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07-24-2018, 02:29 AM   #16
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The DFA version has fixed the field curvature issues of the FA version, I tested it.

I think that MikeSF also tested this in his back yard and it was very good.

I would get either the A35 or the DFA35.

07-30-2018, 03:45 AM   #17
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Some people in a Chinese forum mentioned that for Pentax 645, DA is purely for digital, so the image circle is only covering the 44x33mm, while DFA is good for both digital and film, therefore, have larger image circle that can cover 60x45mm film size. Probably FA is for film and auto focus, then can have larger image circle to cover 60 x45mm film size too. So I hope someone can confirm if DA is having a smaller image circle compare to DFA.

In the Chinese forum, the post is discussing about using the Pentax 645 lenses for tilt and shift adjustment when using on the GFX camera which is also have 44x33mm sensor, as Kipon made a P645-GFX adapter with T&S.

Sorry, found the information on the 645 lens data base, that the 645 DA25 has a more protuded hood such that will have vignet on 60x45 film, but better for 44x33 digital sensor. Therefore, for those wish to do tile/shift, the DFA is better than DA.

Last edited by thomaskplee; 07-30-2018 at 04:12 AM.
07-30-2018, 07:11 AM   #18
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QuoteOriginally posted by 2351HD Quote
The DFA version has fixed the field curvature issues of the FA version, I tested it.

I think that MikeSF also tested this in his back yard and it was very good.

I would get either the A35 or the DFA35.
Can I have more details about this behavior?

Thank you
07-30-2018, 07:49 AM   #19
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QuoteOriginally posted by Andrea K Quote
Can I have more details about this behavior?

Thank you
I think you should look at Rick Denney's most recent tests (rdenney here), published in the forum and now in the database as well.

07-30-2018, 08:11 AM   #20
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QuoteOriginally posted by texandrews Quote
I think you should look at Rick Denney's most recent tests (rdenney here), published in the forum and now in the database as well.
Rick tested the FA not the DFA. I'm interest on a comparison about the field curvature and CA.
07-30-2018, 09:37 AM   #21
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QuoteOriginally posted by Andrea K Quote
Rick tested the FA not the DFA. I'm interest on a comparison about the field curvature and CA.
AFAIK, none is available. I pointed you to Rick's tests since you were querying 2351HD. 2351HD seems to have a DFA and says he has tests, but it's not clear he has tests of the FA---but Rick does and they are recent and published.

You'll have to compare 2 sets of tests---good luck with that in a test of this kind!
07-30-2018, 01:17 PM - 1 Like   #22
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I don’t have either of the FA or DFA lenses at the moment.

I purchased a DFA35 and tested it against my 28-45 and A35. The FA35 was known and proven to have field curvature for a long time.

The DFA35 has a very flat field from my simple tests and was very sharp. I am planning on selling my 28-45 and replacing it with the DFA35, when I get around to it. But I’m just not sure about the future of the Pentax 645 system at the moment, Ricoh give me no confidence that the system or lens line will continue.

As far as I’m concerned it’s a no-brainer, get the DFA. I would even get the A35 before the FA if cost was an issue, the A lens is superb.

---------- Post added 07-31-18 at 06:19 AM ----------

QuoteOriginally posted by Andrea K Quote
Rick tested the FA not the DFA. I'm interest on a comparison about the field curvature and CA.
Read this:

Comprehensive Testing: Results & Observations with Pentax 645 Lenses used on the 645D

08-17-2018, 11:57 AM - 1 Like   #23
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QuoteOriginally posted by 2351HD Quote
The DFA version has fixed the field curvature issues of the FA version, I tested it.

I think that MikeSF also tested this in his back yard and it was very good.

...
I had forgotten I did that, but after digging deep in the archive, lol, here is the thread:

Testing the D FA35/3.5 - PentaxForums.com

in summary, i found field curvature for DFA35 to be quite flat, less pronounced than my A35. (did not test FA35)
08-17-2018, 12:04 PM   #24
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QuoteOriginally posted by boriscleto Quote
I knew there was a reason I used to keep this forum on ignore...I've also read 5 books in the last 7 days, my brain is turning to goo...
’Browse New Posts’ frequently trips me up.

AFA 645, how much better are the FA/DFA versions than the classic A 645 35/3.5 I recently acquired in a batch of 645 lenses?

[edit] Answered in #22 above. The A is preferable to the FA.

Last edited by monochrome; 08-17-2018 at 12:10 PM.
08-18-2018, 08:21 AM - 1 Like   #25
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QuoteOriginally posted by monochrome Quote
’Browse New Posts’ frequently trips me up.

AFA 645, how much better are the FA/DFA versions than the classic A 645 35/3.5 I recently acquired in a batch of 645 lenses?

[edit] Answered in #22 above. The A is preferable to the FA.
It's hard to complain about the A35. One of the best A lenses on the 645D/Z IMO.
08-18-2018, 09:07 AM - 1 Like   #26
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Lens question: FA 35 vs. DFA 35

QuoteOriginally posted by mikeSF Quote
It's hard to complain about the A35. One of the best A lenses on the 645D/Z IMO.

I feel the same about the FA. The field curvature is usually no issue: 1.) It sharpens up the foreground, and it’s really hard to avoid foreground with a wide lens; and 2.) it brings attention to the subject, which is nearly always in the central third. And the FA is very sharp in the center at working apertures.

Rick “just back from Idaho, with a few new photos of EBR-1 and Craters of the Moon” Denney
08-19-2018, 12:54 PM   #27
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FWIW, here is my gallery of 35 pics:
Lens: 645 A 35mm f/3.5 | Flickr


and here are some DFA 35 pics:
Lens: 645 DFA 35mm f/3.5 | Flickr
08-19-2018, 01:17 PM - 1 Like   #28
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QuoteOriginally posted by mikeSF Quote
FWIW, here is my gallery of 35 pics:
Lens: 645 A 35mm f/3.5 | Flickr


and here are some DFA 35 pics:
Lens: 645 DFA 35mm f/3.5 | Flickr
Trouble is, Mike, that your skills are such that any deficiencies in the A vs. the DFA are masked and undetectable.....
08-22-2018, 04:47 AM - 1 Like   #29
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QuoteOriginally posted by mikeSF Quote
FWIW, here is my gallery of 35 pics:
Lens: 645 A 35mm f/3.5 | Flickr


and here are some DFA 35 pics:
Lens: 645 DFA 35mm f/3.5 | Flickr
Hi Mike

Very enjoyable viewing

Dave
09-10-2018, 10:27 AM - 1 Like   #30
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QuoteOriginally posted by mikeSF Quote
FWIW, here is my gallery of 35 pics:
Lens: 645 A 35mm f/3.5 | Flickr


and here are some DFA 35 pics:
Lens: 645 DFA 35mm f/3.5 | Flickr
WOW, astonish
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