The Durst L1840 Owner's Manual is now available at:
http://manuelsphoto.free.fr/
The Durst L1840 Owner's Manual is now available at:
http://manuelsphoto.free.fr/
When I was printing with the two filters I wound up with post-it notes all over with little numbers on them to keep track of the green and blue times for the test prints. (my timer does not have any 'memory' to hold both green and blue exposure times).
I thought it would be easier just to put a map pin in the graph. That way I can keep track of contrast and exposure as I zero in on the perfect print.
Finally got around to testing the intensity of the coldlight. I was noticing some inconsistency in matching final prints to the test prints.
This first graph shows how the light intensity actually decreases as the tube heats up during an exposure.
So, based on this info, it is clear that when the Green and Blue times are different, it is wise to keep the exposure order the same when making the test prints and the final prints.
I also tested the rate of temperature recovery to see how quickly or slowly it cools back to the baseline temperature.
Slowly this enlarger is getting honed into a fantastic piece of equipment. One issue now is that the temporary 12x12 filters I am using are getting to be way too much of a bother to change for each exposure. Basically the filter tray is about six feet from the ground. I need to reach over my head and pull the tray, then swap out the green for blue filter. It is pretty simple, but it is a real pain to do this perhaps 50 times in a printing session.
The Ilford MG filters are about $20 a piece, so that is $240 USD for the set. Still less than a dichroic head but I'm not sure I will like that setup. I'd like to try it out first before I spend the money on these non-returnable, special order filters.
The Ilford under the lens filters are about $50 for the 6x6 inch set. I'd like to try that but finding a 6x6 filter holder is next to impossible.
Durst did not make one and the Omega one that fits the F series 10x10 enlargers is still too small (it is just the same part as the 4x5 filter holder, which is too small for the 300 mm lens opening).
So, I decided to make a filter holder.
I got pictures of these to use as an example. That Lee filter holder is nice, but it is not 6x6 in and with the appropriate adapter, it is almost $200 and I would still need to buy the filters.
A little scrounging at the hardware store looking for building materials I found this acrylic chopping plate for the kitchen. It was 7 inches across and made of 4mm acrylic.
I thought I could turn it into a hybrid, combining the best features of the Omega and Lee filter holders.
This material turned out to be almost impossible to cut. Its melting point was so low that the jugsaw line just sealed up behind the sawblade.
My biggest hole cutter was not quite big enough, but I figured in the time it would take me to go to the hardware store and get a bigger one, I could get that hole open with a drill and the Dremel and a file.
Almost 45 minutes later I had the basic shape.
The part that holds the filter in place will be build up with styrene and brass strips. It will be like the Lee holder, in that it will be adjustable to hold more than one filter.
I also added some reinforcement on the bottom.
Here it is, painted and ready for installation. It will fit at the bottom of the existing shaft on which the red filter resides. The chrome trim screw that was on the bottom of the shaft (which kept the red filter from sliding off) needed to be replaced with a longer bolt. The original chrome screw has a 'safe keeping' spot now, in case I want to put it back the way it was originally.
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