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-   -   EOS lenses and f-stops (https://www.dvinfo.net/forum/alternative-imaging-methods/14841-eos-lenses-f-stops.html)

Matt Manning September 22nd, 2003 02:32 PM

EOS lenses and f-stops
Was wondering if one can adjust the f-stop on a Canon EOS lens with the Mini35. Canon lenses are adjusted through the camera body with no on-lens control. Are you forced to shoot wide open all the time or is there some way around this?

Also, how do Canon lenses stand up versus Nikkor?

Thanks for the help!


Mizell Wilson September 22nd, 2003 03:11 PM


There is currently no EF (EOS) lens control through the Mini35 meaning you do have to shoot wide open. The benefit is that with the Mini35 the best results are from shooting wide open all the time anyway.

The EF lenses are very comparable to the Nikkor but they have interfaced with the Mini35 better i.e. some EF lenses have required additional shimming to work with the Mini35. The lenses would have to go into the shop to do that.


Matt Manning September 22nd, 2003 03:17 PM

Thanks alot Mizell.

I figured there was no control, but had not thought about mounting problems.



Mizell Wilson September 22nd, 2003 03:33 PM

I wouldn't say it's a mounting problem necesarily...

It just seems that Canon does not have as tight a tolerance on their back focus or has something in the EOS cameras that compensate for it.

We only had one or two customers that have had issues with the lenses but we have to mention it because it becomes a "possible" issue with the lenses that we want people to be aware of.

So far, every Nikkon that has been put on the Mini35 has worked without a hitch. Leica as well.

Optically though, the EFs are right up there with them.


Adrian Seah October 3rd, 2003 06:46 PM


I was just wondering... you know there is sort of an iris on the mini 35 itself, on the relay lens, stopping that down equivalent to stopping the lens aperture down, apart from reducing the light... pardon me if I'm not making much sense but what i mean to ask is if stopping the iris on the mini35 down would affect the depth of field of the image captured or would it just reduce the light hitting the CCDs? I've had a fiddle around but didn't have time to do extensive testing (it was a rented unit), and it seemed to me that all it did was to reduce the light hitting the CCDs, not affecting the actual aperture at all.

Pls correct me if I'm wrong.


Mizell Wilson October 6th, 2003 08:47 AM


You've got it right on the head. The back relay iris, which is a leaved iris BTW, nothing electronic, does only control the amount of light. It does not effect the DoF of the image in any way.

The reason is the ground glass. For lack of a better term, the image charateristics are 'frozen' there, with the rest of the optics of the Mini serving as transfer and reduction elements.

Not for you specifically, but for any others reading, it is important to know that this feature, the relay iris, only appears in the Canon configuration of the Mini35. In Sony and Panasonic you have to rely much more on ND.

Since it did come up recently for a rental house's client, everyone needs to remain aware that lenses need to be used as wide open as possible. If you do not like the electronic ND control in your camera (Sony & Panasonic) be prepared to start packing ND1.2 & 1.5 if shooting outdoors. You do not want to go above T4 if at all possible, especially if shooting pans across flat backgrounds.


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