The person that I bought my standard Omega Prolab 4x5 condensor head from said that he used to just throw the 6x6 vc filters over the top of the variable condensor part instead of worrying about a filter holder/drawer. Is this really wise? Would'nt heat or possible filter scratching be a problem? Most opinions are that using filters under the lens is not wise so that's out. Also, Omega lists two different wattage bulbs for the D series, a 75 and a 150 watt one, would'nt brighter be better? Anyone using the 150 watt bulb and why? Finally, has anyone experimented with and had good results from using any different types of bulbs in thier D2's?

-- bill zelinski (willy226@yahoo.com), October 13, 1999

Answers

Hi Bill,

I use a D2V head so my comments may not be all applicable. The D2V head has a small condenser heat absorbing glass that sits above the main condenser and is placed on different racks to match the focal length of the enlarging lens. A 6x6 filter can go either above or below the small condenser. When the filter is above the small condenser and glass I have not noticed the filter heating up to any great degree. Because the filter is not at a focal plane unlike the negative, it can move (pop) without any great effect. I use both Ilford and Agfa VC filters which are a plastic. They are plastic and are fairly tough. They may get scratched, but it doesn't affect their performance as it would an under the lens filter.

The 150W bulb gives short exposure times that make it difficult to dodge or burn especially with paper sizes smaller than 8x10 so I tend to use the 75W bulb. The 150W could save time for prints above 11x14.

If memory serves me the 211 & 212 bulbs are used in the D2V. When I first got the thing it had a 240 (75W) bulb in it. The 240 was smaller than the 211/212 and I think it was the cause of some uniformity problems I was having. I recall seeing that someone else was using a high efficiency fluorescent bulb. I haven't tried that yet. In a pinch I used a standard 60W household bulb. It worked but was not uniform. The internal coating and location of the label has an effect so I suspect that the fluorescent bulb would have a problem too.

I want to experiment with diffusing the light from the bulb, perhaps with a mylar sheet. I'll probably need the 150W bulb then.

If you have any questions, please Email me directly.

Cheers,

-- Duane K (dkucheran@creo.com), October 14, 1999.

We've always used 2x2" VC filters below the lens, hanging in a little filter hanger that hooks on to the round lens-retaining plate/lensboard connecting screws, and have never noticed any image degradation because of it. (Yes, I know it's supposed to affect the image projection, but I'm telling you it doesn't - we've been doing this on our D3v for something like 30 years.) Something to consider if you don't want to worry about filters heating up in the condenser head...

-- Michael Goldfarb (mgoldfar@mobius-inc.com), October 14, 1999.

Thanks for the advice, I will try the 150w bulb for awhile and see if it makes any difference, I'm still curious to experiment with other types of bulbs. I have never used under the lens filters (prior enlarger was a dichro) so I will try both ways, I can understand the argument made as the same one as the one used for using camera lens filters, why put a "cheap" piece of plastic on a big bucks lens? but almost all the older enlargers and books I study did it this way for years so how bad can it be? It also seems under the lens filters would be alot easier to use for split contrast printing.

-- bill zelinski (willy226@yahoo.com), October 14, 1999.