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Paterson Micro Focus Finder


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Yes I know there are several threads on the internet regarding this subject but they are almost invariably poorly written or do not address my problem. I focused the crosswire. That was easy. When viewing the eyepiece under an illuminated black and white negative all I see is a group of very bright dots from the enlarger lamp. I had to use less than full aperture for fear of damaging my eye.

 

I pre-focused the image with a magnifying glass. Then the focus knob was slowly moved ever so slightly in either direction while looking into the eye piece with both eyes open and relaxed. All I saw was the bright light from the enlarger and the crosswire. There was nothing else - nothing like grain or any kind of image - only blackness. I followed the directions and some of the hints from other threads but nothing worked. Either I am remiss in some way or the instrument is defective.

A book's a great place to hide out in - Trevanian
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Using this device is an acquired skill. Check the unit to make sure its intact because height matters. Find a negative with lots of dark area. Place this is the negative carrier and compose and focus on a sacrificial piece of photo paper. Place the grain focuser on the ease atop the photo paper. Focus the eyepiece of the grain focuser so the cross hair is super sharp. Now look through the eyepiece adjusting your distance to the eyepiece. If you can't make out a view of a granny image, try again without the sacrificial photo paper. It's hard to but once you get your first glimpse, it will be easy from then on.
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Alan:

I went back and tried again varying the distance to the eyepiece. You can see the sharply focused crosshair but about 30% of the center of the view is still dominated by the above mentioned extremely bright light. It's like looking at a super bright globular cluster as seen through my 10" Dobsonian telescope.

A book's a great place to hide out in - Trevanian
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You’ll get a bright area in the image if you try to focus anywhere but within the centre of the image - most focus finders are only capable of focusing towards the centre - but you should not be seeing multiple light if that is the case. I have one of these, it is very simple, and it sounds as if you have done things correctly. It might be that the mirror is misaligned, although I can’t see how you are seeing multiple bright lights if that is the case. Persever, I’m sure that if you can’t get it, something must be wrong with your finder. They are cheap enough on eBay.
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Different ones are different, but for some that I remember, the actual visible image is in a bright circle.

It should be bigger than a dot, but not quite as big as you might like.

 

Move your head around, and at an appropriate distance, such that the circle fills the visible area.

It might be that your eye is too close.

 

In any case, when it is focused right, if you move your head a little bit, the grain image will move along with the grid.

That is, that the grain image is in the same plane as the grid. The way the lens works, that isn't always true.

-- glen

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I think I had it for an instant using an old vintage Tri-X negative with a very dense area (the back of a white judo-gi) in the center but I couldn't repeat the experiment. The light is so bright even with a small aperture however. I have decided that any marginal benefits that may be had from the FF is not worth the risk of retinal damage. Anyone want a barely used Paterson FF?

 

Stuart: There are not multiple lights, only one very bright, dense cluster of dots that does not change when adjusting the fine focus on my Beseler Cadet II. I guess my description was not focused properly ;)

A book's a great place to hide out in - Trevanian
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I think I had it for an instant using an old vintage Tri-X negative with a very dense area (the back of a white judo-gi) in the center but I couldn't repeat the experiment. The light is so bright even with a small aperture however. I have decided that any marginal benefits that may be had from the FF is not worth the risk of retinal damage. Anyone want a barely used Paterson FF?

There are not multiple lights, only one very bright, dense cluster of dots that does not change when adjusting the fine focus on my Beseler Cadet II. I guess my description was not focused properly ;)

 

The height of this instrument is critical, it can't be altered in any way. What happens is -- the enlarger projects an image on the easel. This image must be focused by you before you use this instrument. You place the instrument atop the projected image. The image forming rays hit the mirror and reflect to the eyepiece. An aerial image, you can't see is generated except with the instrument, it is on the same plane as the crosshairs. The eyepiece of the instrument acts like the eyepiece of a microscope. You will see a greatly magnified view of the negative. The magnification is so high you see grain. You then touch up the focus with the instrument. Best if the enlarger lens is wide open, you don't want any depth-of-focus. Try wearing sunglasses. Try different eyepiece to eye distance. If the instrument's base height is off, due to damage, all is lost unless dimensions are restored. .

