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[Micah in NC]

Hello again,

I have tried a second type of Polaroid film, Type 72 (ASA 400), in my 4x5" Pre-Anny S.G. The first type I tried was Type 57 (ASA 3000).

It seems that Type 72 doesn't respond to the use of a red Wratten A filter (like #25) like "normal" films. I haven't seen a sensitivity graph or chart for Type 72, but this film is panchromatic, according to Polaroid.

The pack of Type 72 I'm using is slightly (about six months) out of date, but develops normally with good contrast.

The photos I just posted on the Speed Graphic board here were taken with this film. The first one was with no filter; the second one (of the MG sedan) was taken with a Wratten A filter. However, the skies look the same!

Instead of posting the pictures in this thread, I'll just give the link to save bandwidth: http://www.graflex.org/helpboard/viewtopic.php?topic=2495&forum=1&1

(Yes, the sky was blue that day--slightly hazy, but still blue.)

What would explain this? Do red filters not work on Polaroid Type 72 film?

Thanks in advance,
Micah in NC

[t.r.sanford]

As far as I know, "672" packs are the current version of Polaroid's good old 400-speed film, which I first used as "Type 42" in a "Polaroid 110" about 35 years ago. I've exposed a lot of the 4x5 packet variant, "Type 52," often through filters to enhance tonal separation when photographing small products. I never observed anything out of the ordinary about the film's red sensitivity.

As you've probably discovered by now, Polaroid film does not age gracefully; it tends to fall off the edge, soon after its expiration date. If I had to guess, I'd guess that this plays a role in the phenomenon you experienced.

You might try three or four exposures with a #25 or #29 red filter, using different filter factors, and a couple of exposures without the filter, say a half stop under and a half stop over the metered exposure value. The results could be informative.

[Micah in NC]

T.R.,

Thanks. I might try what you suggested. This Polaroid stuff is fun, but expensive...

--Micah in NC

[t.r.sanford]

Polaroid film certainly has its uses, but it is best used when somebody else is paying for it!

On rereading your discussion of the sky conditions, it occurs to me that the diffuse white clouds might explain a great deal. A sky like that is a good deal brighter than the foreground, and so is going to overexpose a bit.

A light but pervasive white cloud cover(almost what Kodak used to call "cloudy bright") is likely to provide enough red light to produce considerable density in the negative, even if the blue and green components are stopped. And you've applied a filter factor to lengthening your exposure so as to compensate for the lack of blue and green wavelengths...

With a deep red filter and a blue sky with no clouds, you get "moonlight" effects by deliberate underexposure. With normal exposure, you can get decent tonal separation between a clear blue sky and well-defined cumulus clouds, but in my experience, the effect isn't a whole lot more pronounced than it is when you use a deep yellow filter. But the red filter does provide a less natural (perhaps more interesting or dramatic) rendering of green foliage.

[Micah in NC]

T.R.,

I see my folly now. I needn't have expected a dark sky in those shots with the super-thin cloud cover/haze.

Hmmm. Now I'll have to try Type 72 film with a Wratten yellow K2 or red A filter on a sunny day when there is a TRUE blue sky and some nice, puffy cumulus clouds...

I'll just chalk those shots up to experience. BTW, Polaroid has spectral sensitivity charts for each of the 4x5" sheet films in the films' individual data sheets, available in PDFs on their website. (You will need Acrobat Reader to open them.)

The main film data page is at: http://www.polaroid.com/service/filmdatasheets/4_5/index.html

Type 72's data sheet (on page 4 of its PDF document) shows no sensitivity after about 650 nm. I think that's normal for pan films, but I don't know for sure.

Thanks,
Micah in NC

[ This Message was edited by: Micah in NC on 2004-04-21 08:26 ]

[t.r.sanford]

I think you're right about spectral sensitivity of normal pan emulsions. Many years ago, Ilford made a material called (I think) "HPS" with red sensitivity that extended beyond 700 millimicrons (what the rising generation calls "nanometers"), and it was thought to be extraordinary.

In my experience, the Polaroid xx2 emulsions (42, 52, 552, 672) have a "look and feel" that's a lot like "Tri-X" printed on #2 paper. The two materials seem to me also to respond similarly to tonal correction filters.

While you're at it, you might test a deep green, perhaps separation (#58 or #62) filter on a sky with clouds. This will darken the blue sky enough to provide good contrast with the clouds, but will lighten foliage, while the red filter darkens it. Depending on the effect you want, all these things can be useful.

[t.r.sanford]

Another bit of flotsam dislodged from the memory bank -- films with extended red sensitivity used to be referred to as "hyperpanchromatic." I can think of little use for this information, other than as something to throw into a sudden awkward pause in conversation, but there it is.

[Micah in NC]

T.R.,

Yes, I need to get busy and try some different filters on this Type 72 film.

I will hopefully be able to scan them and link them to this site (not actually posting them) when I do get done "testing," though since my film is outdated, such an endeavor may be of no use to other folks.

--Micah in NC