Guide scope choices

[Thalestris24]

Hi all

Thinking about changing from my finder guider to a dedicated guide scope. That way I could actually use my finder as a finder which would be quite useful. I'm also keen to get something with low profile mounting and not as big and heavy as my ST80.

I came across these and wonder if anyone has any experience (good or bad!) with any of them:

1) William Optics 50mm - http://www.teleskop-express.de/shop/product_info.php/info/p5752_William-50mm-Guiding-Scope-1-25--Connection-with-rings.html

2) APM 60mm - http://www.365astronomy.com/apm-60mm-finder-guidescope-kit-straight-version-with-125-helical-focuser-p-3937.html

3) ZWO 60mm - http://www.365astronomy.com/zwo-60mm-finder-and-guide-scope-60280-p-3710.html

A 60mm scope might be nice

Another option would be to just get some guide scope rings - http://www.teleskop-express.de/shop/product_info.php/info/p379_Starway-Guiding-scope-clampshells-for-OTAs-from-30-to-80mm.html

They might be cheaper but for not that much more I could get a whole package... Much more therapeutic to buy

Any thoughts or experiences welcome

Cheers

Louise

[Uplooker]

Hi Louise,

I can understand your reason for not wanting to use your finder guider as a dedicated guide scope, so that you could actually use it as finder and I suspect be able to detect more guide stars. Can i ask why you do not want to use your ST80 as a guide scope?

You also say that you may get some guide scope rings. Again, I would ask why? I do not understand why people use guide scope rings. Truth be told, I have never actually used them, but they would certainly introduce flexure. I use an ST80 bolted to the top of my SW 150P for guiding. To do this, i had a spare vixen dovetail which I drilled a couple of holes at the correct spacing, so that i could bolt the ST80 to the existing tube rings of my 150P. I have never had a problem finding a guide star.

The mount that your are using, HEQ5, is more than capable of taking the combined weight of the 150P and ST80. I would save yourself the money and place a wanted add for a vixen dovetail that was of the correct length to maximise the distance between the tube rings of the ST80.

If drilling the dovetail is an issue i.e. not confident or no drill I am sure that even a local garage would pop two holes in one for little if any charge

Ian

[Thalestris24]

Hi

I don't want to use the ST80 because I want something smaller, lighter, low profile and adjustable. It's possible to get a low profile bracket for the SW finder but they are very expensive for what they are, otherwise I could get one plus also a guide scope that I could then use as a finder - a bit of role reversal! I'm not sure about flex problems with guide rings - maybe, maybe not. I imagine lots of people buy guide scope packages which include rings - do they necessarily cause a problem? This is why I was asking!

Cheers

Louise

[lensman57]

Hi

I don't want to use the ST80 because I want something smaller, lighter, low profile and adjustable. It's possible to get a low profile bracket for the SW finder but they are very expensive for what they are, otherwise I could get one plus also a guide scope that I could then use as a finder - a bit of role reversal! I'm not sure about flex problems with guide rings - maybe, maybe not. I imagine lots of people buy guide scope packages which include rings - do they necessarily cause a problem? This is why I was asking!

Cheers

Louise

Hi louise,

Please have a look at the link, I have one of these and it is really good and solid, it is a lot lighter than my other two 60mm guiders ( My Opticstar 60mm guider weighs more than a Kilo ) and it is also cheaper by quite a margin.http://www.scsastro.co.uk/catalogue/orion-mini-50mm-guide-scope.htm?gclid=CMONxc-d0b8CFcbJtAodHlMABw

Regards,

A.G

[Earl]

These have had good reviews

http://www.altairastro.com/product.php?productid=16468&page=1

[ChrisLX200]

I use two small refractors as guiders, one 70mm and the other 80mm, both fairly fast optics (f/5.4 and f/6 respectively). With those aperturss and f/l I don't need guidescope rings or any need to adjust the pointing because there is always a guidestar available in any random frame. I would keep an eye out for a small refractor like that - perhaps an ED doublet.

ChrisH

[Thalestris24]

Hi

Thanks for the links guys. So my current SW finder guider works fine as far as it goes. The main reason for wanting to change is because I want something low profile i.e. that can be mounted close (as possible) to my main ota. Now this is because I image through a window so something which sticks out, like a standard finder, effectively even further limits the width of sky I can make use of. The maximum dimensions of the window are 50cm (w) x 65cm (h) which is not much of a vista!  So you can probably appreciate I have a desire for a guide scope that can be mounted close to the ota! That's why I posted the list of possibles in my OP. I was hoping someone might have experience of using one of them. My current finder would also be ok if there was a way of mounting it close to the tube - hence my consideration of a pair of rings. I'm sure someone has used the ones I linked to - or similar?

