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06-22-2010, 07:59 PM   #1
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Is the FA 50 f1.7 optically the same as A50 1.7

Hello,

My A50 f1.7 is spending a lot of time attached to my camera. To the point I think it controls me.
I was wondering if the FA version is optically the same? Is the only difference the autofocus? If not, how would they compare?
Yes, I did read the review section and it seems to me they are. (6 elements, 5 groups, 6 blades) Just want to make sure.

Thanks,

06-22-2010, 08:32 PM   #2
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QuoteOriginally posted by ismaelg Quote
Hello,

My A50 f1.7 is spending a lot of time attached to my camera. To the point I think it controls me.
I was wondering if the FA version is optically the same? Is the only difference the autofocus? If not, how would they compare?
Yes, I did read the review section and it seems to me they are. (6 elements, 5 groups, 6 blades) Just want to make sure.

Thanks,
As far as I understand, the A, F and FA 50/1.7 are all optically the same.

By the way, how'd the P3 work out?
06-22-2010, 08:34 PM   #3
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QuoteOriginally posted by ismaelg Quote
Hello,

My A50 f1.7 is spending a lot of time attached to my camera. To the point I think it controls me.
I was wondering if the FA version is optically the same? Is the only difference the autofocus? If not, how would they compare?
Yes, I did read the review section and it seems to me they are. (6 elements, 5 groups, 6 blades) Just want to make sure.

Thanks,
Is the 50A1.7 that good? I have an 50A1.4 and I think optically it's OK, very hard to nail the focus at f1.4, not sure how is it compared to the 50A1.7 though.

Sorry for not answering your question
06-22-2010, 08:39 PM   #4
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QuoteOriginally posted by ismaelg Quote
Hello,

My A50 f1.7 is spending a lot of time attached to my camera. To the point I think it controls me.
I was wondering if the FA version is optically the same? Is the only difference the autofocus? If not, how would they compare?
Yes, I did read the review section and it seems to me they are. (6 elements, 5 groups, 6 blades) Just want to make sure.

Thanks,
The M, A, F and FA 50mm lenses are optically the same down 6 elements in 5 groups to the coatings and cement. I'm not sure about the number of aperture blades.

Here is a good resource on all things k-mount.

Pentax Normal Prime Lenses

06-22-2010, 08:41 PM   #5
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QuoteOriginally posted by Blue Quote
The M, A, F and FA 50mm lenses are optically the same down 6 elements in 5 groups to the coatings and cement. I'm not sure about the number of aperture blades.
They all have 6 blades.
06-22-2010, 11:00 PM   #6
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Kind of a coincidence, I planned to post my comparison photos pretty soon that I shot, using the M50/1.7 vs the F50/1.7. Both have 6 blades. The M50 can be used on my K20D either in aperture priority, or manual using the green button.

I had the camera on a tripod, using two-second timer, changing from one lens to the other, with both shot at f1.7. I've had to use the camera's AF-adjust (Custom Menu #35) set to -7, to get the AF right on with the F50.

Anyway, that M50 is a little jewel! Absolutely, incredibly sharp wide open, and amazingly the manual focus on the M-50 outperformed the MF on the F50. (For sure the manual focus ring, and "feel" on the F50 is pretty pathetic in comparison.) I have a FocusScreen.com split-screen plus the Pentax O-ME53, but I still couldn't accurately nail the focus when doing it manually with the F50. (It looked in focus, but the resulting images were just not as sharp.)

However, and this seems odd, the F50 used with AF is actually just as sharp as the M50 focussed manually; then, the resulting images are indistinguishable from each other, very good image quality indeed! So I can definitely understand your love affair with the A50. But I would say that, yes, the optical formulas are the same, but the handling is totally different. I have owned the FA50/1.4 as well, and the image quality wide open was not as sharp as these 1.7 lenses, plus the manual focus on it, again, cannot compare to the M and A lenses. Having done this little test, and now having owned the FA50/1.4, F50/1.7, M50/1.7, (and the Cosina 55/1.2), I would someday still aspire to own an A50/1.2- now THAT would be one beauty of a lens! (Although the Cosina's not too shabby!)
06-23-2010, 04:08 AM   #7
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Thank you all!
I also have the M50 f1.4 (and 2 copies of the A50 f2:The Rodney Dangerfield of primes) Actually, about 90% of the pictures in my museum blog are with the M50 f1.4 But the benefit of the A setting makes the 1.7 more convenient to walk around with, at least for me. Having AF capabilities can probably make it the only lens in my camera.
Stopped down there is little difference between both. But in my non-scientific and subjective tests and opinion, I "think" the 1.7 is a hint better overall, especially below f5.6. But I admit the 1.4 "looks" gorgeous
Now the f1.2 would be a dream to have. Focusing the 1.7 and the 1.4 wide open is not that easy, I imagine the 1.2 would really require skill and practice.

dgaiers, the P3 was cleaned and tested and it seems to be in perfect shape. I plan to take it on a quick trip to a local natural reserve. I'm just hoping to have the time to do that soon.

Thanks,
06-23-2010, 05:14 AM   #8
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I've owned two FA 50/1.4s and noticed that they have two different coating colors: one greenish and blueish. Probably earlier and later version? I kept the green one because it's my perfect copy (the blue one had some minor defects, but I sold it for lower than market price), but I'm not sure if the coating color actually affects image quality.

And contrary to the tests at the Normal Lens Shootout Photo Gallery by Sean Carpenter at pbase.com, I find that SMC Tak 50 and FA 50 have different bokeh. Tak is smoother and FA is has more highlights.

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