Help me work put exposure time please.

VirtualAdept

VirtualAdept

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Mads
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Ive just finished getting set up with q pinhole camera, and I cant for the life of me work put what exposure to use.
The guide says, using the kit provided, about 15 seconds in bright daylight. Here's the kicker... I want to take a shot of the towns Quay after dark.
Is there an easyish way of figuring how long am exposure to use?

TIA
Mads
 
What film are you using? You're going to be getting into the realms of reciprocity failure to take into account at those light levels I reckon.
 
Its just the 3x3 paper that came with the kit, so ive no idea really.

ETA; I should mention that it's a lit quay, street lights, shop fronts etc, its not a completely dark view.
 
Last edited:
VirtualAdept said:
Its just the 3x3 paper that came with the kit, so ive no idea really.

ETA; I should mention that it's a lit quay, street lights, shop fronts etc, its not a completely dark view.
Click to expand...

It would be worthwhile finding out the film speed equivalent of your paper the aperture of the pinhole and using an online calculator such as Mrpinhole. A light meter wouldn't go a miss either
 
Sounds like a use for my new toy(s)!
One of my lecturers just gave me 2 Olympus microscope cameras with the associated control panels etc that he had rescued from getting thrown out when he was at his last job a few years ago. TBH their pretty advanced with being able to calculate exposure from 1/100th to 48 minutes and adjusting the exposure as the light changes during it plus the more high tech one has reciprocal data built in for about a wide range of films from Kodachrome 25 Professional to T-Max 3200 (sadly most are now discontinued and newer ones are not included as its from about 1997) so it will adjust the exposure based on its length so to get a 'perfect' exposure every time. Plus things like auto-bracketing up to 7 frames, a 'B' mode with stopwatch and a manual mode don't go amiss either!

I would post some photos up but I left it at my parents house so I'll take some the next time I am there. This shows you what the more advanced one looks like though: (Control Unit: http://i.ebayimg.com/t/OLYMPUS-PM-20-EXPOSURE-CONTROL-UNIT-W-SPT-CAMERA-/00/$(KGrHqEOKjME3tI!eMJLBOFECfoC)g~~_3.JPG Camera http://i.ebayimg.com/00/$(KGrHqUOKo4E3uWJmlyzBOFECdVPuw~~_3.JPG) BTW, the actual black camera on top of the white 'box' (which mounts on the microscope and has an eyepiece of focusing) just takes the image and is replacable with other types as well like a 4x5 back, the black tube (which I don't have) allows you to mount it on a microscope.

As of yet I don't have a microscope to use with them so I'm actually going to try converting one into a pinhole camera (which essentially they are) for the reasons above, from my rough workings out I calculated an focal length of about 150 and an aperture of about f270. Should be fun.... pity you need to have the control unit connected to the mains!
 
Thanks for the replies guys, I'll have a serious look into that site when I finally get a day off.

In the meantime, a technical question. Ive done an exposure as per the guide, 15 seconds, bright daylight. Upon developing the print (negative of course) is very light with barely any definition of features.
When I do a contact print, it shows as very dark, so... Have I underexposed the shot?
 
yes it's underexposed
 
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