View Full Version : Focusing LF cameras

Steve Springer
3-Aug-1998, 08:44
I am new to the LF cameras and have recently purchased a Toyo 45C. I have many q uestions that I sure will be answered during the use of the 4x5 but at present I am having problems focusing with such a dim image on the ground glass. I have a Ziess 150mm, f3.5 lenses set in a Compur shutter, very old lenses but is clear and scratch free. My question is, are there other types of glass that will give off a brighter image than the stock ground glass back with the grid, 6x7 & 6x9 format lines??? Any help would be appreciated...

Thanks Steve Springer Manufacturing Engineering Composites Manufacturing steve.springer@Wichita.Boeing.com 316-526-2228

Alan Gibson
3-Aug-1998, 12:09
You shouldn't have problems with such a large aperture lens, assuming you are fo cusing wide open, of course. Are you using a focusing cloth? And a loupe? The cl oth will make a huge difference. A fresnel lens can also be used in conjunction with the GG, but will make a much smaller difference, and has its own disadvanta ges (brighter image, but harder to focus).

Ellis Vener
3-Aug-1998, 13:59
All three of my large format cameras have fresnel lens in them and I do not find them hard to focus, especially with normal to long focal length lenses. If you are having trouble with your dark cloth being awkward to deal with or too much l ight bouncing off of the ground let me suggest you try the Darkroom Innovations darkcloth. It has an elasticized collar that goes completely around the back of your camera, and the bottom of the enclosure closes with velcro, except at the b ack where you put your head through. A good loupe is important to, I use the (ex pensive) Schneider 4x loupe but more and more I like using the Toyo 3.5X ground glass viewer. Thirdly, it is important that you remember to move your head aroun d to find the best angle to view different parts of the image; light rays travel in straight lines and the best way to see them is to put yourself in their line . Finally: patience. When you get under the darkcloth let your eyes adjust for a minute or so, like going into a dark movie theater on a bright day.

5-Aug-1998, 08:59
Just a couple other hints, moving your head for optimum viewing is very importan t, as Ellis stated, just remember that means forward and back and around in a ci rcle. I would also recommend that you go out and practice focusing on a bright s unny day, the more sun light the better. Once you learn how all the areas of the ground glass look, the easier it will be to recognize that "look" in more subdu ed light. Lastly, some lenses just look dark, thier maximum f-stop not with stan ding, your may be one of those. Try to borrow a more modern lens and see what it looks like in comparison.

Alan Gibson
6-Aug-1998, 06:28
And here's a tip I've never seen published: I got myself a pair of +4 dioptre (v ery strong) reading glasses. This is because I have difficulty focusing on the s creen under the cloth when it is 8 inches in front of me. With the glasses, no p roblem, I can see the whole screen to set up the composition and movements. But I still use a loupe for fine focusing.