Fancy some long exposure pinhole photography? Say an 8 year shutter speed...?

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Story can be found HERE.
 
Someone attached a pinhole camera made from a cider can to the side of a telescope in 2012 and then forgot about it. After being re-discovered, the paper negative shows eight years of the sun moving across the sky each day. Amazing!

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See if you can beat it with one of yours @sirch :)
 
Probably as much a tribute to the durability of the photo paper and gaffer tape involved than as a photographic wonder!
 
I like a challenge:)

What's the ISO equivalent of photographic paper?
 
Usually reckoned 2 to 6.
 
But, thinking about it, perhaps as it's paper, you should employ the same methods advocated in the darkroom, and make a test strip. Say 2 years, 4 years 8 years and 16 years to get an idea..
 
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Does paper suffer from reciprocity failure? The thing that struck me about the photo in the article is that if it really was exposed for 8 years surely it would be massively over exposed i.e. all white. I rate my pinhole cans at around f200, off the top of my head* with an ISO of 4 and using sunny 16 it would give something like 4100 seconds exposure (4s at f16, f256 is 8 stops smaller so 4x 2^8 = 4*1024) i.e. a bit over an hour.

*which is never very reliable
 
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sirch said:
with an ISO of 4 and using sunny 16 it would give something like 4100 seconds exposure (4s at f16, f256 is 8 stops smaller so 4x 2^8 = 4*1024) i.e. a bit over an hour.
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Why couldn't you have just stuck to making rude words with the digital numbers on the display of your pocket calculator, like all the other boys at school? ;)
 
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Asha said:
From my understanding, No!
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My understanding differs. It's not a factor in normal enlargements but when used at very low light levels such as pinhole cameras I believe reciprocity must be taken into account
Fortunately it's fairly easy to adjust development time to push/pull the exposure.

I've seen other images tracking the sun over the course of many months, but I suspect none where more than a year or so.
 
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I seem to remember reading, and I also may have got it wrong, that there was a pinhole camera set up at Sante Fe University that they hoped would be there for decades, but I can't find it now...
 
Andysnap said:
I seem to remember reading, and I also may have got it wrong, that there was a pinhole camera set up at Sante Fe University that they hoped would be there for decades, but I can't find it now...
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That can be the problem with very long exposures - perhaps someone moves the camera to repaint the thing it's mounted on & then no-one can ever find it again :)
 
Petrochemist said:
My understanding differs. It's not a factor in normal enlargements but when used at very low light levels such as pinhole cameras I believe it must be taken into account
Fortunately it's fairly easy to adjust development time to push/pull the exposure.
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Interesting to hear your views as I made enquiries ( not on here ) a little while ago about reciprocal issues when using paper negatives. The responses were all that there would be no problem and as yet I haven’t experienced any.

To be fair though I’ve only made exposures with times probably not exceeding 20 secs so it’s quite possible that longer durations will kick in recipocracy.
 
Stegosaurus said:
Solargrams are not developed, they just get 'burnt' into the paper. If you try and develop them, they actually go black.
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This could create a black hole, which can be very dangerous if your darkroom is unequipped to deal with it. You can't even see black holes with a red safe light.
 
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Asha said:
Interesting to hear your views as I made enquiries ( not on here ) a little while ago about reciprocal issues when using paper negatives. The responses were all that there would be no problem and as yet I haven’t experienced any.

To be fair though I’ve only made exposures with times probably not exceeding 20 secs so it’s quite possible that longer durations will kick in recipocracy.
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20s would be well within the normal darkroom exposure range. My darkroom experience is very limited but I'm pretty sure I had prints needing several minutes exposure.
Photographic paper uses the same silver halide reactions as used in film negatives. There is no reason why paper would be exempt from the activation energy issues that give rise to reciprocity.

Stegosaurus said:
Reciprocity failure isn't an issue as you are not really making an image like a normal photograph. Solargrams are not developed, they just get 'burnt' into the paper. If you try and develop them, they actually go black.
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If the image is undeveloped that would indeed be a different reaction, but you certainly won't be recording the image at the normal sensitivity of the paper instead getting a drastically reduced sensitivity. That sounds somewhat like reciprocity failure! :)
 
Petrochemist said:
If the image is undeveloped that would indeed be a different reaction, but you certainly won't be recording the image at the normal sensitivity of the paper instead getting a drastically reduced sensitivity. That sounds somewhat like reciprocity failure! :)
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The paper is actually massively overexposed, even beyond what would be required to counteract reciprocity failure. You don't even have to load the paper in a darkroom, merely in darkened ordinary room. And you will get a coloured image on b&w paper. Normal theory just doesn't apply.
 
Petrochemist said:
20s would be well within the normal darkroom exposure range. My darkroom experience is very limited but I'm pretty sure I had prints needing several minutes exposure.
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The 20 seconds exposure that I mentioned relates not to darkroom prints but to exposing the paper as negatives in camera ....ie using paper in place of sheet film;)
 
Asha said:
The 20 seconds exposure that I mentioned relates not to darkroom prints but to exposing the paper as negatives in camera ....ie using paper in place of sheet film;)
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Yes I gathered that, but light levels needed for the chemistry would be identical.
 
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