What is the highest usable gain setting with low or acceptable noise?
 

I am trying to see how much flexibility I have with filming indoors using the letus fe and the canon A1. The 50mm 1.4 I have is to shallow for what I have in mind. So, I will have to use my 28mm 2.8 instead. Problem is, the light lost is a major problem. I'm trying to find out ,what is the highest usable gain setting with low or acceptable noise? 12 seems o.k. but I need input from the pros.Please respond to my question. Thank You!

The $64 question, and the answer depends on your intent/use of the video and what the client will accept.

For a hot news story for the 6 O'colck news the full 36 dB is acceptable if that is the only way to get the story (but it is pretty ugly). For a staged production where you can control the set, lighting, etc. 0 dB gain, and some will insist on -3 dB.

Many if not most users appear to feel that up to 12 db with some custom presets for noise reduction, coring, etc. is acceptable for event work with available light, and some might even go to 18 dB to get an image. Adjusting the custom presets can make a big difference.

After you read what other are using in these forums to get some ideas, run some tests to see what works for you in your application.