Quote:
Originally Posted by PlanetMan
I would have to concur with Brian regarding the quality of the mirrors in the diagonals. Indeed, from my experience images seemed slightly better in my quartz GSO than an everbrite. However, this was a memory comparison over different nights and I wouldn't bet my house on this.
Now - the real question is what actually makes the TV Everbrite better and why everyone buys them. They are IMO as follows:
1) One piece design - when you have that 1k$ 21mm Ethos or 31T5 terminagler in your diagonal and your EQ mount turns onto a horizontal angle you have complete peace of mind the nose won't twist and down goes the EP. You can try threadlock or glue on GSO diagonals but for 100% peace of mind you can't beat a one piece design.
2) Durability - this is both on the construction of the actual diagonal and coatings on the mirror. Basically, you buy the everbrite and that's it for life.
3) Resale value - TV products tend to hold their value better than virtually any other gear
Having said all of this does not down play the excellent piece of equipment the GSO quartz diagonals represent but merely highlighting the main benefits of the Everbrites.
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I agree with all of the above. I have replaced my 1.25" WO diagonal with an Everbrite for different (initial) reasons. The WO is actually pretty good overall, but I had 2 issues with it: vignetting eyepieces (especially the 24 Pan) and a snagging compression ring. Both things I was not prepared to tolerate forever (I did for 2 years) and the Everbrite solved both.
Despite having a greater internal diameter, the Everbrite is smaller than the WO. The recessed area where it connects to the visual back of the refractor is cylindrical not conical, meaning that is is held in place more precisely and securely.
My only complaint about the Everbrite is the thumb screw. It stands out further than on other units and collides with my nose at some observing angles.
In terms of brightness, I can't say I've seen a difference though.