My Thoughts on Pentax 50mm 1.7 M vs A

Discussion in 'Adapted Lenses' started by tjdean01, Jul 6, 2013.

  1. tjdean01

    tjdean01 Mu-43 Top Veteran

    Feb 20, 2013
    I accidentally won both on Ebay auctions. The '77-84 M was $25. The '84-89 A was $60. Both are very sharp, a challenge to manually focus, and optically, from what I've seen, equivalent. They get very sharp around f3.3-4. There was some concern about whether there is a notch between 1.7 and 2.8. Indeed there is. Anyone know if that notch is f2?

    These are similar in FL to the Oly 45mm 1.8 and just as fast (45 is very sharp from f2.5, however). I kind of bought them to play with, see how I like legacy lenses, and to see if I want to buy the lighter, easier, faster 45 (I do). I have fun playing with the manual focus. I would definitely not want to take this lens anywhere where I'm shooting people or animals, however!

    Pentax A 50mm 1.7 - Usually goes for $80-100. This has auto-aperture if attached to the right camera. It's 20 grams lighter than the M. More plastic, I'm assuming. After reading all about nifty fifties, THIS is the lens I wanted.

    Pentax M 50mm 1.7 - Had I known I was going to win the A I wouldn't have I wouldn't have bid on this. I didn't want it. After using it, however, I prefer this to the A. Why? I can't say, really. The aperture ring is a bit smoother? Older is cooler? I'm actually going to sell the A and considering its condition and that it has caps, probably get $100 for it. I might start a thread on here first, however, to give it to someone who appreciates it!




    Attached Files:

  2. RnR

    RnR Mu-43 All-Pro

    Sep 25, 2011
    Brisbane, Australia
    Sounds like you got two good deals. Nice one mate!
  3. Fyi: Pentax-A lenses are not AF. They differ from the M lenses with the addition of A position on the aperture ring which is used with Pentax Bodies that have program modes and shutter priority that requires the camera to select the aperture. Other changes include cosmetic changes. As far as know, the two discussed are identical optically. The AF lenses are designated with Pentax-F markings.
  4. Its easier to focus manual lenses wide open then stop down just before exposure. This allows one to examine focus easier because of the shallow DOF. Many SLR cameras (vintage too) do this automatically. The Pentax K mount is designed with a linkage that the camera engages to open the aperture wide open during focus but stop down the lens just as the user triggers the shutter. If not engaged, the lens is always stopped down.

    So to improve manual focus, sometimes its easier to manually turn the aperture ring to its widest setting, focus, then stop down (count clicks) for exposure.

    The other option is to use an adapter that has "aperture-control". These adapters have a lever that engages the aperture diaphragm linkage. You set your aperture.... then you can quickly open-close the aperture with a twist of the ring on the adapter itself. This is pretty much the same operation as vintage aperture "pre-set" designs.

    I prefer this method and this is the adapter I use:

    Pentax K Lens to Micro 4/3 (MFT) System Camera Lens Mount Adapter V2 w/ Aperture Control Dial fits Olympus Pen E-PL1, E-P2, E-P3, E-P1, E-PL2, E-PL3,Panasonic Lumix DMC-G1, G2, G3, GH2, GF1, GF2, GF3, GH1,GH2,GH3, G10

    3rd one (Dragon fly?).. I like. :smile:
  5. tjdean01

    tjdean01 Mu-43 Top Veteran

    Feb 20, 2013
    Yes, auto aperture. That's what I meant. I fixed it
  6. John Araki

    John Araki New to Mu-43

    May 28, 2013
    Having had both the M & the A 1.7 as well, I'd like to add my thoughts:
    The M is incredibly compact and almost completely metal in construction.
    The aperture ring of the A is flimsy and the usual advice is to always have it locked in the A position. Manual aperture ring movement in the A version tends to result in broken clips (no more clicks), which may actually be good for video usage.
    Image wise, they are near identical I feel that the -A had heaps of pixie dust magic in it while the -M not as much. My experience was that there just seemed to be more depth, more substance out of the -A.
    Ended up giving away the -M, buying an -M /1.4, and giving to my Sister-in-law the -A/1.7. (which I still regret)
  7. Petrochemist

    Petrochemist Mu-43 Top Veteran

    Mar 21, 2013
    N Essex, UK
    The two lenses use identical optical design, so should give very similar results on an adapter.
    However the M lens has a better build quality, whilst the auto aperture option makes the A series more useful for current Pentax DSLR users, hence the higher value.

    I agree resell the A50, and make the most of the M50, it's a great lens.

    BTW I love the dragonfly shot!
  8. snkenai

    snkenai Mu-43 Top Veteran

    Sep 5, 2010
    I also have the -M. Great lens.
  9. spatulaboy

    spatulaboy I'm not really here Subscribing Member

    Jul 13, 2011
    North Carolina
    My buddy shoots the A on his Pentax K-30, and gets good results. However for m4/3 use I would go for the M.
  10. tjdean01

    tjdean01 Mu-43 Top Veteran

    Feb 20, 2013
    Thanks for the replies! Gotta love the Internet. I'm a guy who bought a 2013 camera, bought an adapter from China, and am comparing how a 1970s lens compares to one from the 1980s. And then, to top it all off, I'm not only able to find people who know what I'm talking about, but who have done the same thing! I'd say we're each one of a select few :2thumbs:
  11. spatulaboy

    spatulaboy I'm not really here Subscribing Member

    Jul 13, 2011
    North Carolina
    Not as few as you think! Have you seen the adapted lens camera thread? :cool: