[APML] Re: Guide scope advice

["Renzo Del Rosso" <scrivimi@renzodelrosso.com>]

Emmanuele Sordini Scrive: 

> At 09.49 29/08/2004 -0700, you wrote:
>> > From: "Stuart Heggie" <stuart.j.heggie@sympatico.ca>
>> >
>  
> 
>> I guide 530mm with 200mm.  However, I use a ST7E / CCDOps which
>> supports centroiding.  My understanding is that the ST4 does
>> not support centroiding, so I would look for a better match
>> of FL to the imaging OTA.  (Fwiw, The STV/Efinder is a ST237
>> w/ 100mm FL OTA and it works.)
> 
> Well, but the STV is in another league :-))

Emmanuele,
It's truth that STV is another things but ST-4 still work very well.
I use it to guide my Vixen R200SS 200/800 with a refractor 102/500.
You can see some photos on www.renzodelrosso.com (click on Fotografie and 
then on Profondo cielo). 

I think you cannot use a Maksutov cause its mirror shift.
I use my refractor to guide with a Vixen GA4 proiector of reticle and a 
barlow too. 

>> Since you have the 60/700 refractor, I would also suggest using that.
>> The ST4 chip is sooo tiny; .965 should not be an issue.
>> I suspect its enough aperture to find guidestars in 2 or 3
>> second exposures, though the fov is not great.
>> The only gotcha would be the focuser -- it needs to be
>> somewhat rigid.

> To my feel, it's rigid enough, i.e. I have to put some effort into racking 
> the tube back and forth; also, there doesn't seem to be any noticeable 
> wobbles. 
> 
>> And you'll need rings to mount the OTA.  (maybe get rings
>> sized for an 80mm OTA in case you want to "upgrade".)
> 
> I already have got rings. I built them myself a while ago, because I had 
> thought to go the guidescope route. Their inner diameter is 90 mm, so that 
> I think every refractor less than or equal to 80 mm in diameter should fit 
> them OK.

I had a ring for my guidescope but I got some troubles for the inner 
diameter too large. I found that one or two centimeter of larger diameter is 
enough. 

Clear skies
Renzo Del Rosso 


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