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Using sunglasses I was able to consistently see what you all are talking about. I then made a red filter for the filter tray and voila, "Bob's your uncle!" With the filter I can even close the aperture down a couple of clicks and still see the graiin and I don't need the sunglasses. It's very subtle but effective. I sure hope others see this thread and benefit from it. Too bad the instructions weren't more comprehensive.Thanks much.
A book's a great place to hide out in - Trevanian
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Using sunglasses I was able to consistently see what you all are talking about. I then made a red filter for the filter tray and voila, "Bob's your uncle!" With the filter I can even close the aperture down a couple of clicks and still see the graiin and I don't need the sunglasses. It's very subtle but effective. I sure hope others see this thread and benefit from it. Too bad the instructions weren't more comprehensive.Thanks much.

 

Until you see this for your self you will be skeptical -- The enlarger lens likely slightly changes focal length as you stop down. Also, most suffer from curvature of field. For critical work, stop down to the aperture you will be using to expose the print. Now touch-up the focus. Also try and determine if best results are obtained with or without the instrument sitting of photo paper. Likely it needs to sit on paper to get the right height. Also, to fort curvature of field, set the instrument off-center -- halfway between the center and the far corner of the image. Fine tune the focus at this off-center location at the f-stop you will be using when making the exposure. Also - I know what I am trying to tell you is good stuff.

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Glen: When I enlarge to 5x7 I find that f/8 is too fast but it works for 8x10. This is with Ilford multigrade.

 

Alan: I will certainly try what you said. Today I also found that the FF works more easily with the enlarger head further from the paper (i.e. 8x10 rather than 5x7).

 

All: I will probably stick with the new (to me) Tri-X for it's grain rather than T-Max 400. I like both but the former has a bit more contrast which I prefer. I've been using T-Max 100 for landscapes with no complaints but am almost finished shooting my first roll of FP4+. It will be interesting to see if the grain is more visible with the FF. BTW, all this fun is with 35mm film. I just started doing the entire process again starting in May after a thirty-seven year layoff. Starting over has been a trip what with so many products that I have never used before. Like the man said: "It's never too late to have a happy childhood."

A book's a great place to hide out in - Trevanian
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The Paterson focus-finder follows the same design as most others. I've owned both LPL and Paterson ones, and used the expensive Omega(?) one in a work situation. They all have an angled mirror and crosshairs or etched circle for the eye to focus on, together with magnifying eyepiece. The grain image is an aerial image, effectively floating in space. So this issue the OP is having is likely not limited to the Paterson make or design.

 

Incidentally, I found the tall Paterson 'major' grain viewer definitely the most comfortable to use, and the stubby LPL the least comfortable.

 

Focusing the eye on the aerial image takes a little getting used to in all cases. I also suspect the OP's enlarger may have a point-source/condenser optical system that will effectively focus most of the light from the enlarger lamp straight into the eye. Whereas most condenser enlargers use a semi-diffuse lamp that doesn't have such a coherent beam, nor such a strong Callier effect, which will distort the contrast of the negative.

 

There is an alternative design of focus-aid that uses a mirror and ground glass with no magnifier. However, the ground glass texture interferes with the grain image, and IMO this type of viewer is near useless.

 

I suggest one of 4 solutions:

1) Lower the wattage of the enlarger lamp.

2) Buy an ND filter to swing under the enlarger lens for focusing, or

3) fit the grain-viewer with an ND filter.

4) Fit the enlarger with an opalised bulb.

Edited by rodeo_joe|1
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The Paterson focus-finder follows the same design as most others. I've owned both LPL and Paterson ones, and used the expensive Omega(?) one in a work situation. They all have an angled mirror and crosshairs or etched circle for the eye to focus on, together with magnifying eyepiece. The grain image is an aerial image, effectively floating in space. So this issue the OP is having is likely not limited to the Paterson make or design.

 

(snip)

 

Yes, the image is, as you say, aerial, and it is possible for your eye to focus on it, even when it isn't in the actual right place.

 

I first learned about these devices when I was ten, from my grandfather, not long before I inherited his darkroom equipment.

 

As he told me, and as I wrote above, you move your head around just a little bit. (Too far and you miss the whole spot.)

The image should move along with the crosshairs.

 

If the image has enough edges, then you can focus on them, instead of on grain.

Though it usually only works close to the center, that is, straight below the lens.

 

I also inherited a test negative, which isn't photographic, and doesn't have grain,

but does have sharp edges. Assuming the enlarger holds film flat enough, you can

use a different film strip to focus on.

-- glen

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