What is this? Mystery object to me...

[heartattackandvine]

Sorry for the stupid thread title, but I don't know what this thing is called. I got it when purchasing an old darkroom kit. I don't know what is it, and how it's supposed to be used... (Go ahead, laugh😀)

I am guessing it's something to do with the focussing when using the enlarger, but I could be wrong (and even if I'm not, I have no clue how to use it).

Many thanks in advance for solving my "mystery".

 

[rxmd]

It's a Paterson Micro-focus Finder, a grain focusing aid for darkroom use. The gray bit around the shaft is a shutter that moves, revealing a mirror underneath. There's an eyepiece under the top cap.

When enlarging, you put it roughly on the place where you want to check focus, then look through the eyepiece. You get an enlarged image of that portion of your picture. You can then focus your enlarger so that the grain from the negative is in sharp focus; if the grain is in focus, then so is the entire negative.

It works this way because the distance from the mirror to the eyepiece is the same as from the mirror to the bottom.

 

[Particular]

Ha ha ha...

It is a grain focuser. You place it under your enlarger, slide the white plastic open, and look through the top. You will see an enlarged portion of the image that is projected from the enlarger which you can then get nicely in focus.

 

[heartattackandvine]

Thank you! Now I can try using it. 😀

 

[nikon_sam]

Yes it's a Grain Focuser...one thing you want to do before actually using it is to make sure it's in focus...there should be a knob that will allow you to focus it...also when you do use it make sure there is a piece of paper under it that's the same thickness as the photo paper you're exposing...this will ensure you're focus is the best it can be...

 

[heartattackandvine]

Thanks, nikon sam!

 

[sevo]

Yes it's a Grain Focuser...one thing you want to do before actually using it is to make sure it's in focus...

Right. There is a single wire (or hair?) across the image plane - the eyepiece is adjusted with no negative in the enlarger so that the wire is in focus with relaxed eye. In use, you want to see both the wire and grain in focus.

 

[rxmd]

also when you do use it make sure there is a piece of paper under it that's the same thickness as the photo paper you're exposing...this will ensure you're focus is the best it can be...

I'm under the impression that in practice the difference in paper thickness is neglible. And as soon as you don't enlarge your print with the enlarging lens wide open, DOF completely covers the thickness of the paper.

In fact even whether you put a paper in there at all or not makes a difference that is completely neglible in comparison to other, much more important factors that impact the sharpness of your print - such as whether your enlarger head and baseboard are 100% parallel.

 

[bobbyrab]

You can use this to check if the head is parallel, by checking the focus of all four corners.