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FPL53 is the top glass but you also have to know what the other 2 elements are made out of to maximise its advantage.
TEC160 uses FPL51 glass. I queried Yuri about that and it basically worked out best for that design of lens.
Most triplets though do use an FPL53 centre lens and hopefully something nice for the other 2.
With Stellarvue its a bit hard to evaluate as they source their lenses from other people and don't make their own?? So where are they getting the FPL51 triplet from?
As far as temperature cooldown times for TOA series you can ask on this site as there are several who use TOA130 or TOA150 who could tell you if this is a concern or not. The only place I have heard that comment from was AP Yahoo Group where they are biased against Takahashi as Tak has been the traditional competitor for AP. They would not even know as they would not have owned or used one. I haven't heard any complaints by TOA owners only positive things. One thing I do know is TOA scopes produce some of the highest resolution images of any type of scope for their size and have exceptional, perhaps best in their class colour correction. They are somewhat unbeatable due to their clever design. I also remember reading they have 2 FPL53 lenses not the usual 1.
I know my Planewave CDK17 needs 1-2 hours to cooldown otherwise you can't get a sharp focus and that is kept in an insulated observatory.
I haven't really noticed much of a cooldown time required for my TEC180 triplet, nor FS152 nor AP140 or FSQ106 but I am sure there is one if I were using it visually.
Greg.
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