Printed yesterday. Decided to keep the 300 W ELH bulbs and put a 0.31 ND filter in the drawer. It worked just fine. With the head all the way up, the 1 stop filter works fine. As I lower the head, for smaller enlargements, if I need additional density, I'll just dial it in with the dichroics or add another nd filter in the drawer. L
Hi, Luis,
As I understand it, the UV filter is there for color printing as color papers are sensitive to UV radiation. Though the tungsten halogen bulbs only emit a small (2%) amount of UV light, it is still enough to through off the color rendition.
With B/W, you don't need to worry about it.
The UV filter may be there simply because the enlarger might also be fit with other head options. On a incandescent lamp head there inevitably will be a IR filter, a very massive piece of glass, which will block enough UV that you would not be concerned over a mere 2% from the lamp. But you'll need extra UV filters on (xenon) arc or fluorescent lit heads - which both have far more UV to start with, and might not need a IR filter.
Thanks frotog, I decided that I can always add a UV gel to the filter holder if it's ever an issue. Sevo, the CLS 301 head has built in IR filters in the light path. It was the UV one that went in the holder, but on mine the holder was empty. Just aking though if others had any experience with this. L
Frotog, does your CLS 1000 light have a UV filter? Just curious. I've ordered a Rosco 3114 Tough UV Cinegel Filter sheet to cut down & put in the filter drawer. L
IC, Since the ELH bulb is a 120v bulb, have you heard of anyone rewiring the head to bypass the EST 301 & plug it directly into the timer? I always figured that if my EST 301 died, I could do that as a fix and then just run the blower continuously when I was printing. Any thoughts? Thanks, L
Poly filters are going to get cooked. A bit of scrim material in the filter drawer would work better. Fans should be continuous with these kinds of heads. A pull fan
and heat resistant ducting can be used. These heads are easy to rewire anyway, if you want to bypass all the old electronics. But if you do that, be sure to use
hi-temp "truck wire" or "engine wire" wire.
Drew, this is a CLS 301 head NOT a CLS 300 head. I don't know if you have any experience with the CLS 301 it is a 600 watt head with two ELH 300 watt, 120v bulbs, mine is fully stock with no modifications just the way it came from mother Durst. It has the original Durst 220 v Lafan attached and the head/power supply presently have a thermostat which turns the fan on and off as needed to control the temperature. The fan comes on when the bulbs come on and shuts off when the bulbs shut off. It does NOT run continuously or stay on unless the bulbs have been on for a long time and then the fan will then run longer until the head cools down, and then the fan shuts off. I'm not planning on bypassing the electronics unless my EST301 power supply dies, but at some point, I figured it will. As the bulbs are standard 120 v, it should not be too difficult to rewire directly to the timer. I would need to plug the fan into 220 v outlet or use a transformer or buy a 120 v fan to replace it. The high temp truck wire suggestion is a good one if I decide to do any rewiring inside the head, but I figured that I could just splice to the leads just before it connects to the power supply and not have to do a complete rewire from inside the head, though that could also be done. Don't understand why you say that the filters are going to get cooked! Thanks, L
Hi, Luis,
My CLS 1000 does have a UV filter.
Since your Roscoe ND gel is going underneath the mixing box, it will not be in a direct path with the CLS 301's two bulbs - heat will have no effect. Years before I sold the 301 to you, this is exactly what I would do when printing 8x10 and smaller.
As you probably already know, there's no circuitry in the head and thus no reason to ever rewire it, LOL. No, the "old electronics" are in the EST power supply. You can not bypass this without using some kind of free-standing transformer to convert voltage. Should the power supply bust a cap or fry a board, I have the schematic.
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