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07-31-2011, 08:19 PM   #16
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QuoteOriginally posted by northcoastgreg Quote
My vote would be 50/1.4. The complaints about the 1.4 being less sharp wide open strike me as a tad overblown. To the extent that it's true, it's insignificant. And I'm not even sure it is in fact true. Every resolution test I've seen involving versions of the 1.4 and 1.7 don't support that view.
Well, the arguments might be overblown in terms of whether or not the difference in sharpness is significant (enough to matter), but there is no doubt which lens is sharper below f/2.8. Now, these differences are also somewhat exaggerated by the lack of contrast (especially when you don't use a hood) of the FA50/1.4 at large apertures, but that doesn't take away from the fact that the 1.7 is sharper at larger apertures than the 1.4 when you do a controlled apples-to-apples comparison.

08-01-2011, 02:30 PM   #17
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There is also the 6 vs. 8 aperture blades.
08-01-2011, 02:32 PM   #18
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QuoteOriginally posted by Blue Quote
There is also the 6 vs. 8 aperture blades.
Which probably contributes to the 1.4 having the superior bokeh
08-02-2011, 09:11 AM   #19
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QuoteOriginally posted by dgaies Quote
FA50/1.4 at large apertures, but that doesn't take away from the fact that the 1.7 is sharper at larger apertures than the 1.4 when you do a controlled apples-to-apples comparison.
You sure about this one?

Nifty 50 Shootout on Pentax K-7 (updated 1/22) ERPhotoReview

08-02-2011, 09:50 AM   #20
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QuoteOriginally posted by paperbag846 Quote
You sure about this one?
Yes, despite the data presetned in your link to an individual's test comparing a single copy of the F50/1.7 to a single copy of the A50/1.4, I remained unchanged in my opinion that the 50/1.7 is sharper than the 50/1.4 at apertures below f/2.8. I personally have more faith in the experience and testing that I've done with multiple copies of each lens in which I have come to the conclusion I stated above.

edit: Again, please don't misunderstand what I'm saying throughout this thread. The FA50/1.4 is a great lens and perfectly usable wide open in my opinion. I owned it for the first three years I owned a Pentax (K10D) and found it to be a great lens. I would likely still have a copy if I didn't have the DA*55/1.4 (which IMO is optically superior) and the A50/1.2 (which is half-a-stop faster).

Last edited by dgaies; 08-02-2011 at 10:01 AM.
08-02-2011, 10:18 AM   #21
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QuoteOriginally posted by dgaies Quote
edit: Again, please don't misunderstand what I'm saying throughout this thread. The FA50/1.4 is a great lens and perfectly usable wide open in my opinion. I owned it for the first three years I owned a Pentax (K10D) and found it to be a great lens. I would likely still have a copy if I didn't have the DA*55/1.4 (which IMO is optically superior) and the A50/1.2 (which is half-a-stop faster).
Not a problem . My experience (A 50 1.7 vs. FA 50 1.7) is that when both lenses are properly focused, they are of *equal* sharpness (contrary to the test I posed). But I strongly believe that after a certain threshold, sharpness no longer matters (in a similar fashion to "sampling rate" for audio data). I do think that the 50 1.4 has more CA, which can look like decreased sharpness (most noticeable when focused to infinity at a wide aperture).

I generally find the 1.4 more flexible, but I do prefer the 1.7's rendering (with low CA) for low-light, scene shooting (focused near infinity).
08-02-2011, 10:37 AM   #22
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QuoteOriginally posted by dgaies Quote
Well, the arguments might be overblown in terms of whether or not the difference in sharpness is significant (enough to matter), but there is no doubt which lens is sharper below f/2.8. Now, these differences are also somewhat exaggerated by the lack of contrast (especially when you don't use a hood) of the FA50/1.4 at large apertures, but that doesn't take away from the fact that the 1.7 is sharper at larger apertures than the 1.4 when you do a controlled apples-to-apples comparison.
Disagree. I had both, and from 1.7 up they were equal. Natch, the 1.4 for softer wide open, but I shot digital and film/print for both 1.7/8 and saw no difference whatsoever.

