de vere 5108 blub replacement

[wager123]

the exposure times on my 5108 dicromate color head are way to short on smaller prints can I replace the 300 w elh blubs with 150 w blubs and if so which type of 150 w bulb will work ?
thanks
Mitch

[L&Scape]

I had 250W in my enlarger. Of course you can replace to 150W bulbs. Try to find the same type so you do not need to make any changes in filtration.

[Mick Fagan]

Easiest way to elongate enlarging times in your situation, is to use all three filters in the head as a neutral density (ND) filter. Then add your standard filtration on top of the ND filtration component.

In general with DeVere enlargers, every 30 units of filtration will give you one stop of ND, 60 units is two stops of ND.

[Phil Hudson]

That's really useful info about the ND units - thanks!

[ic-racer]

Durst and some Omegas use the same convention. 30CC = log d 0.3 = 1 stop, etc.

[cowanw]

Easiest way to elongate enlarging times in your situation, is to use all three filters in the head as a neutral density (ND) filter. Then add your standard filtration on top of the ND filtration component.

In general with DeVere enlargers, every 30 units of filtration will give you one stop of ND, 60 units is two stops of ND.
I have heard this alot; but you caught me working with a blue/green enlarger and I tried to work out what the meaning of neutral density using combined colour filters might be in that system. I hurt my brain and the answer was there was no application in a Blue/Green system.

I repeated prints in various ways (plus/minus fstops, time, and 30 units of filter (Magenta, Yellow and plus/minus Cyan)) on my DeVere and I can confirm the concept of the 30 units of yellow and magenta together being neutral density, in my case 1 1/2 stops. I used Kodak numbers with combined settings.
I can also confirm that it is quite unnecessary to dial in cyan (assuming we are talking Black and White here) which only functions as a minus red and just makes it darker to focus, without affect on the print.