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#11
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First contact prints done. Problem with light uniformity.
"Fabio BERETTA" wrote
Height of the bulb within the head... that's probably the mistake!! Now is there any method to correctly estimate if evenness of the light has been reached? The evenness of the contact sheet is a good indication... Seriously: o Eyeball it as best you can o Use a lightmeter with an incident disk attachment or an enlarging meter and see if reads the same in the corners as the center. Most light meters are not sufficiently sensitive and don't have enough resolution, though. o Check by installing a grade 5 polycontrast filter and making a neutral (18% - or so) grey exposure with no negative. See if is even enough to satisfy you. Tear off a corner and place it in the middle of the print to make the comparison. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. |
#12
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First contact prints done. Problem with light uniformity.
Thanks.
Nicholas O. Lindan wrote: "Fabio BERETTA" wrote Height of the bulb within the head... that's probably the mistake!! Now is there any method to correctly estimate if evenness of the light has been reached? The evenness of the contact sheet is a good indication... Seriously: o Eyeball it as best you can o Use a lightmeter with an incident disk attachment or an enlarging meter and see if reads the same in the corners as the center. Most light meters are not sufficiently sensitive and don't have enough resolution, though. o Check by installing a grade 5 polycontrast filter and making a neutral (18% - or so) grey exposure with no negative. See if is even enough to satisfy you. Tear off a corner and place it in the middle of the print to make the comparison. |
#13
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First contact prints done. Problem with light uniformity.
"Dennis O'Connor" wrote in message ... Sounds to me like he needs to install the correct condensors/mixer for the lens... denny yep... you sound like you've got two Sivocon 80's in it. Are both condensors identical? I just tried a 50mm lens with the two '80s and there's definite light fall off. With a Sivocon 50 and one '80 (the 35mm setup) it looks quite even, which I'd expect since I've never had to edge burn my prints. FYI, the '50 condensor has a lot more curviture to it than the '80. Nige. |
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