Maximizing Image Size on the Ground Glass

[Jus10m]

Hey guys,
Brand spanken new adapter question here!
I was doing some lighting tests the other night with the RR adapter. I was using a 50mm lens with the Cinescreen 2 ground glass when I noticed just how much of the original image I was losing when I zoomed in on the GG.
As you can see here, this is the image when zoomed in on the image.
http://i22.photobucket.com/albums/b321/jus10m/ZoomIn.png

But when you zoom out, you can see just how much of the image is actually being projected on to the ground glass. (I also placed a rectangle on the image to show how much I need to zoom in to not get base of the motor in the shot)
http://i22.photobucket.com/albums/b321/jus10m/ZoomOut.png
Is this normal, or am I cutting off more of the image due to faulty placement of the camera on the setup or any other reason? It seems like the camera is aimed too high (or low, I have the flip adapter on) and is pointed too close to the motor, making me have to zoom in even more. It seems I still have a good amount of image on the left and right I could get if the camera was just pointed away from the motor more.
Any help would be greatly appreciated!
Thanks,
Justin

[Lkorver]

I have the same question with the RR I used... curious what they tell you.

[Huy Vu]

Most SLR lenses actually project an image that's wider than its focal length indicate. The problem with vignetting are two fold: 1) the lens doesn't have a large enough rear aperture and 2)the adapter GG doesn't transmit light evenly so you get dark corners; most adapters do this to an extent. User frobozz took some pics that illustrate how much wider a 24mm lens actually is

http://www.dvxuser.com/V6/showpost.php?p=1494652&postcount=94

In any case, to make sure that you're not cropping too much off the FOV, tape an 8 1/2 x 11 piece of paper to the wall and stand about 2' away with the 50mm lens. If the edge of the paper just about touches the edge of the frame then you're at the Academy ratio FOV, which is a good thing.

[Lenilenapi]

The easiest way to tell whetehr you are getting the full frame size is to borrow a Nikon still camera (not a digital Nikon) and compare the Field of view. Even easier I guess would be to find a chart that describes the FOV for one of your lenses on a 35mm SLR and compare it to your adapter.

It looks like your camera may be aimed a touch too high but I'm not sure what's normal for that adapter these days.
You can adjust the centering for the GG inside the unit. I did that when I had one awhile ago.

- Lenny levy

[frobozz]

To fix this problem on my M2, I ended up having to move the motor all the way DOWN. (The screws that hold it to the mount are in slots, so you have quite a bit of adjustment on it.) Unfortunately you have to take off the GG to do it, which means setting the backfocus all over again...

It's possible if you move it all the way down, then you'll have the opposite problem: the curved edge of the GG will be what you hit first as you zoom out. Obviously what you want to do is hit right in the middle. In my case it was having the motor all the way down that did it, which made things easier. (This is why I've said I'd prefer a system with a GG significantly larger than it "needs to be"...so that you don't have to spend all your time on tweaky little adjustments like this.)

Duncan

[Jus10m]

Awesome guys, that was a ton of help!
I'll be shifting the position of the GG later today.
Thanks again!