Yes, they are good size, of course they also made the L184 10x10 enlarger...
Yes, they are good size, of course they also made the L184 10x10 enlarger...
I think that would need a wall to be knocked down, I'll pass on that !
I'm slowly getting my head around the bulb/diffusion issues.
I think a useful step would be to buy some opal diffuser ( in short supply but still available ) from Knight Optical in the UK. They do 100mm dia and 150mm dia sheets, better go for 150, I can have it trimmed at work.
The seller sold me two 400W bulbs but they are are only around 3" dia which I assume ( from the 138 S Manual ) will not be big enough alone to do 5x7".
I am wondering if a good long-term solution is to use a 150W or 200W bare halogen bulb with a reflector behind it, I will have a closer look at the internals and see what can be mounted from where.
I can also get a heat filter from Knight.
I had a look through more threads, and found links to the service manual - however, the ones I tried are dead.
Can anyone help ?
https://www.trippingthroughthedark.c...structions.pdfOriginally Posted by Mark J
You're a hero, thanks Larry.
Now I realise that you're Tripping through the dark ( D'Oh ! ) , that makes sense.
It's a good read that, it helps a lot to understand what projects you've mentioned doing, now I can see the pictures. Good that you have an option to do LED-into-condenser.
i have bought the 138 S for the dual purpose of being able to print from 5 x 7 ( and take more 5x7 .. ) , and to see how condenser illumination looks. Based on what I have seen of the theory on Callier effect , and what i have seen online with an item Greg 'naked photographer' did , I believe it can produce more local contrast, especially in highlights, even if the overall contrast range is equalised.
I'll keep asking you a question or two, if that's OK ?
When you have tried different bulbs, and under-running bulbs, how did you measure colour temperature ? I would guess maybe you have a colour incident meter, like a Minolta or Sekonic ?
Do you have a feel for where the bulb temperature needs to be to get a G5 result in a reasonable time exposure ? ( if doing split-grade ) I say this because I have checked my Meopta diffuser-head details, and it runs a 3300K reflector bulb but through the Meopta box it only delivers G4.5 ; however I am expecting as condenser it will add at least another grade, so somewhere down the scale a bit should be OK.
My current interest is in the consumer security lamps, which have rather nice long transparent bulbs ( horizontal ) at sizes like 118mm overall, plus a dimpled back-reflector. They are billed at colour temperatures up to 2800 or 2900K , although often it's a bit of a range given. However they are really cheap, the bulbs are only eg. $5 and come in wattages from 80 to 500W , so it's not a big risk to try out some tests. I will probably buy one to have a look at the spread pattern to see if it's going to fill a 4" x 4" opal glass at eg 2 to 3".
Is the Opal you used what's referred to as 'Flashed Opal' ?
I have been unable to get any comment from one supplier ( who still has stock ) about its heat-durability. I think it is quite robust up to reasonable wattage/proximity though.
Enough for now ...
Mark, when I experimented with reducing the voltage on the incandescent bulbs I measure the color temperature with a Minolta Color Meter II.
I don't think I measured the maximum print contrast based on color temperature. I did print a few negatives and noticed with the warmer bulb (lower voltage) that it needed a higher contrast filter to produce the same print contrast.
In my tests with the flood lights (probably what you mean by consumer security lamps) that the diffusion was pretty even through the flashed opal glass (clear glass with a thin white layer on one side). I noticed no heat issues, but I didn't really use any of the incandescent bulbs for very long. I think if you run a blower you shouldn't have any heat issues. The blower I hacked together put out plenty of air and kept the lamp chamber cool, at the expense of noise and managing the blower hose. If you have the heat absorbing glass you could try white acrylic or polycarbonate in the filter tray if you can't get the opal glass any more.
I moved onto building an LED head with separate blue and green LEDs and pretty much abandoned the incandescent bulbs after I discovered how well it worked. Regarding contrast, I don't think with Ansco 130 developer I ever got a true grade 5 result with any paper and light source. Looking at the few papers I took the time to profile with the LED head the MGIV was able to produce the highest contrast of 60 (about grade 4.5). I'm sure some of that is the developer, and some is related to how VC paper works with it relying on multiple emulsions to build up density. I don't see that as a real issue for making split grade printing work well with normal negatives. Also note, my tests were all done with diffuse light (step wedge contact printed), so maybe I could get closer to grade 5 with the condensers. I should test that out.
Thanks, that takes me on a couple of steps. i think we are talking about the same thing re. the opal glass. I will order one of their few remaining 100 x 100 mm sheets.
Edit : a bit more searching on EBay and manufacturer's pages shows that I can get 3000 K linear bulbs in the 118 length and 160-240W range. i think that will be enough.
It's not the paper, and it's probably not the chemistry. It's probably the bandpass of the LEDs - the additive version of the MG500 dichroic head can't get all the way to G5 & Ilford's test of the Heiland LED head also showed very similar behaviour. The MG filter set is able to deliver G5 - if anyone wants to spectrally analyse a G5 filter versus a #47 blue...
Has nothing to do with 130 developer. I use that all the time. Yes, things depends on the specific paper. But all three of the kinds of light sources I use - RGB halogen additive, CMY halogen subtractive, and V44 blue-green cold light - will take the contrast right off the cliff with a combination of hard blue filtration, 130 full dev, and the right kind of paper like MGWT. The blue channel on my additive units produces identical results to a 47B filter. I don't know if any LED source will get you there or not. I have no reason to try one. Some papers will achieve their max contrast via a 47 or 47B filter alone, while others seem to need a bit of token "white" light added in too.
And I've never thought of MGIV as a particularly punchy paper - kinda anemic in my opinion, especially compared to Ilfords newer VC papers.
Diffusers? Flashed opal glass comes with quite a illumination loss penalty. You might look into "Sign White" translucent acrylic sheet instead. A little scrap of it might not cost more than a dollar or two from a plastics store leftover bin.
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