exposure times for Zero pinhole?

[air2046]

Hello,

i am new to pinhole photography and would like to ask you if you could give me guidelines and some information on exposure times for zeroimage camera - 612f,please?

i am using iso 100 (ilford FP4) and fuji 160NS

Pinhole Size: 0.25mm
Focal Length: 40mm
F/158 (pinhole), F/55 ( zone plate)

If you could tell me if there is difference in exposure time when using zone palate and normal pinhole ?

Thank you

 

[zzpza]

I use Mr PinHole's website for working out the shutter speed for my Pinholaroid and Holga 120WPC. Set your light meter to the correct film speed, then meter for f/2.8. Use the following conversion tables to get the converted shutter speed. (i.e. match the shutter speed from the meter to the same speed under the f/2.8 column and then read the speed from the f/158 or f/55 column on the same row)

f/158
f/55

These conversion factors do not include reciprocity failure, so depending on the film stock and how long the exposure is you will most likely have to add 1 or 2 stops.

 

[air2046]

hi
thank you for the answer.
just to be sure that i understand.
my iso is 160
i have light meeter,and i have put the iso there
when i make a reading,there is no option to put the F number as there isnt so big, so i put for example f16,and it gives me 8s, so then i check what is the equvalent at f16/ 8s and its 13 min/ is that right please?

thank you

 

[zzpza]

That is correct, but you still need to correct for reciprocity failure of your film.

Here's an explanation of reciprocity failure: http://en.wikipedia.org/wiki/Reciprocity_(photography)#Reciprocity_failure

You can get the manufacturer's recommendation from looking at the film's datasheet. This combined with your experience with the camera will teach you when to add time and how many stops.

I hope that makes sense?

 

[zzpza]

IIRC, it's only 1 stop compensation for exposure times up to 15 minutes. You can get Acros in 120 too, I use it myself, and is as you said a very good film.

 

[uhligfd]

I always count ten stops up from pinhole f number and expose 1000 ~= 10^10 = 1024 times longer than I measure for that reference f number.

So: I would measure exposure at f/5.6, then ten stops down are: 8, 11, 16, 22, 32, 45, 64, 90, 128, 180 ~= 158 and I may add one stop more for reciprocity and long times.

Similarly you could just measure exposure time for f/4 and multiply the time by 1000, such as from 1/500 sec to 2 sec, or from 1/125 sec to 8 sec, 1/30 sec measured at f/4 on the light meter for your film and exposed on pinhole camera for 30 secs etc.

This requires a bit of an ability with fractions and head computations. Ah, middle school anyone? But it is ultimately the simplest way as lightmeters do not go down to f/100+.

 

[rtphotos]

Hi air2046,

When out pinholing, I often have a hand-held light meter, such as a Sekonic L-398, and the FREE Pinhole Exposure Scale by Tsutomu Otsuka:
http://www.geocities.jp/camera_works/resource/pinhole/exposure/index_e.html

I usually take an incident light meter reading (EV), and then convert to the appropriate pinhole aperture by using the Exposure Scale.

It's not painful and you won't suffer much! 🙂

Good luck!
rt