Another Ground Glass question? Focus problems in studio

[johnmarkpainter]

I am looking for tips for focusing in the studio.

 

I can see OK when I use my 210mm lens. When I use my 90 SA or my 65 SA I can see to

focus something in the middle of the glass but I can't see the whole composition or

coverage.

 

I have what is probably the stock screen on an an old Calumet Monorail. I am tyring out a

"Satin Snow" screen. It gives better contrast but doesn't do anything to help with seeing

the edges.

 

I have a Crown Graphic that has a Fresnel in it. That helps a lot.

 

OK.....Do I just need to set up REALLY BRIGHT Focus lights? I can see pretty well (not

great) when I use these lenses outside.

 

jmp

[johnmarkpainter]

BTW,

 

I have been reading the old threads. Thing is, I am confused about the Fresnel screen

thing. You can just overlay a fresnel on the viewing side of the GG and that helps?

 

jmp

[gary_mccutcheon]

The edges of the gg are always a problem especially with WA in the studio. I have a fresnel on all my 4x5's and that helps especially in the center, but for critical work I use a 500watt flood to focus and check dof. Turn it on to check focus, off to set lights(strobes) and shoot. It can be a pain but it works.

Gary

[c_p_goerz]

When you are off axis from a fresnel the darkening of the corners can/often occur, try looking at the overall composition about twice the distance from the groundglass than you normally would. That ought to help.

 

 

 

CP Goerz

[brian_ellis16]

Unless the Fresnel is designed as a wide angle it probably won't solve your problem. In fact it may aggravate the problem. I've read many good things about the Maxwell wide angle Fresnel. It supposedly can be used with longer lenses as well as shorter and the only effect is supposed to be a slight dimming of the screen as the lenses get longer but still a big improvement over a plain ground glass. However, I've never used one myself, this is just what others have said. If you don't wish to pursue the Maxwell then I'd suggest a BosScreen. Search the archives here and you'll find plenty of information about the BosScreen.

[allen_whittier]

John,

 

I've found a wonderful solution to the 90mm focusing problem. I use a fresnel out of an overhead projector. It's 11"x11" and happens to have a focal length of 90mm. I hold it up in front of the ground glass and the corners pop into view, bright.

 

I've picked up several overheads in junk condition for less than $5 and removed the lenses. They all work well, some are unbelievably bright. I haven't looked into the cost of purchasing a new lens from a manufacturer, but they can't be that much, they're only a piece of plastic.

 

My format is 5x7. I have no problems getting the fresnel centered on the ground glass. A 4x5 that has a rail extending behind it may have a problem if the rail is less than 5 1/2 inches from the center of the ground glass.