I found the 1.4 added more flexibility and the 8 blades made a modest improvement to bokeh over the 1.7. The latter's advantage lies mostly in weight and value (when it was available).
08-02-2011, 10:48 AM   #23
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QuoteOriginally posted by Aristophanes Quote
Disagree. I had both, and from 1.7 up they were equal. Natch, the 1.4 for softer wide open, but I shot digital and film/print for both 1.7/8 and saw no difference whatsoever.

I found the 1.4 added more flexibility and the 8 blades made a modest improvement to bokeh over the 1.7. The latter's advantage lies mostly in weight and value (when it was available).
Well, we can agree to disagree then. I don't disagree that the 50/1.4 is more flexible (larger aperture) and has slightly better bokeh. However, my experience with multiple copies of each suggests that sharpness doesn't equal out until closer to f/2.8.

08-02-2011, 01:49 PM   #24
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Photodo ranked the F 50/1.4 at 4.6, F 50/1.7 at 4.4, and the FA 50/1.4 at 4.2. The 4.6 tied the F 50/2.8 macro lenses said to be one of the sharpest Pentax lenses ever.

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They also rated the A 50/2 of 4.0 which I wouldn't have expected, but then its design can be traced back to the 1957 Pre-set Takumar 55/2.2, one of the lenses released on the Asahi Optical 'AP' body. So if that is the worst 50ish lens Asahi Optical/Pentax ever released, that is saying something.
08-02-2011, 06:26 PM   #25
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Ok, I give up. I just received an awesome looking A50/1.4 this afternoon so now I can enjoy the magic of the 50/1.4

Last edited by dgaies; 08-02-2011 at 06:42 PM.
08-03-2011, 09:11 AM   #26
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QuoteOriginally posted by dgaies Quote
Ok, I give up. I just received an awesome looking A50/1.4 this afternoon so now I can enjoy the magic of the 50/1.4
My sharpest lens is my A50/2.8 Macro. From 2.8 it's extremely sharp (as in good luck telling the difference) and from f/4 up it makes my eyes bleed.

In many ways I would much rather shoot with this with no filter (who needs one with the lens recessed so much) than any other 50. It simply delivers.
08-03-2011, 11:31 AM   #27
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I had the same "actual" experience between the 50/1.4 and 50/1.7 as well. although I wouldn't generally want to discredit paperbag's link to someone else's personal evaluative comparison between lenses, I would somehow disagree with the findings even with the provided personal MTF rating between the two lenses concerned. although the 50/1.4 scored highly on certain apertures that were deemed or generally known where the 50/1.7 would excel in sharpness, I would argue that such rating shouldn't be taken with a grain of salt on the basis that on actual real world image comparisons, the image on the f1.7 would appear sharper on those instances the the f1.4 scores a much higher MTF scores. although I wouldn't dismiss that there are copy variations from both lenses or maybe a form of defect or mislignment that could influence the MTF evaluation from both lnses, the general consensus and by numbers, the f1.7 is sharper. let's say there is a 10:1 ratio difference in sharpness between the f1.7 and f1.4. as far as comparing a macro is concerned, the ratio is pretty much nonsensical.
08-03-2011, 11:41 AM   #28
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QuoteOriginally posted by Pentaxor Quote
let's say there is a 10:1 ratio difference in sharpness between the f1.7 and f1.4.
That is preposterous!

There is no way the 1.7 is 10x sharper than the 1.4. What a silly thing to say. The only way you would feel that way is if you have only ever used the 1.4 in autofocus mode, and never bothered to calibrate the autofocus.
08-03-2011, 12:42 PM   #29
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QuoteOriginally posted by Aristophanes Quote
My sharpest lens is my A50/2.8 Macro. From 2.8 it's extremely sharp (as in good luck telling the difference) and from f/4 up it makes my eyes bleed.

In many ways I would much rather shoot with this with no filter (who needs one with the lens recessed so much) than any other 50. It simply delivers.
I have the FA50/2.8 macro. Not sure if it's the same optical formula as the A50/2.8 macro, but I know it's one of the sharpest lenses I've ever used. Period.
08-03-2011, 01:13 PM   #30
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If y'all want sharp, get an M42 Petri CC 55/1.8. It costs a lot less, too.
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