Discussion in 'Telescopes and Mounts' started by Ray of Light, Jul 26, 2016.
Started by Ray of Light on Jul 26, 2016 at 5:34 AM
Tonight's looking promising.
May be time for the super dalek ...
I may only need these two all night.
Zoom shootout in small refractors soon ...
Watch this space.
These are all some very nice pieces of glass. You have quite the collection, Mak
Thanks Reggie. I've used the Baader zoom but the weather hasn't allowed me to night test the Celestron yet. They're quite different in many respects. I'll do a report/comparison when I get the chance.
I decided to put a Lynx Astro visual back adapter with a compression ring on my ED72.
This drastically improves the ability to rotate the diagonal in the focuser.
Why Synta don't put these in as stock is a mystery.
The diagonal is easier to secure now and doesn't rock in the focuser.
The ED72 focuser adapter has a different thread to other Evostar models and I've had to order a different one for my ED80. It's taking its time. I believe they may be made to order in the UK.
I've been experimenting with the 102mm Altair Starwave.
And added a second finder shoe.
This will enable the addition of an RACI for possible zenith viewing.
6x30 or 9x50?
The ST102 has had a makeover ...
I've swapped the GSO focuser for a Sky-Watcher.
There were rotational issues.
Last October I acquired a 32mm GSO ‘RK’ Kellner. Why? I hear you all say. Well, possibly temporary insanity. Seriously though, I had a cunning plan. We all know the *Kellner was invented way back by ‘wiggy blokes’ to use in aerial telescopes or something. OK, I made that up, but even in the Reversed Kellner format it is technically an old design. It is reviled by many because of its edge of field astigmatism and comparatively limited field of view compared to modern eyepieces.
But I digress, as I said, I had a cunning plan. I regularly use 31mm and 36mm Badder Hyperion Aspherics in my small refractors. These are nice, physically light rich field EP’s with a 72° FOV. The weight factor is important for me as I am partially paralysed in my right arm and hand. This complicates the manipulation of both OTA and mount. It also limits the weight of an eyepiece I can comfortably use in a 2” diagonal. The plan was to get a 2” Barlow with a detachable cell and thread it onto either of the Aspheric eyepieces. This then gives me more magnification choices for a minimum of weight increase. Unfortunately, the Baader threads were incompatible with the 2” GSO 2x Barlow. Which is why I ordered the 32mm GSO RK. Most retailers claim these are now discontinued although both Meade and Celestron still market these GSO 2” eyepieces and the GSO 2” Barlow in kits.
I managed to try the 32mm RK in my 72ED Evostar last year a couple of times. It was not very successful in the f/5.8 refractor and edge of field seagulls were more akin to pterodactyls. Not only that they seemed to be flying ever nearer the on-axis view. The addition of the Barlow didn’t appear to ameliorate the astigmatic avian menace either.
However, as Kellners tend to fare better in scopes of f/8 and slower I chanced the RK in my f/7.5 ED80 Evostar a couple of times. The 32mm RK with 56° FOV doesn’t really compare with the 72° of the 31mm Baader. The RK does have about a 35mm field stop though and is ergonomically pleasant to use. With the Barlow threaded directly on to the eyepiece GSO reckon that it magnifies by 1.6x. Therefore technically turning the 32mm into a 20mm EP. This now gives almost exactly one arc degree, fifty two minutes of true field with a magnification of 30x and a 2.6mm exit pupil.
I decided to test this combination on a few open clusters. Then out of curiosity I directly compared it with a 15mm Altair ULTRAFLAT on IC 4665 aka the Summer Beehive. Both eyepieces were used in a 2” Altair dielectric mirror diagonal. The ULTRAFLAT obviously gave a flat, sharp field right to the edge. The RK plus Barlow accounted for itself pretty well however. There is still some EOF avian activity but the large field stop makes on-axis views quite pleasing as it gives the sense of a much larger eyepiece (which it is). Not bad for a 2” EP that cost under fifty quid! I suppose I should have tried the RK in the Barlow for 2x as well but I was distracted by a rising Saturn. The weight of the combination is fairly easy to handle as the ED80 is very nicely balanced on the AZ5. I shall experiment further, I have a cunning plan.
*The original Kellner orthoscopic eyepiece was invented in 1849 by Carl Kellner an optician from Wetzlar (now in Hesse, Germany).
Had a pretty decent session with the ED72 last night. Started off with a twilight Jupiter and ended with a rising Saturn.
I gave the 19mm Luminos a bit of a workout as well.
Sunday night bino session with 127mm Sky-Max/AZ5.
William Optics bino mainly with 20mm WO SWAN's.
Main target was a setting Moon. Jupiter and Saturn also observed.
After the Big Mak had cooled I started off with the 20mm SWAN's for 75x. As it got darker I added the 1.6x GPC for 120x then eventually the 2x GPC for 150x.
I managed Jupiter until transit even though the conditions were deteriorating. Finally ending with a rising Saturn.
Separate names with a comma.