Quote:
Originally Posted by h0ughy
Jerry, i have a few questions:-
- according to the formulae the grid pattern widths change with the focal lengths of the scope - the product you seem to be selling does not look as though you can take that into account but rather have to accept a predetermined grid width that you have setup for manufacturing - IE with the 10" Meade it is 13mm, but for my R200SS vixen f4 it is 5mm grid spacings? Your web site has no options for choosing a grid sizing - just the outer diameter of the grid mask?  |
My math is not the same as the Russian site. I use the clear aperture and not focal length to determine the cutout and spacing. I am not concerned about hitting the 3rd, 5th, and 7th order spectrum as much as getting the maximum light gathering power of the scope. Very simple math- For the horizontal cutouts just take the clear aperture and divide by 35. This will give you a center cutout and 8 more in each direction. So for a mask that will fit an 8 inch SN type scope the math is 8/35= .228 inches. By the way this is the 10 inch mask. For the angled side- multiply the cutout on the horizontal side by 1.05. so the example is .228 X 1.05 = .240 inches.
I think too many people are getting caught up in the math formula that hit the spectrum order for a particular focal length. My test shows that is is not as critical as good straight lines and a mirror image top to bottom and left to right.
For those that just want to hit the spectrum and split the color band, then by all means, take the time to calculate your focal length. But if you just want an easy way to get the best focus fast-- Then keep it simple.
I have posted this to Pavel and his group as a suggestion. And now on to you nice people.