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12-27-2012, 09:34 AM   #16
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Here are my thoughts on the comparison (I own an F50 1.7, which is optically the same as the FA, functions pretty much the same as the FA version):

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/209699-pentax-...ml#post2218199

I'd pick the 1.7 each time, even though I do bump against my higher ISO limit (8000-10000) under concert conditions, it offers me certain benefits.

The 1.4 is excellent, but requires a hood to make it so.

12-27-2012, 03:37 PM   #17
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Na Horuk,
I've wondered about whether or not the DA lens coatings do make a difference on newer digital cameras. Are you aware of any fast 50 tests that were done under controlled conditions to compare the effects of the newer vs older coatings? I'm not questioning you; I really do want to know. It seems to me that they should make a difference but what, specifically, are those differences and are they enough to make me consider switching from my F50/1.7?
12-28-2012, 06:44 AM   #18
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mushin, I don't know of any tests or measurements, just that the SMC coating has been improving over the years. This means, for example, less purple fringing on newer lenses (I think some sample photos might show this), but with 50mm I wouldn't worry about it - the IQ is so high already that a slightly improved coating probably won't be noticeable, especially if you use a lens hood.

With digital sensors I read that purple fringing is a bigger problem than with film (is more noticeable) and the sensor itself is shiny, so it reflects light back at the back element of the lens (which reflects it back and lowers the overall IQ). Modern lenses have coatings on the lenses to minimize those issues. Some people want, for example, the FA limiteds to get a "digital" overhaul, because they are great lenses, but are made for film. But seriously, this is no problem. I personally use a M 50mm f1,7 and love it. In this focal length I also use a 50mm Miranda f1.9, a 50mm Industar f3.5 and 58mm Helios 44-2 f2.0. Even the all-plastic Miranda delivers very decent IQ, as does the Soviet Helios (at least in the image centre), with even older coatings. I think a bigger difference you will notice is automatic aperture control, exif data, AF..
12-28-2012, 12:11 PM   #19
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Thanks! I have heard other folks mention that the newer coatings do make a difference - and I'm a believer in coatings - so I wondered if there was something to document what the differences were. I currently have an F, M, K and two SMC 1.4's and the old screwmount lenses are the best. However, as I age I am appreciating the autofocus of the F. I don't miss the FA I sold but I did wonder if the newer 55 would be something to consider. Now, I think I'll wait.

12-28-2012, 12:26 PM   #20
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QuoteOriginally posted by Na Horuk Quote
With digital sensors I read that . . . the sensor itself is shiny, so it reflects light back at the back element of the lens (which reflects it back and lowers the overall IQ).
Film also reflects back to a limited extent. These reflections were the basis for the real time metering on the LX.
12-28-2012, 12:44 PM   #21
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QuoteOriginally posted by Na Horuk Quote
With digital sensors I read that . . . the sensor itself is shiny, so it reflects light back at the back element of the lens (which reflects it back and lowers the overall IQ). Modern lenses have coatings on the lenses to minimize those issues. Some people want, for example, the FA limiteds to get a "digital" overhaul, because they are great lenses, but are made for film. But seriously, this is no problem.
If you look very carefully at the following photograph, made with an M200/4 on a K-x,
you may notice a dark area extending the vapor trail in front of the airplane.
I've never been able to determine the true cause of the ghost trail,
but it might conceivably be the effect of reflections off the sensor.
It's not an optical illusion, because it's still noticeable if you block off
the rest of the photograph, and just look at the area in front of the plane.

A similar photograph taken at the same time,
but with the vapor trail not going that close to the center of the frame,
did not show this kind of darker area.

I'd be very grateful if anyone could offer a coherent explanation for the effect.

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