Alternative to Hyperstar

[stash_old]

I know a number of you post on CN and I have read the details there about this alternative Hyperstar (cost vs quality) called the "Funstar" .

install https://www.revolutionimager.com/collections/products/products/funstar-sct-adapter

link to CN discussion https://www.cloudynights.com/topic/573637-inexpensive-alternative-to-fastar/

I appreciate the "quality" of the images would be far worse but could this be useful  to EAA without spending mega bucks ?  I am assuming the Lodestar would be usable in the Funstar ?

I will certainly keep an eye on the feed back !

[HiloDon]

Stash,

As someone pointed out on CN, the Celestron C6 is Fastar compatible, and the secondary threads are SCT.  I had a Scope Stuff SCT to T thread adapter, so I connected my Baader twist lock eyepiece holder to the secondary.  It worked and I was able to come to focus in daylight.  When I get a chance I'll test the Lodestar and do a comparison.  The guy on CN was able to use his Celestron 1.25" visual back by installing a washer in the SCT connection.  The threads on the visual back are apparently too deep to seat the back.  He calls his idea Freestar.

As Nytecam pointed out, the use of the primary without some correction may induce some spherical aberration, but it might be ok for EAA use.

I'll report back as soon as I have something.

Don

Edited April 15, 2017 by HiloDon

[RobertI]

Thanks @stash_old for pointing this out and @HiloDon for offering to try this out with the Lodestar - very interested to see how this turns out. If the distortion is restricted to the outer edges of the field, it could be fun to give it a go. I just had a look at my C8 and unscrewed the secondary, and although the fitting is not SCT (the diameter is slightly wider) it looks easy enough to fit a visual back if one could find the right sized washer - I'm guessing even that would be pretty hard though! But funstar looks a nice little product, watching with interest.

[Peter Drew]

It's against my normal nature but I'm rather pessimistic about this one. The SA from an uncorrected F2 sphere is going to be more than "some", the advertising significantly underplays this issue IMO. I look forward to seeing some images in due course and hope I'm wrong. 

[stash_old]

13 minutes ago, Peter Drew said:

It's against my normal nature but I'm rather pessimistic about this one. The SA from an uncorrected F2 sphere is going to be more than "some", the advertising significantly underplays this issue IMO. I look forward to seeing some images in due course and hope I'm wrong. 

I did say that it wouldn't be "Hyperstar quality" - but what would you expect for $99 - As you say we will see when people like Don ,experienced with Hyperstar,reports back.

[Chris]

I'll follow this with interest, maybe there's a chip out there small enough not to be too badly effected by the SA?

If it does work ok, it might be worth looking out for spare or repar SCT's with broken corrector plates. This would make for a cheap fast system 

[Peter Drew]

4 minutes ago, stash_old said:

I did say that it wouldn't be "Hyperstar quality" - but what would you expect for $99 - As you say we will see when people like Don ,experienced with Hyperstar,reports back.

Fair enough. My feeling though is that it will all boil down to acceptance level. The results might satisfy those who are happy with phones held up to an eyepiece but I can't see a following from the gurus on this part of the forum.

[Peter Drew]

4 minutes ago, Chris Lock said:

I'll follow this with interest, maybe there's a chip out there small enough not to be too badly effected by the SA?

If it does work ok, it might be worth looking out for spare or repar SCT's with broken corrector plates. This would make for a cheap fast system 

Me too! Doesn't a smaller chip effectively increase the magnification and exposure time which would tend to negate the hoped for advantage. Installing a secondary support system to replace a corrector would be an interesting challenge, possibly using a circle of selected window glass would be adequate for a trial.  

[Chris]

Just now, Peter Drew said:

Me too! Doesn't a smaller chip effectively increase the magnification and exposure time which would tend to negate the hoped for advantage. Installing a secondary support system to replace a corrector would be an interesting challenge, possibly using a circle of selected window glass would be adequate for a trial.  

Not from my experience, it's purely f/ratio rather than image scale isn't it? 

