Polapan 55 and reciprocity

[einar_faret_saastad]

I have recently tried the Polapan 55 pn. Great film!

The problem of getting the right exposure is discussed here in

several Q&As. I have had some good results exposing at ISO 32 and only

compensating for bellows extension. I normally use a 500w tungsten

lamp.

 

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However, when it comes to longer exposures, the outcome varies, and I

wonder if anybody can give some ideas about how too compensate the

reciprocity?

Thanks in advan

[andrea_milano]

It very much depends on what is the results which you wan to achieve,

you aim at a good positive 32 ISO is a good speed, if on the other hand

you aim at a good negative, I'd rather expose for iso 25 but it depends

on your enlarger as well.

I'd like to put an extra question to you and the readers, and tha is

can you expose for say 100 ISO and thefore develop longer or "warmer"

or a combination of the two?, I've read opposite opinions about this

and would like some direct experience reports.

In some cases I've seen work of photographers where clearly the

exposure exceeded the emulsion limits, how do they do that?

[walter_glover]

Einar,

 

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I have successfully used PN 55 at times - it gives a negative with

a distinctive tonality that can be useful in making a particular

statement about a given motif.

 

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The guidelines for speed and reciprocity I use are from Ansel

Adams' book Polaroid Land Photography - no longer in print

unfortunately. Tis is what he suggests and it has worked for me:

 

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Suggested ISO = 50

 

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Print ISO = 64

 

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Negative ISO = 20

 

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Reciprocity:

 

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Metered 16 sec Factor 2X Time 16 sec

 

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Metered 8 sec Factor 2.5X Time 40 sec

 

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Metered 32 sec Factor 3X Time 96 sec

 

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Metered 64 sec Factor 4X Time 256 sec

 

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Expansion and contraction of development is possible within

limits but I shall have to get back to you later on that.

 

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Cheers ... WG

[walter_glover]

Sorry, obviously the table should read:

 

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Metered 8 sec Factor 2X Time 16 sec

 

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Metered 16 sec Factor 2.5X Time 40 sec

 

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A message preview for checking spelling, grammar and

typographical errors such as this would be a fine thing on this

site.

 

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WG

[walter_glover]

Einar,

 

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On the subject of expansion or contraction of the tonal scale of

P/N55 through variations in processing time, allow me to quote

from the 'Film Characteristics' in Appendix B of Polaroid Land

Photography by Ansel Adams:

 

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"Effect of development changes: Essentially none, since the

print and negative develop to completion. A very slight decrease

of the base-plus-fog density occurred at 60 seconds

(development). Insufficient development must be avoided, since

it produces discoloration of the negative when it is exposed to

light."

 

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Elsewhere on page 47 he says:

 

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"The use of development time changes to control values will

have some effect with the print from either of these films (55 &

665). The negative, however, shows very little, if any, response

to development time changes, except that a slight reduction in

filmbase-plus-fog density will occur if development is extended,

to about 60 seconds or more with Type 55.

 

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"Under any circumstances, it is essential that adequate

development be given to reduce completely the unexposed and

undeveloped silver remaining in the negative. Otherwise, when

the print is separated from the negative, silver which is still

sensitive to light will be exposed and it may then add density or

produce a discoloration in the low values (shadow areas) of the

negative."

 

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I hope that this helps with your pursuits.

 

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WG