Using grains focuser with or without paper on the easel

[Don_ih]

Suppose that your enlarger has an elevator or crank so that you raise and lower the head of the enlarger as you grain focus.

Hypothetically you may find a discrepancy between the elevation at which one stops if focusing on the way up, versus focusing on the way down. A few iterations can rule out user mistakes.

And I would say that discrepancy may indicate a critical range within which all planes will produce a sharp print.

Anyone willing to try this and share their results?

Raising and lowering the head - wouldn't that also move the film? As in, that would keep the film to lens distance the same as the enlarger was adjusted?

I'd rather think of it as film and easel being two fixed points and the lens has one exact location between them that is absolutely correct. That a range of locations above and below that location will produce visually indistinguishable enlargements is a function of how a lens works at a certain aperture. There is no lens with an aperture large enough to completely eliminate that range and I doubt there is a lens with an aperture large enough to produce a range less than the thickness of paper.

I've done lots of looking through a grain focuser with paper under it and not under it these past few days. I'm getting hyperopic as I get older and this is speeding up the process.

 

[Sirius Glass]

Suppose that your enlarger has an elevator or crank so that you raise and lower the head of the enlarger as you grain focus.

Hypothetically you may find a discrepancy between the elevation at which one stops if focusing on the way up, versus focusing on the way down. A few iterations can rule out user mistakes.

And I would say that discrepancy may indicate a critical range within which all planes will produce a sharp print.

Anyone willing to try this and share their results?

I always move the enlarger up and down multiple times as I focus to make sure that the focus is in the middle of the range of positions. Since few have the magic hands to hit the focus exactly the first time every time, I would think most people do that.

 

[Bill Burk]

That’s how my DeVere works. I control the lens and head independently and I focus by moving the head rather than the lens. This allows me to focus without affecting print size since the lens stays stationary. There is a very small window of sharpness as I move it up and down, and as everyone else probably does, I move it back and forth to center in the sharpest point I can get.

Exactly what I expect. A small window of sharpness. Can you estimate how wide that window is? If it’s very small, paper will make a difference. If it’s 13 mm then the argument in favor of using a paper shim loses a bit of merit.

I suspect it’s small enough to sustain a few more pages of reasonable discussion.

 

[Bill Burk]

I set the enlarger negative to easel at 22 inches (for 35mm on 11x14 paper with wide margins).

I grain focused a 50mm lens at f/2.8 and then moved the head far up, and then brought the head down to focus.

Repeated bringing the head far down and then raising it to focus.

Repeated several times to get an average of four tries each.

Then brought head back to 22 inches to check focus was still good.

In most cases, coming down I landed above the mark while coming up I fell short of the mark. This was what I expected.

I didn’t expect the skew. I came closest on the way down - plus 2mm average. On the way up I was minus 5mm average.

This makes me think I might need to alter the skew by putting a 1.5mm shim under it. Not just a piece of paper.

While I am known to display a playful sense of humor, and sometimes I will tell a twisted tale to play devils advocate… I am not pulling your leg. I never would have guessed that an experiment would reveal that a 1.5 mm shim could possibly be what I need to put under my grain focuser.

 

[removed account4]

so glad MCM and TNP posted this, now I can sleep at night !

even though I religiously use paper, now I know if I forget, the world will not end.

 

[Bill Burk]

Shoot. My 1.5mm shim is only useful if grain focusing by raising or lowering the enlarger head. And I don’t do that. I focus the lens.

 

[Sirius Glass]

As far as I know my putting photographic paper under the grain focuser does not endanger any person's or animal's life.

 

[ic-racer]

Paper for me. I don't want to scratch the easel. Though felt would be OK too without disturbing focus in most cases.

 

[Don_ih]

As far as I know my putting photographic paper under the grain focuser endangers any person's or animal's life.

I assume you mean, "As far as I know my putting photographic paper under the grain focuser endangers every person's or animal's life."

