APS-C lenses and K-1 Crop mode 1:1

**jumbleview** · 04-04-2021, 05:51 PM

How APC-S dedicated lenses work on K-1 in crop mode 1:1. In particular I would like to know about DA35 macro limited, DA15 limited, DA 20-40. Are there strong vignetting?

Sandy Hancock · 04-04-2021, 06:15 PM - **2 Likes**

I have all the DA Limiteds. In casual use the 35 Macro Limited is fine at close focus even on the full 36x24 frame. I suspect the 15 will still vignette significantly, and the 20-40 is apparently OK on the whole.

I really should do some formal testing on this. Let me get back to you....

lytrytyr · 04-04-2021, 06:26 PM - **1 Like**

If you go to Ricoh's website

PENTAX K-1 Laboratory | PENTAX K-1 Special site | RICOH IMAGING

you will see lots of samples, full frame and cropped.

I like using the 35 Macro on FF, and even at infinity you don't have to crop down very far. The DA 20 - 40 is sort of OK above around 25 mm, but my $30 DA 18-50 RE does better, from around 30 to 50 mm.

lytrytyr · 04-04-2021, 06:29 PM

Originally posted by Sandy Hancock

I have all the DA Limiteds.

You finally changed your mind about the Zoom?

**jumbleview** · 04-04-2021, 07:09 PM

Originally posted by Sandy Hancock

I have all the DA Limiteds. In casual use the 35 Macro Limited is fine at close focus even on the full 36x24 frame. I suspect the 15 will still vignette significantly, and the 20-40 is apparently OK on the whole.

I really should do some formal testing on this. Let me get back to you....

I would appreciate specifically tests for crop mode 1:1. I do understand that some lens (specifically 15mm) vignettes on full frame. But given the fact that vignettes affects corners first maybe square mode is spared?

---------- Post added 04-04-21 at 07:13 PM ----------

Originally posted by lytrytyr

If you go to Ricoh's website

PENTAX K-1 Laboratory | PENTAX K-1 Special site | RICOH IMAGING

you will see lots of samples, full frame and cropped.

I like using the 35 Macro on FF, and even at infinity you don't have to crop down very far. The DA 20 - 40 is sort of OK above around 25 mm, but my $30 DA 18-50 RE does better, from around 30 to 50 mm.

Thanks, indeed link you gave me is informative in that respect.

Sandy Hancock · 04-04-2021, 07:59 PM

Originally posted by lytrytyr

You finally changed your mind about the Zoom?

After a faulty first offering, I bought a second copy of the zoom a couple of years ago, and it is a very nice lens. I don't love it though, like I do the primes.

DeadJohn · 04-04-2021, 09:31 PM - **2 Likes**

I only have the DA 15 of the 3 lenses you mentioned. Vignetting on the K-1 is severe enough that I never got so far as testing 1:1 mode. Here's a full frame test image you can crop to 1:1 on your own to see how bad it is.

Sandy Hancock · 04-04-2021, 11:56 PM

Yeah, this confirms my impression. The DA 15 Limited is a crop lens. Full stop.

But I'll still do the tests

**acoufap** · 04-05-2021, 12:32 AM - **1 Like**

Concerning DA15 this may be what you‘re looking for. Did the tests after getting the K-1.

A detailled description you can find on my website where I wrote a more comprehensive blog article. It‘s written in german language but the included images give a good impression what I‘m talking about.

Class A · 04-05-2021, 02:55 AM - **3 Likes**

Originally posted by jumbleview

How APC-S dedicated lenses work on K-1 in crop mode 1:1.

The good news is that given their APS-C image circle covers the long side of the image (~24mm) and a 1:1 FF crop does not require more than 24mm in neither the vertical (naturally) nor the horizontal (due to the crop) direction, a large proportion of the 1:1 crop will be fine. Indeed, edge performance will be as good as on APS-C.

The bad news is that the corners of such a 1:1 crop are further out (~34mm) than what the APS-C image circle has been designed for. So the corners of the 1:1 crop may be anything from unusable to completely fine, depending on the lens. It's the last 30% of the diagonals into the corners that one should check for when testing lenses; no need to check the edges outside the corners.

FWIW, vignetting is only one symptom one should look out for. Optical performance can become quite weak before vignetting becomes significant.

**jumbleview** · 04-05-2021, 07:09 AM - **1 Like**

Thanks everybody for response. I think I do understand now what to expect.

04-04-2021, 05:51 PM	#1
jumbleview Site Supporter Join Date: May 2012 Location: Concord, CA Posts: 1,068	APS-C lenses and K-1 Crop mode 1:1 How APC-S dedicated lenses work on K-1 in crop mode 1:1. In particular I would like to know about DA35 macro limited, DA15 limited, DA 20-40. Are there strong vignetting?

