Jump to content


Photo

Why do some consider Hyperstar a 'crude' platform?

  • Please log in to reply
141 replies to this topic

#1 Phil Hosey

Phil Hosey

    Surveyor 1

  • *****
  • Posts: 1626
  • Joined: 29 Oct 2008
  • Loc: LaGrange, GA

Posted 23 April 2013 - 10:20 PM

It has been recommended that I wean myself from Hyperstar because it is a 'Crude' platform. I'm not saying it isn't, I would like to keep an open mind. If we put aside the difficulties in getting the collimation and focus correct at f/2 which can be quite challenging and if we use a camera that gives us a good image scale, what else technically is wrong with it? Just to be clear, I haven't gotten my Hyperstar system working well yet, it is currently at Starizona along with my C11 being setup. So, in the mean time, I would love to hear the arguments both for and against Hyperstar being a crude imaging platform.

#2 David Pavlich

David Pavlich

    Transmographied

  • *****
  • Administrators
  • Posts: 27183
  • Joined: 18 May 2005
  • Loc: Mandeville, LA USA

Posted 23 April 2013 - 10:38 PM

I'm not sure where that comes from, Phil. Yes, it can be fickle when it comes to getting the adjustments correct. I just had first light with mine. With no collimation and focusing with a Bahtinov mask, the stars looked quite good. The image wasn't worth a hoot, it washed out from the Moon being so close to the object, but the stars looked good. I guess everything is lined up pretty well.

One of the complaints is that using a mono camera with a filter wheel can't happen. Well, with the advent of the QSI cameras with their compact size and internal filter wheel, the 8300 based camera will work well with the C11 and really well with the C14.

It's limited to APS-C or smaller chips and it is hanging on the corrector. But I judge it by the images. For the widefield stuff, it's nice. And for a typical object, a 3 minute exposure sucks in a ton of photons.

Then there's the fact that with a proper reducer/corrector, you can remove the HS and get it down to around f7 and for planetary work, you have the native f10 or f11.

David

#3 JJK

JJK

    Surveyor 1

  • -----
  • Posts: 1850
  • Joined: 27 Apr 2008

Posted 23 April 2013 - 10:57 PM

What does "crude" mean in this instance?

#4 mmalik

mmalik

    Fly Me to the Moon

  • *****
  • Posts: 5320
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 23 April 2013 - 11:40 PM

Crude is a harsh word but I can't think of a better word for HyperStar; I am not against the creative design of HyperStar per se but I have my concerns about technical and mechanical validity of such a design (i.e., in conjunction with SCT's).

Here are some thoughts where I am coming from:

•SCTs inherently are herky-jerky design (here we go again with another not so optimal word) from collimation to mirror flop to focusers, etc.

•Corrector plate is not a rigid structure in itself and was originally designed to house just the light weight secondary

•HyperStar's fit, i.e., misfit, within the corrector plate gets mentioned quite often; stressing/flexing imparted by HyperStar is another cause for concern

•Nothing against Starizona, but I have my doubts about Starizona's HyperStar design, workmanship, & glass quality... expertise (e.g., consider a “hypothetical” HyperStar offering form Takahashi on top of a corrected Mewlon for a "hypothetical" comparison)

•HyperStar is limited to Celestron ONLY if I understand it correctly; not an SCT-wide acceptance as far as I know (in other word a proprietary offering, not an industry standard)

•Obstructed design of SCT further gets compromised by cumbersome and further obstructing imaging devices used with HyperStar

•Spiking/obstruction caused by traversing connections

•Rigidity of other designs, e.g., refractors, is just not possible in SCTs and HyperStar makes it even less rigid and more prone to stressing built-in tolerances of the SCT system

•Fastness or short circuiting of optical path ramifications of HyperStar are whole another subject that has been discussed at length in another thread...

•Uncorrected optics/folded design of SCTs


I could go on but I think you get the idea... what I am trying to get at is that we have not so optimal/rigid original design of SCT that gets further compromised by HyperStar and that's what makes it NOT so solid and/or sophisticated. HyperStar may suit video or casual still astro imagery, but high quality/high resolution still astro photography remains the domain of un-obstructed and corrected optics. Regards

#5 JJK

JJK

    Surveyor 1

  • -----
  • Posts: 1850
  • Joined: 27 Apr 2008

Posted 24 April 2013 - 04:07 AM

Malik, a definition of herky jerky is "spasmodic". That has nothing to do with the optical design of the SCT. Now, Celestron's & Meade's implementation of the primary mirror movement was poor because it led to spasmodic focus movement and mirror flop. However, anyone with decent technical skills can rework the focuser of C or M SCTs if they use a more sensible design (move the primary on a plane defined by three points).