 

[Vaughn]

[QUOTE="eddie, post: 2433922, member: 7343">>> I switched to a Saunders with the yellow base. I couldn't get a balanced print. The only change was the easel. I took a piece of black construction paper and placed it over half of the easel. Sure enough, the half covered was correctly balanced. The other half was off a bit. Anyone else experience anything similar?[/QUOTE]

Yeah -- I thought it was a well-known issue with yellow easels and color printing.

Drew: "All those little details cumulatively add up." Which is why we always told our students to place a piece of paper under their focusing devices. Good habit to think of all the factors along the line that affect sharpness.

 

[Bill Burk]

Raising and lowering the head - wouldn't that also move the film? As in, that would keep the film to lens distance the same as the enlarger was adjusted?

I'd rather think of it as film and easel being two fixed points and the lens has one exact location between them that is absolutely correct.

Right. And once that location has been gauged by a focusing tool, an error may exist in the position of the paper plane. To simulate correction for this error you can move the carriage up and down.

Or you can put a piece of paper under the grain focuser and not have any error. Machining is like this, if you can create a perfect sphere with two grinding wheels, why not make a perfect sphere

 

[Sirius Glass]

I assume you mean, "As far as I know my putting photographic paper under the grain focuser endangers every person's or animal's life."

Edited

 

[wiltw]

Right. And once that location has been gauged by a focusing tool, an error may exist in the position of the paper plane. To simulate correction for this error you can move the carriage up and down.

Or you can put a piece of paper under the grain focuser and not have any error. Machining is like this, if you can create a perfect sphere with two grinding wheels, why not make a perfect sphere

^^^
Why start with built in error by focusing with a grain enlarger NOT at the final plane where the exposure is made?! Yes, DOF may mask error, but it makes no sense to start with built in error. We focus our cameras by rocking back and forth to find the center of the range extremes, especially when our lenses are not fast aperture with shallow DOF. Should our engerler focusing technique be different in not striving for center of best focus?

 

[MattKing]

We focus our cameras by rocking back and forth to find the center of the range extremes, especially when our lenses are not fast aperture with shallow DOF. Should our engerler focusing technique be different in not striving for center of best focus?

And if it is impossible to see any difference between the two, which one has the built in error?

 

[Bill Burk]

I laugh because it was funnier before he corrected this statement:

Sirius Glass said:
As far as I know my putting photographic paper under the grain focuser endangers any person's or animal's life.

^^^
Why start with built in error by focusing with a grain enlarger NOT at the final plane where the exposure is made?! Yes, DOF may mask error, but it makes no sense to start with built in error. We focus our cameras by rocking back and forth to find the center of the range extremes, especially when our lenses are not fast aperture with shallow DOF. Should our enlarger focusing technique be different in not striving for center of best focus?

The whole reason for the discussion. But if it harms any person or animal I will take the position which is less harmful.

 

[Sirius Glass]

I laugh because it was funnier before he corrected this statement:

Sirius Glass said:
As far as I know my putting photographic paper under the grain focuser endangers any person's or animal's life.





The whole reason for the discussion. But if it harms any person or animal I will take the position which is less harmful.

Yes it was funnier.

 

[wiltw]

And if it is impossible to see any difference between the two, which one has the built in error?

What works for you works for you, and I will not try to convince you from your position. Perhaps others will see the logic, perhaps not.

 

[faberryman]

And if it is impossible to see any difference between the two, which one has the built in error?

The one that depends on depth of field (focus) to be in focus.

Let’s say you are taking a photo with your camera, and you rack the focusing ring back and forth and whatever you are focusing on snaps into focus and the microprism clears at exactly 7 feet. So you look at the distance scale on your lens and see that if you stop down to f8 everything between 3 and 12 feet will be “in focus”. Are the things at 3 and 12 feet really in focus or do they just look in focus? Whether it makes any practical difference is a separate question.

If you are shooting Tri-X developed in Rodinal you are probably going to want the grain to be knife sharp when your face is right in the print. If you used D-76 and are viewing from 8 feet you may not care.

