Poor focus

[Kilgallb]

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?

 

[B.S.Kumar]

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

Kumar

 

[BrianShaw]

https://toyoview.com/content/fresnel_installation_instructions.pdf

 

[koraks]

Last weekend all ten shots were really out of focus.

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.

 

[Don_ih]

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?

 

[bdial]

Are you using a loupe?

 

[Ian C]

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

 

[John Wiegerink]

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?

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

 

[Kilgallb]

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

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.

 

[BrianShaw]

Which 90 SuperAngulon? I’ve noticed that my f/5.6 in a Copal 0 seems prone to vibration. I’ve not done experiments but think it so from experience.

If you aren’t already, a 90-degree adapter seems to help a bit.

 

[John Wiegerink]

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.

Is that the only lens you are using? Are any of your other lenses doing the same thing?

 

[Doremus Scudder]

Quick test to see if ground glass = film plane:

Set up a ruler/yardstick at an oblique angle to your camera. Use a longish lens up close, wide open. Focus on a particular mark (e.g., the 6" mark) and make an exposure. Do not stop down. Develop the film and see if the focus is shifted from the focus on the ground glass. If so, the film plane is likely different from the ground glass. You'll need to remedy this by 1) checking the placement of your Fresnel to make sure it is correct and 2) shimming or otherwise repositioning the ground glass so it is in the proper position.

Other causes of out-of-focus:

Your lens has an issue. It could be as simple as an element not screwed in all the way or having lost a spacing shim during disassembly or something as catastrophic as having dropped the lens and misaligned an element. Make sure this happens over several lenses. If not, look to the lens in question. I had a 300mm lens that wouldn't focus correctly till I discovered that the rear element was not seating properly due to interference with an overly-thick lens board. Do check for cloudiness, scratches, etc. if one lens is the culprit.

Camera shake. Camera movement has a specific look under magnification, so examine your negatives under magnification (in the enlarger with a grain focuser is good). Look for directional blur, double images, etc.

Film holder seating problems. Make sure your film holders are seating properly and that there is not debris or other obstacles holding the film holder away from its engineered position. Something like a doubled-over light baffle or gunk can make a big difference.

Film loading problems. Check your negatives to make sure the rebates are all there and squarely-aligned with the film edges. If not, you may be loading your film with one edge outside the guide channel.

Ground glass seated improperly. If you've had the ground glass off your camera for cleaning or whatever, it may have gone back together not properly aligned. You may have lost a shim or got something blocking proper seating of the focusing screen. Check to make sure everything is as it should be.

Another suggestion. Try not focusing stopped down to taking aperture. Your focus will be more accurate if you focus wide open as long as your lens does not exhibit focus shift. The bandwidth of acceptable focus increases as you stop down (hence DoF), but that can keep us from easily identifying the sharpest point of focus.

Also, make sure that locking down your focus is not introducing some movement. Likewise, make sure that inserting the film holder is not shifting the back, etc., etc.

If your problem is happening only occasionally, i.e., "every second time," then look for one of the causes that is consistent with that scenario, such as particular lens, moving something when locking down or inserting the holder, etc.

Hope you find your problem,

Doremus

 

[Sharktooth]

If the lensboard is the only thing that's been changed recently, then check that it fits tightly to the front standard with no for/aft play.

Grab the lens and try to push it towards the camera, and then pull it away from the camera. If you feel any for/aft play, then the lens board may not be retained tightly to the front standard. It can then shift forwards or backwards after you've focused, if you jiggle the camera (such as when installing the film holder).

 

[Kilgallb]

Sorry to report, my beloved 90mm super-angulon is caput. It will not focus sharply at any distance. I must have jarred it in transport and moved an element. Other lenses focus nicely.

 

[Sirius Glass]

Sorry to report, my beloved 90mm super-angulon is caput. It will not focus sharply at any distance. I must have jarred it in transport and moved an element. Other lenses focus nicely.

Find a good lens repair place.

