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11-01-2014, 09:41 PM   #1
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645 Lens "A" vs "FA"

In the Pentax Lens Review Databaseit says that "A" lenses are manual focus (1980's) and "FA" lenses are autofocus (1990's)
Are there any difference between these 645 lens ("A" vs "FA") besides focus function?




11-01-2014, 09:45 PM   #2
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The barrels are different, and many FA lenses have different optical formulas compared to the A versions. All that info should be in the lens database for each individual lens

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11-01-2014, 10:32 PM   #3
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QuoteOriginally posted by Adam Quote
The barrels are different, and many FA lenses have different optical formulas compared to the A versions. All that info should be in the lens database for each individual lens
How about image quality between the versions? Infinity focus the same between them?
11-01-2014, 11:42 PM   #4
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QuoteOriginally posted by BBC5 Quote
How about image quality between the versions? Infinity focus the same between them?
The best place to look is the user reviews. But yeah, they can all focus to infinity of course.


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11-02-2014, 02:16 AM - 1 Like   #5
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As Adam says, best to look at each one you're interested in. Some of them are different optically between FA and A, others seem to be much the same (though the coatings might be updated on the FA). There just isn't a single answer for all A-FA comparisons.
11-02-2014, 10:09 AM   #6
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QuoteOriginally posted by Adam Quote
The best place to look is the user reviews. But yeah, they can all focus to infinity of course.
And if the lens doesn't focus to infinity, I must of got a bad copy of the lens...
11-02-2014, 12:06 PM   #7
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IMO, some of the best lenses of the 645 mount are the A-series (35 & 120). There are some differences here and there and hard to say that across the board, FA are better/worse.
I have a few of each as well as some 67 mount lenses for my 645D and overall very pleased with my kit.
11-02-2014, 05:56 PM   #8
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I also prefer the 35mm A to the 35mm FA. With the 120, I think they are optically identical (can't be sure coatings didn't change slightly, but can't see any difference whatever in performance); that it is to say both are world class!

11-02-2014, 05:58 PM   #9
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One example where the lenses are quite different is the 150. The FA is not just faster but better all round IMO. So, in short, treat each case separately and do the homework ;-)
11-02-2014, 05:58 PM   #10
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Some non-lens possibilities...

Could it be that the focusing screen is not seated properly and/or misaligned?

Another possibility is that the mirror is not stopping in the correct position.

QuoteOriginally posted by BBC5 Quote
And if the lens doesn't focus to infinity, I must of got a bad copy of the lens...
11-02-2014, 06:10 PM   #11
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QuoteOriginally posted by yurihuta Quote
Some non-lens possibilities...

Could it be that the focusing screen is not seated properly and/or misaligned?

Another possibility is that the mirror is not stopping in the correct position.
Thanks, but I'm using live view to focus...
11-03-2014, 10:07 AM   #12
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QuoteOriginally posted by Ed Hurst Quote
One example where the lenses are quite different is the 150. The FA is not just faster but better all round IMO. So, in short, treat each case separately and do the homework ;-)
agree
11-05-2014, 04:10 PM   #13
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I noticed the FA 45-85 gets great marks but there is no reviews for the A version. Does anyone have a comparison of the two? Or has anyone here used the manual A 45-85?
11-06-2014, 03:06 PM   #14
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QuoteOriginally posted by Flyflickr Quote
I noticed the FA 45-85 gets great marks but there is no reviews for the A version. Does anyone have a comparison of the two? Or has anyone here used the manual A 45-85?
this may help: https://www.pentaxforums.com/forums/48-pentax-medium-format/268494-45-85mm-fa-v.html

https://www.pentaxforums.com/forums/48-pentax-medium-format/189788-645-45-85-vs-fa-lens.html

Last edited by BBC5; 11-06-2014 at 03:53 PM. Reason: more info
11-06-2014, 03:16 PM   #15
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The FA 45mm gets far poorer reviews than the A version. I think they changed the optical formula, no idea why. 55mm is plenty wide enough for me on medium format.
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