FAQ FAQ  Forum Search   Events   Register Register  Login Login

Apple versus prune

Author
windhorse View Drop Down
Senior Member
Senior Member

Joined: 11 February 2013
Country: Australia
Location: Denmark
Status: Offline
Posts: 358
Post Options Post Options   Quote windhorse Quote  Post ReplyReply Direct Link To This Post Topic: Apple versus prune
    Posted: 20 August 2021 at 17:15
I used to be a sharp-shooter like Clint Eastwood but nowadays have more in common with Borges and Galileo, so would like to ask about the difference in terms of lens performance you see between these two images taken with the same Sony A7RII body but different other mount lenses.

The first photo 690 is made with my trusty 50mm Zeiss Planar 1,4 50/ZE lens via a Metabones adapter. To me it looks as it should.

690

https://pasteboard.co/KgMmStR.jpg

692

https://pasteboard.co/KgVDN2p.jpg


The second photo 692 is made with an old Pentax-M 2,8 40mm lens via a Fotga PK-NEX adapter on the same camera. To me it looks like crap, which is not particularly surprising ie this is also what you expect when comparing the smoothness of the ride in a Rolls Royce with a Toyota Corolla, right?

However apart from this the Pentax-M image seems to be wonky?

What is confusing me is what is causing the difference that I see not only comparing these two photos but other similar ones from the same trip, on which I took both lenses, primarily because of laziness ie the Pentax lens weighs about half the weight of the venerable Zeiss.

Based on experience my guess is the most likely cause of the problem is not the difference in lenses but more likely due to operator error (ie me!). But before leaping to this conclusion, I would appreciate your opinion about any possible technical issues related to lens performance, adapter alignment or any other error that you can detect?

Edited by windhorse - 21 August 2021 at 16:14
 



Back to Top
addy landzaat View Drop Down
Senior Member
Senior Member

Joined: 22 April 2006
Country: Netherlands
Location: Netherlands
Status: Offline
Posts: 12963
Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 20 August 2021 at 17:37
Some observations:
The Zeiss one is very contrasty, maybe slightly to dark. The Pentax is less contrasty and looks better in that respect.

Looking at the details, the Zeiss is much, much better. At first I thought you miss focussed the Pentax, but I could not find the plane of focus - so, the Pentax is soft it seems. Looking at the Pentax forums reviews it is not that good of a lens - a compromise lens that shows its age. Newer versions, like the AF ones, supposedly are better.

Bottom line: it is not a great lens and you might even have a slightly worse sample.

If you like it, you might consider the Canon EF 40/2.8 or any of the newer copies of the Pentax.
Why not follow me on Instagram? @Addy_101
Back to Top
windhorse View Drop Down
Senior Member
Senior Member

Joined: 11 February 2013
Country: Australia
Location: Denmark
Status: Offline
Posts: 358
Post Options Post Options   Quote windhorse Quote  Post ReplyReply Direct Link To This Post Posted: 20 August 2021 at 18:02
Thanks Addy for this very useful reply.

I am happy you seem to also see what I suspect I am seeing but was not confident enough to conclude by myself ie the Pentax appears to be not just soft but seems to be completely mushy when compared to the Zeiss.

If so, I am surprised that the difference is so great and wonder if this is primarily attributable to the quality of the lens, or mostly to do with the life it has lead before it had the bad luck to fall in my hands and be put to work rather than being left alone to enjoy a well-deserved retirement.
Back to Top
pegelli View Drop Down
Admin Group
Admin Group
Dyxum Administrator

Joined: 02 June 2007
Country: Belgium
Location: Schilde
Status: Online
Posts: 33766
Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 20 August 2021 at 20:32
I agree with Addy's observations but have one question two comments:

Q: What aperture were these two photo's taken at?


C1: Don't forget the 40 mm covers a wider angle so you're bound to lose a little on detail

C2: Try some "deconvolution sharpening" on the Pentax image (not USM sharpening) and I think it will shape up quite a bit, not to the Zeiss level but a lot better than it looks now. To me it has the same "fuzzy" impression as being taken with a very small aperture where you start seeing the effect of diffraction, which can also be partly corrected with that sharpening technique.


And a last obvious remark, nothing to do with the lenses but your sensor needs a good clean.
You can see the April Foolishness 2021 exhibition here Another great show of the talent we have on Dyxum
Back to Top
windhorse View Drop Down
Senior Member
Senior Member

Joined: 11 February 2013
Country: Australia
Location: Denmark
Status: Offline
Posts: 358
Post Options Post Options   Quote windhorse Quote  Post ReplyReply Direct Link To This Post Posted: 21 August 2021 at 13:23
Good question!

I will google "deconvolution sharpening" and hope it helps.

EXIF data for the first image 690 taken with the Zeiss ZE shows: 1/125 f16 @100 asa. I don't have EXIF data for the second image 692 since the Pentax lens was connected to the camera with a dumb adapter, but it was probably quite similar to the first image, as the light was bright, and I remember pushing up the aperture to get as much DOF as possible @ 100asa.

If I understand right the appearance of the spots from the dust on the sensor also indicates a high aperture (as well as the overdue need for cleaning).

I hadn't thought much about this before you asked, but dialling in such a high aperture may have further aggravated the already borderline performance of the Pentax lens, which, come to think of it, may not be so surprising since it was designed and produced long before the very demanding 42MP sensor in the A7RII?

Back to Top
windhorse View Drop Down
Senior Member
Senior Member

Joined: 11 February 2013
Country: Australia
Location: Denmark
Status: Offline
Posts: 358
Post Options Post Options   Quote windhorse Quote  Post ReplyReply Direct Link To This Post Posted: 21 August 2021 at 15:54
Meanwhile, back at the ranch, I found this useful tutorial by Greg Benz about deconvolution sharpening and am happily surprised by the results, which are easy to see at 100% and perceptible enough at 300 dpi print size to salvage images with the Pentax lens from the trash can, so thanks very much for this good suggestion!

Here is a copy of the deconvoluted image:

692 deconvoluted

https://pasteboard.co/KgVCtPL.jpg


Edited by windhorse - 21 August 2021 at 16:13
 



Back to Top
addy landzaat View Drop Down
Senior Member
Senior Member

Joined: 22 April 2006
Country: Netherlands
Location: Netherlands
Status: Offline
Posts: 12963
Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 21 August 2021 at 17:35
Could it be that you put the Pentax at the maximum aperture of f/22? That might be part. The second Pentax picture is a little better, but not much - it could benefit from a little contrast boost.
Why not follow me on Instagram? @Addy_101
Back to Top
windhorse View Drop Down
Senior Member
Senior Member

Joined: 11 February 2013
Country: Australia
Location: Denmark
Status: Offline
Posts: 358
Post Options Post Options   Quote windhorse Quote  Post ReplyReply Direct Link To This Post Posted: 21 August 2021 at 17:48
Yes, it could be the aperture was set to f22, but it was more than a month ago now, so am not sure.

I also agree with you about the contrast, as have not started to work on any of these files yet, apart from RAW conversion to B&W that is my current hobby horse, and deconvolution, that is their salvation.
Back to Top
Dyxum main page >  Forum Home > Equipment forums > Lens Talk > Other mount lenses

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.047 seconds.

Monitor calibration strip

Dyxum.com - Home of the alpha system photographer

In memory of Cameron Hill - brettania

Feel free to contact us if needed.