timthelder
September 19th, 2007, 02:33 AM
Ok,after two beautifully clear nights of viewing I feel like I can rate this 99% reflectivity diagonal with some degree of confidence.
In doing this comparison with my stock Celestron diagonal,basically I just swapped the two diagonals back and forth a few times on each object,looking for the variances between the two.
The first object I tried it on was NGC 7662 the 'blue snowball',a planetary nebula.At first I didn't notice much of a difference until I noticed a faint star with the 99% that wasn't visible with the stock diagonal.
Next I thought I would try M57.After swapping D's a few times it seems like it appears to be a little bit more luminous with the 99% diagonal.
Being that Epslon Lyrae is close I thought I would see how well it splits binary stars.It did very well,the double binaries are more well resolved and easy to distinguish.
Seeing as how it did well with binaries,I slewed on over to M13 to see how well it performs on clusters.And,yes,the stars in that cluster are more resolved as well,quite a bit in fact.
For the final comparison,I thought I would try it on some harder objects.I chose M54,M69 and M70.The reason being these have been very hard for me to see/find, if I can see/find them at all.
M54 which is usually very faint and hard to find was very easy to spot.M69&70 was still somewhat faint,but I could not see them at all with the stock diagonal.
My observations were made with no focal reducer at 267x magnification.
In conclusion :thumbsupmate: :thumbsupmate: ...I put my stock diagonal in the 99% diagonal's box for safekeeping.
A little math.Celestron's starbright coatings are 96%reflective.Which should mean my primary mirror is reflecting 96% of light entering the optical tube.My secondary mirror is reflecting 96% of that(.96x.96).Which gives me a total of 92% @ the diagonal which means I have 91%(.92x.99) of the reflected light that enters the optical tube going to the eyepiece.
With my stock multicoated diagonal which is only 90 to 92% reflective,I only had 83 to 85% of reflected light reaching the eyepiece.
In doing this comparison with my stock Celestron diagonal,basically I just swapped the two diagonals back and forth a few times on each object,looking for the variances between the two.
The first object I tried it on was NGC 7662 the 'blue snowball',a planetary nebula.At first I didn't notice much of a difference until I noticed a faint star with the 99% that wasn't visible with the stock diagonal.
Next I thought I would try M57.After swapping D's a few times it seems like it appears to be a little bit more luminous with the 99% diagonal.
Being that Epslon Lyrae is close I thought I would see how well it splits binary stars.It did very well,the double binaries are more well resolved and easy to distinguish.
Seeing as how it did well with binaries,I slewed on over to M13 to see how well it performs on clusters.And,yes,the stars in that cluster are more resolved as well,quite a bit in fact.
For the final comparison,I thought I would try it on some harder objects.I chose M54,M69 and M70.The reason being these have been very hard for me to see/find, if I can see/find them at all.
M54 which is usually very faint and hard to find was very easy to spot.M69&70 was still somewhat faint,but I could not see them at all with the stock diagonal.
My observations were made with no focal reducer at 267x magnification.
In conclusion :thumbsupmate: :thumbsupmate: ...I put my stock diagonal in the 99% diagonal's box for safekeeping.
A little math.Celestron's starbright coatings are 96%reflective.Which should mean my primary mirror is reflecting 96% of light entering the optical tube.My secondary mirror is reflecting 96% of that(.96x.96).Which gives me a total of 92% @ the diagonal which means I have 91%(.92x.99) of the reflected light that enters the optical tube going to the eyepiece.
With my stock multicoated diagonal which is only 90 to 92% reflective,I only had 83 to 85% of reflected light reaching the eyepiece.