Re: Your question about Bronica filmback and filters

[Jaap Los <imagefotografie@xxxxxx>]

Jaap Los wrote:
> 
> Hi Don,
> As owner of same equipment I'm very interested in the subject you
> forward to the List. IMHO a good quality filter placed in front of the
> lens doesn't alter the focus. When placed behind the lens there will be
> no alteration either. Also in your case where the filter is placed in
> the filmback. So you still have to correct your focus for IR as usual. I
> don't have that special 70 mm back, but I think that this also applies
> for your back. What do others think about this?
> 
> I own a 35 mm Wide Bronica filmback and it would be very easy to have
> the filter-sheet mounted over the filmwindow. I already used a #87C
> filter sheet between the filmrails on my Nikkormat EL. Technically it
> works beautiful, however you must be aware of dust and have it cleaned
> all the time! I have noticed, that the negatives are not so sharp and
> contrasty as compared with the #25 red filter. I have ordered a piece of
> #87 from W J Markerink and I hope, that this much thinner sheet (0.1 mm)
> gives better sharpness and contrast than the #87C (0.4 mm). Also fixing
> and cutting is easier.
> 
> This reminds me that some weeks ago a member of this list made a
> critical note about the #87C filter as compared with the #87. Why should
> we use a #87C, since a #87 gives you one stop more light and the IR
> effects are (almost) the same! I hope to find this out myself as soon as
> I have the #87-filter from WJ.
> 
> Don, I follow your filter-excercises with great interest and I like to
> hear from you soon!
> --
> Sincere greetings
> Jaap Los
> The Netherlands
> 
> See also my Infrared Photography Homepage with lots of information and
> links at:   http://home.wxs.nl/~losjb/

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