Re: critique on infra article and more questions

[ADavidhazy <ANDPPH@xxxxxxxxxxxxxxxxxx>]

Chris, ... not much time to review the whole article but here are some thoughts
on your questions:

>      Bertha raised an interesting question.  Does putting a red filter on
> your lens INCREASE the amount of infrared light available to the film?  From
> what I understand of filters this is not so, it just decreases the visible
> light it blocks.

Putting a filter on a lens will decrease the amount of ALL wavelengths. Some
more soem less but since no filter material is completely transparent at all
wavelengths some minute amount is always lost when an additional "element" is
added to a system. 

>      Is there truly no difference with Konica with the 15, 25 and 29 filter?

Depends on the color of subject. It has to. The transmission qualities of the
filters are slightly different ... slight changes in the spectral reflectance
qualities of red-ish subjects seems to me will cause a minute difference. It
depends on what your criterion of "no" is. And this is not a joke!  

>      Do fluorescent lights in the darkroom that take a while to subside
> truly not fog infra film if you turn them off and immediately start
> developing, e.g. in trays in the dark?

They _will_ fog film ... any film. Infrared sensitive films are sensitive to IR
as well as visible. Exposing them to any light or IR energy is bound to cause
a problem that manifests itself as fog. How much fog anyone can tolerate is a
matter of discussion. I am usually in a fog!

>      Should I not even recommend Rodinal as an infrared developer because
> the grain is golfball size?

Some people like grain. Grain with Rodinal is not golf ball sized ... unless
you play really, really, miniature golf. Rodinal has many redeeming qualities.
Fine grain is generally not considered to be one of them.

take care,

Andrew  o o  0 0 o . o  Davidhazy, Imaging and Photo Tech
         \/\/\/\/\/\/          http://www.rit.edu/~andpph
__________|        |_____________________________________

>      It is so nice to have you experts here to bounce these concerns off of.
> I do not want to xerox these notes for 40 students if there is wrong info on
> them.
> Chris

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