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  #1  
Old 27th November 2010, 09:11 PM
MarkWalker MarkWalker is offline
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Default Devere dichromat dim

I have recently acquired a Devere 504 - I was getting a 203 chassis but the nice gentleman made me an offer I couldn't refuse and I ended up with the pick of his darkroom equipment. I have made a few prints on the 504 with its Dichromat Mk 1 head and it seems, to me, quite dimly illuminated. The bulb is 250 watt, everything is clean, the 5x4 mixing chamber is fine and I painstakingly made a 6x6 chamber insert to try to improve things for roll film, but still dim. Would it be be normal for this older head to have an exposure time for a 12"x12" print of a minute and a half at f8 on some pretty fast Kentmere VC ?
I remember reading that dichroic halogen enlarger lamps should have a more acutely angled reflector and wonder wether the generic lamps are just too wide, thus not creating the designed illumination to the baseboard ? Any thoughts ?

Regards, Mark Walker.
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Old 28th November 2010, 08:38 AM
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Hi Mark,

I have the same head on my 504. I find that with a 'normal' 6x6 negative my exposures are around 20 seconds for 8x10 on MG IV so I would say that yours are a slightly long, but of course it depends on the density of the negative.

You say the 4x5 mixing chamber is OK. When I was investigating mine I found that the diffuser at the bottom looked fine but a good wash on warm soapy water made a big difference. I also washed the polystyrene inserts as well.

Where I am having difficulty is with 35 mm which is for me very dim. I am thinking of making a dedicated light chamber as an experiment with the existing one shows that I can gain a stop of light by masking the bottom diffuser and filling the chamber with polystyrene just leaving a 40 x 40 mm light path. I would be interested in details of your 6x6 modification. My thought was to line the chamber with crumpled aluminium kitchen foil to see if that improved things for 35 mm.

Of course if anybody has a spare 6x6 mixing chamber they don't need then I would be interested.

I use generic light bulbs intended for disco lighting.

Hope this helps

Bill
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Old 28th November 2010, 10:18 AM
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I have heard that the dichroic filters tend to get more dense with age.
I have seen them for sale once or twice on the auction site.
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Old 28th November 2010, 01:23 PM
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vanannan vanannan is offline
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Hi
I also have a DV504 with Mk1 Dichro head, I too found this rather dim for the smaller formats, I also have a Durst M800 with mixing boxes for 35mm, 6x6 and 6x9 I have adapted these for use in the dichro head using a piece of dropspout lined with silver reflector material, see pics.

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DV504 Dichro head

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setup in head

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showing lightbox in head with light tube removed

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light diverting tube

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Durst M800 light mixing boxes with adapter plate in front

All quite crudely made from bits of scrap material the Durst mixing boxes appear on Ebay quite frequently and usually sell for a lot less than DV504 boxes and probably transmit more light.
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Old 28th November 2010, 01:46 PM
Dave miller Dave miller is offline
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Mark alludes to the use of narrow-beam reflector lamps which may be a requirement here as it is on a Leica V35 enlarger, worth checking in the manual otherwise a lot of light will be lost.
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Old 28th November 2010, 06:39 PM
Paul. Paul. is offline
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Quote:
Originally Posted by Barry View Post
I have heard that the dichroic filters tend to get more dense with age.
I have seen them for sale once or twice on the auction site.
I also thought this but was informed by the nice man at Odessy who stock the spares for deVere enlargers that the filters do not fade but do get dirty. I cleaned mine by carefuly wipeing with medical achohol on cotton buds in situe, a bit of a faf but the results were well worth the effort. Oh the filters were selling for 65/70 each and that was 4 years ago, so decided I had nothing to loose and if I had cracked them would only of been back where I started thinking the filters needed replacement. Apparently the cost is because they are like stained glass with the colour all the way through the glass not coated to the surface which is why its safe to clean them.

Regards Paul.
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Old 28th November 2010, 07:15 PM
MarkWalker MarkWalker is offline
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Thanks for your considered responses guys, much appreciated.
The negatives I've used are all normal and I checked them against my Multigrade 400 head on the 203 which gave exposure times of 20 -30 seconds for a 12" enlargement. Also, I had cleaned everything and the previous owner had been using it for many years until only a couple of months ago for 5x4, I haven't talked to him yet to see how he got on.

Vanaan, what a great contribution. I have attached a picture of the mixing chamber I made for 6x6 out of some scored, bent and taped sign laminate (@ 3.00 for over A4 size: v. useful stuff). The device was wedged into place with polystyrene sheet - the short 2" diameter tube to the light portal isn't shown.. I very much like your contraption, are you like me, always scouring for materials to improvise with because it can't be found off the shelf ? I suspect many are on this forum. You have given me an idea to utilise a spare mixing chamber I have, and to use some thinner white perspex for the bottom diffuser.
Dave may have repeated the most salient point, however, which is the narrow beam lamps which I feel sure were originally manufactured.
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Old 28th November 2010, 09:06 PM
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Jon Butler Jon Butler is offline
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Mark pleased to hear you improved the light output but this does still seems a long exposure time to me if your using f8.
If I enlarge from a 6x6 neg to produce a 12" print the time would be about 8s @ f16.
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Old 28th November 2010, 09:16 PM
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vanannan vanannan is offline
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Quote:
Originally Posted by MarkWalker View Post
Thanks for your considered responses guys, much appreciated.
The negatives I've used are all normal and I checked them against my Multigrade 400 head on the 203 which gave exposure times of 20 -30 seconds for a 12" enlargement. Also, I had cleaned everything and the previous owner had been using it for many years until only a couple of months ago for 5x4, I haven't talked to him yet to see how he got on.

Vanaan, what a great contribution. I have attached a picture of the mixing chamber I made for 6x6 out of some scored, bent and taped sign laminate (@ 3.00 for over A4 size: v. useful stuff). The device was wedged into place with polystyrene sheet - the short 2" diameter tube to the light portal isn't shown.. I very much like your contraption, are you like me, always scouring for materials to improvise with because it can't be found off the shelf ? I suspect many are on this forum. You have given me an idea to utilise a spare mixing chamber I have, and to use some thinner white perspex for the bottom diffuser.
Dave may have repeated the most salient point, however, which is the narrow beam lamps which I feel sure were originally manufactured.
Hi Mark
I am exactly like you. I am always finding and storing scrap materials obtained from various sources and subsequently cutting, filing, pop riveting and epoxy glueing to fabricate things that are either unobtainable or ridiculously expensive, many of my creations maybe rather ugly which doesn't bother me in the slightest.

Best wishes
Regards
Tony
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Old 29th November 2010, 11:30 AM
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Thanks to Tony and Mark for sharing their solutions for the lamp house.

I will now start looking for the bits.

Bill
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