Unsharp masking

[Drew Wiley]

Pere - one can certainly learn the basics of masking without either a densitometer of special registration equipment. But if you do it a lot or get involved with multiple masks per image, not having the right equipment is a prescription for insanity. There are two companies involved in making simple masking punches and registration frames for up to 4X5 film. My own gear was custom made for me by Condit, and I have full 4X5/5X7 and 8X10 sets. Sometimes this kind of thing comes up for sale used; but one
needs to be very careful that matched sets are involved : the registration glass, punch, strips or carriers must all have been
made at the same time or there will be a problem. Simply having the same brand and film size is not sufficient for the necessary
degree of accuracy. Or if one is a skilled machinist, they could make their own, but ideal glass types no longer exist, at least
in drillable Anti-Newton form. But you avoid Newton rings using a second thin sheet of diffuse polyester between the glass and
sheet of film. How often one makes masks is wholly a personal choice. If someone really enjoys it, they might gravitate toward
shooting images which are appropriate to begin with. I get plenty of practice during color printing season, but once in awhile
have nice 8X10 b&w neg which might benefit. It's hard to know until the final print has dried down. I did two images a couple
days ago, and one really sings having used the mask, and on the other image it was counterproductive. With color work athings
are actually far more predictable, at least if you've done a ton of homework first, like I have.

[interneg]

Does anyone make a simplified unsharp system for a stupid bloke like me? I mean something like a punch with adjustable micro variable offsets, and a printing unit to align them?
.

There's folk like Alistair Inglis if you want a full system, but if you're only making contrast reducing unsharp masks, you can do the registration by hand with a light box, a magnifier & tape. The contrast boosting masks are the ones that demand tight register.

[Jac@stafford.net]

IMHO this is not necessary for UM as common practice is to pin register the negative and the mask before contact exposure, so the registration system keeps it aligned again once the mask developed and sanwidched again with the pin register.

If you use the Alan Ross described way [...]

I do not do scanning of any kind. No digital in my image making.

Okay, I will continue to look for registration methods. I do have a Linhof punch, but no print platform which uses it. A punch without a registered negative holder seems useless. I am open to suggestions.
.

[Drew Wiley]

One tremendously important thing I forgot to mention is that only polyester films or tapes are dimensionally stable. Anything acetate can drive you nuts, esp in sheet film sizes as humidity or age related dimensional changes proportionately increase.
Even attaching sheets of film with common tape can spoil registration. I use thin mylar graphics art tape. Diffusion sheets should also be polyester, frosted both sides. The reason for this is that acetate sheeting is far more likely to show a pattern. The degree of diffusion is important. I generally use 5-mil material for sheet film, but keep 3-mil on hand as well. The more unsharp a mask is, the easier it is to register if you don't have dedicated equipment, but the higher the risk will be of getting a distracting halo around edges and details. My favorite films for masking are FP4 and TMX100.

[Jac@stafford.net]

There's folk like Alistair Inglis if you want a full system, but if you're only making contrast reducing unsharp masks, you can do the registration by hand with a light box, a magnifier & tape. The contrast boosting masks are the ones that demand tight register.

^{Thank you very much for that!}
.

[Dan O'Farrell]

I've been following this thread with a lot of interest, and with the back-of-my-head thought that I had read a pretty interesting article about "Unsharp Masking" a few years ago.

Tonight, I found my source, a copy of Photo Techniques magazine, Special Issue #11, " Mastering the Black & White Fine Print".
The article about masking in this issue is, as mentioned above, by Howard Bond.

The magazine has, as well, articles by or about David Vestal ( a favourite ), Gene Smith and Brett Weston.

This issue is a real treasure and I'm glad to have found it.

[Pere Casals]

but ideal glass types no longer exist, at least in drillable Anti-Newton form.

Drew, thanks for that practical information.

Just I'd like to point a tip about manufacturing glass parts, waterjet cutting machines do a very good job with any glass, you can cut any shape, make drills, etc.. and at very competitive cost, in special with series.

[Drew Wiley]

The problem is with drilling a very precise tiny hole for micopins in thick current AN glass which spalls quite easily. There is another method where you can very shallowly grind a slot for a registration strip on the glass. If the pins are outside the glass in an aluminum frame, some image area is lost. And registered tabs are not as accurate.This is a technical aspect of the craft that was once well known to the print trade. There are still companies like Ternes Burton and Olec Stosser making large punches and registration surfaces, incl vac easel, but the smaller film equip like 8X10 is now harder to find. 4x5 has two sources for basic unsharp work, but not a full selection. This could be done in a personal shop with a precision drill press (not cheap) or comparable milling machine.

[Pere Casals]

The problem is with drilling a very precise tiny hole for micopins in thick current AN glass which spalls quite easily. There is another method where you can very shallowly grind a slot for a registration strip on the glass. If the pins are outside the glass in an aluminum frame, some image area is lost. And registered tabs are not as accurate.This is a technical aspect of the craft that was once well known to the print trade. There are still companies like Ternes Burton and Olec Stosser making large punches and registration surfaces, incl vac easel, but the smaller film equip like 8X10 is now harder to find. 4x5 has two sources for basic unsharp work, but not a full selection. This could be done in a personal shop with a precision drill press (not cheap) or comparable milling machine.

With waterjet you can cut within 0.1mm precision, I cut plenty of 304 stainless steel in a waterjet workshop, several Tm yearly, and same machine is often also used to cut glass. The machine has to be calibrated for each kind of material, but it really makes a nice job with glass.

Waterjet cutting is used for demanding jobs, for example alluminium plate for fuselage and wings of the airliners made with alluminium, the advantage is that the material crystalline structure is not modified, if cut with laser the boundary of the holes for rivets takes a defective thermal treatment, and a crack may strat there with repetitive stress. Also as the part heats up with the laser cutting the metal dimensions change, and when the part is cold it has a different size

Waterjet cutting is smart and cheap, still for some jobs laser is preferred...

[Drew Wiley]

That isn't even remotely precise enough for this kind of application. I really don't want to make this sound daunting. One could simply take quarter-inch non-tempered float glass and drill it with special micro-drills. Then a simple sheet of 3-mil frosted mylar between the glass and film to suppress Newton rings. Best done by a skilled machine shop. Typical home-use or even cabinet shop drill presses have wobbly spindles. Or, if you're just working with 4X5 and smaller negs, just order a pre-made masking kit.