I thought I'd pass this on: I've built a pinhole
shutter around the Graflex "Speed-I-O-Scope" shutter.
I know that a lot of pinholes are just affixed to a
box & then covered with black tape, which is removed
for the exposure. I wanted to cheat a bit and use my
4x5 & not have to resort to the tape s
I used a graphing calculator.
John
> What do you call this sort of shareware and how would you find it on the
> internet?
> Hello Shannon,
>
> Taking into account all uncertainity concerning reciprocity failure and
> relating it to the problems you're facing, are you sure these problems
> aren't on the exposure side of the situation ? Rather than struggling so
> much with development, haven't you thought trying to al
Hello Shannon,
Taking into account all uncertainity concerning reciprocity failure and
relating it to the problems you're facing, are you sure these problems
aren't on the exposure side of the situation ? Rather than struggling so
much with development, haven't you thought trying to alter your exp
What do you call this sort of shareware and how would you find it on the
internet? I did do some calculations manually and the exponent went down as
the times went up. That is, for a metered time of 3 seconds, raising it to
the 2.1 power gave you ten, which was what the chart said the adjusted t
- Original Message -
From: "Shannon Stoney"
> This is interesting, a variation on the formula I was given. Where did you
> get this formula? I wonder if such formulas exist for all films?
> I have been using this formula successfully for about a month. It seems to
> give good times. I
I have some photos up at a show at San Francisco city hall. If any one on
the list lives in SF drop by if you have the time. the show will be up
until September.
(I also have some photos up in Sacramento at the True Love cafe. But those
are drawing with light instead of pin hole. )
John wrote:
> I use the formula, y=.91x^1.51, where x is the metered time and y is the
> corrected time. It approximates the reciprocity pretty closely, and has
> worked for me for exposures up to 2 hours on FP4+, which shares the same
> reciprocity failure as HP5+. I've always processed normal
>
> This has probably been discussed recently, but can anyone out there
> recommend a good formula/rule of thumb for adjusting exposure for
> reciprocity in Ilford films? The technical data on their webpage is merely
> a chart, and I am hoping to get more specific information, based on the
> exp
I use the formula, y=.91x^1.51, where x is the metered time and y is the
corrected time. It approximates the reciprocity pretty closely, and has worked
for me for exposures up to 2 hours on FP4+, which shares the same reciprocity
failure as HP5+. I've always processed normally, with pmk pyro.
How about trying the overexposure or rather exposing for the darker parts of
the subject and then using a two bath compensating development such as
emofin which will prevent blocking of highlights and give full developments
the shadows. With pinhole and compensation development there is no such
th
I use the same formula as I do for TMAX. The other forgiving factor is that
when you correct for reciprocity failure, the failure itself buffers
overexposure risk. Don't try to hit a mark too closely. Overexposure may be a
wrong, but it's only a misdemeanor. Underexposure is a felony.
- O
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