Durst F60 bulb replacement with led bulb ?

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FrancoisM

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Hi everyone,

I inherited of a very well preserved Durst F60 enlarger but i'm quite surprised by the amount of heat generated by the bulb. Even after just 1 minute
The bulb is a Sylvania 212 (150W I guess)
As I intend to use the enlarger in an Ilford Darkroom Tent, I'm afraid the heat will become a problem
Can I replace the original bulb with a LED equivalent ? (150W, same dimensions, etc.) Like this one for example: https://www.homedepot.ca/product/philips-philips-3-way-50w-100w-150w-soft-white/1001015360
FWIW, I only use Black & White

Thanks for any info and/or hint

Have a nice day

F.
 
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Paul Howell

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I use GE banded LED, 1600 lums same output as a 100 watt bulb that I use on my D3, and 1800 lum or 150 watt output I use on my Metopa 6. As my negatives are scaled for grade 2 and I print with no 2, 2 1/2 and some times number 3 filters I have not had any problems with contrast. As the Durst F60 uses an off set bulb and mirror set up you need to make sure that an LED will work as only the top maybe 1/2 of the bulb emits light.

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MattKing

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It depends on the bulb and any variable contrast filters and papers you may be using.
At the very least, any speed matching characteristics of the variable contrast materials you are using will be gone, because the spectral distribution of the LED bulb will be very different from the tungsten bulb the enlarger is designed for.
In the case of my LPL enlargers, the LED replacement that fit put out significantly less usable light than the 100W halogen bulb the heads are designed for - leading to rather long exposure times for 35mm negatives.
 

albada

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Some LED bulbs work well and others don't. And I agree with the cautions that Matt posted. In addition:
  1. Some bulbs emit most light from their sides, and others emit most from the top.
  2. Some bulbs have writing on the top, which will appear in prints with most condenser optics. Acetone or emery paper might remove such writing.
  3. With condenser heads, the physical size and shape of the bulb affects uniformity of illumination on the paper. Try to use a bulb with the same size/shape as the proper tungsten bulb.
Mark Overton
 

Paul Howell

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The GE LED I use have the maker stamp on the lower part of the bulb that does not emit light. If your printing time get too long you can move up to a stronger LED bulb.
 

albada

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MattKing

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f your printing time get too long you can move up to a stronger LED bulb.

As the PH212 bulb has a 2300 lumen output, you probably need something like this to achieve similar output:
 

albada

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As the PH212 bulb has a 2300 lumen output, you probably need something like this to achieve similar output:


This seller provides detailed specifications:
https://www.grainger.com/product/PHILIPS-LED-Bulb-A35-449V04

This bulb is large. If it's about the same size as the PH212, I suspect it will work well.
Note that its color temperature is 6500K, which is much higher than the roughly 3000K that tungsten emits. That higher proportion of blue will force one to use lower-numbered grade-filters.

Mark Overton
 
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FrancoisM

FrancoisM

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Thanks everyone for all the advices and tips

@MattKing : I'm a total newbie in printing, so I have no prior settings to take care of when changing the bulb
@albada : Thanks for the Grainger link. I've found the same bulb on amazon.ca as they don't have it on their canadian website

Have all a great day

F.
 

MattKing

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@MattKing : I'm a total newbie in printing, so I have no prior settings to take care of when changing the bulb

Understood, but you may find that a bulb that puts out substantially less light may result in print times that are exceptionally and inconveniently long.
 
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Not familiar with your enlarger but if you are only printing 35mm and you have the right condenser you could probably drop down to a 75w bulb or even less.

The other obvious solution is to limit how much time you leave the enlarger turned on. It only needs to be on a few seconds for focusing and getting everything lined up and a few for the exposure.

I have used LED bulbs in the past. One issue with them is the time it takes for them to turn on and off. Not that big a deal, but it is there. It will only cost you a few bucks so you might as well try it.
 

ags2mikon

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I converted one of my Kodak precision enlargers to 12 volt LED. This enlarger is in my motorhome and will run off the coach batteries. It is 4000K so close to tungsten enlarger bulbs at 3400K. It is barely a half grade different in contrast. It is 1050 lumens so a little weak, meaning 22 seconds instead of 11 seconds. But no heat build up so I don't get any negative popping. It is a condenser enlarger with 35mm 6x6 and 6x9 condenser sets. I may try a conversion in the main darkroom some day.
 

koraks

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One issue with them is the time it takes for them to turn on and off

Some (many) bulbs do this, but not all. Since they're not all that expensive, it's worth a thought to try a few and select ones that turn off instantly.
Btw, turning on is always instant, but the 'afterglow' can certainly be problematically long. The only upshot is that it tends to be constant, but with short-ish exposure times this will induce significant non-linearities when changing aperture and exposure in tandem.

A technically more challenging but also superior option is to work with discrete blue and green LEDs for B&W and fashion a controller that mixes both colors just like a proper multigrade head. For the electronically inclined, it's not overly complex, but without prior experience DIY-ing electronics I'd stick with store-bought bulbs.
 
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