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03-21-2018, 12:55 PM   #16
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QuoteOriginally posted by UncleVanya Quote
The F series is fully automatic and autofocus. But I have used an M 50mm f/1.7 before on my K-3 without problems. Steps:

1) Focus - manually. Either using viewfinder and focus confirmation, a 3rd party screen calibrated and with a split prism or better matte area, or magnified live view.

2) Meter (This may be omitted if you already did this on a previous shot and you are satisfied lighting hasn't changed much.) Typically with Green Button or Depth of Field Preview mode. The Usage of Green Button - PentaxForums.com

3) Take the shot.

Computers have nothing to do with it. Sure they make some things easier. Matrix metering can be more accurate with focus distance info, mtf can be observed, autofocus can track a subject, etc. But you don't NEED any of that to take a shot.
Thanks. No, I was confused as to wether I needed to control the f-stop or the camera did that for me like a more modern lens. I know on M and A series lenses (which aren't auto focus) I do everything just like an SLR, just wasn't sure about the F/FA series.

03-21-2018, 01:04 PM   #17
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QuoteOriginally posted by bikehead90 Quote
Thanks. No, I was confused as to wether I needed to control the f-stop or the camera did that for me like a more modern lens. I know on M and A series lenses (which aren't auto focus) I do everything just like an SLR, just wasn't sure about the F/FA series.
The A series brought with it in-body control of the aperture. Put the aperture ring into the A position at the end of its travel and run it like a DA, F, FA etc lens. Focusing is still manual as you mentioned.
03-21-2018, 01:18 PM   #18
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I have on K-1: smc Pentax: F 28/2.8 and F50 / 1.7, at F50 / 1.7 I put the AF ADAPTER smc Pentax-F x1.7 and i get smc Pentax F85 / 2.8 " no soft "
so on K-1 there is a "sacred trinity" in the F series: 28 / 2.8 + 50 / 1.7 + 85 / 2.8 and I'm very pleased , much more than with Tokino ATXPROSV 28-70 / 2.8

Last edited by mbukal; 03-21-2018 at 01:29 PM.
03-21-2018, 02:10 PM   #19
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QuoteOriginally posted by bikehead90 Quote
How does the 1.7 work on a modern camera? That's something I've yet to comprehend how to use a non-computerized lens on a contemporary camera.
For the lenses you are considering, FA 50mm 1.4/1.7 you put the aperture ring to the "A" setting , and operate the aperture through the camera just like a modern lens. Autofocus is screwdrive and works fine.

03-21-2018, 02:25 PM   #20
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QuoteOriginally posted by mbukal Quote
I have on K-1: smc Pentax: F 28/2.8 and F50 / 1.7, at F50 / 1.7 I put the AF ADAPTER smc Pentax-F x1.7 and i get smc Pentax F85 / 2.8 " no soft "
so on K-1 there is a "sacred trinity" in the F series: 28 / 2.8 + 50 / 1.7 + 85 / 2.8 and I'm very pleased , much more than with Tokino ATXPROSV 28-70 / 2.8
LOL - that's a different 1.7, the 1.7x with the same 1.7 the F 50 1.7. Head spinning....
I haven't tried my F 50 1.7 on my 1.7x AFA but I have the FA 77 1.8 and the DFA 100 2.8 so I have less need.
03-21-2018, 02:48 PM   #21
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The only difference between the F 1.7 & the FA 1.7 is that the FA has a serial data port and a chip in the lens that provides MTF data to the camera.
03-21-2018, 03:23 PM   #22
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Either of the F or FA lenses will work just fine on a modern DSLR. On APS-C bodies, 50mm is a very good focal length for portraits. As others have said, the bokeh of the f/1.4 is a little better. Also, while f/1.4 would not often be employed for portrait on a film or FF DSLR body due to the extremely shallow depth of field (DOF), used with APS-C for the same framing, it might not be as extreme.

The "F" 50mm f/1.7 is a very good lens and should be less $$ than the FA 50mm f/1.4, which is still available new- a worthwhile thought. Another thing about being sharp at wide-open f/1.7- tests have shown this to be true. Probably less so for f/1.8 for the FA 50mm f/1.4 but then ultra-sharpness is not generally sought-after for pleasing portraitures, unless one wants to emphasize a rugged appearance.

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