Minolta Rokkor 20-80mm f/2.5 zoom lens

Discussion in 'Extreme, Retro, Instant and More' started by rdm, Jan 5, 2011.

  1. rdm

    rdm

    I got a Minolta Rokkor 20-80mm f/2.5 TV zoom lens "for S.V. color".
    Does anyone know anything about this lens?
    It is not a C-mount lens , because those are a 25mm screw thread mount. Instead it has a 30mm screw thread mount.
    I have no idea what the flange back, image register distance it is. I wish i knew the distance because i am wondering if i can get this mount converted. Since the rear element is not in the thread mount like many C-mount lenses i believe the entire metal mount can be removed and replaced with something else.
    Does anyone know of Lens technicians that change mounts on C-mount lenses to m4/3 or the NX10 or the like?
    I am thinking this might make a very good lens for an Olympus pen or if the distance from rear lens element to image plane is long enough , it would be ideal to use on the NX10. However i have no idea who would be able to tell me the flange back to image plane distance , or who would be able to figure it out , let alone be able to convert the mount.
    I have yet to purchase a digital camera, but I have to soon. I have a budget of about 500. Whatever i get i plan to use all the Rokkor and MD mount lenses i have and, I been leaning towards a used NX10 because of its larger sensor and form factor. However I do like the in body IS of the Olympus but not the fact i need to pay extra for an EVF. I thought if this lens could be converted to one of those mounts that would be something to factor in.
    Any help would be much appreciated.
    00Xydv-317933584.jpg
     
  2. rdm

    rdm

    Well thanks , at least its a step in the right direction. And you did answer my question really..
    last line was " Any help would be much appreciated. " and you did help :)
     
  3. Have you checked this list for any matches? Also, it may be possible to remove the lens mount and replace it with a different mount that you can adapt to another camera.
    http://en.wikipedia.org/wiki/Lens_mount
    What is the *exact* throat diameter? that may help. It's also possible that this was for a small run video camera, or one sold in Japan or Europe that is not commonly known other places. Poking around online, it looks like the initials SV were used quite a bit by different people for different things... I'm guessing "Surveillance Video" is the most obvious moniker.
     
  4. rdm

    rdm

    Update:
    Still no luck from anyone online knowing of such places. I think i will have to make my own mount. I will CAD the plans myself an then find a facility that can mill it. It would be helpful to find a whole-sale place for the m4/3 mount, like on the adapters i see made of brass and plated chrome like used on Cirrus adapters.
    First tho i will have to find the flange to film plane focal distance of the lens.
     
  5. rdm

    rdm

    Oh wow Patric, i did not mean to Ignore your response. I didn't notice it when i posted the other night. But, yea like i said in my original post, its 30mm and I cant find my good calipers to do an exact measurement. I first did it using a ruler.. I found a few posts online of other people having this lens in 30mm thread mount also, and they too are perplexed by it and are like me asking if anyone knew anything about the lens.
    The other night i removed the set screws that held the mount on and took some measurements with a cheap three dollar plastic caliper I purchased at the local auto parts store. I measured the outer diameter of the rear barrel to be 40mm and having a protection from the locking ring of rear element to be about 9mm and with a complete barrel length from the aperture ring of about 11mm. Not shown in the photos I measured the rear element too as having a diameter of 28mm. SO yea removing and replacing the mount would be best even if it was the standard 25mm C-mount since the image projection cone would most likely be cropped by it.
    00Y0Vp-319605584.jpg
     
  6. rdm

    rdm

    Just out of curiosity, should i keep this thread updated for what i do with the lens?
    I am not sure if anyone is interested.
     
  7. I'd be interested, and I'm also still curious as to what the lens fit originally...
     
  8. rdm

    rdm

    Hi, Donnie Strickland. I was emailed and been told it was for a certain type of Studio Production Camera; one of the earliest color CCD types made by Sanyo, but also that Minolta also offered the lens in C-mount too for Surveillance cameras. I guess that is why the mount is so easily removable and there's not a rear element in it like on my Canon made Sony branded c-mount lens. They probably just sold it also with a different rear mount piece.
     
  9. I see. Thanks dan!
     

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