I've been concerned about the stress on the corrector plate caused by a CCD camera. Do you have any data that illustrates this issue?

You also stated that the corrector plate is not rigid (in a non-Hyperstar mode). Please provide solid evidence for that claim.

#6 Tapio

Tapio

    Apollo

  • -----
  • Posts: 1327
  • Joined: 24 Sep 2006
  • Loc: Tampere, Finland

Posted 24 April 2013 - 04:37 AM

(Certain) Meade SC-scopes can also be used with Hyperstar.
http://www.hyperstar...mpatibility.php

#7 bilgebay

bilgebay

    Skylab

  • *****
  • Moderators
  • Posts: 4114
  • Joined: 06 Nov 2008
  • Loc: Turkiye - Istanbul and Marmaris

Posted 24 April 2013 - 05:00 AM

As an astroimager who has a very satisfactory Hyperstar experience of almost 3+ years I cannot agree with your statement that HS is a crude platform.

•SCTs inherently are herky-jerky design (here we go again with another not so optimal word) from collimation to mirror flop to focusers, etc.

( The new Edge series have mirror locks to deal with the mirror flop )

•Corrector plate is not a rigid structure in itself and was originally designed to house just the light weight secondary

( You don't have to hang a heavy camera to the HS lens. My Atik 460 is only 400 grams. When I used a T2i with my C11 HS, I haven't witnessed any deformation of the corrector by looking at the results the system produced.)

•HyperStar's fit, i.e., misfit, within the corrector plate gets mentioned quite often; stressing/flexing imparted by HyperStar is another cause for concern

( It's not the Hyperstar but secondary holder which is loose to the corrector plate. But this is easy to cure )

•Nothing against Starizona, but I have my doubts about Starizona's HyperStar design, workmanship, & glass quality... expertise (e.g., consider a “hypothetical” HyperStar offering form Takahashi on top of a corrected Mewlon for a "hypothetical" comparison)

( Again I haven't noticed any color aberrations. Sometimes, I get strange reflections but almost all systems have this problem, eg when shooting near Alnitak or Gamma Cass. )

•HyperStar is limited to Celestron ONLY if I understand it correctly; not an SCT-wide acceptance as far as I know (in other word a proprietary offering, not an industry standard)

(Nope, there are HS lenses for Meade SCTs as well)

•Obstructed design of SCT further gets compromised by cumbersome and further obstructing by imaging devices used with HyperStar

( Not necessarily, you can use Pepsi cameras, or make a donut mask to hide the silhouetteof a DSLR. See Samir Kharusi's website for the tips )

•Spiking/obstruction caused by traversing connections

( Not necessarily, there are ways to avoid this. But again, what about Newtonian and RC based astrographs ? )

•Rigidity of other designs, e.g., refractors, is just not possible in SCTs and HyperStar makes it even less rigid and more prone to stressing built-in tolerances of the SCT system

( Quite the contrary... how can you say this after we have discussed for so many pages about FSQ106's shortcoming on this front, which is a "dedicated astrograph" ? I had none of those flexure problems with C11 Hyperstar system )

•Fastness or short circuiting of optical path ramifications of HyperStar are whole another subject that has been discussed at length in another thread...

( This is the whole point... Speed... nothing can beat Hyperstar at this price! )

•Uncorrected optics/folded design of SCTs

( Irrelevant in the context of Hyperstar...I get full flat frame with an APS-C size sensor)

Please continue with your other arguments

Sedat

#8 JJK

JJK

    Surveyor 1

  • -----
  • Posts: 1850
  • Joined: 27 Apr 2008

Posted 24 April 2013 - 06:02 AM

(Certain) Meade SC-scopes can also be used with Hyperstar.
http://www.hyperstar...mpatibility.php


I didn't suggest otherwise.

#9 Da Bear

Da Bear

    Viking 1

  • *****
  • Posts: 988
  • Joined: 21 Nov 2006
  • Loc: Kali-Forn-Ya

Posted 24 April 2013 - 07:21 AM

One of my favorite astro gear stories:

A guy was selling his very expensive, high end scope widget to me and complained endlessly in emails what a stupid design company X had realeased in to the market.

I finally asked about his set up and what he steps he used to get the widget working. After three email exchanges, I figured out he just failed to index the optics, as Company X laid out in the instructions, in bold red letters.

