tmax100 35mm unsharp mask questions

[group 11]

i think the film forum is as good as any. feel free to move if it fits

better elsewhere. <p>

 

<p>i have, over time, extensively searched this site and some other

sites for

some answers and have come up short of anything that i can confidently

take to

the darkroom. </p>

<p>groundwork:<br>

- 35mm negative panf developed in pmk <br>

- condenser enlarger<br>

- have duratrans and other diffusion materials<br>

- can work out registration issues<br>

- as mentioned, i've done research and have come up empty. further, i

own the

Radeka book on the subject, but although tmax100 is mentioned for an

unsharp

mask, it stops there. </p>

<p> </p>

<p>my questions are these:</p>

<p>1) using tmax100 as an unsharp mask, not a contrast mask, what

exposure time

would be a good beginning? the research i've done varies tremendously;

so much

so that there isn't a common ground that i could use even as an

educated guess.

the answers i've found range from setting the enlarger to an 8x10

height and

expose starting at 1 second all the way up to 30 seconds.... i imagine

some of

these are realistic, but aperture openings are missing from some of the

suggestions as well as the use of a diffusion material, etc.</p>

<p> </p>

<p>2) i could <i>probably</i> figure out the first question with some

hours of

trial and error (which i, naturally, would like to avoid), but i'd

probably fail

in that i've seen too many recommendations for developing the tmax100

us mask

and most are lacking one of the variables (time, dilution, temp). i

found some

suggestions for hc110 that are missing the temp (which i could assume

is 68),

but a) hc110 has been noted as the least favorable of developers for this

purpose and b) i don't own it :) i've seen suggestions for using

dektol, but

again, not all the variables are listed. i'd like to be able to use a

developer

that i have in the dr (pmk, dektol, rodinal, edwal ultra black (i've

seen this

used)). </p>

<p>so it's either many hours with too many variables in the darkroom

or some

help from you kind folks.</p>

[tom_menegatos]

I'd love to know how you work out the registration issues with 35mm. The couple of times I've tried it with unsharp maks haven't been all that easy. I've used ortho lith film in 4x5 sheets as the mask.

[donald_miller1]

For the unsharp masking that I do (4X5) I use aristo ortho half tone film. My process involves placing the halftone film emulsion side down on a black surface to prevent halation issues. I then place a sheet of unexposed and fixed halftone film (clear film base). Above that I place my camera negative emulsion side up. Above that I place a sheet of diffusion material which is then held down by a sheet of 3/16 in glass.

 

Exposure times are going to vary somewhat due to your camera negative density. In my case I develop my negatives to arrive at a 1.25-.45 net peak density and then create an unsharp mask of approximately .15-.35 peak density and this then brings my sandwich of camera negative and unsharp mask back to a 1.10-1.20 net peak density when I print. This then lets me increase the contrast filtration and gain the increased local contrast that unsharp masking is capable of producing.

 

In my system I find that an unsharp mask made with the film that I use and set up as described above will normally be on the order of 12-18 seconds at f-16 at an enlarger height of an 8X10 enlargement. My enlarger is a Saunder 4550 XLG. This enlarger has a 250 watt light bulb and your times will vary from my times if your enlarger is of a different light source.

 

If you persist in using the film that you choose in making unsharp masks then you must compensate for the difference between the ortho lith film iso 3 to your iso 100. That is five stops of difference.

 

This is not brain surgery. If you don't have a densitometer, then the unsharp mask peak density will be very weak (1/2 of a .30 ND filter)in the shadow regions of your camera negative and no density above FB+fog in the regions which correspond to your camera negatives highlight areas. If you make an unsharp mask of too much density you will know it in that you will not be able to get enough contrast on the print no matter how much you dial in on the enlarger. If you get too little density on the unsharp mask then you will not be able to dial in much beyond one half grade higher then the camera negative by itself.

 

Registration is not terribly critical on an unsharp mask (it is unsharp after all). The alignment of the two can be done close enough by aligning them on a light table.

 

I did unsharp masking on 35 mm 20 years ago. I do unsharp and sharp masking on 4X5 today. It is a tool, but a very valuable tool in many cases.

 

Now since you have Radeka's book, I can't understand why you didn't find his reference to ortho lith film. Good luck. If you have further questions, you may email me off post.

[d_poinsett]

Hi Will,

 

You are lucky to get such a comprehensive answer from Mr. Miller. I concur with everything he said.

 

I too recommend that you try using an ortho film for starters. It's way easier to manage this process with the safelight on (use red only with ortho film - not amber). I use Ilford Ortho Plus film.

 

If you insist on using TMX it can still be done but of course it must be done in total darkness. TMX is the film that Howard Bond uses for making his unsharp masks which he makes for virtually every one of his fine prints now.

 

The Duratrans from the Radeka kit knocks the light intensity down about 2 stops. With TMX you may need to use an ND filter, maybe as high as log 0.9, to get the light intensity low enough and keep the exposures to reasonable time lengths. With the ortho films the ND filter is usually not neccessary.

 

I stack the layers a little differently than Mr. Miller. From the top: Duratrans, glass, neg (emulsion up), ortho film (emulsion up), black paper, glass. With Mr. Miller's setup, he has an extra gap between the neg and mask film for extra blur. You can experiment with that. He also prints through the back of the ortho film (it has no anti-halation back). You cannot do that with TMX.

 

My standard exposure is 6 seconds around f-22. I use the Aristo V-54 cold lamp in my enlarger for illumination with the enlarger lens about 25 inches from the base. It is not uncommon to adjust the aperture or exposure time depending on the negative. I use HC-110B for 1.5 minutes. I'm sure you can use any of the developers that you mentioned but you will have to test. My negatives and mask densities are similar to those described by Mr. Miller.

 

I have experimented with registration systems but currently use a light table and magnifying goggles to do it by eye. I use a glass carrier and tape the neg to the carrier (non-acid tape). Then, with the carrier on the light table, I line up the mask on top of the neg and tape it to the carrier.

 

I learned to make unsharp masks from Howard Bond. I had the Radeka kit before that and could not get it to work although in fairness to Mr. Radeka I can see that if I would have experimented some more I probably would have gotten it. The thing I liked about Mr. Bond's workshop is that there is very little judgement in the process. Mr. Bond relies on density measurements and a set of initial tests that allow you to chose the correct exposures. Now that I know what the mask should look like, I could probably get in the ballpark without the densitometer. However, with density measurements and data from intitial tests, I usually make the correct mask on the first try and almost never need to make more than two.

 

Without Mr. Bond's process or access to a densitometer, experiment with what you consider a normal to slightly higher contrast negative. Try a few different exposure times, developer dilutions, and development times until you get a mask that looks extremely thin. Vary only one element at a time in order to see the effect. Keep notes. Once you get the developer dilution and development time established, that can stay the same from then on. You will only need to alter exposures. If your negative densities are consistent, the exposure times needed to make the masks will likely be consistent too.

 

Good luck.

[group 11]

folks; <p>

 

thank you very kindly for the comprehensive detailed responses.

<p>

i did indeed many times read the ortho references by Radeka. matter of fact, tmax is mentioned only in the back of the book, but it has been suggested to me to use tmax for unsharp masks and ortho lith for true contrast masks. <p>

 

i'll give this a whirl. thanks again.

[donald_miller1]

One other thing that I failed to mention was in regard to developers and dilutions. For unsharp masks using lith film, I use Dektol at a dilution of 1-30 and 70 degrees. I typically develop my unsharp masks for 1 1/2 - 2 minutes. Good luck.