Here are the links again:

1) William Optics 50mm - http://www.teleskop-...with-rings.html

2) APM 60mm - http://www.365astron...ser-p-3937.html

3) ZWO 60mm - http://www.365astron...280-p-3710.html

4) Guide scope rings - http://www.teleskop-...30-to-80mm.html

Cheers

Louise

[ollypenrice]

I think guide rings are a total waste of time, expensive, potentially flexible and, above, all redundant with modern guide cameras which always find stars. I do use them on one rig but that is only because I didn't have anything else lying around with which to attach the guide scope!

The Altair finder guider is nicely done and compact. Your most compact option would be an OAG but they are on the overkill side for small imaging scopes.

Olly

[Thalestris24]

I think guide rings are a total waste of time, expensive, potentially flexible and, above, all redundant with modern guide cameras which always find stars. I do use them on one rig but that is only because I didn't have anything else lying around with which to attach the guide scope!

The Altair finder guider is nicely done and compact. Your most compact option would be an OAG but they are on the overkill side for small imaging scopes.

Olly

Hi Olly!

I'm sure you're right (as always!) but why do they sell so many guide scopes with rings? I wish they sold them with other attachment options. The William Optics version appears to be designed to attach to one of their APOs and looks otherwise well made http://www.teleskop-express.de/shop/product_info.php/language/en/info/p5752_William-50mm-Guiding-Scope-1-25--Connection-with-rings.html

Can it really be so bad? Maybe I'm naïve. I've no experience of these rings... Teleskop Service generally sell good hardware. The ZWO one also looks ok. Also the APM looks 'solid'...

Yeah, an oag might be an alternative but I don't think I want to go down that route with my 150pds.

Sigh.

Frustrated.

Louise

[lensman57]

Hi Olly!

I'm sure you're right (as always!) but why do they sell so many guide scopes with rings? I wish they sold them with other attachment options. The William Optics version appears to be designed to attach to one of their APOs and looks otherwise well made http://www.teleskop-express.de/shop/product_info.php/language/en/info/p5752_William-50mm-Guiding-Scope-1-25--Connection-with-rings.html

Can it really be so bad? Maybe I'm naïve. I've no experience of these rings... Teleskop Service generally sell good hardware. The ZWO one also looks ok. Also the APM looks 'solid'...

Yeah, an oag might be an alternative but I don't think I want to go down that route with my 150pds.

Sigh.

Frustrated.

Louishie

Hi louise,

I think that you should give OAG a real consideration as if you want to image with a 150PDS the OAG is the only sure way of compensating for the mirror flop.

A.G

[Thalestris24]

Hi louise,

I think that you should give OAG a real consideration as if you want to image with a 150PDS the OAG is the only sure way of compensating for the mirror flop.

A.G

Hiya

Um, I don't think I get mirror flop - can only image between about 68 deg and 90 deg in azimuth, and 28 to 46 deg in altitude (cos of the east-facing window)...

With my pedestal mount the primary mirror end is always pointing down and the open end up. Anyway, didn't think that newts suffered from it but I plead ignorance!

Cheers

Louise

[ollypenrice]

Anything with a mirror can have mirror flop, though it isn't compulsory! This arises from the need not to pinch the mirror at all in its mountings. A little slack is good but can lead to shifting.

Those TS rings, like the rings on the Altair finder guider, are perfectly good. They just aren't necessary. I've been imaging for nine years, often with three rigs running, and I have never ever needed guide rings to find a star. Good job because I rarely have any! I thnk they are just a throwback to the days of insensitive guide cameras and manual guiding.

Olly

[Thalestris24]

Ok Olly, I understand. My main driving force is for low profile because of the above limitations. I just need a way to attach either my current finder guider or a second guidescope close to the ota so that I can squeeze the most out of the window. I've tried bolting the ST80 to the scope rings but that sticks out too much really - just a 50 or 60mm scope would be fine. Also, would be nice to sometimes have a plain old finder that can see through with my eyes. The PC display always seems so 'second hand', if you know what I mean. It may not be absolutely necessary to have everything lined up and centred but I do prefer it (something to do with my horoscope , I think! ). This is not the first thread I've started on the topic and I keep coming back to it!  Anyway, I shall mull over the options.

Cheers

Louise