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Old 11-05-2018, 03:07 PM
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How does Hypestar or Fastar work.

Making a say a 12 inch f2.2 would be a challenge as would building somthing for it to ride in. ..anyways lets skip those details ...so you have your perfect mirror etc rather than fit a fastar make something.
Or could you just drop fastar and place the camera sensor in prime focus...or what?
I would rather buy a f2.2 fl mirror than make it...someone mustt sell them...I think surplus shed had something years ago but maybe not.
F2.2 on hand made home made carbon fiber rod housing...I wonder if you could lead up jusr three maybe four carbon fiber poles to where the camera sits?
Alex
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Old 11-05-2018, 03:10 PM
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Lognic04 (Logan)
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Quote:
Originally Posted by xelasnave View Post
Making a say a 12 inch f2.2 would be a challenge as would building somthing for it to ride in. ..anyways lets skip those details ...so you have your perfect mirror etc rather than fit a fastar make something.
Or could you just drop fastar and place the camera sensor in prime focus...or what?
I would rather buy a f2.2 fl mirror than make it...someone mustt sell them...I think surplus shed had something years ago but maybe not.
F2.2 on hand made home made carbon fiber rod housing...I wonder if you could lead up jusr three maybe four carbon fiber poles to where the camera sits?
Alex
Well, a cassegrain mirror simply is an f2.2 or whatever mirror - if you could make ne, then it would work just as good as a hyperstar (with the corrector and cameta at the secondary position of course) Or maybe you could use a diagonal?
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Old 11-05-2018, 03:10 PM
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I am thinking the scope to attach to the mount on a plate directly under the primary and a small protrustion out the back with a counter weight...that should minimise flex.
Alex
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Old 11-05-2018, 03:18 PM
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redbeard (Damien)
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One of these?

36 CM ROWE-ACKERMANN SCHMIDT ASTROGRAPH

Cheers,
Damien
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  #5  
Old 11-05-2018, 03:20 PM
glend (Glen)
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Alex, i have done some research on this topic. I was considering converting my Edge HD8 to Hyperstar. You may find that just buying a used SCT, which is Faststar or Hyperstar ready (ie, the secondary can be removed from the front) would be a fairly easy way into it. However, there are complications, and costs. Hyperstar is the only product on the market now, and you looking at near $1k USD for the lense element, add more if you want to use a filter drawer. In order to avoid blocking the light path, you should be using a small body cylinder type camera, like an ASI1600 at the biggest. Next think about filters, if your running mono and want to shoot narrowband you may need high speed filters, another cost. If your going to shoot OSC, like with and ASI1600MC then you don't need to worry about filter drawers and HSO filters, in fact you would probably be able to forget about cooling the camera as well because your subs at f2 are going to be very short.

If your building one, good luck, I don't know if you could get a mirror made but maybe find a damaged SCT to source the mirror from. Good luck.
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Old 11-05-2018, 03:26 PM
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Sorry Logan I was typing whilst you posted.
Let me now reply.
Imagine this the mirror in front of you in the air...dont ask how its held up ..its just there.
Flat like a plate on a table.
Rising upwards is three poles or four from the ring that holds the mirror...they meet like a TP or tipi I think...or to use geometric terms which I avoid ...heck I dont know...lets say pyramid☺
And at the peak where they meet in the middle we put a ring with a focuser ( not a problem) where they join.
The issue will be refraction but I think if you present a flat plan to the incoming light you can fix this...I have reasons to think such but not a specific test to review the exact result.
So our mirror in the air has a pyramid section going up with appropriate imaging gear.
From the bottom of the mirror we have three or four poles going a ery short didtance before they meet..an upside down pyramid.
The ring around the primary has the mounting bracket.
The only flex is in the pyramid but with conventional newt scope mounts the mount bracket is between the scondaru and the primary...this approach reduces flex potential by 50% in my view ...
But I guess the question is can you use prime focus with an f2.2 ..reducers coma corrector I am not sure.
Alex
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Old 11-05-2018, 03:30 PM
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Doing some research, a 4.25 inch diagonal would work at f2.2 (not unlike current RH scopes)
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  #8  
Old 11-05-2018, 03:32 PM
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Quote:
Originally Posted by redbeard View Post
One of these?

36 CM ROWE-ACKERMANN SCHMIDT ASTROGRAPH

Cheers,
Damien
I guess so...

Wow so relatively cheap...but I know I could build one for only four times their price ☺

And mine is new age...its what everyine will want next year.

