Re-Focusing W/Grain Focuser - Necessary Or Neurosis?

DF

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After the whole slew of test strips are in and I decide to go with whatever seconds/enlarger lens opening for the 1st print, I again check the grain in the focuser and notice there needs an adjustment at times and sometimes not. Is it heat from the lamp on the negative the cause - and is it temporary? Should you wait for a cool-down - then check again?
 

mrosenlof

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I use a grain focuser for every negative I print. But I don't adjust after the initial focus. Lamp heat can certainly affect how much "bow" you have in the neg, but I haven't felt to re-check focus after a test strip, or print. I'm using glassless neg carriers. I was once very fussy about lens sharpness. I'm less so these days, but still care, and don't think I'm making unsharp prints. whatever all that means
 

Theo Sulphate

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Maybe I'm neurotic, but I re-check the focus.
 

ac12

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Actually you should study the situation.
You WANT the print focused.
So you need to determine how much it is going out of focus and what time frame.
Is the film bowing after 10 sec or 15 sec or ?
And is this for ALL films or just certain films?
Maybe you have to preheat the film before making your print.
In the extreme, maybe you need to switch to a glass negative carrier.
 

Patrick Robert James

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If you don't have a glass negative carrier then yes, you probably need to refocus after the negative absorbs some heat from the lamp. Do yourself a favor and get a glass negative carrier! Life is too short to deal with accidentally unsharp prints.
 

RalphLambrecht

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sharpness is a bourgeois concept.
 

juan

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With an incandescent head, the negative will pop. I've never seen a cold light do it. Don't know about leds.
Why wouldn't you want to recheck focus just before exposure anyway? Unless you agree with Ralph.
 

bdial

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If you check and notice a need to adjust, then yes, you need to check.
There are various things that could cause it though, any possibility the focus or head is creeping out of position, for example?
 

Alan9940

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Probably unnecessary, but I always do one final last check of focus with a grain magnifier just before making a final print.
 

MattKing

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A check of focus isn't necessarily the same as re-focusing. And you can do the check at the aperture chosen for exposure. So there isn't a big reason not to check.
 

tedr1

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The points made above are good, I'll add one.
A lot depends on the aperture setting of the lens, this changes the depth of field at the negative in just the same way that it is changed by the aperture of the camera taking lens. Using the lens wide open gives the brightest image for focusing and the most shallow depth of field, this combination is good for making focus adjustments, provided nothing changes. If the negative bows after focusing the focus adjustment is now incorrect and needs to be redone. Using the lens stopped down gives a more dim image however depth of focus is greater, best focus may be more difficult to locate precisely. In this situation the effect on sharpness of the negative bow after focusing is less due to the greater depth of field.
Many enlarging lenses are designed to be used closed down two stops or so.
If it seems negative bow is occurring a good idea is to make tests, prints aren't needed; let the negative and negative carrier cool, set the lens wide open, turn on the lamp and focus immediately, then with the lamp on watch the sharpness of focus while things heat up. If there is a change due to negative bow then refocusing is needed.
 

Arklatexian

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Theo Sulphate said:
Maybe I'm neurotic, but I re-check the focus.
Click to expand...

Theo, I am with you but I do have a question. Why should anyone care whether I do because it is necessary or because I am neurotic? What I do in my own darkroom is my business and no one else's and I am certainly not going to feel "guilty" if I recheck the grain one time or one hundred times. Not upset or anything, just don't think it is important........Regards!
 

Sirius Glass

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Once I was introduced to a grain focuser at Kodak, I have used one every time ever since.
 

Frank53

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If this bothers you, you better switch to glass negative holders. If the negative bows, it means it is not flat anymore, so you can refocus the middle and than the sides will be out of focus. Imo the only solution is keeping the negative flat, not refocussing. I switched to glass after I noticed the same problem and my prints look really sharp now.
Regards,
Frank
 
OP
OP

DF

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Just how heated up can a negative get so it renders the image differently then if it were cool?
 

kwm

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With my Durst enlarger I`m still using the small Paterson grainfinder, that I started with in the mid-seventies. Never tryed to get one of those overpriced finders. Making prints is just a hobby, no rocket-science ...
 

MattKing

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DF said:
Just how heated up can a negative get so it renders the image differently then if it were cool?
Click to expand...
When negatives get warm, they pop and curl.
Which means parts of them can go out of focus.
If you wish to maximize the benefit of depth of focus at the negative, you may need to adjust the enlarger's actual point of focus.
 

tim_walls

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Patrick Robert James said:
If you don't have a glass negative carrier then yes, you probably need to refocus after the negative absorbs some heat from the lamp. Do yourself a favor and get a glass negative carrier! Life is too short to deal with accidentally unsharp prints.
Click to expand...
Life is even shorter when it comes to dealing with bloody dust, though...

Having used both, I prefer glassless. But that may be because my "darkroom" is shambolic, and it's taken enough effort to conquer light without making it a cleanroom too...
 

Sirius Glass

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I will stick with dirty dust, not bloody dust.
 

RalphLambrecht

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well said!
 

RichardJack

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The answer depends on your vision. If your near sighted and don't have a problem getting close to the projected image you might not benefit from the focuser. If you do use a focuser place it on top of a waste piece of enlarging paper of the same thickness.
 

chip j

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Get a Leica enlarger, any model--only one glass surface to touch the neg & keep it FLAT!!
 

DREW WILEY

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First of all, not all grain magnifiers are crested equal. Some of the cheap ones are way off. Second, if you're not willing to use a glass carrier ... chuckle, chuckle (no sympathy).
 

Patrick Robert James

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That "put a piece of paper under the grain focuser" is basically an old wives tale at this point. Your easel can be moved quite a bit off from where you focus and it won't make a difference. The distance between the neg and the lens has to be critically maintained though. Any little change will cause a large effect, which is why glass carriers are good and negative "pop" is bad.
 
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