Unsharp after burning

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kpphoto - 04 Nov 2004 23:42 GMT

I am having a problem with sharpness when I am burning in an area of a
print. I am using a D5 with a dicro head. On larger prints, 14x14 and
up from a 6.45 neg, I have areas that go out of focus almost like a
doubling of the image over the original. The enlarger is stable & so
is the easel. It does not happen all the time. It is sharp on a
straight print. What varieing factor am I overlooking.
The lens is stopped down 4 stops. I use my hands halfway between the
lens and paper with a large opening than smaller. Is it a form of
diffraction that is causing the image to do this? Has any one had this
happen?

Keith

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Michael A. Covington - 05 Nov 2004 02:14 GMT

Does the negative bend, from heat, after the light has been on for a while?

>I am having a problem with sharpness when I am burning in an area of a
> print. I am using a D5 with a dicro head. On larger prints, 14x14 and
[quoted text clipped - 8 lines]
>
> Keith

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Francis A. Miniter - 05 Nov 2004 03:16 GMT

When burning and dodging, I use a piece of flat black paper or board to absorb
light from the enlarger instead of reflecting or refracting it. Your hands are
curved and are also bright and may cause light scattering.

Francis A. Miniter

> I am having a problem with sharpness when I am burning in an area of a
> print. I am using a D5 with a dicro head. On larger prints, 14x14 and
[quoted text clipped - 8 lines]
>
> Keith

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jjs - 05 Nov 2004 03:41 GMT

kpphoto wrote:

>[...] I have areas that go out of focus almost like a
> doubling of the image over the original.

That is usually indicative of negative movement, usually from heat but that
seems unlikely in your case. Is there anything else that might be making the
enlarger move?

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Ken Hart - 05 Nov 2004 04:46 GMT

> I am having a problem with sharpness when I am burning in an area of a
> print. I am using a D5 with a dicro head. On larger prints, 14x14 and
[quoted text clipped - 8 lines]
>
> Keith

Just a guess: Is the lamp heat causing the negative to "pop"?
Possible causes: Are you using a glassless negative holder? Does this only
happen with longer exposures and not shorter exposures? Is the fault more
noticeable in the center of the print than the edge (the edge of the neg
would be held solidly and can't move)? What is the room temperature-- can
you aim a fan at the enlarger head (taking clear that the vibration of the
fan doesn't affect the enlarger)?

Ken Hart

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Stefan Kahlert - 05 Nov 2004 10:24 GMT

> up from a 6.45 neg, I have areas that go out of focus almost like a

"areas" that are sometimes but not always blurred... sounds like you
are using a glassless carrier.

> doubling of the image over the original.

If the neg pops (forth or back) between basic and additional exposure
the image will be blurred the way you describe it.

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Gregory W Blank - 05 Nov 2004 14:33 GMT

> > up from a 6.45 neg, I have areas that go out of focus almost like a
>
[quoted text clipped - 5 lines]
> If the neg pops (forth or back) between basic and additional exposure
> the image will be blurred the way you describe it.

Yep As stated;
120 film on longer exposures is suseptable to negative popping
and that would cause the problem described. I've never seen it happen
because 99% of my negatives print around 15 seconds at mid range on the
apeture scale.

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Mike King - 05 Nov 2004 18:01 GMT

Try a carrier with glass for 120. Sounds like negative popping for sure.

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darkroommike

----------

>
> > > up from a 6.45 neg, I have areas that go out of focus almost like a
[quoted text clipped - 12 lines]
> because 99% of my negatives print around 15 seconds at mid range on the
> apeture scale.

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Stefan Patric - 05 Nov 2004 19:35 GMT

> I am having a problem with sharpness when I am burning in an area of
> a print. I am using a D5 with a dicro head. On larger prints, 14x14
[quoted text clipped - 7 lines]
> diffraction that is causing the image to do this? Has any one had
> this happen?

If the change in the image is "large" as you say, this sounds like
negative pop due most likely to heat from the dichroic head. You say
this doesn't happen all the time. Does it happen mostly with longer
rather than shorter burn times? If yes, then it's probably negative
popping. Check that your light head has the heat absorbing glass in
place. The only way to be sure this no longer occurs is to use a
glass carrier, but that of course introduces a whole other set of
problems.

Are you changing the f-stop of the enlarger lens between the primary
exposure and the burn exposure? If yes, you may be experiencing lens
focus shift. This is usually more of a problem with Tessar (4
element) or Trinar (3 element) lenses than with Plasmats (6 element)
ones. In any case, always do the final focus with a grain focuser at
the printing aperture, and to be on the safe side, don't change the
f-stop when burning.

Is your enlarger REALLY stable? Do this test: Put a glass of water
on top of the enlarger head, and have someone walk/stomp around your
apartment or home. Do little vibration rings form in the water?
Does a large vehicle going by outside do the same thing? Rap firmly
with a couple of fingers on the side of the dichroic head. How long
does it take for the water rings to decay? If in any of these tests,
it takes longer than about 20% of your normal print exposure time,
you should consider bracing your enlarger and/or the column. I have
a Beseler 45M which is mounted on a custom-built, free standing bench
on a concrete floor, and it only takes about 2 to 3 seconds for the
water to calm. My base exposure is around 20 seconds.

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Stefan Patric
tootek2@yahoo.com

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