Focusing on Ground Glass??

[tron_]

Hello,

My name is Suraj and I'm a 25 year old photographer from Detroit Mi. I have been shooting film for about 6 years now and got into large format photography last winter after picking up a Toyo 45CX with a Fujinon 135mm lens.

I have had focusing problems and was wondering if someone here could give me some tips. Right now I am using a Nikkor 50mm 1.8 lens as a loupe. I place the lens filter threads on the ground glass and look through the lens (from the lens mount side) to check focus. From here I use the fine focus on the front standard to make sure everything looks good.

This hasn't been working well and my photos are many times out of focus.

Do you guys know what I am doing wrong? I've heard of people taking the lens off the camera to focus, some people say using a reverse lens like mine will result in the photograph being out of focus by the thickness of the ground glass since the image is made on the grain side of the glass, etc.

Any tips on what I can do to remedy the problem?

[Bob Salomon]

First make sure that your ground glass is properly installed and in proper register. Then return the lens to the camera and get a proper, focusing eyepiece loupe and adjust its focus so it is focused on the grain side of the ground glass.

[tron_]

First make sure that your ground glass is properly installed and in proper register. Then return the lens to the camera and get a proper, focusing eyepiece loupe and adjust its focus so it is focused on the grain side of the ground glass.

Thank you very much for the reply. So the loupe will allow me to adjust it's focus such that it will focus on the grain side of the gg?

Also is there any way I can get by with my current setup in the mean time?

[Bob Salomon]

Thank you very much for the reply. So the loupe will allow me to adjust it's focus such that it will focus on the grain side of the gg?

Also is there any way I can get by with my current setup in the mean time?

Not if you want to eliminate the problems that you are currently having.

[BrianShaw]

Try focusing without a loupe. You may be surprised at how well it works. (or is that, how GOOD it works?) Some folks report good success using drug store magnifying spectacles.

[cowanw]

I don't think your using the lens as a loupe will be the problem. You cannot make a Ground glass that is out of focus come into focus with a loupe. Incorrect use of a loupe will make a out of focus Ground Glass even more blurry.
Eyeball your focus on a ruler laid out long ways as a subject; write down the number you are focussed on. When that neg is developed you can measure how far you are out by looking at what is the best focus on the ruler.
If nothing is in focus you have a bad lens. If you are out by x amount the GG and your film are a different distances or you are misfocussing.
Remember you are looking for the best focus of your subject on the GG not necessarily perfect focus. After all your eyes may be bad too.

[Jon Shiu]

Your problem is due to placing the lens against the ground glass, not any "calibration" errors. First practice with the magnifier/lens by holding it a few inches from your eye and then moving it close to some print like a newspaper or something until in sharp focus. Note that the lens will be not in contact with the newspaper when in focus! Now that you have a feel for how far away from the ground glass to be it should be easy to use the "loupe" lens.

Jon

[Neal Chaves]

When using a lens like that for a loupe, and I have several surplus copier lenses for that purpose, first focus the loupe on the grain of the ground glass first and hold it there. Then focus the image on the ground glass.

[tron_]

Unfortunately I think you guys are correct saying using my reversed lens may be causing my focusing error. I did some testing today and wound up with blurry negatives again, very disappointing.

I decided I should just get a dedicated loupe. Are these steps correct for "calibrating" the loupe?

1. Remove lensboard
2. Put loupe against ground glass
3. Adjust the loupe so the grain of the ground glass is focused

Also, can someone recommend a loupe that is <$75? I was looking at the Toyo 3.6x loupe but it appears it is not made anymore.

Respectfully,
Suraj

[Alan Gales]

http://www.bhphotovideo.com/c/produc..._4x_Loupe.html

A little above your price range. You can check Ebay for a used loupe in your price range or buy some new reader glasses at your local drug store.