In less than one minute, he finally indexed the "stupid" widget from the "idiots" at company X and it worked perfectly.

Da Bear

#10 Phil Hosey

Phil Hosey

    Surveyor 1

  • *****
  • Posts: 1626
  • Joined: 29 Oct 2008
  • Loc: LaGrange, GA

Posted 24 April 2013 - 07:47 AM

I for one have no complaints about the design of the Hyperstar and C11. I know my limitations and this time I could not get it working correctly. I do know it is possible though as I have done before with a previous C11 and Hyperstar. That is why I sent both the scope and Hyperstar to Starizona to have Dean set it up. It is now o n the way back to me and should be good to go. There are trade-offs everywhere in this hobby, and I sure love that f/2 imaging and when the Hyperstar is working properly I can accept it's other shortcomings.

#11 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15361
  • Joined: 06 Jul 2007

Posted 24 April 2013 - 08:25 AM


Here are some thoughts where I am coming from:

•SCTs inherently are herky-jerky design (here we go again with another not so optimal word) from collimation to mirror flop to focusers, etc.

•Corrector plate is not a rigid structure in itself and was originally designed to house just the light weight secondary

•HyperStar's fit, i.e., misfit, within the corrector plate gets mentioned quite often; stressing/flexing imparted by HyperStar is another cause for concern

•Nothing against Starizona, but I have my doubts about Starizona's HyperStar design, workmanship, & glass quality... expertise (e.g., consider a “hypothetical” HyperStar offering form Takahashi on top of a corrected Mewlon for a "hypothetical" comparison)

•HyperStar is limited to Celestron ONLY if I understand it correctly; not an SCT-wide acceptance as far as I know (in other word a proprietary offering, not an industry standard)

•Obstructed design of SCT further gets compromised by cumbersome and further obstructing by imaging devices used with HyperStar

•Spiking/obstruction caused by traversing connections

•Rigidity of other designs, e.g., refractors, is just not possible in SCTs and HyperStar makes it even less rigid and more prone to stressing built-in tolerances of the SCT system

•Fastness or short circuiting of optical path ramifications of HyperStar are whole another subject that has been discussed at length in another thread...

•Uncorrected optics/folded design of SCTs


I could go on but I think you get the idea... what I am trying to get at is that we have not so optimal/rigid original design of SCT that gets further compromised by HyperStar and that's what makes it NOT so solid and/or sophisticated. HyperStar may suit video or casual still astro imagery, but high quality/high resolution still astro photography remains the domain of un-obstructed and corrected optics. Regards


Collimation is neither herky nor jerky. A PROPERLY collimated SCT can hold collimation for months or even years. Mirror flop? I've had ONE image ruined by flop over the last 30 plus years. It's not much of a problem, frankly. With current Meades and Celestrons with mirror locks, it is no problem at all. The SCT focuser provides more focus range than any alternative.

There is no doubt you could break a corrector if you banged a camera into something with it mounted in Fastar position. And this has happened to a couple of folks. But not many and that is the bottom line.

The Hyperstars are collimateable.

They appear to have plenty of very satisfied customers. Not sure where you are going with Takahashi, but they don't offer anything like Hyperstar for the Mewlon.

So what? And it WAS offered (the secondary conversion) for Meades for some time.

The quality of Hyperstar images (within the guidelines established for camera/aperture) says otherwise.

These can be minimized. You'll get worse with a Newtonian.

You've mentioned this already, and it is still not a factor.

No idea what "fastness or short circuiting" means... sorry.

Uncorrected what? You do know the supplemental lens that goes in front of a camera in the Hyperstar/Fastar setup is a corrector, don't you?

Nope, I don't get the idea. Are you a Hyperstar/Fastar user? Fastar imaging is not for everyone, no doubt about that. But there is also no doubt it works and works fine as thousands of images taken that way demonstrate.

;)

#12 jrcrilly

jrcrilly

    Refractor wienie no more

  • *****
  • Administrators
  • Posts: 33724
  • Joined: 30 Apr 2003
  • Loc: NE Ohio

Posted 24 April 2013 - 08:33 AM

"Crude" is a subjective term. It's certainly less sophisticated an an RH-200 or an Epsilon, both of which offer far less optical compromise and also permit the use of very large chips and arbitrary camera sizes/shapes. Both are thousands of dollars more than a Fastar-adapted C8, though. If it is crude only compared to those, it is hardly without value.

