Sunday, February 20, 2011

Taylor Hobson Ortal 3 inch 75mm f2 TV Lens Sample

This lens, without modification, can not be used on DSLRs and achieve infinity focus, even on the Sony NEX, it's tough to get it to work, because the flange is so short.  It was designed as a TV lens with fixed mount.  I have been dying to to try it, but without much success.

I was tinkering with adding aperture control to the projection lens, and looking for some adapters, and found that I had a Series 8 to Series 7 step down ring.  This ring fits almost perfectly to the mount of the Ortal 75mm f2 lens.  Eventually, the ring was fixed to the mount, and with a Series 7 to 55mm stop-down ring, I was able to add four 55mm filter rings to make an extension tube that allows me to focus the lens to about five feet, just long enough for some portraiture samples.  I could add/remove rings to make it focus further/closer.  This is the best solution so far until I get my hands on a very thin focusing helicoid.

A word about the C-Mount to NEX adapter I got.  Whoever designed this put a lot of though into it.  The center of the adapter has a 42mm thread size.  This has many uses.  You can attach an M42 lens directly to the adapter, or, I guess the original purpose, is to allow one to attach a focusing helicoid with M42 mount on it.  The surprise, is that the outer ring of the adapter.  It has a 55mm thread size.  I don't know what the reason for this was, but it was perfect for me, as I can attach the Ortal 75mm f2 lens with the filter rings directly on it.

All this means that I can take pictures with the lens with a fixed focus range, and I have to move the camera back and forth to focus.  Pain in the neck, but pictures can be taken.

Taylor-Hobson Ortal 75mm f2 TV Lens mounted on the NEX-5. Click to see larger.

The ugly beast

Megan, my favourite model - NEX-5 & Taylor-Hobson 75mm f2 TV Lens. @ f2.8 


  1. lens looks funny on the camera ... then again saw one of the Standard Sony zooms the other day ... gosh ... looked like the old 707

  2. okbakesan, any lens on the NEX would look funny, because the body is so small :)

  3. The pic of Megan is awesome. Looks damn sharp @ f2.8 for a frankenstein lens. :) Can you also mount on the G1?

  4. @Chester, it's indeed quite a nice lens. It can be mounted on the G1 but would be difficult to achieve infinity focus with a helicoid. I am ordering a 12-17mm focusing helicoid and hopefully it will work on both the G1 and the NEX.

  5. I'm in the midst of a sticking anything that bends light on my NEX frenzy and your c-mount adapter sounds great. Would you mind telling where you bought it from ?
    The 42mm and 52mm threads would come in handy for some stuff I'm doing

  6. @hugh, I bought mine from Rainbow Imaging. They ship from USA rather than China or Hong Kong like most others. Price is very reasonable with free shipping.

    However, I found that some of my c-mount lenses do not focus to infinity, but works fine on the G1. So not really sure why. Please keep that in mind.

  7. great! Rainbow Imaging is in my home town , I've bought from them before , and they give great service.


  8. Looking at this image, I checked the lens on ebay it is so expensive. All the canon dslr movie shooters have killed the affordable mf lens market.