Originally posted by aleonx3 There is one advantage I noticed using the A lens; which can provide more aperture setting than marked on the aperture ring. For example, between 1.7 to 2.8, you can set the camera to the 1.8 and 2.0. Don't know if these actually have finer control of the aperture on the lens, but the EXIF seems to indicate the aperture used.
Yes, that's an advantage indeed, although most M lenses have "half" stops - clicks between the actual markings. But the first click after 1.7 on the 50/1.7 is actually around f/2.4, no f/2.0 as one might assume. with an "A" lens, you can set f/2.0 if you want.
Another advantage of "A" lenses is that when the ring is in the "A" position, the onboard flash will work normally (and same for external P-TTL flashes, I think) rather than always firing full power as they do if the aperture ring is used to set the aperture.
Quote: Marc, thanks for shedding the light for me on the K-mount (no A setting) lens, that I can only have "wide-open" aperture setting no matter what I set on the aperture ring. So that means I can not stop down on the K or M lens. Does this apply to Aperture priority? Would it be different if I use M mode? May be I should try it too.
You should :-). What I said only applies to Av mode. actually, it applies to all modes except M mode - which is to say, all other modes *behave* like this crippled version of Av mode (ie, you can have any aperture you want, as long as its wide open). M mode works as it should - lens stops down when you take the picture (and stops down temporarily for metering using the Green button or DOF preview).
Quote: One thing I am not comfortable with the K or M lens is that I can never get the aperture setting of the shots taken since it is blanked out in the EXIF.
True enough. I tend to do most of my shooting either wide open or at f/8 (lazy, yes I know) and it's normally pretty obvious to me which is which, but there are times I wish I knew. Not for any reasons that really matter, of course - just so I can put the right captions on the picture when posting, etc.
BTW, I know nothing about the Chinon lens, but tend to doubt it would be better than any Pentax 50/1.7 or 50/1.4. I also don't know if the particular one supports camera control of aperture, but visual inspection should tell you that quickly enough: if oyu see an "A" position on the aperture ring and/or a series of electrical contacts on the bottom of the lens, then it does. I think it's pretty rare for non-Pentax lenses, though.
And FWIW, the main reason I didn't recommend the A50/1.4 is that it tends to be two or three times more expensive than yhe 50/1.7, but some would argue not any better.