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S4 36 degree Focus problem

Hi all,

We have a number of S4 36 degree lenses, recently one of our customers noted that when shuttering down the lower projected shutter had a "bleed through" or "shadow".

we have looked at most of our kit and this is true for a lot of our units, also I can not focus out to get the "doughnut" or dark area,

we have cleaned the most of the lenes's, one at a time so as not to mix things up, all back in the right slots, only got this problem with 36 degree 

has any one else had this problem ?

and if you did how did you fix it ? 

  • The double lens of the 36° barrel makes killer sharp focusing tricky; you'll find two images projected. Other barrels only have a single lens.
  • in reply to mpilyih
    You'll need to make sure they lamps and lenses are aligned as best as possible.

  • It's true... this has always been a problem with the 36° lens tubes.  Bench focusing the lamp can help a bit, but you'll never get it as crisp as a 26° or 19° tube will be.  In practice, I never expect to get a clean field or a sharp edge out of a 36° fixture, and I try to put frost in them whenever possible.  Frost goes a long way to hide their less-than-perfect optics.

    If you require better optics from a 36° lens, take a look at the Enhanced Definition Lens Tubes (EDLT).  You'll get crisper sharp edges and darker blacks, and the biggest difference vs. a standard tube is a 36° EDLT for sure.

  • Two things I do that sometimes help:
    1) If you can't center the lamp well when adjusting bench focus because the filaments are sagging too much you can 180 the lamp (only 575w lamps) then try re-centering the lamp. If the lamp is centered well the bleed is usually less.

    2) If you tighten the inner knob (field adjustment) this can sometimes help, although this won't produce the brightest output. Experiment a little and you may be able to get it more acceptable than it was.
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