Polarisers on Enlarger lenses?

[Stephen Frizza]

I used to work along side an extremely talented printer who pretty much said nothing to me in the year and a half I knew him but i did watch on and something he did which made me extremely curious was on occasion he would print with a polariser on the enlarger lens....why would anyone do this?

 

[John Koehrer]

Extend exposure time??

 

[Kevin Caulfield]

That was my thought too. Just to use the polariser as a neutral density filter in order to achieve a longer exposure time to get more control over the printing.

 

[Stephen Frizza]

he was printing on a durst 2501 which had inbuilt ND filers ...exposure time was not the reason.

 

[ic-racer]

Glass carrier? Minimize Newton's rings?

 

[polyglot]

Was it below the lens and attached in the traditional way? Was it a circular or linear? I imagine a CPL attached in the usual way (quarter-wave plate towards the film) would not be effective in eliminating newton's rings.

Did he know there were ND filters and/or had he exhausted their range? Was he pranking you?

Have you tried a polariser yourself to see if there is any difference other than ND?

 

[Poisson Du Jour]

Maybe to intensify primaries beyond what is available to adjust on the head. Other than that, probably trying to reduce the light; it does sound quirky and offbeat. The exposure problems of using a polariser are well known beside what Polyglot has pointed out re newton rings. Go after him and bring him back, then we'll haul him before the Honorable APUG Jury!

 

[Tom1956]

I put A-1 on my pork chops. Everyone knows you're supposed to use Heinz 51. But I can't afford both So I eat more beef as a rule anyway, so I settle on A-1. So as it seems with the OP when he really needs a ND.
On the other hand, if he shoots lots of lakes, inlets, and other water bodies and wants to see the fish below the surface in his prints and forgot to bring the polarizer when he shot it, then he uses it on his enlarger so the fish will print, instead of the glare off the lake.
Two perfetly viable answers. There aren't any others.

 

[MattKing]

Here is the brochure for the Durst 2501: http://www.durst-pro-usa.com/pdf/brochure/HL2501AF%20BROCHURE.pdf

With a closed loop system like the one used on that enlarger, maybe polarization of the light has a role to play.

 

[Neal]

Dear Stephen,

As the reason for using a polarizing filter on an enlarger must be quite arcane, wouldn't it be better to ask the fellow directly? (And then get back to us. )

Neal Wydra

 

[Stephen Frizza]

Dear Stephen,

As the reason for using a polarizing filter on an enlarger must be quite arcane, wouldn't it be better to ask the fellow directly? (And then get back to us. )

Neal Wydra

If only I could unfortunately I cant but I can say he was one of the countries best mural printers. I was 23 when I worked along side him. I would say hello to him every day and all I ever got back was a nod of the head if I was lucky, he was notoriously quiet but technically brilliant. He knew every intricate function of the enlarger, The polarizing filter was no joke and it wasn't used for all prints but I'm still stumped as to what it was for. Shrugs guess I will never know.

 

[AgX]

I guess Steven asks here as that other printer is quite taciturn...

 

[Mainecoonmaniac]

Possibly you can put 2 polarizers so he can have a variable ND filter.

 

[MDR]

To darken the sky of course and hold back the exposure for the rest. Use the darkening part of the polarizer on the non sky part and it will get lighter the sky on the other hand about 1/3 stop darker as it receives about that amount more exposure. Of course it could be that I am talking complete rubbish but it kinda seems logical from my point of view.

 

[AgX]

You could darken the sky if that light is polarized. What it partially is in nature.

On a film image though that polarisation will no longer be there.


The issue discussed here is about printing with a polarizer on the enlarger lens.

 

[cliveh]

I put A-1 on my pork chops. Everyone knows you're supposed to use Heinz 51. But I can't afford both So I eat more beef as a rule anyway, so I settle on A-1. So as it seems with the OP when he really needs a ND.
On the other hand, if he shoots lots of lakes, inlets, and other water bodies and wants to see the fish below the surface in his prints and forgot to bring the polarizer when he shot it, then he uses it on his enlarger so the fish will print, instead of the glare off the lake.
Two perfetly viable answers. There aren't any others.

 

[anikin]

You say he was a mural printer? Did he use a mirror under the enlarger to throw the image onto mural? If that's the case, then polarizer would make a lot of sense to eliminate the double image from the mirror. You see, unless you use the first surface mirror under the enlarger, you'll get two reflections - one from surface of the glass and another from the silver surface. It's been a while since I've taken the optics course, but polarizer might eliminate one and not the other as such improving sharpness of the image. However, I'm really just speculating here

 

[MDR]

I found some sources that claim that using polarized light in the enlarger gives deeper blacks and crisper clearer images

 

[DREW WILEY]

Seems like an interesting way to slightly mess up the sharpness and color balance of what you're printing. The only thing I can think of, is that
certain Durst enlargers could also be used as copystands, with a special sheet film holder (LARKA) going into the negative carrier position.
Then the system could be cross-polarized, with polarizing sheets over the lights themselves, and cross-polarization on the lens. But for
printing???? Makes no sense to me. I guess you could turn an enlarger into a giant polarizing macroscope if you had unlimited funds - that would be a fun pictorial project for rock slices thin enough to transmit light, but would probably be useless for true scientific purposes.

 

[polyglot]

You say he was a mural printer? Did he use a mirror under the enlarger to throw the image onto mural? If that's the case, then polarizer would make a lot of sense to eliminate the double image from the mirror. You see, unless you use the first surface mirror under the enlarger, you'll get two reflections - one from surface of the glass and another from the silver surface. It's been a while since I've taken the optics course, but polarizer might eliminate one and not the other as such improving sharpness of the image. However, I'm really just speculating here

I like that explanation. The polariser will have no effect on metallic reflections, but will help to cut down front-surface reflections off non-metallic (glass) surfaces.

Was there a mirror involved when he was printing these murals?

 

[DREW WILEY]

Why on earth would anyone use anything other than a front surface mirror in a serious optical system? But you'd still have to polarize the light in the first place. So no answer there. ... A long time ago there was an analog predecessor to holographic images, a Dupont Vectograph film,which you could enlarge onto, with polarized light I think, and create a 3D color print. A very complex process; and of course, nothing directly related to the present question, but interesting anyway. ... So I'm just going to take a wild guess and suggest that this guy might be practicing some kind of old wives' fable about printing, with no scientifically real advantage.

 

[cliveh]

Perhaps he was trying to impress you by doing something that he knew you would not understand and he didn't either.

 

[Hexavalent]

"he was printing on a durst 2501"

Isn't that horizontal enlarger? If so, the mirror concept doesn't make sense.

 

[Prof_Pixel]

I had heard that in the 'old days' (like the '30s) folks used to do things they felt gave them 'an edge' like spit in their developer. I wonder if this is the same sort of attempt to 'get an edge' on other printers.

 

[Jim Jones]

Why on earth would anyone use anything other than a front surface mirror in a serious optical system? But you'd still have to polarize the light in the first place. So no answer there. ...

A front surface mirror certainly would be preferable. It would require more care in an open mount than they do in a SLR. The mirror or prism as sometimes used on process cameras should work well. If one must use a rear surface mirror, the polarizer would reduce the ghost image from the front surface, although not quite eliminating it completely.