Question about Ilford Ilfospeed Multigrade 500H enlarger head

[Marco B]

Hi all,

Two years ago, I've acquired a Durst Laborator 1200 including an Ilford Ilfospeed Multigrade 500H enlarger head and all electronics. Since then, I've grown two love this setup and get great results from my 4*5 negs. However, there is one small question I would like to have answered:

The Ilfospeed 500H head comes with a variety of white metal diffuser boxes for different negative formats. I only use the 4*5 box, since I have a second enlarger for 24*36 negs. However, the diffuser box for 4*5 contains an extra carton box inside. This box neatly fits inside the white metal box, and the lower 1/3 of this carton box (just above the diffusers milky plastic) is lined with a kind of tough aluminium foil, as an extra reflective surface.

My question:
Is this carton box supposed to be in there, or is this a "homegrown" adaptation of the last owner of the enlarger? And what is it's function? Sometimes the carton has a tendency to buckle in and impair light distribution, and hence I have considered removing it, but I'm bit weary of the effect on the light distribution with it completely removed. Of course I could simple give it a try, but I thought it good to hear some informed comments from others.

Thanks for any info,

Marco

 

[wfwhitaker]

The box is supposed to be there. As you suggest, it aids in the light distribution. With age and humidity they do tend to buckle as yours has. They also tend to yellow over time, lowering the available contrast of the system. If yours isn't yellowed, you could try an adhesive to keep it flat against the walls of the diffuser box or you could simply try making a new one out of white mat board.

 

[Marco B]

Thanks for the reply, I will give it a try with some adhesive and see if that works.

Marco

 

[hal9000]

uh oh - no inner box!

My 500 system doesn't have the box within the 4x5 diffusor box, i suppose a previous owner removed it. Is this causing bad things to happen? I haven't noticed anything yet, what would be the result of not having it?

 

[wfwhitaker]

...what would be the result of not having it?

Presumably the inner box is there to insure that the light distribution is even. Have you looked at the projected light on the easel without a negative? How do your prints look? If they look fine, then I wouldn't worry about it.

 

[keeds]

Mine has the inner box, and I have a definate hot spot in middle of the projected image. Not sure if it's to do with the sheet of ND I placed above the diffuser to increase printing times.

 

[Marco B]

Hi Andrew,

If I were you, I would remove that ND sheet...

The light distribution is actually one of the very good things about the Ilfospeed 500H head in combination with supplied diffuser boxes: there is almost NO light fall-of to the corners of the images.

Additionally, I have now run two tests WITH and WITHOUT the carton box, to see what effect it has...

This is what I've done:

- Removed my negative from the negative holder and inserted the empty negative holder back into the enlarger (I use full frame 4*5 glass in the negative holder).
- Now aimed for an illumination that would supply something close to "grey card" grey (9sec at F16 for the Ilford Warmtone FB paper I used and the height of the enlarger head I set), and than normally developed and fixed the paper.
- Now I've removed the carton box in the diffuser and gone through the same procedure.

RESULTS:
The differences are minimal, BUT I do see a slight "hotspot" for the paper that had the carton box REMOVED. There is a slight, but visible, light fall-of to the corners of the grey image (corners are lighter, so have received less light).

So it does seem the carton box helps to even out the illumination. Personally, I think this is mainly due to the alluminium foil in the lower 1/3 third of the carton box, and not so much an effect of the entire white carton box (the diffuser box is already bright white).

Additionally, since William remarked that the box might influence contrast (my box is indeed slightly discoloured), I have done a similar test using one of my negatives. I could see almost no difference in terms of contrast, so although a reduction in contrast is likely when the carton box ages, it's effect in reality is luckily not so big.

Cheers,

Marco

 

[keeds]

Marco, thanks for the input. I have yet to do some testing to see if it is the ND sheet, but I think it probably is because I didn't notice the issue before I placed it there. How do you get longer than a few seconds exposure without it? My exposure times were in the realms of a few seconds, even with stopping the lens down. I use a 150mm lens for 5x4? Any clues?

