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  #21  
Old 18th December 2023, 04:32 PM
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Martin Aislabie Martin Aislabie is offline
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Welcome to FADU Jolyon.

I'm impressed with your dedication to making your enlarger a 6x6 machine.

It would be great if you can make it to the Dartmoor weekend - with or without prints.

Hopefully, you'll find us a friendly and helpful lot here at FADU.

Martin
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  #22  
Old 18th December 2023, 07:51 PM
Jolyon Jolyon is offline
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Quote:
Originally Posted by BuzzNL View Post
I've done some extensive testing with LED bulbs in the past, including measuring and comparing the color spectrum, edge falloff on the baseboard and doing some real-world tests on all grades using Ilford filters.
In short, warm white LEDs worked the best for me. Cold white have much more blue than warm whiter LEDs (and the original tungsten bulb ofcourse), slightly messing up the contrast filter spacing.
Not dramatically and still very usable, but warm white worked better with my filters and papers (I tested Ilford MGIV RC and Fomaspeed Variant).

Even between different warm white bulbs there can be a great difference among them but it's definitely possible to get good results with decent contrast spacing if you use VC paper with an LED bulb.
With all bulbs startup time was no issue and test strips vs final print were at least equally close compared to a normal tungsten bulb.

I also use the LED bulb for graded paper and that gives me good prints too but I have not done any proper contrast testing with that as I only have a limited amount of graded paper, not really worth it to do proper testing in my case.

I've found the cheapest warm white bulb to work best in my setup by the way. I bought it a couple years ago at the Dutch discounter "Action", of which I've also seen stores in France. It's one of those E27 bulbs in a green half-open cardboard box.
That was an 11.5W Warm White bulb, cutting my exposure times roughly in half compared to the original Osram 60W bulb.
Thanks. Yes we have an Action store in Limoges (and one or two similar competitors). I didn't realise they were european. That lamp must be a bit more powerful, perhaps closer to 100w equivalent. The advantage with leds is that there isn't the same problem with heat dissipation compared to incandescent.
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  #23  
Old 18th December 2023, 08:02 PM
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Reginald S Reginald S is offline
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Welcome, Jolyon.


For us (modern) b&w guys we have to look for what our paper will need.

As you have said at first it needs strong light which led me to High Power LEDs.
Comparing to my enlargers you don't need much light intensity; maybe you could use easier solutions with normal LEDs (no High Power) but there I have no experience.

It's not easy to find all specs needed in the datasheets - but there exist data sheets for this HiPo LEDs.
And that's the great advantage - I was able to fit the spectral needs of my papers with specified LEDs.

The choice is now between white LEDs only for straight printing corrected with filters, or some blue and green LEDs for splitgrade printing.

Me I bought white, green, blue and red LEDs for being most flexible.
Red is for adjustments under sight and light, no red filter needed then.

The downside is that you have to build your own creation which can take month for collecting knowledge. That's what i have learned.
At least it's not such complex as described in the web - just do it :-)

Last edited by Reginald S; 18th December 2023 at 08:05 PM.
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  #24  
Old 18th December 2023, 08:16 PM
Jolyon Jolyon is offline
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Thanks Alex I will have a look tonight and see how what I have compares to that. I could visit Tesco over the next couple of months although the local store for where I am is Sainsbury. I am thinking in terms of something a bit more powerful but the temperature is a good starting point..

Thank you Martin for the kind comment. For the record I would not have bothered with the F30 if I had known that the M370 was going to come my way. But, given that there was little point in making a second head for 35mm (including making a new condenser housing probably) the choice was bin it or hack it. 6x6 or 6x7 condensers for the M370 look to be way too expensive or otherwise unobtainable so the experience with the hack helps me a lot. I'm planning to get a 35mm condenser complete (which is affordable and available), remove the condenser and hack the rest into a diffuser support. I need the plastic support, it retains the negative carrier. I already have a working option for the diffuser material (there may be better, like glass instead of plastic but it works), I have a working option for the negative carrier; it just needs a bit more light (the M370 BW uses the same 75w, although perhaps a bigger bulb as the F30 which is much smaller). Watch this space, as they say in the adverts!
I will do my best to be at Dartmoor and to bring some (very rough) prints to show what happens.
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  #25  
Old 18th December 2023, 08:28 PM
alexmuir alexmuir is offline
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One problem I recall when trying to fit an LED globe type bulb into a Durst (M601) condenser head was the physical size of the bulb. Some have a larger dimension from the base of the metal cap to the top of the globe. This meant that it would not fit into the metal casing of the enlarger head. Itís worth making a quick measurement to establish the maximum height of bulb you can use.
Alex


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  #26  
Old 20th December 2023, 01:48 PM
Jolyon Jolyon is offline
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I have a bulb with a small globe like in a bedside lamp in the F30 there doesn't seem to be space for a big globe and 60W equivalent is the biggest I can find in a small globe (which is not nearly enough with the diffuser soaking up the watts).
The M370 has a lot more space and has a bulb with a big cylindrical envelope (although the instructions only quote 75W). I will have to check the headroom though. Since there is vertical adjustment it never occurred to me that this might cause a problem
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