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Atracksler
7-Sep-2015, 13:27
I don't have an enlarger.

Id like to try out some DP paper.

I do have flashed, and strobes... Anyone prefacing with a strobe/speedlight set to 1/32 or 1/64? or any other solutions without an enlarger?

Thanks...

Jim Noel
7-Sep-2015, 13:49
Get a very small incandescent bulb, 5W or 7 1/2W. Mount it in a receptacle about 18-24 inches from the paper. Use either a switch to turn it on and off, or something opaque to block the light path. This was the method used by press photographers 70-80 years ago, and it still works.

Atracksler
7-Sep-2015, 13:51
how long should I pre flash?

SMBooth
7-Sep-2015, 16:32
Depends on the bulb , distance etc. Test, your looking for the first sign of change.

Michael E
7-Sep-2015, 17:13
Point your camera a white wall. Make sure it's out of focus, preferably with the camera set at infinity. Set the exposure according to previous test results (meter the white wall wall and subtract x stops). Expose the DPP in the camera.

Gary Beasley
7-Sep-2015, 18:44
I made a preflash for printing from a small desk lamp that I wired a dimmer to then hung on the wall over the work table. Hooked to a timer it made for some very easy to control preflashing.

Atracksler
9-Sep-2015, 10:22
So there isn't a hard and fast formula, probably a box to test and then I can get rolling.....??

Peter De Smidt
9-Sep-2015, 11:16
Out-of-focus white wall, a piece of white acrylic in front of the lens...all of those should work. As a starting place, try placing the exposure on Zone 0, i.e. meter it and close down 5 stops.

Jim Noel
9-Sep-2015, 11:29
how long should I pre flash?

Make test strips. Pick the time which just shows density above paper white.

Peter De Smidt
9-Sep-2015, 11:34
Jim gives good advice. You might also try pre-flashing for the amount just before the time that shows density above paper white.

Eric Woodbury
9-Sep-2015, 12:03
Jim, I pick the one that is just before a change in paper white.

younghoon Kil
18-Jun-2019, 22:42
In the field, I set the ISO to 3, put a diffuser filter in front of the spotmeter, measured towards the dark part of the scene I was going to shoot, and then set this exposure to Zone II.
After pre-flashing, the actual exposure was taken with the dark part set to Zone III.
In this way, my first and second Harman Direct Positive Papers was developed very successfully.
But ever since then, all Harman Direct Positive Papers has been developed white.

When measuring exposure with a diffuser filter in front of the spotmeter, I wonder if it is correct to measure the dark part of the scene.
And after pre-flashing, do I have to shoot within 1 to 2 hours?

I was wondering if you could give me some advice.

Thanks,

Pere Casals
19-Jun-2019, 00:33
I don't have an enlarger.

Id like to try out some DP paper.

I do have flashed, and strobes... Anyone prefacing with a strobe/speedlight set to 1/32 or 1/64? or any other solutions without an enlarger?

Thanks...

You can preflash the paper in camera just before shooting, just point the camera to sky and defocus a lot, meter and apply the bellows factor (from the defocus bellows extension), in that way you may expose the preflash amount that the particular scene requires. Of course you may also preflash all paper in the holders at home, also with the camera pointing to a wall that's illuminated uniformly, for that I had been using a TV displaying a white screen.

If you do in camera preflashing it's important to use a lens with little fall-off, so a long lens with a large circle is suitable, also stopping a bit is good, and finally as you defocus the circle grows so you take the center of it, also mitigating fall-off.

Finally, if any preflashing method, you can make a "test strip". This is preflashing the paper several times and each time you insert the dark slide of the holder (say) half an inch, so in a silgle paper sheet you have several bands with different amounts of preflashing.

You may develop that "test paper" to see at what exposure level you start noticing fog density, and of course you may shot an scene with that "test paper" to see the practical effect.