I need a new GG..?

[mark]

On my new very used Sinar F1 the corners of the GG are snipped off. I blame this for me not noticing that I had exceeded the image circle of my 135 lens when using front rise. This vignette ruined a couple of shots as, for once I was able to fill the frame top to bottom on these two shots. IMO they would have been considered keepers. because of this I am planning on getting a Satin Snow gg w/o the corners snipped. My question is this.

Will I be able to transfer the marks on the sinar GG onto the satinsnow GG with a sharpie or something? These marks have become invaluable as I learn to use the cool sinar focusing calculator and movement thingy.

 

[L Gebhardt]

Use a sharp pencil and a ruler over a sharpie. I have made marks on the ground glass this way and they work fine. They do come off with glass cleaner, so you may need to redraw them. Draw on the ground side.

 

[Dave Parker]

Hi Mark,

I actually have the pattern for the Sinar on file, that I could either send you or you can download from our website, it is quite easy to lay the ground glass over the template and then trace your pattern onto the glass, I use a 0.7mm drafting pencil to transfer my templates, I have also used transparancy overheads blanks and printed the pattern on and then mounted the transparancy over the glass when mounting on the camera.

Let me know if I can help further.

Dave Parker
Ground Glass Specialties
Satin Snow(TM) Ground Glass

 

[David A. Goldfarb]

The reason the corners are snipped is so that you can tell if you have vignetting in the corners. If you can see the full aperture through the corner clip, then you are okay. If you cannot see the aperture, then you will have vignetting. If you can see part of the aperture, then you will have falloff, but not complete vignetting.

This is often a more reliable method than using an unclipped groundglass with a wide lens, because the corners may be so dark at the shooting aperture that you just can't tell if there is vignetting or not.

 

[Dave Parker]

I have had many customers tell us they can see right into the corners on our glass, especially on 4 x 5, 5 x 7 and 8 x 10...most of our customers report back that the corners are brighter on our glass than what they have used in the past.

Dave Parker
Ground Glass Specialties.

 

[mark]

The reason the corners are snipped is so that you can tell if you have vignetting in the corners. If you can see the full aperture through the corner clip, then you are okay. If you cannot see the aperture, then you will have vignetting. If you can see part of the aperture, then you will have falloff, but not complete vignetting.

This is often a more reliable method than using an unclipped groundglass with a wide lens, because the corners may be so dark at the shooting aperture that you just can't tell if there is vignetting or not.

This is what I thought and, maybe it was the position I was in, I could see the entire aperature. When I got the slides back I was very surprised. My thinking was That, if the satin snow GG is as bright as it is advertised I would be able to see the vignette no matter what. I could be wrong though.

By the way thanks for the really fast replys.

 

[David A. Goldfarb]

Did the aperture appear round in the corners? If it looks like a football, you'll have dark corners (not always a bad thing, but obviously not always a good thing either).

 

[fotar-2]

the need for clipped corners

Without the clipped corners the bellows can blow out when compressing, and can cave in when expanding. the clipped corners allow air to travel freely into and out of the bellows.

 

[John Kasaian]

Regarding the bellows blowing out or collapsing---I don't see that as a problem. When you're setting up and focusing you won't have a film holder in situ. What you have is a very "leaky" spring back and given the amount of air thats moved I don't think it would be a problem. If you try it with a film holder in place, or experience a relatively small difference in air pressure when changing locations with a film holder in place(especially the smooth surfaced wooden ones) well, I know that grief from experience!

 

[sergio caetano]

Air compression and vignetting control, these are the reasons for clipped corners.
AA suggested unclipped corners with a little hole in the center ; very strange, and as far as I know, neither he himself used that idea.

 

[mark]

Did the aperture appear round in the corners? If it looks like a football, you'll have dark corners (not always a bad thing, but obviously not always a good thing either).

No football look. As I said I was not able to see straight into the camera. I will test it out this weekend.

To Zion I will go,
To Zion I will go,
Hi Ho the Dairy-o toZion I will go

Even if it is only for one day.