One day I was at Vaughn's, who owns a .4 A filter and has an 80mm F30. I brought the clubs .5 A filter and the 50mm F30. We switched the filters between scopes, the .4 on the 50mm clearly out preformed the .5 on the 80mm. It also seemed to me the performance of the .4 was the same on the 50mm vs the 80mm. Vaughn also agreed.
It is hard to imagine that 1x more mag would make any difference is resolution, in white light. Another 10x seems like it would. Actually increased resolution will show you smaller sunspots, but it's up
to you to decide if tinier sunspots are worth the extra weight of larger aperture. I have Baader white-light filters for my 70mm binos (both 15x and 20x), but for the sun, I think a 20x50mm bino would be just about right. There are no exit-pupil concerns for daytime viewing.
H-alpha resolution on the sun is limited more by the bandpass of the filter than aperture.
Some of you may recall my PSO (Pocket Solar Observatory) which is merely a 12x25mm bino equipped with Baader solar filters in lathe-turned plastic cells. My "grab and go" white light setup.
I'll take a photo of it soon and post it to the SLAS Gallery, if anyone is interested.
On Sat, Apr 3, 2010 at 10:35 PM, Craig Smith <cs2560@gmail.com> wrote:
You would get increased resolution, which would be of value for h-alpha but probably not much for sunspots.
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