Your thoughts on printing.

[false_Aesthetic]

Hrm, well I have a few new packs of Ilford multigrade filters on their way to test this.

The heads we have at school are totally abused. I can't tell you how many times I've walked into find a head left on for 5+ minutes. I suspect that before I got here, the heads were probably left on all night every once and a while. (Stupid Kids)

anywho. thanks guys.

[Peter De Smidt]

I am using a Deveere for split printing all the time, and I do get a good Dmax like that I get when using the Ilford filters on my Omega condensers.
Of course the light is a bit more diffused which gives a smoother transition but never have I felt that I am lacking black when I dial in 200 magenta vs 5 filter.

Well, maybe it was only me with the problem. Let's hope that's the case!

Nonetheless, would it really show with split printing? With split printing one uses a high contrast setting to get one's blacks and a low contrast setting to get the higher print values. If the high contrast setting was a little lower contrast than expected, wouldn't exposing a bit more give the required black density?

I used a Stouffer test strip negative to count the steps between black and white to determine the contrast at various settings with my color head. Getting the new filter really helped.

[Greg Blank]

That could also mean that Focal Point was simply able to supply a better or cleaner filter than the original. I would love to see the older Magenta filter, even if it merely means posting or emailing me a jpeg. Heres a thought though, does either side look somewhat pitted or have a visible deposit layer? There is always a mirror side shiney, and a dull side but a deposit should be visible and non cleanable with Isopropyl alcohol or Vodka

Well, all I can say is that I couldn't get above a true grade 3.5 with my De Vere. After trying everything else I could think of, I bought new dichroic filters from Focal Point. Visually, they were significantly denser than the old filters, especially the magenta one, and with it replaced I could achieve a true grade 4.5 . With De Vere, the dichroic filters are between the halogen lights and the heat reflecting glass, and they're very close to the bulbs, and so they really get blasted.

[Vlad Soare]

And dichroic filters do fade, especially, in my experience, magenta ones.

In my experience of repairing heads that is almost never true, I say almost because I have NEVER seen it to happen.

If I remember correctly, one reason why Omega introduced the Chromega Dichroic II series was that the filters in the original Chromega Dichroic head had a tendency to fade. So, I guess some dichroic filters can fade even when not abused (though, as your experience suggests, this may not happen as often as most people think).

[nolindan]

And dichroic filters do fade

Dichroic filters don't fade - but then one almost never sees a 'naked' dichroic filter. They are backed up with a dye filter, which does fade. As the dichroic filter is close to the light source the dye filter sees little light (the dichroic blocks/reflects most of it) and so the dye fades much more slowly than it would if it were the only filter. A dye filter mounted close to a halogen lamp wouldn't last long at all.

The 'filter' in a dichroic filter is a thin layer (usually metal) that forms a resonant cavity for the light beam. Being metal, or a metal compound, it is given to corroding unless well protected - the result of the corrosion is as if the filter had faded.

[ic-racer]

If I remember correctly, one reason why Omega introduced the Chromega Dichroic II series was that the filters in the original Chromega Dichroic head had a tendency to fade. So, I guess some dichroic filters can fade even when not abused (though, as your experience suggests, this may not happen as often as most people think).

I don't know about that. I do know the original Chromega heads were NOT dichroic heads and had filters that did fade.

Anyway I have a standing offer to pay $5 for all faded dichroic filters, any size (not broken).

[Peter De Smidt]

Well, I'm happy to amend my claim: Replacing my old dichroic magenta filter with a new one led to a full grade improvement in maximum contrast when printing on VC paper. My thesis that this was due to fading appears unlikely.

[Drew Wiley]

Dichroic filters do not fade per se. If they get overheated they can shift spectral
sensitivity somewhat, and over time the coatings will slowly start flaking off, leading to the need for actual filter replacement - a much bigger problem with hi-wattage color mural enlargers than any Chromega. The actual transmission characteristics of Chromega filters did become narrower and improved at some point in time. One problem with split printing is that it usually takes some exposure of both VC layers to get the best DMax. In other words, you might print using a deep blue filter to get the highest contrast, but then have to punch it with a bit of green light too to get full Dmax on certain papers. Using a colorhead with M filtration does this automatically because you always get a small amt of white light spillover in subtractive filtration.
I use both techniques and can achieve identical results either way.