Re: Re: Bellows factor

----- Original Message -----
From: "Guy Glorieux" <guy.glorieux@sympatico.ca>

> > just plain physics of light.
> > This case is in no way different than if you were using a glass lens.
> > <snip>
> > 84.5 seconds (uncorrected for reciprocity, time)
>
> Guillermo,
> Can you remind me how you worked this out.
> Guy

Guy, sorry the delay in answering you, between my darkroom construction (I
didn't realize how much work, designing, planning, time and money it
required!!) and the demise of @home (network which my ISP use) my email has
been totally screwed up. Anyway, stop excuses and get to the answer .

The short answer is: ......well, short IMO, anyway.

Time Factor = ( B2 / B1 ) * ( B2 / B1 ) or more concisely:

Time Factor = ( B2 / B1 ) ^ 2 Remember that "^" stands for "to the
power of"

Where B1 =Initial bellows extension and B2 = New bellows extension

So for the original poster case:

Time Factor = ( 32.5 / 5 ) ^ 2 = 6.5 ^ 2 = 42,25

Since his "B1" exposure time was 2 seconds, the "B2" exposure time
(uncorrected) should be 2 seconds time the "Time Factor" of 42.25, which is
equal to 84.5 seconds.

The long answer, well, tell me if you need a longer answer.

BTW, the darkroom is slowly getting there, all framing done, all existing
electrical wiring, fixtures, outlets, wall shelves, etc had been removed
from the area, provisions for connecting sink to sewer system in place, new
rough wiring on ceiling and walls has also been done. I am ready now to go
rent a truck a bring stuff that doesn't fit in my car, stuff like door, wall
and ceiling material and some additional lumber. Once the wall and ceiling
covering is in place, it will definitely look like a darkroom.

PS: Andy, I still have not decided which door to use, but I am inclined for
a regular door. I saw a prehung door (is this what it is called) that is
intended for facing the outside (like for a garage side door for instance)
and has very good seals all around the 4 sides of it, it is an overkill as
far as strength goes, but it will be easier to install and just 20 bucks
more that if I buy a plain door plus hinges, jams, etc and do the whole
assembling myself.

Guillermo
Received on Sun Dec 2 12:38:37 2001