Poor focus

I am not talking about movements or tilt or swing, just how do you set focus on the ground glass.

I am at wits end. The last twenty or thirty sheets on my Toyo 45CF are not well focused. I thought I was not locking down focus and movements well enough or maybe things shift when I put the film pack in place. I carry a check now to make sure things are locked.

I even went to my optometrist, I have better than 20/20 vision with my glasses.

Last weekend all ten shots were really out of focus.

So how do I check that the ground glass is the same plane as a film pack?

All Toyo cameras, except for the 45AX, come with the fresnel lens installed in this configuration: Focusing Screen > Fresnel > Lens.
Check this first.

Kumar

Kilgallb said:

Last weekend all ten shots were really out of focus.

Click to expand...

Can you please show some examples? I'd like to understand a little better how severe the problem exactly is and perhaps see if there's a pattern to it.
Of course, also follow up on @B.S.Kumar's suggestion.

Is it perhaps cameras shake? Are you using a cable to release the shutter or your finger? Make sure the lens can't move in the board --even a cable would move the lens if the lens is loose.

Do you recheck focus after stopping down the lens?

Are you using a loupe?

A Quick Check of Film Position and View Screen Agreement

Use a small diameter wood dowel, say, 1/4" diameter to gage the distance from the front of an empty lens board to the ground glass. Position the dowel slowly and gently towards the view screen until it touches the ground glass. Holding the dowel in place, use a pencil to make a mark on the dowel flush to the front of the lens board.

Now insert the holder with a scrap sheet of film and use the dowel to touch the scrap sheet of film in the holder. The pencil mark should line up with the front of the lens board as before. Your view screen and holder-plus-film distances should agree. If so, then you need to consider your method of setting focus.


Setting Focus

Think about the depth of field you require for the given situation.

Determine the desired subject plane. This is where you’ll set the focus, even if the required zone of good resolution is much deeper. If hyperfocal focusing is wanted, carry a table of hyperfocal distances with you. They are easy to calculate with a calculator or using DOF Master. Such a table is easy to construct and record in a pocket notebook or on a 3” x 5” index card.

https://www.dofmaster.com/dofjs.html

Choose a large enough element in the subject plane with sufficient contrast that allows you to see it on the view screen.

Fine tune the focus using a loupe of about 7X to 8X so that you can set the focus accurately.

Lock the standards to the rail or bed.

Set the aperture to the required value.

Close and cock the shutter.

Make the exposure.


Hyperfocal Table Example

For the 4” x 5” format, I’ve chosen circle-of-confusion 0.10 mm. This is for a 90 mm lens. The values are aperture, near limit of DOF, and hyperfocal distance—the distance at which you set focus. The resolution should be acceptable from the near limit to infinity. If you're not satisfied, you can choose the next smaller aperture.

f/5.6, 7.2 m, 14.4 m

f/8, 5.1 m, 10.2 m

f/11, 3.7 m, 7.5 m

f/16, 2.6 m, 5.2 m

f/22, 18.3 m, 36.7 m

f/32, 13.1 m, 26.2 m

f/45, 0.9 m, 18.8 m

Kilgallb said:

I am not talking about movements or tilt or swing, just how do you set focus on the ground glass.

I am at wits end. The last twenty or thirty sheets on my Toyo 45CF are not well focused. I thought I was not locking down focus and movements well enough or maybe things shift when I put the film pack in place. I carry a check now to make sure things are locked.

I even went to my optometrist, I have better than 20/20 vision with my glasses.

Last weekend all ten shots were really out of focus.

So how do I check that the ground glass is the same plane as a film pack?

Click to expand...

Question?? Did this just start 20 or 30 sheets ago and was totally sharp before that?

John Wiegerink said:

Question?? Did this just start 20 or 30 sheets ago and was totally sharp before that?

Click to expand...

It was really sharp for several years. It is only in the last year I seem to get this random out of focus thing. Now it is every second time.

In answer to others, I use a jewelers loupe (x10) to check focus. I always check after stopping down.

I use a heavy manfrotto tripod and head. I have used it for years.

One thing that has changed is I now use a recessed lens board on my 90mm Superangulon. I will check for shake while pressing the cable release.