Source Four Lens Tubes: 36 --> 50 seem like a big jump?

Could you lamp the 50s up to 750? Or are they already lamped that high?

I can't imagine you are getting that much of an output loss. Trying to get yet another barrel made for this seems a little over the top. 

Could you lamp the 50s up to 750? Or are they already lamped that high?

I can't imagine you are getting that much of an output loss. Trying to get yet another barrel made for this seems a little over the top. 

Yes, we're using all 750W lamps.  The issue is that the upstage (behind the proscenium) is about ten feet wider than the downstage area, so if we use 36's on the downstage (which works great), and shutter down 50's on the upstage, there is a dramatic difference in intensity when you walk upstage.  Of course, we can program the cues so that the 50's are always at a higher intensity than the 36's, but then the color temperature difference means different gels, etc for the color to match... And yes, we could use shuttered 50's for the downstage also, but the point is that we're happy with the intensity of the 36's, and don't want everything dimmer.  Also, yes, we could I suppose use additional 36's on the upstage, but at that point we're talking about enough of a cost increase that we could spring for the zoom fixtures.  It just seems that with the present repertoire of 5, 10, 14, 19, 26, 36, 50, 70, 90, the jump from 36 to 50 is one of the biggest in the more commonly used sizes.  After all, if the 9 degree jump between 10 and 19 was unacceptable, shouldn't the 14 degree jump between 36 and 50 be even more so?

P.S. _You_ don't have to agree, I'm just trying to see if some users do.

I own a set of 8 spare 50 deg. barrels that I think have been used once.  The standard inventory has 36 deg., 26 deg. and 19 deg. fixtures (FOH) as well as a ton of 25/50 and 15/30 zooms (80 total).  Note that in my rep. plot the 26 & 36 are are side lighting, with the zooms either box booms or overhead and pipe ends.  

The 25/50 unit pretty much solves your problem, as it does for a lot of mine and I;d recommend them. They are more cost effective then a 36 deg unit, plus a spare 50 deg. and 26 deg. lens tubes.  With a zoom you hang once and zoom as needed.  They are extremely useful for gobo imaging as you can very the size.  

Steve Bailey

Brooklyn College

Interesting way to look at it.

I think there have to be some limits on lens tube choice otherwise we are all going to find ourselves with piles of extra lens tubes floating around our shops.  We all know that if an LD has an option to change something or request something they will.

What is reasonable for you you a lens tube for every 5 or 7 degrees from 5 to 90?

I can honestly say this has never been a problem for me... If I was faced with a slightly wider space to light, I'd just add one more 36°.  Even if you had a 41° lens tube, there would still be a noticeable change in the brightness between the 36's on your apron and the 41's upstage.

The 9° jump between the 19's and the 10's was a problem because that was a 47% change in beam spread.  The change between 36° and 50° is 14°, but that's only a 28% change, which is actually quite in line with the other jumps.

If you find that you really need an exact beam spread, the Zooms are a good option.  The Source 4 Zoom is actually slightly brighter than a fixed lens Source 4 at the same beam spread (the larger optics are more efficient, though they don't project gobos quite as well), which might be perfect for your application.

there would only be a noticeable change in intensity if the throw distances of the 36s and 41s were the same.  The reason I would like a 41 and or a 44 is more choice when you have a very short throw.