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  #11  
Old 29th November 2010, 02:19 PM
MarkWalker MarkWalker is offline
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I'm happy to report that the dimness has been solved. I've never come across this before: the lamp failed and I had a spare included with the enlarger, so I fitted it and hey presto, illumination back to what I thought should have been normal (around 25-30 seconds for 12" enlargement). It appears that before it failed the lamp (250 watt) must have dimmed considerably and for a few weeks: I'm not aware of this as a characteristic of halogen lamps. But, problem solved and thanks again for the great responses.

P.S. to Bill, you might also come across some polystyrene sheet used for packing allsorts of stuff that, say, your local computer/electrical shop might have in a bundle to throw out. The advantage of this is that with equal thickness inside the box you won't have to do any centreing of a 'free standing' insert - watch out for static balls (!) of it on the diffuser.
Regards.
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  #12  
Old 29th November 2010, 02:37 PM
MarkWalker MarkWalker is offline
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Bill, I am sorry for telling you something you have already tried, I have just tracked back.
I think the solution is probably as good as you might get though, because you are still concentrating the light in a similar manner even with a dedicated chamber. I also made a quick attempt with foil and thought there was a hot spot in the illumination and no discernable increase overall. Also, using a piece of thinner perspex (off a light box) didn't help and illumination was uneven - the Devere diffuser is cleverly domed to compensate for fall off.
Please show us what you come up with, anyway, I think it is a helpful subject for anyone struggling with illumination who can't necessarily get or afford manufacturers spares - have you seen the price of a 6x6 mixing chamber from Odyssey ?

Mark.
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  #13  
Old 29th November 2010, 03:32 PM
Dave miller Dave miller is offline
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Quote:
Originally Posted by MarkWalker View Post
I'm happy to report that the dimness has been solved. I've never come across this before: the lamp failed and I had a spare included with the enlarger, so I fitted it and hey presto, illumination back to what I thought should have been normal (around 25-30 seconds for 12" enlargement). It appears that before it failed the lamp (250 watt) must have dimmed considerably and for a few weeks: I'm not aware of this as a characteristic of halogen lamps. But, problem solved and thanks again for the great responses.

P.S. to Bill, you might also come across some polystyrene sheet used for packing allsorts of stuff that, say, your local computer/electrical shop might have in a bundle to throw out. The advantage of this is that with equal thickness inside the box you won't have to do any centreing of a 'free standing' insert - watch out for static balls (!) of it on the diffuser.
Regards.
All lamps dim with age, but some types more than others; although yours seems to have set a record. It's one reason I no longer keep printing exposure time records. The other thing to watch for is corrosion of the lampholder, it's a component that is subject to a great deal of heat, which in itself adds to the corrosion problem. Ideally this should be replaced with the lamp to maintain a low resistance path.
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  #14  
Old 29th November 2010, 04:26 PM
MarkWalker MarkWalker is offline
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Thanks, Dave, when I changed the lamp I noticed the holder and leads looked quite recent, the contacts were clean and the porcelain holder quite white. I shall investigate further if there is a lamp burn out problem.
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  #15  
Old 1st December 2010, 02:39 PM
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Quote:
Originally Posted by MarkWalker View Post
Bill, I am sorry for telling you something you have already tried, I have just tracked back.
I think the solution is probably as good as you might get though, because you are still concentrating the light in a similar manner even with a dedicated chamber. I also made a quick attempt with foil and thought there was a hot spot in the illumination and no discernable increase overall. Also, using a piece of thinner perspex (off a light box) didn't help and illumination was uneven - the Devere diffuser is cleverly domed to compensate for fall off.
Please show us what you come up with, anyway, I think it is a helpful subject for anyone struggling with illumination who can't necessarily get or afford manufacturers spares - have you seen the price of a 6x6 mixing chamber from Odyssey ?

Mark.
OK Mark will let you know how I get on. I have been looking for either a De VEre light box or failing that a Durst one I could cannibalise similar to Tony.

I dare not think what Odessey would want for one, probably more than I paid for the enlarger.

Bill
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  #16  
Old 1st December 2010, 04:47 PM
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RH Designs RH Designs is offline
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Halogen lamps do indeed dim with age. I replaced the one in my LPL once and got a whole stop more light!
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  #17  
Old 4th December 2010, 06:41 PM
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vanannan vanannan is offline
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Sesibox 6x6 and 6x9 on Ebay starting this evening start price 20 each, maybe an opportunity for someone to adapt as I did.
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  #18  
Old 4th December 2010, 07:08 PM
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Sesibox 6x6 and 6x9 on Ebay starting this evening start price 20 each, maybe an opportunity for someone to adapt as I did.
Bought a Sivobox 35 this afternoon as the first step to improving my light output.

Will need to work out how to channel the light once it arrives.

Bill
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  #19  
Old 24th December 2010, 06:30 PM
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Quote:
Originally Posted by MarkWalker View Post
Bill,
Please show us what you come up with, anyway, I think it is a helpful subject for anyone struggling with illumination who can't necessarily get or afford manufacturers spares - have you seen the price of a 6x6 mixing chamber from Odyssey ?

Mark.
It's taken some time but I finished my modified piece this afternoon.

I started by buying a Durst Sivobox 35 off the auction site to give me a small shaped diffuser.

It is a bit Heath Robinson but I sort of added bits on as I went. I made a bottom flange by drawing round the existing light box. To this I mounted the Sivobox using the existing tapped holes and screws that came with the box. I discarded the original bottom plastic piece. I then made a 'chimney' out of ply with a bend to change the direction of the light. The whole was lined with metallised Mylar courtesy of BobRob. This was fixed to the Sivobox by a top flange and drilling 4 holes in the Sivobox flange. I have added some images which I hope will show it better. Perhaps if I did it again I would make the side cheek pieces in one.

Just taken some readings with my Analyser Pro. The negative was enlarged to 91/2 x 12 and was measured using the original 4x5 light box and that came in at 57.4 seconds exposure. That was with the enlarger lens 2 stops down. Without changing anything else but the light box I measured again and got 11 seconds exposure. So well worth doing.

Bill
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  #20  
Old 24th December 2010, 11:10 PM
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vanannan vanannan is offline
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Quote:
Originally Posted by Bill View Post
It's taken some time but I finished my modified piece this afternoon.

I started by buying a Durst Sivobox 35 off the auction site to give me a small shaped diffuser.

It is a bit Heath Robinson but I sort of added bits on as I went. I made a bottom flange by drawing round the existing light box. To this I mounted the Sivobox using the existing tapped holes and screws that came with the box. I discarded the original bottom plastic piece. I then made a 'chimney' out of ply with a bend to change the direction of the light. The whole was lined with metallised Mylar courtesy of BobRob. This was fixed to the Sivobox by a top flange and drilling 4 holes in the Sivobox flange. I have added some images which I hope will show it better. Perhaps if I did it again I would make the side cheek pieces in one.

Just taken some readings with my Analyser Pro. The negative was enlarged to 91/2 x 12 and was measured using the original 4x5 light box and that came in at 57.4 seconds exposure. That was with the enlarger lens 2 stops down. Without changing anything else but the light box I measured again and got 11 seconds exposure. So well worth doing.

Bill
Well done, merry xmas
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