Focusing problem on 6X9 horseman fieldcameragreenspun.com : LUSENET : Large format photography : One Thread
I have aquired an old horseman 6X9 fieldcamera( model name is ER-1) with three lenses.(75mm, 105mm, 180mm). The problem is even though I focus correctly on the groundglass using 6X loupe, result are always not sharp. It seems that critical focus is always a bit further from the plane of focus where I thought IS the plane of focus in groundglass. Are there any economical way to fix this problem? Is this the lens alignment problem? thanks in advance. Taewon from Chicago.
-- Taewon Yoon (firstname.lastname@example.org), August 29, 2000
This sounds odd. I have the VH, which is, I believe, virtually identical to the ER-1. If you're doing everything right, then the problem is probably you're ground glass/fresnel. Is there a fresnel in your camera? It may have been installed incorrectly and throwing off the focus plane.
-- Howard Slavitt (email@example.com), August 29, 2000.
Assuming that nothing is moving between focussing and taking the photo, it should be WYSIWYG. You see what the film is supposed to see, so there is no problem with the lens if the image looks right on the glass.
The main thing that has to be in alignment in a rigid LF camera is the position of the film holder in the back. The film plane MUST be in the same plane as the ground glass. As mentioned, if a fresnel lens has been installed, or the back inproperly reassembled (shims forgotten or such), then your photos will be blurred.
Are you using sheet film or a rollfilm back? If it's a roll film back, you might have a problem with film flatness.
-- John H. Henderson (firstname.lastname@example.org), August 29, 2000.
Check if the rollfilm holder is in the right position or it might even be of a type not suited to your particular camera. I figured that the only thing that could have happened is , yes you focus correctly but then your film holder is (I don't know how that would be possible but that's all I can think) not in the right focal plane , so , out of focus. Get in touch with Jin Yamaguchi at Horseman in Japan he is very kind and will help if he can. Good luck
-- andrea milano (email@example.com), August 29, 2000.
Taewon it does sound as if your ground glass is in the wrong focal plane. As John as already mentioned someone may have made an incorrect assembly. Make sure that the mat/frosted side of the g.g is facing towards the lens. Good luck,
-- Trevor Crone (firstname.lastname@example.org), August 29, 2000.
Even if Horseman holders are being used, there is still a possibility of unsharpness with a factory-spec setup. Key unknowns include what apertures the exposures are made at, whether the unsharpness is uniform across each frame, and whether all frames on a roll are unsharp. Reverse curl film paths can badly shift focus under certain circumstances.
-- Sal Santamaura (email@example.com), August 29, 2000.
Wow! I'm deeply moved by all the kind and thoughtful answers to my post. I, too think that the problem lies in the way g.g and fresnel screen is attached. I have unsrcewed the g.g and the f.screen before I realized that the g.g orientation can be a problem and I forgot how it was installed, so I took it to Calumet photo in Chicago to have the repair person check and reinstall properly today. Since I Do see a sharply focused plane in my test slide, even though it is not where I actually focused, I will test again and see if that was the problem. Thanks again for all of you for the prompt responses. God Bless! Taewon.
-- Taewon Yoon (firstname.lastname@example.org), August 29, 2000.