When I mount my 35mm adapter to the front element of my EX-1 lens, I need to calibrate focus first, and then adjust the CAMERA's zoom so that the image fills the frame. If I don't adjust the Camera's zoom, I run the risk of vignetting.

My question is, once I've found the sweet spot and mark the zoom barrel, can I zoom in further if I wish--in effect using the camera's zoom as a tele-extender--and if so, to what extent. Will I have image degradation if I do? Or should I just leave it on the sweet spot, and treat it as a fixed focal length lens.

For example, when I have a 50mm prime mounted on the adapter, the EX-1's zoom is set to about 40mm to fill the frame. If the zoom is set wider, I get vignetting. Zoom tighter--to say 80m--and I am in effect changing the mounted lens' focal length, making it longer. I wonder if there is perceptible image degradation.

I am new to video, so judging whether or not there is degradation, is not easy for my eye to see but I wonder what others think and have observed.

Thanks in advance for your help.

Cheers,

-Emile

No degradation that I've ever observed or could imagine in theory. It can be very useful to zoom farther in than the minimum to prevent vignetting. You can't really zoom within a shot and maintain focus, but I don't think that's what you're talking about.

yes, it is possible if you need to do it. you don't get much zoom, but you get a little.

You certainly can zoom in somewhat without quality loss on some adapters - (Letus Extreme, Ultimate or SG Blade) , but there are no hard and fast rules about it, and every camera/adapter combination is different. Some will suffer very badly from zooming in.
You simply need to figure out what looks good to you and good monitoring is very helpful.
Don't assume that your video cameras focus will remain sharp as you zoom in on the Gr glass screen. Double check it at every focal length.

A very good idea is to find something flat and sharp as a reference and experiment. I blew up a lens resolution chart to various sizes & mounted them on foam core. The first problem you may see is that your corners may start to go out of focus as you zoom in.

Usually not a good idea to go zoom in too far as you are increasing the grain size in the screen and compromising the optics of both the adapter achromat and the 35mm lens.

Thanks for the feedback. I posted the same query to another forum and received the same feedback. No lone dissenters suggesting otherwise.

I've since run some tests, and don't see any degradation in quality. Then again, my eye is still not quite trained for video, so there may be some things there that I'm just not seeing.

Nevertheless, in the meantime, I will use this technique with confidence, as long as I don't "push to far" as suggested.

Thanks again for your comments.

Cheers,

-Emile