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Controlling light and dark in ambrotypes.
Posted by: Iancathcart ()
Date: June 18, 2012 08:35PM

How does one control contrast with glass plates? I was able to get recognizable images with a one second exposure full open. Is it in the developing time, or elsewhere?? Getting mostly blacker images, how do I get the lighter tones?

Thanks,

I

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Re: Controlling light and dark in ambrotypes.
Posted by: phuphuphnik ()
Date: June 19, 2012 12:18PM

If I am reading this right, you are getting a really dark image. If that is the case I would say that you should double your exposure, or ever go to 4 seconds. Over exposure will be lighter, that is more white.
A little more information would help assess the issue:

what f/ are you using, in bright sun at f/32 I'm using 3-4 second exposures.

how long are you developing, I average 15-20 seconds.

What is your developer? I use 5Ml alcohol, 100 Ml vinagar, and 3g iron sulfide.
(as an aside, I ran out of acetic acid, so I'm using vinagar which is 5% acetic, lowered the iron from 4g to 3g to compensate, it works OK)

Hope this helps,
cheers,
chriso

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Re: Controlling light and dark in ambrotypes.
Posted by: Iancathcart ()
Date: June 19, 2012 12:43PM

I was using the simple cap on cap off method. My chemistry was aggressive. I
Diluted my developer down (iron and acetic acid), the first image had nice tones. Other images were
Blacker. I used a petzval magic lantern lens (Probably f 4). I thought that I
Pulled them from the developer too late. I just guess its a game of looking for the
Correct tones!!!

Thanks

I

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Re: Controlling light and dark in ambrotypes.
Posted by: RobertSzabo ()
Date: June 21, 2012 02:34AM

Do you have a stop? If the lens doesnt have a slot you can put a stop inside the barrel. I do the on and off thing too in bright sun but it is really hard to have any control. Its difficult to make accurate changes in exposure when its that short. Too dark sounds like not enough exposure. How long are you developing? I try not to go more than about 15-20 seconds. Ill change the exposure if they seem to need much more or less than that.

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