04-05-2021, 12:32 AM - 1 Like	#9
acoufap Site Supporter Join Date: Jan 2011 Location: Munich, Germany Photos: Gallery \| Albums Posts: 4,187	Concerning DA15 this may be what you‘re looking for. Did the tests after getting the K-1. A detailled description you can find on my website where I wrote a more comprehensive blog article. It‘s written in german language but the included images give a good impression what I‘m talking about. Last edited by acoufap; 04-05-2021 at 12:59 AM.

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04-04-2021, 06:15 PM - 2 Likes	#2
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	I have all the DA Limiteds. In casual use the 35 Macro Limited is fine at close focus even on the full 36x24 frame. I suspect the 15 will still vignette significantly, and the 20-40 is apparently OK on the whole. I really should do some formal testing on this. Let me get back to you....

04-04-2021, 06:26 PM - 1 Like	#3
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	If you go to Ricoh's website PENTAX K-1 Laboratory \| PENTAX K-1 Special site \| RICOH IMAGING you will see lots of samples, full frame and cropped. I like using the 35 Macro on FF, and even at infinity you don't have to crop down very far. The DA 20 - 40 is sort of OK above around 25 mm, but my $30 DA 18-50 RE does better, from around 30 to 50 mm.

04-04-2021, 06:29 PM	#4
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by Sandy Hancock I have all the DA Limiteds. You finally changed your mind about the Zoom?

04-04-2021, 07:09 PM	#5
jumbleview Site Supporter Join Date: May 2012 Location: Concord, CA Posts: 1,068 Original Poster	Originally posted by Sandy Hancock I have all the DA Limiteds. In casual use the 35 Macro Limited is fine at close focus even on the full 36x24 frame. I suspect the 15 will still vignette significantly, and the 20-40 is apparently OK on the whole. I really should do some formal testing on this. Let me get back to you.... I would appreciate specifically tests for crop mode 1:1. I do understand that some lens (specifically 15mm) vignettes on full frame. But given the fact that vignettes affects corners first maybe square mode is spared? ---------- Post added 04-04-21 at 07:13 PM ---------- Originally posted by lytrytyr If you go to Ricoh's website PENTAX K-1 Laboratory \| PENTAX K-1 Special site \| RICOH IMAGING you will see lots of samples, full frame and cropped. I like using the 35 Macro on FF, and even at infinity you don't have to crop down very far. The DA 20 - 40 is sort of OK above around 25 mm, but my $30 DA 18-50 RE does better, from around 30 to 50 mm. Thanks, indeed link you gave me is informative in that respect.

04-04-2021, 07:59 PM	#6
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	Originally posted by lytrytyr You finally changed your mind about the Zoom? After a faulty first offering, I bought a second copy of the zoom a couple of years ago, and it is a very nice lens. I don't love it though, like I do the primes.

04-04-2021, 09:31 PM - 2 Likes	#7
DeadJohn Pentaxian Join Date: Jan 2011 Location: New York Posts: 4,833	I only have the DA 15 of the 3 lenses you mentioned. Vignetting on the K-1 is severe enough that I never got so far as testing 1:1 mode. Here's a full frame test image you can crop to 1:1 on your own to see how bad it is.

04-04-2021, 11:56 PM	#8
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	Yeah, this confirms my impression. The DA 15 Limited is a crop lens. Full stop. But I'll still do the tests

04-05-2021, 02:55 AM - 3 Likes	#10
Class A Pentaxian Join Date: Aug 2008 Location: Wellington, New Zealand Posts: 11,251	Originally posted by jumbleview How APC-S dedicated lenses work on K-1 in crop mode 1:1. The good news is that given their APS-C image circle covers the long side of the image (~24mm) and a 1:1 FF crop does not require more than 24mm in neither the vertical (naturally) nor the horizontal (due to the crop) direction, a large proportion of the 1:1 crop will be fine. Indeed, edge performance will be as good as on APS-C. The bad news is that the corners of such a 1:1 crop are further out (~34mm) than what the APS-C image circle has been designed for. So the corners of the 1:1 crop may be anything from unusable to completely fine, depending on the lens. It's the last 30% of the diagonals into the corners that one should check for when testing lenses; no need to check the edges outside the corners. FWIW, vignetting is only one symptom one should look out for. Optical performance can become quite weak before vignetting becomes significant.

04-05-2021, 07:09 AM - 1 Like	#11
jumbleview Site Supporter Join Date: May 2012 Location: Concord, CA Posts: 1,068 Original Poster	Thanks everybody for response. I think I do understand now what to expect.