durst m301 color gradient filter help

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Juha Juntunen - 23 Nov 2005 19:28 GMT

What I am now asking is most likely simple and silly, but it has been
bothering me for quite some time.

My Durst m301 enlarger (black and white, no color head) has in addition to a
typical red filter some sort of a color gradient filter that can be turned
on. I don't have a manual, but I read somewhere that it is supposed to be
some kind of a focusing aid. Is this true? Any advice, how one is supposed
to use it? I admit that I am pretty clueless... it does not seem to help at
all if I put it on and try to focus - quite the opposite.

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Jan T - 23 Nov 2005 21:23 GMT

If there's a wheel or knob to turn this filter and if therewith the light
changes from yellow to magenta, then you are very lucky to have a variable
contrast enlarger head. Only the really red filter is used for looking at
the image with a paper in the easel, without actually exposing it.
The yellow-to-magenta color is ment for changing the contrast of your print,
where yellow = filter # 00 (the softest) and magenta = 5 (the hardest
contrast).
Focusing is better without red filter (and no paper in the easel of course).
Red light has a different diffraction than white light, hence focusing with
red filter gives you a slightly faulty result. Put your focusing device on a
piece of scrap paper to simulate the thickness of the photographic paper and
focus with the contrast filter you'll use for the final print.

| What I am now asking is most likely simple and silly, but it has been
| bothering me for quite some time.
[quoted text clipped - 5 lines]
| to use it? I admit that I am pretty clueless... it does not seem to help at
| all if I put it on and try to focus - quite the opposite.

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Juha Juntunen - 23 Nov 2005 23:04 GMT

> If there's a wheel or knob to turn this filter and if therewith the light
> changes from yellow to magenta, then you are very lucky to have a variable
[quoted text clipped - 13 lines]
> and
> focus with the contrast filter you'll use for the final print.

Thanks for your help. The filter is not a contrast filter, since I can
pretty much only turn it on/off the same way as the normal red filter.

Calling it a color gradient is maybe not so accurate, either. Sorry.
Anyways - the filter sort of splits the frame in such a way that the other
side is blue/cyan and the other side is almost the same red as the red
filter. In between these two colors there is some kind of a narrow
transition area, maybe.

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James Robinson - 24 Nov 2005 02:42 GMT

> My Durst m301 enlarger (black and white, no color head) has in
> addition to a typical red filter some sort of a color gradient filter
> that can be turned on. I don't have a manual, but I read somewhere
> that it is supposed to be some kind of a focusing aid. Is this true?

Yes, it's a focussing aid. As I recall, you move it into the light path,
and look at the image on the easel. When you move the focus wheel, the
images should move relative to each other. When the two color images
coincide, the image is in focus. Try it and let us know how it worked.

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Juha Juntunen - 24 Nov 2005 10:21 GMT

> Yes, it's a focussing aid. As I recall, you move it into the light path,
> and look at the image on the easel. When you move the focus wheel, the
> images should move relative to each other. When the two color images
> coincide, the image is in focus. Try it and let us know how it worked.

Thanks for the instructions! Now that I know how it is supposed to work,
stupid me, I actually might have a chance figuring it out :).
I will try it tonight one more time to see if it works or if it is at all
useful.

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Upper East Side - 24 Nov 2005 16:24 GMT

>Yes, it's a focussing aid. As I recall, you move it into the

light path,

>and look at the image on the easel. When you move the focus

wheel, the

>images should move relative to each other. When the two color

images

>coincide, the image is in focus. Try it and let us know how it

worked.

Yes, this is what it is.

It is not particularly accurate, and most users focus manually
or use a separate focusing aid.

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