I doubt that fall-off with different units is consistent as there are different mechanisms used to even out the light, and some units don't even try to even it out. Some NuArc units I have seen had a piece of glass under the bulb that was patterned to even out the light, others have plain glass.
At one time I owned a NuArc 26-1k and the fall-off at the far corners was about 1.5 stops as I recall.
Sandy King
Thats quite a lot! I am getting fall off with my exposure unit with twin 300w mercury bulbs on 11x14 inch prints. Am i likely to get with 1k unit?
I print 8x10, 8x20, and 12x20 images with a 26-1k with no discernible fall off at all. 1.5 stops would lead me to think that the either the bulb was very old or the diffusion dots on the glass were gone, or both. I have heard of some fall off with people printing 20x24 with a 26-1k but no where near a 1.5 stop fall off. Mine seems to work fine within a 20" square. Although Dick Arentz probably has the latest and best exposure units available to him, if you look in his book there are pictures of him using a 26-1k.
The 26-1K I owned and tested had plain tempered glass beneath the bulb, nothing at all to even the light. The ones that have the pattern on the glass to even the light probably give better results.
However, if you are interested in testing this just expose four step wedges at the far corners of the frame and compare the results with one in the middle.
Sandy
Originally Posted by RobertP
I print 8x10, 8x20, and 12x20 images with a 26-1k with no discernible fall off at all. 1.5 stops would lead me to think that the either the bulb was very old or the diffusion dots on the glass were gone, or both. I have heard of some fall off with people printing 20x24 with a 26-1k but no where near a 1.5 stop fall off. Mine seems to work fine within a 20" square. Although Dick Arentz probably has the latest and best exposure units available to him, if you look in his book there are pictures of him using a 26-1k.
Last edited by sanking; 11-27-2008 at 02:13 PM. Click to view previous post history.
I print 8x10, 8x20, and 12x20 images with a 26-1k with no discernible fall off at all. 1.5 stops would lead me to think that the either the bulb was very old or the diffusion dots on the glass were gone, or both. I have heard of some fall off with people printing 20x24 with a 26-1k but no where near a 1.5 stop fall off. Mine seems to work fine within a 20" square. Although Dick Arentz probably has the latest and best exposure units available to him, if you look in his book there are pictures of him using a 26-1k.
Okay thats good news Robert, just hope when i get my Parker Countess Royal 1k unit (see atached a pic of it in the warehouse) that i dont have any problems as i really want to print larger. Thanks
Saw this unit on ebay, would have loved to bid on it if the seller would ship to U.K. but alas , looks like some other lucky person will get their hands on it in the U.S, here is the link for those interested, only two days left :
Originally Posted by sanking
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, looks like some other lucky person will get their hands on it in the U.S, here is the link for those interested, only two days left :
