PrimaLuce Lab Guide Rings........Oh dear!

[ollypenrice]

We came across this issue here just before Christmas with a recently ordered PL setup. Not good.

Personally I think adjustable guide scope rings are a waste of time anyway. Their original purpose was to allow the guidescope to be taken off-axis in search of a guide star because early guide cams were very insensitive. Now the idea has grown up from somewhere that you need guide rings to set the guidescope up on-axis! Both explanations can't be right...  I would far rather bolt the guidescope down hard and permanently and not care whether it's bang on axis or not. With a good PA it doesn't matter. (With a bad PA it is better to have the guide scope on axis but I don't see Ray having a bad PA!)

Olly

[Davey-T]

1 hour ago, Sinan said:

I know this is an older post but, since I ordered the PrimaLuceLab guide rings, the info in the post worried me. It seems like they have fixed this issue by supplying additional plates that allow the screws to sit flush against the rings. Here's a photo from their site (I will see if they work when they arrive):

Hi Sinan and welcome to SGL.

Thanks for the update on the tube rings, all new info is good.

Dave

[Jkulin]

46 minutes ago, ollypenrice said:

We came across this issue here just before Christmas with a recently ordered PL setup. Not good.

Personally I think adjustable guide scope rings are a waste of time anyway. Their original purpose was to allow the guidescope to be taken off-axis in search of a guide star because early guide cams were very insensitive. Now the idea has grown up from somewhere that you need guide rings to set the guidescope up on-axis! Both explanations can't be right...  I would far rather bolt the guidescope down hard and permanently and not care whether it's bang on axis or not. With a good PA it doesn't matter. (With a bad PA it is better to have the guide scope on axis but I don't see Ray having a bad PA!)

Olly

I agree Olly, I use a Skywatcher Guidescope Mount, which locks every thing up rock solid and then I adjust my guide scope so that it is in line with the imaging I am capturing, I fitted to all my guidescopes a Vixen rail so that they were locked up as I hate guide scope rings. In addition I am advised by my mate @peter shahthat it is fairly important that your guide scope should be inline with the image you are capturing in order to get the best out of your guiding.

It's not a problem on the bigger scopes as I use an OAG but for the Esprits where I can't get enough back focus to fit an OAG into the image train I have to use a guide scope.

[Sinan]

1 hour ago, ollypenrice said:

We came across this issue here just before Christmas with a recently ordered PL setup. Not good.

Personally I think adjustable guide scope rings are a waste of time anyway. Their original purpose was to allow the guidescope to be taken off-axis in search of a guide star because early guide cams were very insensitive. Now the idea has grown up from somewhere that you need guide rings to set the guidescope up on-axis! Both explanations can't be right...  I would far rather bolt the guidescope down hard and permanently and not care whether it's bang on axis or not. With a good PA it doesn't matter. (With a bad PA it is better to have the guide scope on axis but I don't see Ray having a bad PA!)

Olly

Hi Olly,

Thank you for the information. Did the PL setup you came across come with these new plates that allow the screws to sit flush? Can I infer from your comment that the rings would cause flexure even with these new plates?

Sorry if I am asking a silly question, I'm new to AP.

Sinan

[Sinan]

53 minutes ago, Davey-T said:

Hi Sinan and welcome to SGL.

Thanks for the update on the tube rings, all new info is good.

Dave

Thank you Dave. I've been making good use of the valuable information present in these forums. I hope I can contribute more in the future.

Sinan

[RayD]

Great news that they have fixed this, thanks for the confirmation and post.  Maybe they will even commit to providing a free set to those with the original rings (wishful or foolish thinking)?

[ollypenrice]

On 29/01/2019 at 15:43, Sinan said:

Hi Olly,

Thank you for the information. Did the PL setup you came across come with these new plates that allow the screws to sit flush? Can I infer from your comment that the rings would cause flexure even with these new plates?

Sorry if I am asking a silly question, I'm new to AP.

Sinan

It was one of my robotic clients who had the PL rings and, no, he didn't get the 'half moon' devices.

I think your rings will work well but I simply don't find them necessary and think they are a potential source of flexure which doesn't mean they actually will flex.

On 29/01/2019 at 15:15, Jkulin said:

I agree Olly, I use a Skywatcher Guidescope Mount, which locks every thing up rock solid and then I adjust my guide scope so that it is in line with the imaging I am capturing, I fitted to all my guidescopes a Vixen rail so that they were locked up as I hate guide scope rings. In addition I am advised by my mate @peter shahthat it is fairly important that your guide scope should be inline with the image you are capturing in order to get the best out of your guiding.

It's not a problem on the bigger scopes as I use an OAG but for the Esprits where I can't get enough back focus to fit an OAG into the image train I have to use a guide scope.

I wouldn't like to disagree with Peter, whose expertise is very well known!  All I can say is that I have not, for many years, used adjustable guidescope brackets and so my guide scopes point where they point - which is not a million miles off axis but nor is it precisely on axis either. If we think it through I'd say that, with a bad PA, you'll get field rotation around the guide star. If that's a long way off axis this will most adversely affect the stars furthest from the guide star. Having the guide star in the middle of the image will, therefore, cause the least damage overall. However, if we consider a very widefield image taken under guiding and with good PA, we can have sensibly perfect stars across the image. This suggests to me that any of those stars could have been used to guide with no effect on the result. I'm happy to be corrected if this thinking is erroneous.

Olly

[Jkulin]

Reading your comments Olly for Widefield that makes perfect sense because of the FOV, but with subjects with a much narrower FOV Peter's suggestions work for me, I think the key is like we both do is to have everything locked up tight so there is no flexure, that is the main reason why with my Esprits I will not use guide rings and the guide scope mounts really do lock things up but allow you flexibility at the same time.

[RayD]

As a follow up to this, PLL have emailed me via my YouTube channel having seen the video, and are going to send me a set of the modified rings to do an updated video, so at least they are listening and acting which is a great sign.

[RayD]

Just to close this off, Filippo was good to his word and did indeed give me a set of the modification wedges so I have made a short update video just showing what the kit consists of and how it fits on the rings.  It is nothing more than we were suggesting, but they have made the mod look nice and it all works a treat, so far play to PLL for listening and fixing the issue.

 

[Rusted]

All it needs now is a big, coarse, half-round file to make room for the telescope.

Smaller heads on the Csk. screws would leave much more room for a concave radius on the pretty, new "thingy." 

Or a curved, flat bottomed, external foot for the un-flattened[?] ring to sit on.  Using Csk. screws of course.

Sorry, I couldn't resist it. We'll get there in the end.