It is a colour head, diffuser. The colours are dialed in using three knobs.
I use red and yellow for contrast control/in lieu of graded filters for b&w.
http://www.novadarkroom.com/product/..._Enlarger.html
It is a colour head, diffuser. The colours are dialed in using three knobs.
I use red and yellow for contrast control/in lieu of graded filters for b&w.
http://www.novadarkroom.com/product/..._Enlarger.html
Originally Posted by Ash
Ash,
It may be that they have redesigned the head since mine was manufactured. Mine is a dichroic head (three color diffusion). It has one halogen lamp.
Mine has a single screw in the top cover of the lamp house that allows the top cover to be removed and the mixing chambers to be interchanged.
Sorry if there is a difference between our heads and that I caused you undue confusion.
If the vignetting is occuring toward the front of the enlarger, I would remove the negative holder and place a white substrate beneath the enlarger lens and see if the vignetting is present without the neg holder installed. Next, if the vignetting is present with the neg holder removed, I would check for the condition with the enlarging lens removed. It still sounds to me like a coverage problem occuring in the light mixing chamber...however I have been wrong before.
I'm under the assumption it's down to the placement of the neg holder.
There's no access to the mixing chamber, you must unscrew two long thumb screws to get to the lamp. That is placed to the back end of the head.
I'll check next time I'm in the darkroom (sometime this week) but AFAIK without a neg holder the light will scatter to such an extent I won't be able to measure an accurate frame. Does that make sense?
It must be in the mixing chamber, but I'm not sure how. If it was a coverage issue surely it would affect the whole frame, or else the corners furthest from the lamp as opposed to the whole side that is closest?
As noted, the vignetting is coming from a shadowing of the side closest to the lamp, not the side closest to me.
We'll see but thanks for the clarity.
Make sure the halogen lamp is aligned properly in its holder. Mine was not resulting in long exposures. Just a thought.
Thanks, I'll do that.
You should get a reasonably good image of the edge of the light source. If not try stopping down. If you lens has enough coverage for the format, it has to show an image of an 'edge' of the light source. It may be way out of focus, but see what stopping down does. On all of my enlargers I get a somewhat blurry square outline, but it is easy to measure or trace on the baseboard. Then put the carrier in place and see if that image projects totally inside the box you traced.
The above procedure is de rigueur norm when using, say a 4x5 glass carrier with the 35mm light box. You need to see the shadow of the lightbox edge on the baseboard to get the 35mm frame in the exact center.
ic I'm not sure what you're suggesting will achieve. The lens isn't an issue, and the edges are clear and sharp, it's literally coverage in a straight line down one edge.
I've not been back in the darkroom since this last incident, so I'll probably go in tonight if I find the time and check the light box first of all.
Its a check to see that the negative carrier opening is exactly centered under the light box. That is to make sure the edge of the light box is not cutting off the light to the negative on one edge.
If you draw a box on your baseboard that shows the edges of your light box (as projected by your enlarger lens) then put your negative and carrier in place it will be clearly obvious if you negative image projects real close to one of the edges of the box you drew. That is where your vignetting will be coming from. It will also be clear then, which direction the negative carrier needs to be shifted to wind up perfectly in the middle of the box.
Sometimes a picture is worth a thousand words...
...or maybe even more confusing now...
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