Quote: I am hoping more people will measure and post though, so we have the facts.
SCOPES: CPC1100; AT66ED; EdgeHD 8";SVR90 RAPTOR MOUNTS: CGEM; Vixen GP2; iOptron Sky Tracker; Celestron AVX CAMERAS: Canon 60D;Lodestar EYEPIECES:31T5;D14;D8;P20;P25;P32;TMB9 The Lord sits enthroned above the circle of the earth...He stretched out the heavens like a canopy.
Quote:I suspect the EdgeHDs will be worse than the standard scope for apeture reduction based on my own experience with the EdgeHD 8".
B Cuddihee 1968 Jason Empire 60X700mm refractor 1977 Jason Empire 313 discoveror EQ Celestron Nexstar8SE "The Bumblebee", with Feathertouch Microfocuser, and Celestron CPC Heavy Duty Tripod. Stellarvue 50mm "Sparrowhawk" finder Denk bino's with Power x switch. Pair of Edmund 28 plossls. Pair of Edmund 28 RKE'S Pair of 24mm Brandons. Pair of Smart Astronomy 19 EF's. Pair of 18mm Celestron Ultimas
Quote:Well, for general viewing, it is not really an issue I don't think. I mean it doesn't help any because in essence, the scope is turned into something like 7.5" f/11 scope with a 38% obstruction.Where I would be concerned though is for planetary observations.I found the dimming even using a pair of 15mm Plossls to be enough that I was having trouble with the view.
Leica 8x20; Nikon 7x35; Vixen 8x42; Orion 15x63; Docter 15x60
WO Megrez II 80 FD / APM 107mm f/6.5 / Mewlon 210 on DM-6 + Berlebach Planet
Quote: So in the case of a C11 vs. a C11 Edge HD, is the former more accepting of back focus without as much aperture loss compared to the latter?
Takahashi FS128, TSA 102, FSQ106N, Losmandy GM-8, Baader Mark V, Leica ASPH, Takahashi, Ethos and Panoptic eyepieces.
Quote:Easy answer The proceedure to measure... A green laser works best, but a single emitter LED light might work OK.Next time you use the telescope with binoviewers, bring it to focus with the configuration you want to test on a a star or planet with an eyepeice that gives about a 1mm exit pupil (infinity focus).Do not touch the focuser knob until after you have made the measurment. It is critical that the telescope be in focus for the configuration you want to test.When you are ready to do the test, position the telescope facing square to a wall, maybe 1 foot from the wall. Get it as square as possible. Now, holding your light source above the same eyepeice you used earlier, shine it into the eyepeice. It will take some trial and error, but when you have aligned the laser, you will see a green projection on the wall. This circle will contain the secondary shadow.You can measure the apeture directly by simply marking the edges of the circle with a piece of tape (it would help to have somone do this part for you). Once you have the edges marked, you can measure the distance between the marks and you have your effective aperture.You can also use a Finder scope as a beam collimator. Place the finder with the objective pointing toward the laser and the eyepiece pointing into the binoviewer.One person mounted the laser on a camera tripod so he could make tiny adjustments. He rotated the binoviwer to one side so the laser could be horizontal. This may help because it is very difficult to get the laser exactly over the exit pupil of the eyepiiece.I usually use a lower power eyepecie and I have been told that it can affect the accuracy, but I would think that if anything, it would overstate the amount of aperture, but I think it is still pretty accurate to within a millimeter or two.Anyway, if you measure some different configurations, please let us know what you find.