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rbrigham
10-21-2012, 04:00 AM
Hi

I am doing some portraits and would like to use a red filter to clear up blemishes on the skin
I know that this will not work due to the paper not being red sensitive
Is there another filter that will work with paper negatives

thanks

robin

ic-racer
10-21-2012, 08:07 AM
Hi

I am doing some portraits and would like to use a red filter to clear up blemishes on the skin
I know that this will not work due to the paper not being red sensitive
Is there another filter that will work with paper negatives

thanks

robin

?
The paper accomplishes what you intended without any additional intervention or filter.

desertrat
10-21-2012, 10:26 AM
Hi

I am doing some portraits and would like to use a red filter to clear up blemishes on the skin
I know that this will not work due to the paper not being red sensitive
Is there another filter that will work with paper negatives

thanks

robin
If you're using variable contrast paper for your negatives, you can use a yellow filter. It probably won't have much effect on reducing blemishes beyond lowering overall contrast. I've found a yellow filter lowers the contrast of variable contrast paper negatives considerably.

If you're using graded paper, I think that emulsion is blue sensitive, so red, orange, or yellow filters won't work.

polyglot
10-21-2012, 05:43 PM
Green and yellow filters should have similar effect as they both cut out blue light (yellow filter also admits red; irrelevant to paper) and therefore give you a lower-contrast image on VC paper, which is probably a good idea since paper contrast is much higher than film contrast. The spectral response of a green filter is often good for realistic-looking portraits too.

You can't make an image on B&W paper using red light though, so you won't get the spectral effects you would with a red filter on panchromatic film.

polyglot
10-21-2012, 05:44 PM
?
The paper accomplishes what you intended without any additional intervention or filter.

Actually it does the opposite. Paper is blind to red whereas with a red filter you're aiming to record only the red light.


Edit: has anyone tried using RA4 for paper negs? One should be able to get fairly panchromatic sensitisation (though the spectrum might be really lumpy or gappy), colour filters on the objective lens will work and if you skip the bleach (just fix) there will be silver in the image that will allow you to make a contact print to B&W paper. I don't think the dyes in the paper would be very useful, e.g. red light will produce cyan dye, which will not cause a density change when printed to a B&W paper. Bonus: supercheap.

MattKing
10-21-2012, 06:02 PM
Actually it does the opposite. Paper is blind to red whereas with a red filter you're aiming to record only the red light.


Edit: has anyone tried using RA4 for paper negs? One should be able to get fairly panchromatic sensitisation (though the spectrum might be really lumpy or gappy), colour filters on the objective lens will work and if you skip the bleach (just fix) there will be silver in the image that will allow you to make a contact print to B&W paper. I don't think the dyes in the paper would be very useful, e.g. red light will produce cyan dye, which will not cause a density change when printed to a B&W paper. Bonus: supercheap.

Wouldn't the RC substrate cause a bit of a problem?

I guess if you did this, it would be necessary to add an orange filter similar to the mask in C41 colour film.

jnanian
10-21-2012, 08:02 PM
hi robin

your previous thread asked about fast paper ...
using poly contrast filters ( red + yellow ) are about a 1.5x "base" ( non filter) time
( you can test this in your darkroom )

what you might want to do is COAT your own paper with a liquid emulsion
use THIN paper, or use SINGLE WEIGHT PAPER then with PENCIL LEAD retouch the negatives on the reverse side
and contact print them.

( that is the way paper has been retouched ( and FILM ) for 100+ years ... )

it really isn't too hard ... and you can probably pick up
a ROC retouching stand on eboink for 50$ or less...

if you are freaking out about your slow exposure ( asa 1-18 ? ) with liquid emulsion
you need to work with your subject ( even kids ) to tell them what the game is.
shoot bright! overcast days ... even if your emulsion / paper is asa 1
that is 1/15 @ f4 which isn't too bad ...
ilford mg seems to be faster so that is about 60thS @ f4 which sounds about what you might want.

i've photographed people ( adults ) who had to remain still for 45 seconds or more
and kids ( under 6 years old ) who had to stay still for 5 or 10 seconds,
so i don't think 1/15 or 1/60th S is too slow ...
use FB paper so you can easily work the back with pencil.

i'm not sure what the speed of slavich paper is, or if you can get it anymore, but
if you don't want to go the liquid emulsion on THIN paper, it is the only current single weight paper
you will be able to find ... and contact prints from single weight paper are easier than
double weight ...

paper negatives are probably one of the most fun thing there is !
good luck !
john

polyglot
10-21-2012, 09:48 PM
Wouldn't the RC substrate cause a bit of a problem?

I guess if you did this, it would be necessary to add an orange filter similar to the mask in C41 colour film.

Seems to me it'd be the same RC substrate as present on RC B&W papers.

While my understanding of C41 masking is a little shaky, I don't believe it's necessary in order to get a balanced exposure from RA4 - see the Rollei maskless film for example. The orange mask is not a uniform filter layer but rather a dye layer that gets produced during development to counteract shortcomings spectral sensitivity of the cyan dye. You can have maskless C41 film, it will merely have poorer colour accuracy.

However CTO (daylight->tungsten) conversion filter might be beneficial since RA4 is tungsten-balanced for use in an enlarger. Unfiltered use in daylight would (I imagine) hit the blue layers much more strongly than you want.