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Old 8th June 2012, 09:08 AM
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photomi7ch photomi7ch is offline
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Default How do you meter your pinhole.

I read an article the other day that suggested that they did not take into account reciprosity when exposing their film. This may have been because the shutter times were short enough not to.

I us a hand held meter take two readings one of the sky and one for the ground. Then average it out. Then when I open the shutter disregard it and do what I think is best. so am I. but has work well so far.

How do others meter or not there exposures when using their pinhole cameras.
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Old 8th June 2012, 09:31 AM
numnutz numnutz is offline
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Use Pinhole designer free from here:

http://www.pinhole.cz/en/pinholedesigner/

copied from the website:

PINHOLEDESIGNER 2.0
PinholeDesigner is a program for Windows and is aimed at making the calculations for designing and using pinhole cameras easier. Amongst its main features are calculations for the optimal diameter of the pinhole and the exposure times for pinhole cameras.

This program offers:
calculation of the optimal diameter of the pinhole
calculation of the optimal focal length
calculation of the f number for a given combination of pinhole and focal length
calculation of the exposure factor for f 22
calculation of the exposure times for a given f number of the pinhole camera
calculation of the extended exposure times due to reciprocity failure for the majority of commonly used films
saving exposure table as Microsoft Excel file or text file
calculation of the angle of view, with diagram
calculation of the magnification and size of the subject on light-sensitive material
calculation of the zone plate with optional number of zones
calculation of the f number for the zone plate
saving the zone plate in Adobe PDF format
conversion of millimetres to inches and back

As stated it has the facility for calculating reciprocity failure for many different films

Hope this helps

nn
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Old 8th June 2012, 09:35 AM
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Paul Mitchell Paul Mitchell is offline
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I've found that it's far from being an exact science... almost like wetting your finger and sticking it up in the air and saying ahh 2 seconds!

I always carry a little Gossen Digisix meter, take a reading and calculate what it's roughly going to be using the brass dial on the back of my Zero 2000. Anything between 1 - 5 seconds I don't add anything on for reciprocity. Between 5 - 10 seconds I add on about half as much again. 10 - 30 seconds I double it and anything beyond that I just leave the shutter open and have a cup of tea!

Paul
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Old 8th June 2012, 10:16 AM
Dave miller Dave miller is offline
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Quote:
Originally Posted by Paul Mitchell View Post
I've found that it's far from being an exact science... almost like wetting your finger and sticking it up in the air and saying ahh 2 seconds!

I always carry a little Gossen Digisix meter, take a reading and calculate what it's roughly going to be using the brass dial on the back of my Zero 2000. Anything between 1 - 5 seconds I don't add anything on for reciprocity. Between 5 - 10 seconds I add on about half as much again. 10 - 30 seconds I double it and anything beyond that I just leave the shutter open and have a cup of tea!

Paul
That sounds very exact to me, but I'm concerned that the temperature of the tea may effect the longer exposures.

I took a meter reading at the film's iso then multiplied the time to allow for the smaller f-stop and then made a further correction for reciprocity failure.
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Old 8th June 2012, 11:33 AM
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I'd be carefull about sticking my finger in the air some people mite get th wrong idea.

For me part of the fun is the lack of control. you know the fingers crossed and hope it turns out well.

To be serious for a moment I take a little more care than these posts suggest.
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Old 8th June 2012, 12:20 PM
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I meter and get a reading for f64, then use the calculator shown on Page 525 of Way Beyond Monochrome to adjust to the correct f stop. It can be found by scrolling down HERE. Then I allow for reciprocity using Les McLean's table.

Bill
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Old 8th June 2012, 02:53 PM
Mike O'Pray Mike O'Pray is offline
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I am sure this is well known but I'll add it anyway. As I understand it Fuji Acros requires no reciprocity correction for up to 2 mins.

2 mins might not be enough for some conditions of course. I have read somewhere that in the old days some photographer taking a shot of the inside of a very gloomy( lightwise) cathedral opened the shutter then went and had his lunch in a nearby pub!

Makes Dave's cup of tea seem like action photography

Mike

PS if Acros doesn't come in sheet form then just ignore this post. Well, try and remember the last line and then buy my memoirs to see more such one line gems
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Old 9th June 2012, 07:53 AM
Shane Shane is offline
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I use the conversion chart generated on "pinhole designer" just copy it in excel and print it out for each camera. I certainly take into account reciprocity, the film acts the same if there is a lens or not. That why I use Acro too, no reciprocity in most cases.
http://www.pinhole.cz/en/pinholedesigner/
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Old 10th June 2012, 09:42 AM
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From the replies there are a lot of ways at arriving at the same place.

I use a simple method of doubling the time upto five seconds and then mulitiplying it by five up fifty seconds and has so far worked well. I find keeping things simple can be quite difficult in this age of computerized complecation.

Does anyone not take reciprocity into account excluding those who use Acros Or is it a case that we are hard wired by what we read to do so.
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Old 13th June 2012, 11:00 AM
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Like I said, I believe you need to take it into account otherwise you end up with underexposed negatives.
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