Grain focusers not agreeing.

[sruddy]

I have a 25X microsight and a plastic Peak enlarging focuser II prof. z Koana System. They are showing different focus points. Which one should I beleive to be correct??

 

[MattKing]

One or both of them have probably suffered damage, or been incorrectly adjusted. If the mirrors have ever come off in the past, they may have been re-attached or replaced incorrectly.
You check these by printing tests - preferably at the maximum aperture for your lens.

 

[Pieter12]

I wasn't aware the Peak was every made in plastic. Maybe not a Peak Koana System? Have you adjusted the focuser(s) before using them? There really shouldn't be any difference. In focus is in focus, unless the negative isn't flat the grain is on one plane.

 

[Sirius Glass]

Use the one that is correct.

 

[sruddy]

So how would I go about testing? I assume I should blow it up really large and and make two prints and the use a loop or macro lens to see the results?

 

[MattKing]

So how would I go about testing? I assume I should blow it up really large and and make two prints and the use a loop or macro lens to see the results?

Yes - or a simple magnifying glass.
A small piece of photographic paper should do.

 

[tedr1]

Some models include adjustment of the eyepiece, the PEAK does, not sure about the Micro. Before use adjust focus to obtain the line/cross hair in sharp focus.

 

[Jim Jones]

Some experts recommend placing a scrap of the photo paper you'll be using under the focusing aid to bring its bottom up to the level of the emulsion. Depth of focus should be enough to mask any errors from disregarding this.

 

[Patrick Robert James]

You need to adjust the focus to your eye. Look through the magnifier at a diffuse light then adjust the eyepiece so the line you see is sharp. Check them again. They will probably match if you do this. All three of mine do (Microsight, Patterson and a Micromega).

If they don't match after that, then focus with a magnifying glass and see which one agrees with actual focus on the baseboard.

Hope that helps.

 

[Mick Fagan]

I have not used that actual model Peak focuser, but it is similar to the one I own and use. Other Peak units have a focusing aid similar to binoculars whereby you twist the focusing until the grid line is sharp to your eyesight.

If I am correct, there should be a small locking screw on the right side, this allows you to slide the viewfinder part up or down which allows you to adjust the focusing system to your particular eyesight.

There will either be a line, or a circular image, you adjust the mechanism until the line or circular grid system is sharp to your eyes. Once that is done, lock the unit and you are ready to go. You should be able to see grain popping in and out like a door opening on any Peak I have used, they are the best in the world.

Mick.

 

[Sirius Glass]

Some experts recommend placing a scrap of the photo paper you'll be using under the focusing aid to bring its bottom up to the level of the emulsion. Depth of focus should be enough to mask any errors from disregarding this.

I do that. It is important to adjust the focus on the wire before using to focus the negative.

 

[darkroommike]

The eyepiece focus is to adjust the focus of the reticle, usually a wire or sting you can see in the finder. Eyepiece adjustments will not affect the overall precision of the finder. Scratch an "X" on the emulsion side of a piece of film, crank the enlarger up (not all the way), focus the enlarger, make a test print and examine the "X", repeat for the other finder. You may want to make a few prints at various apertures, marking the backs, and pass the prints around to your "panel of experts" to get a consensus. The test can be done at various apertures, etc. Ctein found that using a scrap of paper under the focus finder made little difference, but the wavelength of the light mattered with some lenses and papers,.

see "Grain-Focuser "Gotchas" in Post Exposure, 2nd. Ed. (at one time this book was a free PDF download.

And as Confucius famously did not say. "Man with two watches never knows what time it is."

 

[sruddy]

Thanks for all the replies. I havent determined which focuser is more acurate however they are so close that the dof should definitly take care of the difference. I lifted them of the easel last night and was amazed at how high I could go before the grain blurred!

The eyepiece focus is to adjust the focus of the reticle, usually a wire or sting you can see in the finder. Eyepiece adjustments will not affect the overall precision of the finder. Scratch an "X" on the emulsion side of a piece of film, crank the enlarger up (not all the way), focus the enlarger, make a test print and examine the "X", repeat for the other finder. You may want to make a few prints at various apertures, marking the backs, and pass the prints around to your "panel of experts" to get a consensus. The test can be done at various apertures, etc. Ctein found that using a scrap of paper under the focus finder made little difference, but the wavelength of the light mattered with some lenses and papers,.

see "Grain-Focuser "Gotchas" in Post Exposure, 2nd. Ed. (at one time this book was a free PDF download.

And as Confucius famously did not say. "Man with two watches never knows what time it is."

Thanks Mike, I fiound the pdf. Should be good reading.

 

[DREW WILEY]

Not all grain magnifiers are created equally. And some can change over time. How? I've seen models with cardboard shims on the base that can shrink or swell with humidity changes, truly a bad idea! Even Peak made several models. Their Critical Focus Magnifier is pretty much the gold standard. Pricey but worth it. Because they have a tilting eyepiece relative to the front-surface mirror, you can use them even in the corners of the projected image - good for checking lens performance
itself. But all this is still contingent on precise enlarger alignment, a truly flat easel, and flat paper itself. Then, for those of you who prefer glassless holders, good luck with any of this, and welcome to a warped universe.

 

[Arklatexian]

I do that. It is important to adjust the focus on the wire before using to focus the negative.

It is good to know that all you "Experts" put a piece of photographic paper under the grain focuser because I do that also. My grain focuser started working much better right after I had cataract surgery. Don't even use glasses to use the focuser any more......Regards!......Camera lenses got sharper also.

 

[DREW WILEY]

Well, of course you want to focus with the magnifier sitting on a sheet of paper of the same thickness as the media you're going to print on. But papers don't hold a totally crisp image, especially if there is texture present. So it's best to double check under the grain magnifier even when a strong pair of reading glasses tells you
it's in focus. I use both.

 

[David Lyga]

I put my eyeball right next to a hand-held magnifying glass, go down to the easel, and judge focus that way. It is easy, entirely and highly accurate, never misleading, and cheaper than anything else. It took me forty years to discover this.

Sometimes there is no inherent need for undue complexity. - David Lyga