Guidance on Guiding

[PaulG_SF]

Hi everyone. This is a question that has no doubt been done to death, but I want to ask it because tech has changed so much since last time I considered guiding options.

Was not too sure where to post this - Mods feel free to move it if there is a better place!

It's kind of a question of two parts.

My current setup is - Skywatched 200P-DS on an EQ-6 Mount. I'm not permanently mounted so have to set up for every session

So first general question.  What's the current wisdom re guide scope vs off axis guiding?  When I've built "dream setups" in the past it never occured to me to investigate it. I appeals to me as it seem like a good way to reduce weight, but I wonder how it would work if imaging something with no obvious guide stars.

The second part of the question assumes using a guide scope.  

My initial thoughts were to acquire a colour camera capable of planetary imaging and guiding - like the ZWO ASO120 and hook it up to a startravel ST80. I figure this would be a flexible setup.  

However the idea of a a dedicated mono guide cam and dedicated guide scope (around 50mm?) again this strikes as a more compact solution - less weight, hopefully less setup.

Anyway that's kind of where I'm thinking at the moment. Really keen to tap into your opinions, experience and so on.  I'm open to all options - so of if there is something I've missed - let me know!

Thanks

Paul

[almcl]

 I use a SW 200p and the improvement in star shapes when I switched to guiding with an OAG was dramatic.  Prior to this I used an ST80, initially with a QHY 5l ii mono until the USB connector on that broke and then switched to an ASI120 mini mono.  The ST80's focuser was very floppy and that coupled with mirror movement was probably at the root cause of the poor guiding.  

As to whether a 50 mm guide scope (likely focal length about 180 mm?) will do rather depends on your imaging scale.  I use a suitably adapted SW finderscope with the ASI 120 to guide my EQ5 with Canon + 200mm lens and it usually achieves just over 1" guiding.  As the 200 mm lens is imaging at a little over 4"per pixel, this is fine but when imaging with the 200p (.85" per pixel) on an Alt Az EQ6 it wouldn't (and didn't) do.  With the OAG the guiding is usually somewhere between .6" and .7" and on rare occasions drops below  .5".  This gives nice round stars.

I use the dedicated Canon OAG and it certainly saves weight compared with the ST80.  Another benefit is that I no longer need a dew strip for the guidescope: the ST80 was an absolute dew magnet - an OAG doesn't need heating. 

I've never had a problem finding a guide star with either camera (both mono) in any of the configurations, although focusing the guide camera is slightly more time consuming to start with.

 

 

 

[PaulG_SF]

That's interesting - focal lengths, dew and focusing were factors I had not considered. Dew control never even entered my thought process (it should have as my Evostar 120 is a due magnet!).

Having hopped around the net yesterday, the feeling I'm getting is OAG is a lot more convenient - certainly in my circumstances.