 

[John Wiegerink]

Sorry to report, my beloved 90mm super-angulon is caput. It will not focus sharply at any distance. I must have jarred it in transport and moved an element. Other lenses focus nicely.

Wow, that's hard to loss to take and even harder to believe it happened in the first place. Does it rattle when you shake it? Are both front and rear groups screwed into the shutter tightly? As far as getting it repaired goes you might want to check what it cost to repair and what it would cost to replace. Sometimes it is cheaper to just replace it than it is to get it repaired. If you replaced the lens with the same model you could then sell your faulty front and rear groups in "as is" condition and the shutter alone as "good working" and probably get close to what you have to pay for a complete replacement lens.

 

[RalphLambrecht]

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?

Is overall focus poor or just corners? Is it limited to one film holder o all? Is the groundglass in there the right way around?

 

[Ian Grant]

Sorry to report, my beloved 90mm super-angulon is caput. It will not focus sharply at any distance. I must have jarred it in transport and moved an element. Other lenses focus nicely.

Sometimes LF wide angle lenses are shimmed, my 90mm Grandagon has two shims, my 80mm Super Angulon isn't. If a shim has been lost when fitting to a lens board that could be the problem.

The early post WWII 90mm f6.8 Angulon lenses were very hit-and-miss, in terms of sharpness, that's why Linhof started selecting lenses after testing them, by SN 5 million the issue was resolved, The late Dean Jones (Razzledog) found that the issue was inconsistent tube length of the Compur shutters, It was a batch of shutters only used with this Angulon, Dean machined the casings to the correct specification and that improved sharpness.

Does TheCameraStore have a repair department?

Ian

 

[Doremus Scudder]

Sorry to report, my beloved 90mm super-angulon is caput. It will not focus sharply at any distance. I must have jarred it in transport and moved an element. Other lenses focus nicely.

I had focus problems with my SA 90mm f/8 for a while till I figured out that the rear lens group was not screwing all the way into the shutter due to interference from the lensboard. Do check that both front and rear groups are seating properly.

Best,

Doremus

 

[Kilgallb]

Thanks for the suggestions everyone. The lens was real sharp when I first used it. I will get someone to check the mounting and shutter.

 

[Alan Edward Klein]

Did you check to see if the lens unscrewed a little in the front or back from the lens board? I found that happened to me and I had to just retighten it. But I don't know how that might effect focus. Can someone else here expand on this?

 

[Rod Klukas]

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

The first suggestion with a dowel works with a Ground glass, it does not work with a fresnel/ground glass. That is because the fresnel moves the focus 1/3 the thickness of the fresnel.

Also, in reality 7-8x is a bit too strong for a focus aid, with 6x being the ceiling, and around 4x the least agrivating to your eyes. Ansel Adam's did use a 6x Zeiss, I beleive, for many years. Or other sources.

The higher magnifications will magnify the grind of the glass and/or the fresnel lens. This can be especially fatiging to your eyes when working a long day, etc.

The Toyo 3.6x is an excellent choice. But others are good as well. You do want one with multiple lenses, achromatic, for best results.

Rod

 

[Kilgallb]

B

The first suggestion with a dowel works with a Ground glass, it does not work with a fresnel/ground glass. That is because the fresnel moves the focus 1/3 the thickness of the fresnel.

Also, in reality 7-8x is a bit too strong for a focus aid, with 6x being the ceiling, and around 4x the least agrivating to your eyes. Ansel Adam's did use a 6x Zeiss, I beleive, for many years. Or other sources.

The higher magnifications will magnify the grind of the glass and/or the fresnel lens. This can be especially fatiging to your eyes when working a long day, etc.

The Toyo 3.6x is an excellent choice. But others are good as well. You do want one with multiple lenses, achromatic, for best results.

Rod

I did change from a 6x to 10x loup. (l lost my 6x and started using an old slide viewer loup.)

My 210mm focuses well. The 90mm is damaged. I can hear something shaking inside. I must have banged it