This is an update, I sort of decided that it was not worthwhile spending the money on this, but Kevin Brown of KHB Photografix wrote me a very detailed explanation of the single vs multiple lamp systems for different mixing boxes. I thought I'd share for general knowledge to the list:
Single lamp systems like most 4x5 enlargers work well when you concentrate the light down to smaller formats. Most will give you a 1-1½ stops increase in light output from 4x5 to 6x7 and 2-2½ stops from 4x5 to 35mm. However the multilamp systems like the 5108 are not nearly so efficient. The 4 lamp system of your 5108 was designed not for maximum light output but for maximum evenness of the light (both intensity and colour) from corner to corner. Efforts to concentrate the light from 4 widely spaced lamps down to 5x5 or smaller do not work so well. I have checked for actual specs and I don't believe DeVere ever published any. But, my recollection is that going from 8x10 to 5x5 the light output is increased by only 1 f-stop and going to 6x7cm gives only a marginal further increase of about ½ stop.
In general the concept of using 1200W to evenly illuminate a 10x10 negative area does not translate very well when trying to print from 120 or 35mm negatives where you are using (in the case of 35mm) les than 2% of that light.
There are vast differences in the light output of different enlargers. The Wattage alone means very little. I had one customer making wall murals from 2 Durst 184 enlargers. One outfitted with a 2000W Durst lamphouse and the other with a 1000W Chromega F lamphouse. The 2000W watt exposure was in the neighbourhood of 20 minutes and the 1000w Omega less than 4 minutes. But, they loved the Durst because the light was so so even. Eventually they manipulated the negative to compensate for the unevenness of the Omega and banged out prints in about 6 minutes.
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