exposure times for Zero image?

[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

[Thomas Bertilsson]

With an f/158 pinhole, in broad daylight, I would wager about 1s exposure time.

I use the Zero 2000 6x6 camera, which has an f/138 aperture, and with Plus-X / Foma 100 / Acros / TMax 100 I shot it at about 1s in bright sunlight. That worked pretty well. A bit over-exposed, but it was the slowest I could open and close the manual shutter with any accuracy. Beyond broad daylight you'd have to use a meter.

I have not used the Fuji 160NS, but since it's similar speed one second seems a reasonable starting point there too.

For the Zone plate, you'd be more like between 1/15 and 1/8 second exposure since it has a larger effective aperture.

[rich815]

Depends on the hole size. I shoot my ZeroImage 6x9 mostly with 400 speed B&W film and expose for 4-16 seconds depending how bright the day is.

[ced]

With your parameters on the link below 1/2 sec but as also posted in response to your question here 1 sec was suggested and I would go for that and also even 2 sec won't be a disaster, try it and let us know. For 100 iso that is.
http://www.mrpinhole.com/calcpinh.php

[markbarendt]

Thank you Thomas for the correction, see post below.

Brightness of scene, time, film rating, and aperture. Three of those four variables are needed to solve the exposure question.

So for example a sunny 16 front lit scene (EV 15), the normal setting for FP4 (ISO 125) at f/16 would be 1/125th of a second.

You are changing the aperture and need to apply the f/ number indicated. F/158 for the pinhole or f/55 for the zone plate.

To get close you can just count stops. From f/16 1-stop less light is f/22, 2-stops f/32, 3-stops f/45, 4-stops f/64, 5-stops f/90, 6-stops f/128, 7-stops f/180

The corresponding times count from 1/125 1-stop brighter is 1/64th, 2-stops 1/32, 3-stops 1/16, 4-stops 1/8, 5-stops 1/4, 6-stops 1/2, 7-stops 1

So for the pinhole (f/158) in "sunny 16" (EV 15) with FP4 (ISO 125) somewhere just longer than 1 second would be the target.

The zone plate's target time would be between a 1/16th and 1/8th.

If you move from the sunny 16-EV 15 situation to something darker, say EV 10; you will need to adjust the speed 5-stops to let in more light.

So in an EV 10 lighting situation the time would adjust from the sunny setting at 1-second to about 32-seconds (2,4,8,16,32) then factor on reciprocity.

Here's a good reference for EV numbers to estimate with. http://www.fredparker.com/ultexp1.htm

[Michael W]

Test, test, test & keep notes. Then you will know what works.
Don't forget reciprocity failure.
With my 6x6 Zero a sunny outdoor exposure is probably a few seconds. Interiors can range from 15 minutes to a couple of hours, depending on the light level. I used to use my Sekonic meter & adjust from that, now I use the iPhone pocket light meter app. I mostly use Tmax 100.

[Thomas Bertilsson]

Brightness of scene, time, film rating, and aperture. Three of those four variables are needed to solve the exposure question.

So for example a sunny 16 front lit scene (EV 15), the normal setting for FP4 (ISO 125) at f/16 would be 1/125th of a second.

You are changing the aperture and need to apply the f/ number indicated. F/158 for the pinhole or f/55 for the zone plate.

To get close you can just count stops. From f/16 1-stop less light is f/32, 2-stops f/64, 3-stops f/125, 4-stops f/256.

The corresponding times count from 1/125 1-stop brighter is 1/64th, 2-stops 1/32, 3-stops 1/16, 4-stops 1/8.

So for the pinhole (f/158) in "sunny 16" (EV 15) with FP4 (ISO 125) somewhere just longer than 1/16th of a second would be the target.

The zone plate's target time would be a hair shorter than 1/32nd.

If you move from the sunny 16-EV 15 situation to something darker, say EV 10; you will need to adjust the speed 5-stops to let in more light.

So in an EV 10 lighting situation the time would adjust from the sunny setting at 1/32nd to about 1-second. (1/16, 1/8, 1/4, 1/2, 1)

Here's a good reference for EV numbers to estimate with.

Mark,

The scale goes, stop by stop:

f/16, f/22, f/32, f/45, f/64, f/90, f/128, f/180, and you have to, without counting reciprocity failure, double the exposure.

So, from f/16 you have seven stops less light to f/180, the closest full aperture to f/158. From 1/125th of a second that makes 1s.

[markbarendt]

Doh!

Note to self: finish coffee before doing photographic Maths.

[Tom Miller]

The best way to determine the proper exposure for any pinhole film and camera combination is to test. It will use up a roll of film; but the time and money initially expended will pay off in a future of good exposures.

The exposure calculator that is built into my Zero 6x9 gives a good indication of proper exposure, and provides a good starting point for the test. It is easiest to do the test on a bright sunny day with a subject that includes a full range of tones (both lights with detail and darks with detail). Make five exposures ranging from two stops below to two stops above what the calculator indicates. When the film is processed, evaluate visually on a light table to see which exposure best captures the full range of tones in the subject. This is the proper exposure on a bright sunny day (the EV 15 situation noted above). This exposure time is a "magic number" for your camera and film.

As mentioned above, in darker lighting situations, subtract the EV of the ambient light (EV 15 above) to determine how many extra stops of exposure to give. Let's say your magic number is 5 seconds and the ambient EV is 12, you'd need to make a 40 second exposure.
5" = magic number
10" = one extra stop
20" = two stops extra
40" = three stops extra

Doing the test to determine the proper exposure on the pinhole camera itself eliminates the need to factor in the film's reciprocity failure characteristics since the test exposure was so long. In practice, I've found this approach to work great up to six or seven extra stops of exposure.

The testing can continue by doing prints or scans to determine the best film exposure; but doing the visual examination suffices.

[Thomas Bertilsson]

Doh!

Note to self: finish coffee before doing photographic Maths.

I know you knew that. Just wanted to poke some fun at you while I had a chance.