Posts Made By: Peter Loggie

I have a Losmandy WS rail on my C8 and a new (to me) WO Megrez 72 that I want to use a guidescope. Its diameter is 87mm or 3.43". The Losmandy RDF90 and DR90 rings both claim to take scopes of diameter up to 3.5". Can anyone tell me the actual inside diameter of the 90mm rings? I need to know whether I would have enough adjustment for guiding with them or whether I need bigger rings. Thanks, Peter

Does anyone know if the Celestron Quick Release Finder Bracket (51149-A) will fit onto the Losmandy narrow rail system (WS rail) or onto their RDFS base? The Bracket seems to be almost identical to one called RDF65 by Losmandy except it is listed as being heavier and having rings 2mm smaller than the Losmandy one. Thanks

Having had no luck with off axis guiding I want to fit a guidescope to my C8 on a piggyback rail. I see that there are various sizes of rings available and rail systems. How much spare diameter should I allow around an 3.5" diameter tube so as to give me sufficient adjustment, or alternatively how much angular adjustment should I allow? I recognize that I need to balance this against the aim of keeping the guidescope as low as possible and minimizing the space that it takes up on top of the C8. Thanks

Although expensive the Slider 2, would save the cost of a guide scope, all its fitting, extra counterweight etc. But does it work that much better than other OAGs? Would the guide port image when used with an 8" SCT in normal conditions be bright enough to find and focus on guide stars? My experience with other OAGs has been bad.

As part of larger purchase I'm now the proud owner of what seems to be a dsc set for CI-700, intended for connection to an Advanced Astromaster. Although the connecting cable and Astromaster are not included the instruction booklet and all the mounting hardware is there including two 4000 tic encoders.

As I do not have a CI-700 I'll be looking for someone who needs this set but unfortunately, on one of encoders, one of the 5 connector pins is broken. Is that it ruined or can the connector be repaired or replaced? I see that new encoders of the same type seem to be available for around $50.

Following many glowing comments on Berlebach tripods and adverse comments on the Losmandy GM-8 tripod I managed to pick up a used UNI 5. This is an older model but is rated for up to 132 lb., which is as much as for any of their models other than the very top ones such as the Planet. I've added one of the Berlebach trays which is supposed to further stiffen it up.

My question is what a realistic maximum all-up weight should be to put on such a tripod when using it for astrophotography (assuming not constrained by the mount)? Do I need to reduce from the 132 lb., as I would expect from the mount's maximum carrying capacity or could I load it up to the limit without degrading performance?

I'm looking for advice on what would be a good focal reducer to use with this combination: TMB 100 f8 CNC + SBIG ST7XME + CFW8 +AO8? I see that there is a Borg model 7887?, an Astro-physics model 27TVPH, and a Televue RFL-4087 that might be appropriate. I had thought that the TMB designed WO flattener for the FLT 100 etc. might have been ideal but the owner of one has said its not compatible. I'm sure that there are probably other options too. APM make specific flatteners for the TMB OTAs but they are not reducers and are very expensive to buy new so that's not an option for me. The Baader T2 system also seems to flatten but not reduce focal length.

Any guidance including on how to interface reducers of different diameters to the TMB's 3" focuser would be greatly appreciated.

Thanks

Peter

In case anyone was interested I am told that the Celestron is larger and not compatible - but I would have liked to see a side-by-side comparison.