SunActinon 24mm lens

Discussion in 'Classic Manual Cameras' started by robert_chadwick, Dec 21, 2011.

  1. Hi all, I aquired this Sun Actinon 24mm lens recently, cost me a fiver, it is in excellent condition, but... when I ran a B & W film through it, the resulting pics are what I got, I did see that the focus was'nt right, close focus on lens said 25 centimetres when actual distance was 20 cms, at 3 ft measured lens was showing 5 ft next mark was infinity. I think someone has had this lens dismantled and put one of the elements back in the wrong way round, what do you clever people out there think? Is it worth the effort of dismantling, I have had the rear group out but they come out as a unit so I think it could be one of the front ones. First picture is close focus second one between 5ft and Infinity.
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  3. I do not think that someone has put in one of the lens elements the wrong way. This usually would result in severe optical aberrations (i.e. almost everything - possibly except for the very center - would seem extremly soft).
    I rather think that the focussing ring has some misalignment. On many lenses there are tiny grub screws under the rubber covering. To loosen them you will need a very small and sharp screwdriver. Then you can move the focus ring slightly until it matches the distance markings.
     
  4. I do not think that someone has put in one of the lens elements the wrong way. This usually would result in severe optical aberrations (i.e. almost everything - possibly except for the very center - would seem extremly soft).
    I rather think that the focussing ring has some misalignment. On many lenses there are tiny grub screws under the rubber covering. To loosen them you will need a very small and sharp screwdriver. Then you can move the focus ring slightly until it matches the distance markings.
     
  5. Provide a picture shooting square onto a subject, like a newspaper. The images do look somewhat wonky.
    Could be a backwards element, could be a poorly seated element. Could be an element from a different lens. (Just read someone where someone "repaired" a wide angle lens with a damaged front element by taking the front element from some zoom lens. It was rendering an image, but certainly not optimally!)
     
  6. Also try different shots with the lens set at different apertures.
     
  7. For a fin you've got nothing to lose except your dignity and your patience.
     
  8. Robert,
    I would get new lens, made by the same brand that made Your camera.
    Even if it's $150 that's an investment for years.
    This lens is a paperweight, but You can use it as a special "Petzval Effect" lens :)
     
  9. Thanks everyone for the tips, Maciek I think you are right, it is a paperweigh!, I will attempt to strip it down and see if there is anything obviously amiss, it may have been dropped and something inside gone askew. There are no obvious signs of damage, just scratch marks on the rear screws which indicate someone has opened it up. Ho hum, seeing as it was mounted on a Contax 137 I think I will stick to useing my Yashica 28mmML . Thanks again everyone.
     
  10. A 24 mm lens should be practically focus free at any setting other than its closest. If it's not conspicuously dropped or mis-assembled, I'd guess that the focusing helicoid was screwed together wrong. Many lenses have multi-start threads, meaning that there are several wrong ways to reassemble them, depending on where you start the threads. If, for example, there are four different thread starting points, three will be wrong, but you should be able to get it right by elimination if you're patient.
    If it's a paperweight anyway, there's not much to lose except the time.
     

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