Mmmm so far I am going to build a mount out of carbon fibre and balsa (acting as a permanent male mold) and a revolutionary new scope...theres next week down the tube.
Alex
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  #9  
Old 11-05-2018, 03:32 PM
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Quote:
Originally Posted by xelasnave View Post
Sorry Logan I was typing whilst you posted.
Let me now reply.
Imagine this the mirror in front of you in the air...dont ask how its held up ..its just there.
Flat like a plate on a table.
Rising upwards is three poles or four from the ring that holds the mirror...they meet like a TP or tipi I think...or to use geometric terms which I avoid ...heck I dont know...lets say pyramid☺
And at the peak where they meet in the middle we put a ring with a focuser ( not a problem) where they join.
The issue will be refraction but I think if you present a flat plan to the incoming light you can fix this...I have reasons to think such but not a specific test to review the exact result.
So our mirror in the air has a pyramid section going up with appropriate imaging gear.
From the bottom of the mirror we have three or four poles going a ery short didtance before they meet..an upside down pyramid.
The ring around the primary has the mounting bracket.
The only flex is in the pyramid but with conventional newt scope mounts the mount bracket is between the scondaru and the primary...this approach reduces flex potential by 50% in my view ...
But I guess the question is can you use prime focus with an f2.2 ..reducers coma corrector I am not sure.
Alex
Sounds interesting! (would be good for your mount idea! ) You just need to ask Stefan to design you a corrector hehe
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  #10  
Old 11-05-2018, 04:04 PM
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Originally Posted by Lognic04 View Post
Sounds interesting! (would be good for your mount idea! ) You just need to ask Stefan to design you a corrector hehe
Now where did I put that box of old military lens...I wish.

What does a fastar do from an optical path point of view..I have no idea firstly their function nor do I know the lens used...heck it may be a fancy mount with just piece of glass in it...

I do like the idea for the mirror mounted direcy over the mount connection...not an isue if you go with a tube...

I just like designing things.
Today I set up a peltie device under the little solar panel so the peltie device could cool the panel and increase its eficiency so it could run the peltie device��..sadly its like the solar powered torch that you have to go outside for it to work.

And this scope and mount has to have a gyro scope ...I am pretty sure, unless I have it wrong that a gyro scopes axis stays still relative to space so it stays put whilst the world turns...and when you think about it from the outside looking in you realise that we need a scope in space...adding a gyro scope should do that...it would make the mount track where pointed...no dou t it would need corrections but well imagine having a mount with gyros ot would possibly be better...
Alex
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  #11  
Old 11-05-2018, 04:12 PM
bratislav (Bratislav)
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Nope

Quote:
Originally Posted by Lognic04 View Post
Well, a cassegrain mirror simply is an f2.2 or whatever mirror - if you could make ne, then it would work just as good as a hyperstar (with the corrector and cameta at the secondary position of course) Or maybe you could use a diagonal?
Sorry to burst the perennial bubbles, but there is ZERO chance that Fastar lens assembly will work with an f/2.2 mirror (spherical or parabolic).
There's a lot more than spherical correction in any optical element. Entrance pupil position, correction of other aberrations (there's FIVE of them in any optical element - read up Seidel Aberrations), it all has a significant impact to final image quality.
Again, no single mirror will work well with Fastar. (and combination of Schmidt plate and spherical primary works as an ELLIPSOID, so not even spherical aberration will be corrected, that is even on axis images will be blurry)

Optics is not that complicated, but neither is that simple. Buy a good book on optics and learn to use any of many free raytrace programs (Beam4 has been made freeware for example https://www.stellarsoftware.com/). It will save you many hours of disappointment.

Bratislav
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  #12  
Old 11-05-2018, 04:31 PM
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Lognic04 (Logan)
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Quote:
Originally Posted by bratislav View Post
Sorry to burst the perennial bubbles, but there is ZERO chance that Fastar lens assembly will work with an f/2.2 mirror (spherical or parabolic).
There's a lot more than spherical correction in any optical element. Entrance pupil position, correction of other aberrations (there's FIVE of them in any optical element - read up Seidel Aberrations), it all has a significant impact to final image quality.
Again, no single mirror will work well with Fastar. (and combination of Schmidt plate and spherical primary works as an ELLIPSOID, so not even spherical aberration will be corrected, that is even on axis images will be blurry)

Optics is not that complicated, but neither is that simple. Buy a good book on optics and learn to use any of many free raytrace programs (Beam4 has been made freeware for example https://www.stellarsoftware.com/). It will save you many hours of disappointment.

Bratislav
Damn Would even just a parabolic 2.2 mirror, diagonal and corrector work?
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  #13  
Old 11-05-2018, 04:32 PM
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Thanks Bratislav,
Now what will I do next week☺.
I know read the book.
Thanks again.
Alex
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