OAG choices

[x6gas]

I already have an Atik OAG, but I am thinking of getting a second OAG so that I can dispense with the ST80+guide rings set up for my second imaging rig.

I am very pleased with the Atik OAG, but the second rig will be run without a filter wheel so I am not wedded to Atik. I'm also not struggling for backfocus so it doesn't have to be particularly short...

Any thoughts on the current options?

[pete_l]

Have you considered the On axis guider that was reviewed on CN?

[x6gas]

Looks like a nice bit of kit, but I can't run to a grand!

[ollypenrice]

Not the Starlight Xpress. The locking bolt that holds the turret at the right depth makes a pivot so you get flexure with an OAG. There are verious solutions but the simplest is to buy a different make!

Olly

[Astroscot2]

Olly, can you expand on your thoughts of the SX OAG, i was considering purchasing one as a camera package quite soon

[ollypenrice]

Olly, can you expand on your thoughts of the SX OAG, i was considering purchasing one as a camera package quite soon

Yes, the problem is plain old bad design and various solutions have been put forward. I gather there's an unused thread into which a second turret-clamping grubscrew can be inserted. Soft tipped ones are recomended.

I didn't fancy all that faffing around so I went for simple external brace as seen in the picture. Without it the turret with the periscope can rock around the screw which holds the chosen depth so you get flexure - with an OAG. I just feel this should have been sorted. This is not the only 'iffy' bit of SX kit in the setup so I'm feeling a bit sharp on the matter.

Here's my solution. Thus modified the device is fine but you can buy ones which just work.

Olly

A black metal brace runs from the main camera's retro-fit (but still inadequate) cooler to the top of the Lodestar (the bit for which Telescope Service make a nylon attachment to improve the cable contacts... Ahem.)

[x6gas]

Thanks for the replies (and the additional info on the SX model, Olly).

Having considered the TS version I am now thinking it's between the Orion OAG or just sticking with the devil I know and getting another Atik...

[Tinker1947]

I got to say the Lodestar guide cable/connector is about as awful as a cable/connection could ever get. mine the cable had a broken connection, then a replacement sourced by FLO and posted by Starlight arrived but could only get the Lodestar to track in one plane, so waiting on a replacement Lodestar, just handy that our years worth of clouds have arrived while its away.......

[ollypenrice]

I got to say the Lodestar guide cable/connector is about as awful as a cable/connection could ever get. mine the cable had a broken connection, then a replacement sourced by FLO and posted by Starlight arrived but could only get the Lodestar to track in one plane, so waiting on a replacement Lodestar, just handy that our years worth of clouds have arrived while its away.......

Yes. What bugs me here is that the problem is well enough known for TS to bring out a dedicated moulding to cure it but SX themselves haven't done anything. How can this be right? I use two Lodestars, both permanent, and still I have to be ultra careful with those cables. Likewise the OAG. The problem is well known but a pretty new one was here last week wobbling away like a good 'un.

x6gas, is the Atik OAG a devil? I only know the SX at first hand.

Olly

[x6gas]

x6gas, is the Atik OAG a devil? I only know the SX at first hand.

Olly

Sorry Olly - figure of speech! I don't think it's particularly devilish, but then it's the only OAG I have ever used. There is not facility to rotate the prism around the OAG body so if you can't find a suitable guide star you have to rotate the whole imaging train which isn't ideal for framing and the mechanism for moving the prism in and out is a bit Heath Robinson but it works. I'm not unhappy with the Atik but am tempted by the Orion as this version seems to have some good reviews and it is a bit less expensive...

[x6gas]

...the Atik is well engineering and well finished and the helical focuser works really well...