[pure-silver] Re: Condenser size versus negative size?
- From: Nick Zentena <zentena@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 12 May 2005 15:54:58 -0400
On Thursday 12 May 2005 14:25, Edward C. Zimmermann wrote:
> Quoting Nick Zentena <zentena@xxxxxxxxxxxx>:
> > Am I right in assuming condensors should be bigger then the negative
> > diagonal?
>
> Typically a condensor is SIGNIFICANTLY larger than the negative diagonal. A
> condensor that is around the size of the negative would hardly colimate
> light to cover the negative format. How large must the lens elements be
> etc. differ from design to design just as the lens size and elements in an
> objective design are hardly the same. We are discussing optical systems and
> to talk about the size of a single piece of glass among many pieces of
> glass and illuminators does not really make sense. One way of thinking
> about a condensor is as a funnel. The top of the funnel is large and the
> exit is smaller. That's their reason.
I was looking at a 5x7 enlarger. The light source has only 6 1/2"
condensers
which is smaller then my 4x5 enlarger. I didn't think that was right. I'm
guessing some time in the past somebody replaced the old original head with
the current one.
Thanks
Nick
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