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  #1  
Old 18th August 2014, 07:29 PM
CarlH CarlH is offline
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Default Darkroom up and running....

Finally got everything setup and started printing some negatives.
discovered my old Gnome MasterII doesn't have a very even light pattern.
very noticeable dark corners, so tried the condenser lenses from a old Czech enlarger, much better pattern just misses the corners off as the lenses are smaller.
The only thing is its now a lot brighter so am needing to use f16-f22 at 10 seconds, question.. can you use ND filters on enlargers?
Once the prints are dry I'll get my brother to scan them so I can post them up for any helpful advice
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Old 18th August 2014, 07:45 PM
Mike O'Pray Mike O'Pray is offline
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Glad you're up and running. As I understand things you can use ND filters. It is often the solution proposed when others ask about ways of increasing exposure.

If your exposure figures are based on no filters at all then you might find that Ilford under-the-lens filters will increase the exposure sufficiently.

Might be worth trying before buying an ND filter.

Mike
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Old 18th August 2014, 07:47 PM
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Argentum Argentum is offline
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you can use this above lens (not under as they are not optical quality) . I use them on top of my mixing box sometimes. Very cheap and you can use several layers if necessary.

http://www.stage-electrics.co.uk/sho...?code=501-7519

note: being lighting filters they can take the heat of a lamp.
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Old 18th August 2014, 08:17 PM
alexmuir alexmuir is online now
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With some enlargers, like the Gnome models, it's possible to raise or lower the lamp in its housing to improve the coverage. If the cable comes out of the top of the lamp house, there is sometimes a collar with a screw that can be loosened off to allow adjustment. I'm thinking that the original condensers may be best if they are the ones that came with the enlarger. The other option for longer exposure times might be a lower power lamp. The standard opal enlarger lamp tends to be 75Watts, but some are 150W. If it's the latter, times would be very short. I don't think, however, that the bulbs come in anything less than 75W.
I used a Gnome for a number of years, and it was easy to work with. I gave it away eventually, but I reckon it will still be in service somewhere.
Alex.
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Old 18th August 2014, 10:37 PM
CarlH CarlH is offline
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the current bulb is 150W bayonet fitting so have searched the internet and found a 75W one.
the lamp will adjust up and down but is already as high as it will go, lowering it makes things worse. I suspect the bulb is physically bigger than what was originally in there so will always be too low. As I bought 2 enlargers, 3 lenses, 6 trays, film tanks and various other items off ebay for very little money, I can't be sure the condenser lenses are 6x9 or 35mm ones.
Argentum excellent idea with the stage lighting filters, would never have thought of that!

Last edited by CarlH; 18th August 2014 at 10:42 PM. Reason: more info added
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Old 18th August 2014, 10:40 PM
Steven Steven is offline
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I would vote for a lower power lamp, too. Less wattage means less heat and therefore less chance of the negative 'popping' with the heat. What is in there at the moment?

Am I right in believing this is a 2.25 x 3.25 enlarger? If so the condenser lenses should be at least 4 inches in diameter. Are they this big? I was just wondering if maybe they had been changed for something smaller at some point if the enlarger had been used for 35mm or 6 x 6?

But yes... You can adjust the bulb up and down for more even illumination on some enlargers (but not mine )
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Old 18th August 2014, 10:46 PM
Steven Steven is offline
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Whoops, overlapping post....

So, the bulb was too big. 75w should help... But the bulb position would depend on the focal length of the condensers, so that also hints, with the uneven illumination, of the condensers being the wrong ones. The diameter should give you a clue. And is there a pair? I have a 35mm enlarger that uses a single lens and a medium format one that uses a pair. Both have the same 75 watt bulb but the lamp housing is much taller in the MF enlarger.
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Old 20th August 2014, 01:29 AM
CarlH CarlH is offline
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the condenser lenses that came with the Gnome are 4.25 inch diameter with a focal length of 21 inches. the ones out of the Czech enlarger are 3.75 inches in diameter with a focal length of 19 inches.
It will take a maximum negative size of 2.25 x 3.25 inches.
I have a third Gnome enlarger a lot older with the same diameter lenses which are 22.5 in focal length, even worse than the 21 inch ones!
I will get a working enlarger even if I have to dig out my old physics books from school to re-learn all about lenses and rebuild the thing!
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