I have a Source 4 focus issue with a
lens tube that we have in inventory at a local
theatre where I regularly volunteer. I have posted pictures of the tube at two different focuses below and then I cracked the tube open and took a look...
1. At this focus you can see the sharp focus of a faint inner ring of light, the soft focus
line is the bottom
shutter which also corresponds to a larger and much brighter outer pool of light at a slightly soft focus.
2. Here is the same
shutter cut in sharp focus. Now the "inner ring" of light is in softer focus and there is odd flaring at the bottom.
3. Here is the
barrel opened up. I am not all that knowledgeable about the various revisions of the Source 4
lens tubes, but I think that this likely one of the original design 1992-ish tubes. I infer this from the fact that there is absolutely nothing stamped anywhere on the tube that says "Rev. A" or "Rev. G",
etc.; there are only 5
lens slots instead of 6; and the fact that the front color frame/accessory slots are both thin. Visually the
lens placement looks correct, at least from later 36-degree
lens barrels that I have worked with. We have 15 36-degree barrels in the inventory here and they range in age from the mid-1990s all the way up to "Rev. G".
With all of that said, my question is this: were there different lenses used in the 36-degree tubes in earlier iterations of the Sounce 4? Neither of the lenses in this
barrel have ANY dots on them. I'm not sure if there never were dots OR if they got washed off inadvertently by a clueless volunteer. Is it possible that one or BOTH of these lenses belong in a Rev. G
lens tube and that there is a set of lenses that belong in this tube floating around in another tube? We have not had any serious focusing issues with the 14 other 36-degree tubes.
Can anyone
shed some light on this or should I just
call ETC and chat with someone there who knows the history of the
lens tube revisions?