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[David Allred]

Kind of out of the blue (one gig to the next), my old Altman Dyna-Spot started projecting the vertical bulb filaments.  The layout of the spotlight is back reflector, 1000w bulb with filament rows running side to side (flat to lens), a multi-ringed lens, iris, fixed focus(?) lens, then the adjustable focus lens.  Has one of my fixed lenses moved on the positioning rails?  I already tried a new bulb.  Any advise or knowledge?

Thanks,
David

[Lester Seidenberg]

Kind of out of the blue (one gig to the next), my old Altman Dyna-Spot started projecting the vertical bulb filaments.  The layout of the spotlight is back reflector, 1000w bulb with filament rows running side to side (flat to lens), a multi-ringed lens, iris, fixed focus(?) lens, then the adjustable focus lens.  Has one of my fixed lenses moved on the positioning rails?  I already tried a new bulb.  Any advise or knowledge?

Thanks,
David

Your lamp holder or the mirror has shifted.  Did you remove either to change the lamp? If so look and see if there are any marks to show their original positions and adjust accordingly.  BTW the multi-ring lens is called a Fresnel lens (named after the inventor) ad was originally used in lighthouses.

[Scott Hofmann]

I believe the "multi-ringed lens" is referred to as a "conza" lens by Altman. From this picture:
http://www.ebay.com/itm/4-1-2-in-diameter-conza-lens-for-Altman-followspots-/271116243773?nma=true&si=J%252F%252Fuke4w2Edvx5J20oWZUNk3Cik%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
it looks to be a "step" lens, which is the reverse of a Fresnel lens. The plano face of the lens is ground away into steps or rings, whereas the convex face of the lens is ground away in a Fresnel lens.

[David Allred]

Your lamp holder or the mirror has shifted.  Did you remove either to change the lamp? If so look and see if there are any marks to show their original positions and adjust accordingly.  BTW the multi-ring lens is called a Fresnel lens (named after the inventor) and was originally used in lighthouses.

I have never removed either.  The lamp holder I suppose could have shifted if the mounting screws (assuming) have loosened over time and transport with an agressive bulb insertion or removal by a helper.  A while back the light developed a nasty rattle.  The fan was the cause, but the rattle was from a worn out shutter assembly.  I never really used the shutter (plus the douser is, to me, a nicer effect), so I removed the entire assembly.  To do that I had to slide the "conza lens" out of the way, but marked the location on the bars before moving.  I don't recall the filaments showing the next time used, but perhaps.    I wish I knew for sure.

I can't imagine that bulb rotation would cause it, since a perfect 90 degrees would be the next logical postion, and logically the holder could not "accidently" shift a perfect 1/4 turn.  Side to side or front to back maybe.

Should I loosen the conza holder where I can lean toward and away from the bulb to see if it helps?  I guess that "Oove Gloove"  will come in handy.

Any other advise?

Thanks,
David

[David Allred]

The Conza lens has ripples on the lampside.  On a whim I rotated the lens 90 degrees.  The lens would not budge until I loosened the 3 clamp springs.  After rotating 90 degrees there was definite improvement.  I continued to rotate it a couple of degrees at a time until it was as close to perfect as I could get it.  The ripples in the lens ended up 45 degrees off axis with the vertical filament lines.

Anyone care to offer a theory. 

David

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