Quote:
Originally Posted by rally
You are not paying for aperture so much as you are paying for a higher level of chromatic correction and quality of optics.
The TOA is an acronym for Tak. Ortho Apochromatic Vs Tak Super Apochromat (TSA)
Have a look at a longitudinal aberration plots for these and you will see the difference.
The TOA series is highly corrected (near perfectly !) from well into the Infrared to well into the UV spectrum.
Like most things - if you want 50% of perfection - its cheap, if you want 85% its getting more expensive, if you want 95% its getting really expensive and if you want 97% it starts getting ridiculous.
For visual I think it would be hard to justify and difficult to discern.
Rally
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+1
For purely visual the better choice would be the TSA120, cheaper, lighter, cools quicker, smaller mount required. I doubt you would see any difference visually.
I think there are many valid reasons to choose a 5" refractor over light- buckets for visual but that has been discussed to death previously.
The TSA120 is an excellent scope and can be used on an EQ5 or similar mount as well as any of the small AltAz mounts. It is ready for viewing immediately upon being carried outside up to 100x and as it cools will take up to 300x in good conditions. However, I too would recommend the Mewlon 210 as an alternative for visual.