Tamron TV lens 16mm f1.8

[stingOM]

Hi,

I received my c-mount adapters today. Two versions - one flat version and another with a lip. Both does not allow the Tamron TV lens to focus to infinity with my Panny G1 to my disappointment. Also the sensor coverage is not great - but I had expected this anyway. I noticed there is lip (inner circle) on the lens mount (it is not flat). I wonder if it was filed away will it bring the lens closer to inifity focus? I don't really want to destroy the lens.



Lens is very well constructed, with smooth focusing helicoid. I don't know which version it is, but according to Tamron website:
http://www.tamron-usa.com/about/history.asp


It is suppose to be the 16mm F/1.8 for 1” Vidicon are the first CCTV lenses made by Tamron. If I am correct.

Any thoughts or info on this lens?

Thx

[Attila]

Looks a nice piece, finger crossed to solve infinity problems.
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[fatdeeman]

Sometimes a stop screw in the focusing barrel can be loosened or temporarily removed and then you can focus past infinity but the only way to improve frame coverage is to have the lens physically closer to the sensor.
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[stingOM]

Thanks Folks. I will give it a go. But I prefer not to damage the lens and sell it to someone who has the metal work skills to modify it.

At what point would you know that the modification is in danger of hitting the camera sensor?

I was looking at Industar 50 collapsible lenses. Then I realised it will damage the sensor if focused to infinity.

Just looking at the adapter again. It looks like the edge of the lens mount may be hitting the ridge of the adapter. I am not sure, but if you look at this post, you get the idea:
http://forum.getdpi.com/forum/showthread.php?t=8062&highlight=cosmicar

[stingOM]

OK, I checked it with my digital caliper. The outer most diameter of the lens mount is 38.30 mm, whilst the inner opening of the c-mount adapter is 37.3mm. So it is colliding and preventing the lens from turning inwards correctly.

Correction can only be made on the lens side, as the c-mount adapter is too thin to modify.

A lot more detail is give here (thanks to another forum post)

http://cjeastwd.blogspot.com/2009/06/adapting-lens-to-fit-mount.html

[Nordentro]

This is a known problem, I had the same difficulties with my Fujinon 25mm. You can see the thread here
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