If you found a cheap SCT due to a crack/cracks in the corrector for example, maybe you could thinly tape up the cracks to seal them and use the broken corrector to support the secondary holder. Yes this would introduce diff spikes but you could run the wires from the camera along the tape to limit the impact. That's the kind of thing I had in mind. Not that you see that many cheap SCT's with broken correctors for sale, so just thinking out loud really   

Edited April 16, 2017 by Chris Lock

[shirva]

Had read the posts the other night on cm and mike at oc telescopes comments, as said it's never going to be to hyperstar quality as it has no lens's to clean up the image,, but it may be a bit of fun to someone who has an interest at imaging at f2,, the other thing is it's video astronomy not astrophotography it's all about the live or near live view and the captured images are only for prosperity for most and a visual reminder of that nights viewing,,

On saying all this mike has put some pretty decent kit on the market and we all know that folk will like it or slate it,,but it's new and different and for the price I'm shure somebody will have fun with it and give the rest of us something to discuss.

Great post ?

[Stu]

11 hours ago, Peter Drew said:

Fair enough. My feeling though is that it will all boil down to acceptance level. The results might satisfy those who are happy with phones held up to an eyepiece but I can't see a following from the gurus on this part of the forum.

What are you trying to say Peter??  

[shirva]

Will be interesting to get a comparison from don and he hasn't needed to buy the fun star as he has adapted a piece of kit to emulate it,, like the thought behind it ?.  About a year ago my uncle had the thought,, what if the secondary mirror was removed on a Newtonian telescope and a focus mechanism made how would this go,, I actually think a truss scope would be ideal candidate.. one for the future ?

Looking forward to don's findings ,, and I don't own one of these scopes,, just opens up new avenues for video astronomy 

[Stu]

Quite interested in this myself. I have a C925 whitch is Fastar compatible so if there is an easy/cheap way of attaching a camera to it I would give it a go. I have a Samsung SCB2000 which might work?

[RobertI]

Having looked at Nytecams 's post on the CN thread and done a bit of research it seems that spherical abberation isn't the type of abberation which is restrcited to edges (as I thought in my earlier post)  so the result will probably be large stars, even in Ha? I am guessing that, although the corrector plate ciorrects for spherical abberation, it is designed to correct for two spherical mirrors, so if one is removed, the correction is gone, or new abberations introduced? So presumably, stoppjng down the scope would not help either as the presence of the corrector means its not a simple spherical abberation issue any more?

Edited April 17, 2017 by RobertI

[Stu]

1 minute ago, RobertI said:

Having looked at Nytecams 's post on the CN thread and done a bit of research it seems that spherical abberation isn't the type of abberation which is restrcited to edges, so the result will probably be large stars, even in Ha? I am guessing that, although the corrector plate ciorrects for spherical abberation, it is designed to correct for two spherical mirrors, so if one is removed, the correction is gone, or new abberations introduced? So presumably, stoppjng down the scope would not help either as the presence of the corrector means its not a simple spherical abberation issue any more?

I'm sure that is correct. I guess that if, as Peter says, you are just looking for a cheap and convenient result on nebulae and perhaps galaxies then it might have something to offer. I could cope with big stars if it showed me faint stuff from home...

[Chris]

32 minutes ago, RobertI said:

Having looked at Nytecams 's post on the CN thread and done a bit of research it seems that spherical abberation isn't the type of abberation which is restrcited to edges (as I thought in my earlier post)  so the result will probably be large stars, even in Ha? I am guessing that, although the corrector plate ciorrects for spherical abberation, it is designed to correct for two spherical mirrors, so if one is removed, the correction is gone, or new abberations introduced? So presumably, stoppjng down the scope would not help either as the presence of the corrector means its not a simple spherical abberation issue any more?

Sounds like good reasoning to me, Rob. I too thought SA would only effect off axis towards the edges, but if this isn't the case then some acceptance of a less than perfect image will definitely be needed. The proof is in the pudding, so looking forward to seeing the pudding...I mean images  

[shirva]

2 hours ago, Stu said:

Quite interested in this myself. I have a C925 whitch is Fastar compatible so if there is an easy/cheap way of attaching a camera to it I would give it a go. I have a Samsung SCB2000 which might work?

Or even better ,a watec 902h

[Stu]

1 hour ago, shirva said:

Or even better ,a watec 902h

Sounds good, but need to stick with kit I've got at the moment. Funds are non existent really!