 

[Marco B]

Hi Andrew,

What paper sizes do you print? How high above the paper is your enlarger's head? What's the wattage of the halogen lamps in your enlarger? If I read the manual correctly, it should be a maximum of 2*150 Watt. Well, with a higher wattage, I guess you would not only have a hotspot on your paper... LOL ;-)

I have a 150 mm lens too, and usually print on either 30*40 or 40*50 cm paper at heights of around 60 - 75 cm (measured from the bottom of the enlargers head!). I get times varying between 20-60 (..90) sec's for F11 with Ilford Warmtone Fibre based paper, which is a slower paper than normal Fibre based. So just a few sec's is REALLY short.

Maybe a stupid question, but does your diffuser box actually have the white milky plastic at the bottom? If it didn't, if it got lost somehow with the previous owner of your enlarger, than that would probably make a huge difference in exposure time, and be a major cause of your "hotspot" ;-)...

 

[keeds]

Marco, I believe mine has 2 x 300 Watt bulbs, probably a different model then, and yes I do have the white milky plastic. I only print to 10x8. The extra wattage would explain the short exposure times...

 

[Marco B]

Hi Andrew,

I don't think you have a different model (not at least if it read 500H on the outside as well). Please note that the sticker on the inside of the enlarger's head falsely suggests 300W lamps. The official manual explains that it should be 2*150W maximum. However, I seriously believe that this head wouldn't even be able to cope with 2*300W and result in a melted "hotspot" of an enlarger head. If I consider how hot the outside of the enlarger's head already becomes with 2*150W with prolonged exposures, it could hardly withstand more than that... even with the active cooling. 600W of halogen leaves at least 500W of heat to get rid of...

You might indeed consider simply replacing the current bulbs with a lower wattage, maybe 2*100 or 2*50 W or so, also saves on the energy bill...

By the way, I have now examined the dried fibre test prints (drying makes a lot of difference with fibre based paper). Although the conclusions remain the same, I can now be a bit more specific:

- WITHOUT the carton box, a rather clear hotspot is visible. I think one would need to burn in all corners about 1/4 to 1/3 of a stop to compensate the light fall of.

- WITH the carton box in the diffuser, the illumination is as good as it could be, I see no reason to burn in corners in this setup.

- There is a visible slight reduction in contrast in the negative print WITH the carton box, probably due to the yellowing / aging of the carton, but it is still not that worrying. I may try creating a new box once, but it is not an urgent matter.

- Additionaly, the negative print with the carton box has a distinctly "cold" tone as compared to the warmer print created without the carton box inside. Maybe this is due to some more fogging in the highlights, hence less contrast, in the print with the yellowed / aged carton box.

Marco

 

[wfwhitaker]

In one set of instructions I have for the 500 there's a note that additional heat shields need to be in place to use the 300W bulbs. Those instructions aren't accessible right now and I'm going from memory, but I had inferred from reading them that there was a modification made mid-production to increase the wattage from 150 to 300 to reduce printing times. If that's true, then it's entirely possible that there would be both units in use. In the units I've seen, some had the additional heat shields, some didn't. Take it strictly for what it's worth.

 

[Marco B]

Hi William,

That may indeed be so, but there is another easy way (besides disableming the lamps and see what wattage it is) to check the max. wattage: simply look at your transformers output. My Ilford 500S transformer has a max. output of 400W, so I am sure it's 2*150W in my case.

By the way, I do have something that looks like a "heat" shield in front of each lamp... (white carton?) to protect the front side of the enlarger's head.

Marco

 

[wfwhitaker]

... simply look at your transformers output. ...

That would tell you what the output is, not what lamps are actually installed.

The heat shields I'm referring to are metal. Unfortunately I won't have any access to that stuff for a few months to check it more closely.