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Archive 2009 · C-mount 12.5 - 75mm (macro)

Tom Harpstead
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p.1 #1 · C-mount 12.5 - 75mm (macro)


Hello,

I have a 12.5 - 75mm TV lens with macro capabilities. Is this a lens that would be adaptable to any of the camera bodies? It has a 52mm front thread.



Oct 06, 2009 at 10:51 AM
thrice
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p.1 #2 · C-mount 12.5 - 75mm (macro)


Maybe micro 4/3rds bodies but someone more knowledgeable in these bodies should chime in.


Oct 06, 2009 at 10:57 AM
dan101
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p.1 #3 · C-mount 12.5 - 75mm (macro)


I doubt the macro capabilities built into the lens would be useful, but you could try reversing it and putting it on the camera body or reversing it and putting it on the front of another lens. My guess is that it probably will not cover a full sensor mounted directly to the body but with extension tubes it probably would. I am also guessing the magnification would be quite high and the focusing distance would be extremely short. But you have very little to lose by trying it.


Oct 06, 2009 at 10:59 AM
Tom Harpstead
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p.1 #4 · C-mount 12.5 - 75mm (macro)


dan101 wrote:
reversing it and putting it on the front of another lens.


I had thought of that as it has a 52mm front thread.



Oct 06, 2009 at 11:07 AM
Tom Harpstead
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p.1 #5 · C-mount 12.5 - 75mm (macro)


thrice wrote:
Maybe micro 4/3rds bodies but someone more knowledgeable in these bodies should chime in.


Good point I had not thought of 4/3rds. I was thinking of the 5D mark II owners, who make movies with them. I agree that it may not cover the full size sensor.



Oct 06, 2009 at 11:10 AM
mcbroomf
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p.1 #6 · C-mount 12.5 - 75mm (macro)


There are some people on getdpi.com who have tried some c mount lenses on the G1 and EP1. If I recall they don't quite cover 4/3 and/or vignette pretty badly, but some people like them.

Mike



Oct 06, 2009 at 11:31 AM
dasrocket
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p.1 #7 · C-mount 12.5 - 75mm (macro)


If it is a C or CS mount lens take a look at this link. They will fit onto a m43 mount and the wider, faster glass like the 8mm 2.8 have potential. The culprit is that most are made for lower resolution sensors, as well as smaller sensors. It's a trial and error from what I hear. One of these days I will get a fast wide and try it mysalf

Take a look at this article in particular about fitting C mount lenses on the G1.

cheers, George.



Oct 06, 2009 at 11:46 AM
Tom Harpstead
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p.1 #8 · C-mount 12.5 - 75mm (macro)


George,

It looks like it might cover a full size sensor, certainly a 4/3rds, from those web sites. Mine is a f/1.8 lens with 6 aperture blades.

Thomas




Oct 06, 2009 at 12:12 PM
mawz
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p.1 #9 · C-mount 12.5 - 75mm (macro)


It may cover 4/3rds and may or may not be mountable on a micro-4/3rds body.


Oct 06, 2009 at 05:32 PM
Roland W
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p.1 #10 · C-mount 12.5 - 75mm (macro)


The original C mount was made to cover 16mm film, which had a diagional of 12.7 mm. The full frame 35mm still camera has a diagional of 43.2 mm, which is much much larger than 12.7 mm. So if you want to use the lens in the normal direction, withoug reversing it, I think is is very unlikely it would be of much use on a full frame DSLR. It is easy to get an idea of how big the image circle is by projecting an image on to a piece of white paper, and noting the size. You can then draw a 24 by 36 mm rectangle around it to see what you would get, and decide if you want to work further on the project.

If you are wanting to try reversing it for macro, then depending on the magnification ratio, it may become useful and cover the full frame of a DSLR. But the image quality may be poor because the zoom will have been designed for working well at only one lens to film distance, and you will want to try to use it at different distances.



Oct 06, 2009 at 06:05 PM
dasrocket
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p.1 #11 · C-mount 12.5 - 75mm (macro)


Tom Harpstead wrote:
George,

It looks like it might cover a full size sensor, certainly a 4/3rds, from those web sites. Mine is a f/1.8 lens with 6 aperture blades.

Thomas




Thomas, most C lenses will cover a 1/4", 1/3" or 2/3" sensors; a lot of them carry an image circle of 9 to 11mm, whereas the G1 sensor I think has a 21mm I.C.. so you'll get severe vignetting.

If you want to test your lens the easy way, do like was suggested and try it over a piece of white paper. The C mounts are made to sit aprox 12mm away from the sensor, and the CS mounts 17.5mm +-. Draw the 13.5X18mm sensor size of the Gi, place the lens the proper distance from it ans see what happens. If it works, get a C to M4/3 adapter and you got a gem. If it works and the rsolution is ther, you go the holly grail of glass: tiny, inexpensive and ridiculously fast
Let us know how it goes, I have been researching this for a while and would like to hear your findings.
g



Oct 06, 2009 at 10:09 PM





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