Advice please - Fitting Protostar or AstroSystems secondary holder

richardda1st (Richard) · #1 07-09-2010, 01:02 AM

As I'm fitting a new secondary mirror to my 10"LB I'm thinking of fitting a heated secondary holder. I'm looking at the Protostar or the AstroSystems holders. I would like to keep the existing spider and hub and just replace the plastic holder which is much to big for my new secondary mirror.

Has anyone got any useful

comments or advice they would like to share.
Is Protostar's electrically active spiders a good idea?

Thanks, as usual any advice would be appreciated.

Richard

pmrid (Peter) · #2 08-09-2010, 01:28 PM

I've had a look at the ProtoStar spiders and secondary cells too but decided against them. I'm looking instead at the goodies made by these people:
http://www.observatory.org/spiders.htm

and while they seem pretty expensive they look very well made.

For my purpose (a Cassegrain secondary, not a Newt), they win over Protostar.

I could not find AstroIndustries anywhere. Do you have a link?

Peter.

richardda1st (Richard) · #3 08-09-2010, 08:02 PM

Why did you decide against Protostar?

It's AstroSystems not AstroIndustries

- link is http://www.astrosystems.biz/index.htm

Those VSI products look like the real thing, made for the profesional. Look at those prices.

pmrid (Peter) · #4 08-09-2010, 08:28 PM

Quote:

Originally Posted by richardda1st

Why did you decide against Protostar?

Reasons not likely to impact on you as a Dob/Newt user. I was looking for a Cassegrain spider/secondary and wanted one with a fair range of axial adjustment so I could manage back-focus. I'm refurbishing a 12.5 inch Dall Kirkham f/20 and backfocus is a real issue.
Peter

gbeal · #5 10-09-2010, 09:23 AM

If all you are after is a secondary heater, look local first perhaps. Peter Read the SDM guy (I think, this is all from memory) sells them. Give them a try first perhaps.
Gary

JethroB76 (Jeff) · #6 10-09-2010, 02:36 PM

I can vouch that the astrosystem heaters are very good and simple to install; but you are actually after a new solution for the secondary mirror mount itself, are you not?

richardda1st (Richard) · #7 10-09-2010, 08:58 PM

Quote:

Originally Posted by gbeal

If all you are after is a secondary heater, look local first perhaps. Peter Read the SDM guy (I think, this is all from memory) sells them. Give them a try first perhaps.
Gary

Yes Gary, I would prefer to by all my stuff from a local dealer, but as yet I have not found what I need.

I’m not aware that SDM are suppliers of components. I thought they make and supply complete custom built telescopes. I have been to the SDM site a few times,

there’s nothing to indicate that they are suppliers of bits and pieces.

Quote:

Originally Posted by JethroB76

I can vouch that the astrosystem heaters are very good and simple to install; but you are actually after a new solution for the secondary mirror mount itself, are you not?

That’s right Jethro, I’m looking for a secondary holder to match a new 2.14” Antares secondary mirror I plan on buying. Might as well get or fit a heater to it while I’m at it.

I’m looking for a holder that will replace the current one. I want it to fit straight onto the current spider hub, anyway that’s the idea.

The full Astrosystem holder and spider is much too tall, I would prefer to avoid drilling new holes virtually near the edge of the tube.

The Protostar design looks like it will bolt straight on, I’m not sure about their electrically live spider arms. I think it may cause a short, they even recommend not to use it if the tube is wet.

Maybe a user of one of these can set me right.

Anyway I think I can make an aluminum holder myself, and fit an Astrosystem DG-1 heater to it. I have been in touch (email) with Astrosystems, strangely enough they matched the DG-2 with the 2.14”, which is wrong according to their specs.!!

Thanks
Richard

erick (Eric) · #8 10-09-2010, 09:39 PM

Peter Read (SDM) used to sell components - I bought a DG-1 from him. I think he is now concentrating on the scope business - but give him a call - he might help you out since he still uses these secondary heaters.

I initially bought the wrong size so it was nice he was in Victoria and I could swap.

richardda1st (Richard) · #9 10-09-2010, 10:15 PM

Two recomendations to contact SDM, I will do that tomorrow.

I hope Peter is not a good salesman. I can see it now, I'll call him about a small secondarry holder and he'll sell me a new SDM

Eric, regarding the DG-1 heater, am I right in saying that the heater is self controled, ie. no need for a controler. Just and the power and the unit switches itself on & off to the pre set but adjustable temp.

What do you think of using a small solar panel as the power supply or a small wind turbine?

erick (Eric) · #10 10-09-2010, 11:00 PM

Quote:

Originally Posted by richardda1st

Eric, regarding the DG-1 heater, am I right in saying that the heater is self controled, ie. no need for a controler. Just and the power and the unit switches itself on & off to the pre set but adjustable temp.

Yes, supply 12V and it does the rest. Actually, it probably works on less than 12V if that was an issue.

I think the specs give power consumption? If not, I can measure it sometime.

richardda1st (Richard) · #11 11-09-2010, 07:36 PM

Phoned Peter Read of SDM today, whilst he couldn't supply me with a holder he generously gave me some good advice. What I thought was a problem with the Astrosystem spider arrangement turns out to be a better more solid mounting than the original.

The Astrosystem's much taller assembly requires it to be mounted right on the tube end ring approximately 40mm further up the tube. So instead of mounting onto the thin tube I can mount them onto the 9mm thick end ring. Sounds good to me anyway.

I have ordered the Astrosystem heavy Duty Holder with the DG-1 heater and an Antares 2.14" 1/30pv mirror. Should be a nice match with my new primary.

So thanks to all, again.

JethroB76 (Jeff) · #12 13-09-2010, 03:01 PM

What primary are you putting in the lightbridge?

richardda1st (Richard) · #13 13-09-2010, 11:17 PM

This link will explain. http://www.iceinspace.com.au/forum/s...ad.php?t=48574

I had planed on one of Mark Sutchon's mirrors but that was going to take some time. When this mirror came up I thought it's worth a try, especially as it came with a good rap.

JethroB76 (Jeff) · #14 14-09-2010, 02:05 PM

Ah okay. So your LB mirror was really poor? Or damaged?

richardda1st (Richard) · #15 14-09-2010, 05:21 PM

Jeff, I would say that my LB mirror is as new with some minor marks which only show up at certain angles when you shine a light on to it, that's probably normal and the same as every other one. As to how good it's figured,I have no idea. I have asked these sort of questions here before but no real meaningful answers.
Most would say it's perfectly okay and be happy with it. But with me (and it's just a personal thing) knowing that there is better quality optics out there I just had to improve on what I had. I was advised that the mass produced glass is generally badly annealed and not worth re-figuring.

This replacement mirror was affordable, as to how good it really is only time will tell, I may not even notice the difference

but here's hoping.

Cheers
Richard