[shirva]

I try and identify where I need to upgrade and just look for a bargain,pretty much at a kit level I'm happy with, a filter wheel and some narrow band filters and I'm finished,, been upgrading for years,, next up an observatory.. but keep backing down due to cost v weather. But kit is heavy and time consuming to set up,, even went to portable kit but miss the big set up of my heq5 extension pier, twin scope saddle,8" explorer,ed80 and twin DSLRs,eqmod,byeos and astrotoaster.. maybe this year I will make the jump

[stash_old]

5 minutes ago, shirva said:

I try and identify where I need to upgrade and just look for a bargain,pretty much at a kit level I'm happy with, a filter wheel and some narrow band filters and I'm finished,, been upgrading for years,, next up an observatory.. but keep backing down due to cost v weather. But kit is heavy and time consuming to set up,, even went to portable kit but miss the big set up of my heq5 extension pier, twin scope saddle,8" explorer,ed80 and twin DSLRs,eqmod,byeos and astrotoaster.. maybe this year I will make the jump

Go for the Obsys - I made my own using an old scaffolding tower , tin shed, corr sheets and OSB3 - now takes me 10mins to set up , roll off the roof and off I go - best investment I ever made. Also at the same time extended my wired Ethernet so all now remote (AND WARM ). Now saving for better scope or Hyperstar or camera or this and that (list endless ) but still having fun !

Perhaps someone will convert the Funstar with a corrective lens to help the SA but cheaper than the Hyperstar - or the pound will go mad and jump to £1 to $2.40 and HM R & C wont look at my "gift" from my American cousin in CA 

[Chris]

37 minutes ago, shirva said:

I try and identify where I need to upgrade and just look for a bargain,pretty much at a kit level I'm happy with, a filter wheel and some narrow band filters and I'm finished,, been upgrading for years,, next up an observatory.. but keep backing down due to cost v weather. But kit is heavy and time consuming to set up,, even went to portable kit but miss the big set up of my heq5 extension pier, twin scope saddle,8" explorer,ed80 and twin DSLRs,eqmod,byeos and astrotoaster.. maybe this year I will make the jump

I miss my obsy, built it at my old house by converting a 6x10' shed to have a roof that rolls over a small warm room onto large angle brackets. I really enjoyed the process of building it too! I had plenty of help from SGL

 Techinically I still have the obsy as we rent the old house out. It's not worth building another one hear as the garden is very small with little in the way of an horizon, so I just have a small 5x3' scope shed to pull kit out of...works with the space available.

I know we're going off topic, but maybe you could build something like a fixed pier in the garden with a small shed that rolls off it? 

Edited April 17, 2017 by Chris Lock

[HiloDon]

I tried to get some comparison last night with the C6.  Skies looked pretty good, so I aligned and set up the Freestar with the Lodestar.  Went to the Rosette Nebula.  Tried to get focused, but some of the brighter star were showing severe aberrations.  Kept playing with the focus and the inevitable happened.  Clouds moved in and it started to rain.  Gave up at about 11:00pm.  The initial view was not promising.  Much of what some of you said seems to be true.  I will try again, hopefully this week some time.

Don

[RobertI]

11 hours ago, HiloDon said:

I tried to get some comparison last night with the C6.  Skies looked pretty good, so I aligned and set up the Freestar with the Lodestar.  Went to the Rosette Nebula.  Tried to get focused, but some of the brighter star were showing severe aberrations.  Kept playing with the focus and the inevitable happened.  Clouds moved in and it started to rain.  Gave up at about 11:00pm.  The initial view was not promising.  Much of what some of you said seems to be true.  I will try again, hopefully this week some time.

Don

Doesn't sound promising, thanks for sharing your first go.

[stash_old]

On 17/04/2017 at 20:33, HiloDon said:

I tried to get some comparison last night with the C6.  Skies looked pretty good, so I aligned and set up the Freestar with the Lodestar.  Went to the Rosette Nebula.  Tried to get focused, but some of the brighter star were showing severe aberrations.  Kept playing with the focus and the inevitable happened.  Clouds moved in and it started to rain.  Gave up at about 11:00pm.  The initial view was not promising.  Much of what some of you said seems to be true.  I will try again, hopefully this week some time.

Don

Thanks for trying !   

[HiloDon]

Had some clear skies last night and did a comparison of the Freestar and Hyperstar on my Evo 6 and Lodestar X2c.  All settings were the same.  M8 was the target.  If I tried to get better focus on the bright stars, the smaller dim stars would go out of focus.  

I'm hoping someone can explain what's going on optically, but it's not good without Hyperstar.  First one is Freestar, then Hyperstar.

Edited April 20, 2017 by HiloDon