine.

2) the actual image quality. There is no reason a designed for aps-c lens will do any better or worse (in general) on the k-1 than it did on the k-5. Except for the image circle issue as noted above the quality of the image should be relatively unchanged. It might actually look better depending on the lens.

More reading here: pentax k-1 laboratory | pentax k-1 special site | ricoh imaging

and here: https://www.pentaxforums.com/forums/54-pentax-lens-articles/31629-da-lenses-f...ts-thread.html
thanks!!
04-21-2016, 01:09 PM   #4
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Welcome to the forum, put simply my understanding with APS-C lenses of FF... is you could end with one helluva vignette.

04-21-2016, 01:25 PM   #5
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Well, if you shoot in the crop mode, you do gain the much better SR which will give you the ability to shoot at a lower speed for still subjects and use a lower ISO setting. The ISO should also be better, so you do gain some positive benefits even with APS-C lenses.

This is my main interest......but having the FF advantage for other lenses and other styles of shooting, like portraits etc. is the added bonus. Basically you have a K5 and a FF in the same body. Add the pixel shift and other fine features and it makes it a great all around camera for most any type of shooter.

Regards!
04-21-2016, 01:33 PM   #6
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QuoteOriginally posted by Kerrowdown Quote
Welcome to the forum, put simply my understanding with APS-C lenses of FF... is you could end with one helluva vignette.
Unless, with the K-1, you set crop mode to auto or manually select such. Expectations at present is that crop mode will provide results essentially similar to the K-5, though at a little lower resolution (megapixels).

To the OP: Welcome to the Pentax Forums!


Steve
04-24-2016, 03:02 AM   #7
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QuoteOriginally posted by stevebrot Quote
Unless, with the K-1, you set crop mode to auto or manually select such
If that happens it will be pilot error on my part... what is this crop mode malarkey.
04-24-2016, 04:14 AM   #8
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QuoteOriginally posted by Kerrowdown Quote
If that happens it will be pilot error on my part... what is this crop mode malarkey.
Have a look at Jatrax's link and the test shots on the Pentax website, Kerrowdown. Plenty of DA lenses do not vignette badly or even visibly.

I just received a DA*55 this week and it's looking great on Full Frame.



04-24-2016, 07:55 AM   #9
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QuoteOriginally posted by clackers Quote
Plenty of DA lenses do not vignette badly or even visibly.
I'll take your word for that... I don't own anything other than FF lenses, hence my mentioning "pilot error" in a previous posting.
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