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Grain enlarger/focuser

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RalphLambrecht said:
as you suspected,the depth of focus eliminates this issue;there is absolutely no need for an extra piece of paper under the grain focuser;none!
Click to expand...
Ralph is right. Most of the time, I don't consider the height of the paper when I use my grain focuser. My enlarger lenses is normally used at f/8-11 at it's sharpest.
 
Doremus Scudder said:
I've always got a scrap piece of photo paper on the easel, upside down, so I can view the image on the white paper instead of the yellow of my Saunders easels. So, I place my grain focuser on that to focus. And, why not be as accurate as possible, even if the difference is negligible?

Best,

Doremus
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nothing wrong with that.
 
I generally don't put a sheet of white paper on my easel, as it's painted white already. But reading this thread, it has made me wonder why I don't do so when I OCCASIONALLY use one of the yellow set size easels. I will next time! :smile:

Terry S
 
I'm a couple of years late to this thread, but the title caught my eye when I was bored. I'm one of those who does use a waste print underneath the focussing aid. Although I understand that in the DOF(ocus) of the enlarger lens should take care of any focussing inaccuracy, I'm not convinced that careful focussing is pointless. Almost everyone uses their focussing aid in the centre of the image (indeed cheap ones like mine will only work near the centre). For various reasons, corner focus (curvature of the focus plane, curvature of the negative, misalignment of the enlarger head relative to baseboard) may be slightly different from centre focus. If you make an error the wrong way at the centre, the corners may be better focussed as a result, or they may be pushed further out of focus. In the latter case, DOF may not cover the error. So as Doremus said above, why not be as accurate as possible? Then at least you know have control, rather than relying on a fudge.
 
snusmumriken said:
Oooops! Sorry. (Creeps away...)
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Oh, dear. Didn't mean to come down like a ton of bricks. It was one of those threads that never ended, and even when it ended it didn't end.

At about the same time there was an interminable thread about the use of stop bath. It seems if folks can't find anything to talk about they talk about anything.
 
Nicholas Lindan said:
Oh, dear. Didn't mean to come down like a ton of bricks. It was one of those threads that never ended, and even when it ended it didn't end.

At about the same time there was an interminable thread about the use of stop bath. It seems if folks can't find anything to talk about they talk about anything.
Click to expand...

No problem.
 
snusmumriken said:
I'm a couple of years late to this thread, but the title caught my eye when I was bored. I'm one of those who does use a waste print underneath the focussing aid. Although I understand that in the DOF(ocus) of the enlarger lens should take care of any focussing inaccuracy, I'm not convinced that careful focussing is pointless. Almost everyone uses their focussing aid in the centre of the image (indeed cheap ones like mine will only work near the centre). For various reasons, corner focus (curvature of the focus plane, curvature of the negative, misalignment of the enlarger head relative to baseboard) may be slightly different from centre focus. If you make an error the wrong way at the centre, the corners may be better focussed as a result, or they may be pushed further out of focus. In the latter case, DOF may not cover the error. So as Doremus said above, why not be as accurate as possible? Then at least you know have control, rather than relying on a fudge.
Click to expand...

I can focus by eye. I did it for years. Then at Kodak I was shown a grain focuser and I have been sold ever since. I check the corners and my corners are sharp on my enlarger too.
 
Omid_K said:
When focusing, should I place the grain enlarger on a sacrificial piece of paper or directly on the easel? Essentially I’m wondering if they are calibrated to take into account the millimeter or so of paper thickness. I know some paper is thicker than others which is what got me wondering this. At the same time I’m thinking that the plane of focus may be deep enough to render this question moot.



Thanks,
Omid
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the error introduced by the paper thickness it's too little to worry about. Nevertheless it's easy and fast to use a scrap piece of paper for ease of mind.
 
RalphLambrecht said:
the error introduced by the paper thickness it's too little to worry about. Nevertheless it's easy and fast to use a scrap piece of paper for ease of mind.
Click to expand...

I agree and I use a piece of paper just to be sure.
 
Experiment.
Try making two prints. One with, and one without the focussing paper. Close down a couple of f stops,expose and process.
Examine the results with the strongest magnifier available to you.
You can then tell us if it makes any discernible difference. QED
 
snusmumriken said:
I'm a couple of years late to this thread, but the title caught my eye when I was bored. I'm one of those who does use a waste print underneath the focussing aid.
Click to expand...
It's totally OK to put paper under the grain focuser to account for the thickness of paper because it is more accurate.

It's totally unnecessary, proven by experiments.

I occasionally use a piece of paper, even though I proved there is a great range of focus at the easel.

With this setup, there is precision of 0.001” at the negative stage.

With 50mm lens and 35mm negative enlarged to 11x14, crisp focus falls within a range of 0.006” at the negative stage. With paper you can dial into precise and accurate focus. Without paper you throw away 0.001” of accuracy.

That’s about a sixth of the tolerance.

The time spent paying attention to this detail is better spent checking the cleanliness of your sink, because a stray splash of fix that you touch before picking up a fresh sheet of enlarging paper will ruin a print more quickly.

39CE346C-C57E-4CC6-B87D-A1747A4BFF97.jpeg
 
snusmumriken said:
Oh dear, what have I done, what have I done? .... :cry:
Click to expand...

Uh, you done did open a can of worms that have been beaten to death.

  1. It is more accurate.
  2. It does not matter.
  3. Do what you want.
 
One of the advantages for me of using a sheet of paper in the easel is I have various sheets marked out with grids or at least center axes. That helps me precisely align horizons or other important horizontal or vertical aspects of the composition should I choose to do so.
 
Ian C said:
This is essentially a restatement of post #8.

Many enlarging papers are about 0.0115” or about 0.29 mm in thickness. This can vary somewhat depending on the particular paper.
Precisely
In theory, the thickness of a sheet of scrap paper of the same type as you're using under the grain magnifier will help you to perfect the focus. In practice, it makes no difference. For example, when making an 8” x 10” full-frame enlargement from a 35 mm negative with a 50 mm lens the required magnification is about 9.1X.

At that magnification, and with the aperture set at f/5.6, the depth of focus about the image plane is 29.9 mm using circle-of-confusion diameter 0.029 mm. About half of the depth of focus lies above, and half lies below the image plane. Whether the grain focuser is resting on a sheet of enlarging paper or not won’t make a discernable difference in the result.

The main benefit of using an upside-down scrap print in the easel is that it makes rough focusing easy due to the reflectance of the white paper. This makes it easier to see the projection. It also makes sizing and composing the image (adjusting the position of the easel) to fit the projection easy.
Click to expand...
 
Just go 8 x 10 and contact print everything, never have to worry about grain focusers again! :smile:
 
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