It is not unlike getting your shutter calibrated. Does it really make any difference if the shutter speed marked 1/60 is really 1/45? At what point do you say it’s close enough for horseshoes and hand grenades…and your photography?

Of course, there is a continuum on stuff like this. I am sure I am pretty sloppy compared to Drew.

 

[Bill Burk]

The setup…

I’m thinking about 20 three inch prints will take me through the range of sharpest focus. I’ll cut the sheets to three inches, mark a diagonal line across so I can reassemble them in order after processing. I will focus with 10 sheets in the film box. Then I will put 9 more sheets in the box and one in the home made speed ez-el. Expose, put the exposed sheet in the paper safe and take the next unexposed piece of paper out from under. Each exposure will lower the height of the film box under the speed ez-el by the thickness of one sheet of paper until they are done.

 

[Vaughn]

But what if some residual longitudinal chromatic aberration causes the violet/blue focal plane to be slightly higher than the easel plane - say by, oh I don't know, the thickness of the paper?

Then we all get naked and sing 'Kodachrome' by Paul Simon in a circle around the processing sink until the Blues pass on.

 

[wiltw]

The setup…

I’m thinking about 20 three inch prints will take me through the range of sharpest focus. I’ll cut the sheets to three inches, mark a diagonal line across so I can reassemble them in order after processing. I will focus with 10 sheets in the film box. Then I will put 9 more sheets in the box and one in the home made speed ez-el. Expose, put the exposed sheet in the paper safe and take the next unexposed piece of paper out from under. Each exposure will lower the height of the film box under the speed ez-el by the thickness of one sheet of paper until they are done.

Sounds like a nice experiment. With lens set to what aperture? I say f/5.6...after all f/8 is used for 'cover my butt better'.

 

[Bill Burk]

I was thinking 2.8 to show “even wide open you can not tell until x sheets.” Hoping to find it’s less than 10 where you can see the difference. Going to make a video you can loop through and see where it becomes crisp and where it starts to get fuzzy

 

[wiltw]

I laugh because it was funnier before he corrected this statement:

Sirius Glass said:
As far as I know my putting photographic paper under the grain focuser endangers any person's or animal's life.





The whole reason for the discussion. But if it harms any person or animal I will take the position which is less harmful.

Since there is no harm to animal or person due to focus metholodogy, we come back to "But it does not matter!"

 

[MattKing]

And if it is impossible to see any difference between the two, which one has the built in error?

The one that depends on depth of field (focus) to be in focus.

And if you cannot differentiate between the two using either of the two measurements, which of the two depends on depth of focus?
Both of them, to exactly the same amount, within the same and almost completely overlapping margin for error.
With the tools available to you, you are unable to tell which is closer to being perfectly correct. The one without the paper is just as likely to be optimal as the one with the paper, and because you can't see a difference between the two in the finder, it makes no sense to prefer one over the other. Or to put it another way, if you focus without paper, and then insert paper, nothing about what you are able to see will cause you to change the focus. So don't bother adding the paper, unless it pleases you to do so.
I can certainly see the possibility of there being a technological approach that would resolve the issue to a much higher level of precision than the optical system we use when we make enlargements, and where the thickness of a sheet of paper at the easel would make a measurable difference, but:
1) we wouldn't be able to check or confirm that with our eyes and grain focusers - they don't work to that level of precision; and
2) that more precise system wouldn't make a difference to our prints, because the level of precision in the optical systems we use nicely matches the (quite high) level of precision that our optical prints can give us, when we use good technique on properly maintained, good quality equipment.

 

[wiltw]

I was thinking 2.8 to show “even wide open you can not tell until x sheets.” Hoping to find it’s less than 10 where you can see the difference. Going to make a video you can loop through and see where it becomes crisp and where it starts to get fuzzy

Really good idea, since increasing DOF with aperture is a simply arithmetic progression.