So I have had this ETX 90 that I have been using for about 10 years as a spotting scope at the rifle range. It's poor mount and finderscope precluded use for astronomy. Well, finally gave the de-forked ETX a good workout on the FTX mount - I'm impressed!
Mainly I intend to use it for double star observations, so I can use my larger scope time for DSO's.
But just for kicks, I wanted to see how it would do with my L3 NV monocular. We all obsess over getting the fastest optics for our NV tubes, and I wanted to gain some experience with a slow scope. This is not an exhaustive report, because we only hit a few objects before switching out the ETX for the Comet Catcher.
Surprisingly, it did really well. With a focal ratio of f/13.8 I was not expecting much. Yet NGC 2362 and NGC 2354 were actually better in the NV eyepiece than in the 22 Panoptic or the 12 Morpheus. Many more faint cluster members revealed. In fact, given the moon was still up, the sparse 2354 was barely distinguishable without NV.
Just for kicks, we tried the HorseHead nebula in the ETX - and we both saw it with a 12nm H-alpha filter. Not a great view, the filter and long focal ratio caused photon starvation of the tube and scintillation. But it was definitely there.
Mainly, I see the ETX as a double star scope - I was able to push as high as 278x with a very good image on Gamma Leonis. But it may also be viable for NV work in limited roles - such as open clusters.