SM60 vs SM90

I own 3.3 inch and 4.0 inch APO refractors, and I am trying to decide between a Coronado SM60 vs SM90. There is a obvious cost differential. Is the extra cost of the SM90 really worth it? Is there a quantum leap in image resolution/quality between the two filters?

The Solarmax 60 is excellent but if you start going into something like a Solarmax 90 then at that price point a whole 'nother world opens up to you, e.g., Daystar and Solar Spectrums h-alpha filters. Solar Spectrum filters can be bought with a digital oven for around $4250 including telecentric lens and energy rejection filter that fits on the front of the scope. That's a .2A filter as opposed to the .7A filter of Coronado. Way more detail (check the cloudy nights review on the Daystar vs. Coronado filters; Solar Spectrum is similar but you can get a narrower bandwidth and I think, though won't swear, a nicer digitally controlled oven and the filter heated in 2 minutes and has a fan to cool it or heater makes any change within 30 secs). Also, I find the "other" company much better more pleasant to deal with.

I think for the money the Solarmax 60 (and the convenience, admittedly) is excellent. I'd go for the Daystar or Solar Spectrum instead of the SM90. Just my 2 cents.

Good luck.

David