plans for homemade large format enlarger

[jimmygcreative]

the enlarger wil be a vertical unit.

we will be using a brass lens anastigmat 16.25 inch welling camera works lens and a process lens around 300-600mm not purchased as of now.

thanks

JG

[Richard Ide]

Make a bellows extension out of wood. That is the easiest solution. I made extensions for one of my frankenlargers which gave me 48" of extra bellows. I never had any problems and I was doing enlargements with very tight exposure tolerances.

[resummerfield]

the enlarger wil be a vertical unit.......we will be using a brass lens anastigmat 16.25 inch welling camera works lens and a process lens around 300-600mm not purchased as of now....

I’m just thinking aloud here, and I may have my formulas mixed up, but…... I am not familiar with the lens you mention, but a 16.25-inch lens would need 70-degree coverage for the 11x20 neg, and I’m guessing a lens of that coverage would have problems with edge definition in enlarging. A process lens would probably work better, but with its smaller angle of coverage it would need to be around 600mm. A 600mm lens of a vertical enlarger will need more than the average 8-foot ceiling, unless you print on the floor and have a very thin light source. I would consider a horizontal design for such a large negative.

[Roc Chan]

You could use prism/mirror attachments from graphic art cameras to convert vertical into horizontal projection for bigger images.A front surface mirror will also works.
If I am going to put my 8X10 enlarger back into operation,I am thinking of using studio flash as the light source because of the heat problems from quartz lamps.

[Tom Kershaw]

First post here, although I've been lurking for a while.

Firstly, thanks to all those who have contributed to this thread. The discussion has been very helpful as I'm thinking about building an 8x10 enlarger sometime in 2007, and have a some "getting started" points or questions:

1) Not yet decided whether I want to go for a vertical or horizontal design. Any pointers? I suppose I could figure out the distance between the film plane and paper needed given for the enlargement factor, which might favour a horizontal design.

2) Light source: Considering two 500W 230V (I'm in the UK) halogens with some kind of reflector, I think Donald Miller suggested white ceramic earlier in the thread.

3) Cooling: The fan in the case. This obviously needs to be light tight. Presumably ducting could be used to extract the air into a light trapping device either internal or external.

Tom.

[vinny]

For the fluorescent option which i think may be your easiest, check out http://www.kinoflo.com. They make a few new fixtures that use biax tubes which are much brighter than any standard flourescent and available in 2900K or 5600K. The Parabeam and the Diva Light are very expensive units but you can get alternative ballasts from an industrial supply store.

[snuck]

something that you might want to put into serious consideration is going the Ansel route... that is to find an old junked wooden camera chassis with a half decent bellows and turn it into a horizontal enlarger. Or if you're really brave, a vertical enlarger. Here look at this:
http://cgi.ebay.ca/ws/eBayISAPI.dll?...5978&rd=1&rd=1
You could make a 14x14 enlarger!... uh.. right... Of course you'd have to pay 29384872373943827493287 dollars for freight, and there's the matter of how to hook it up with lamps, but that's life I guess....

[resummerfield]

I agree with VINNY. The fluorescent option would produce much less heat and most likely give more even light. Aristo makes the T-12 unit for 8x10.

[jimmygcreative]

Hello and Happy Holidays to All,

I showed my plans to an electrical contractor and he said I should go with outdoor low voltage 50 watt landscaping fixtures. The question would be what amount of wattage would we need to make a 42"-50" x (neg aspect) fiber based print from a 8 x 10 neg. keeping in mind 2-3 min. exposure time, with max contrast filters used.

Our guess for the wattage formula would be around 500-600 watts- Xenon MR16 dichroic halogen reflector will be our lamps.


thanks!

[Turner Reich]

Jimmygcreative, how did the enlarger project go? Did you finish it and what route did you take in its construction?