Old Altmans

[carsonld]

I have a about 20 Altmans and some of them do not focus. I believe they are the 360Q in a 36,26, and 19 form. I have tried changing the bulb, cleaning the lenses, moving the lamp, and looking at the piece of glass and comparing the ridge side to one that focus. After fixing the direction of all the glass in the lights, I still can't get it to focus. Any ideas?

I uploaded a picture of it. The bottom one is the one that focus. The top, bigger one doesn't not. They are supposed to be 19°

 

[gafftapegreenia]

With the 360 and 360Q line, the lens train tubes will fit in the body of any model in the line. So a 6x9 tube will fit in a 6x12 body. It's an easy mistake to make especially when you have a bunch apart for cleaning. I have to start my workday but if someone hasn't done it I'll detail measuring the instrument and checking lens focal length on my break.


Sent from my iPhone using Tapatalk

 

[theatricalmatt]

Like gafftapegreenia mentioned, the lens tunes may have been swapped. Try marking the lens tubes once you'very determined their actual designation.

In addition, check that all the lenses are seated properly. There should be two lens elements in each tube, and they sit so the flat sides point out, and the curved sides point toward each other inside the tube.

I don't have the data for the lens thicknesses in front of me, but essentially the thicker the lenses, the wider it's beam spread will be.

The "collar" the separates the two lensespecially also needs to be the right size.

Also, 360Q's have a different designation for their lenses, which incorporates the lens diameter and it's focal length.

A 6 X 9 is *approximately* a 36-degree
A 6 X 12 is *approximately* a 26-degree
A 6 X 16 is *alproximately* a 19-degree

 

[derekleffew]

I have been puzzling over the information presented here for my own needs and would like to share what I found out after contacting Altman directly. The following are the Lens Tube (or Barrel Lengths) Sizes for the current Altman 360Q as sent to me from Altman customer service:

4.5/6x9 > 5 1/2 inches

6x12 > 7 1/2 inches

6x16 > 10 inches

6 x22 > 16 inches

The "greater than" listed above is important. I found a half inch difference between a standard 360Q and a 360Q with an iris. This is not to be confused with the Lens Assembly which contains the actual glass lens elements and the gel frame holder. Hope this helps!

 

[kicknargel]

I like the swapped tube theory, but another possibility is that the reflectors have gone cloudy or lost their coating.

 

[JD]

Are you sure no one took the lenses out to clean and then assembled them with the wrong lenses?
You can test the reflector theory by swapping the lens tube on a known good unit with one that is bad. (same type) If the problem moves with the tube, then look at the lenses. If it stays with the fixture.... Still, I suspect the reflector is not the issue as the ring in the focus is the projected image of the gate, not the reflector. A bad reflector will give you off-axis background spill, but the unit will still focus.

 

[Les]

I have approximate lens measurements and a visual aid.

Thickness, left to right:
6x9: ~1-1/4"
6x12: ~7/8"
6x16: ~5/8"

Note: 6x22 uses a single 6x16 lens (correct me if I'm wrong).



Interestingly, any time I've ended up with mismatched lenses, I'll get a projection of the reflector rather than a fuzzy spot, but I'll admit that I haven't tried all combinations and lens types and that's definitely something you should check. I'm sure you've tried it, but aside from changing the axis of the lamp (3 screws), work on the depth (center screw with jam nuts). A lamp too deep in the reflector will get you a bright center and dim, unfocused edges - at least in my experience. Lamp too far out gets you a dark center.

The "collar" the separates the two lens especially also needs to be the right size.

I have never observed a difference in the size of the spacer/baffle. Anyone else?

 

[JChenault]

In terms of size. There is an easier way.

A 6x9 lens is 6 inches in diameter with a focus length of 9 inches.

6x12 has a focal length of 12 inches, etc.

If you have work lights / house lights turn them on. Hold the lens over the floor moving up and down until you have a sharp image of the light. Measure the distance from the floor to the lens. That is the focal length.

You also may have different size lenses in a tube. IE check to see that they are both 6x12 or 6x9 etc.


if the reflector has gone cloudy, it should still be sharp, just not bright.