#13 jrcrilly

jrcrilly

    Refractor wienie no more

  • *****
  • Administrators
  • Posts: 33724
  • Joined: 30 Apr 2003
  • Loc: NE Ohio

Posted 24 April 2013 - 08:36 AM

Not sure where you are going with Takahashi, but they don't offer anything like Hyperstar for the Mewlon.


They went in a different (and more Takahashi-like) direction by offering the Epsilon.

#14 David Pavlich

David Pavlich

    Transmographied

  • *****
  • Administrators
  • Posts: 27183
  • Joined: 18 May 2005
  • Loc: Mandeville, LA USA

Posted 24 April 2013 - 08:39 AM

This image isn't the greatest until you look at the fact that a total exposure time of 100 seconds and the fact that it was an unmodified Canon 40D is what produced the image. I wonder how it would have looked with 30 minutes of exposure using a modified 40D. :question:

Like Rod said, HS isn't for everyone, but it seems to me that those that have used it successfully really like the fact that it takes relatively little time to take the pictures. Used within its limitations, it is a good imaging platform.

David

#15 Starhawk

Starhawk

    Space Ranger

  • *****
  • Posts: 5489
  • Joined: 16 Sep 2008
  • Loc: Tucson, Arizona

Posted 24 April 2013 - 09:04 AM

Mmalik, you're simply inexperienced with hyperstar. The original design came from the 60" scope on Mount Lemmon. The scope was originally a cassegrain and got a new front end built to allow deep sky searches for asteroids. It has found more than any other telescope. I've had a chance to use it- most galaxies wind up overexposed.

The same person at the University of Arizona here in Tucson designed hyperstar.

It makes it possible to get complete images of a half dozen objects in one night. And your objections just aren't based on reality.

-Rich

Attached Files



#16 Starhawk

Starhawk

    Space Ranger

  • *****
  • Posts: 5489
  • Joined: 16 Sep 2008
  • Loc: Tucson, Arizona

Posted 24 April 2013 - 09:07 AM

And here's a detail from that frame:

Note the wee little background galaxies. This is a stack of 30 second images from a Pentax K-5. I was kicking myself for operating at ISO 12800 instead of ISO 51200.

-Rich

Attached Files



#17 jrcrilly

jrcrilly

    Refractor wienie no more

  • *****
  • Administrators
  • Posts: 33724
  • Joined: 30 Apr 2003
  • Loc: NE Ohio

Posted 24 April 2013 - 09:17 AM

The original design came from the 60" scope on Mount Lemmon. The scope was originally a cassegrain and got a new front end built to allow deep sky searches for asteroids.


To be fair, that was a classical Cass with a paraboloid mirror at F/4 or thereabouts. All that would be required to switch to prime focus would be removal of the secondary and addition of a coma corrector. Takahashi offered a convertable classical Cass/Newt for years. Converting an SCT with a spherical F/2 primary is much more of a compromise and definitely not the same design.

It's OK to like Hyperstar but let's remain realistic. ;)

#18 Alph

Alph

    Surveyor 1

  • -----
  • Posts: 1755
  • Joined: 23 Nov 2006
  • Loc: Melmac

Posted 24 April 2013 - 10:54 AM

As an astroimager who has a very satisfactory Hyperstar experience of almost 3+ years I cannot agree with your statement that HS is a crude platform.


Didn't you forget to mention that you don't image with the Hyperstar anymore? I see only beginners using the Hyperstar.
How about alignment? Do you expect everybody to go through the same process as you did?

#19 bilgebay

bilgebay

    Skylab

  • *****
  • Moderators
  • Posts: 4114
  • Joined: 06 Nov 2008
  • Loc: Turkiye - Istanbul and Marmaris

Posted 24 April 2013 - 11:06 AM

Nope, where do you get this idea?

I have, just last weekend, purchased a a brand new C8 Edge and a Hyperstar lense for it... Actually I have purchased them 3 months ago but was able to collect them last weekend when I was in US for NEAIC/NEAF.

Do you think I paid so much money not to use it ? You're funny :lol:

My problem was the size and weight of my C11 system. I have to tear down my system when I come back to Istanbul. I cannot leave my imaging setup out in the elements unattended for a week or two.

#20 bilgebay

bilgebay

    Skylab

  • *****
  • Moderators
  • Posts: 4114
  • Joined: 06 Nov 2008
  • Loc: Turkiye - Istanbul and Marmaris

Posted 24 April 2013 - 11:09 AM

I see only beginners using the Hyperstar.



No problem, you can consider me as a beginner. I am not claiming that I'm a master in this art.

#21 UnderDriven

UnderDriven

    Sputnik

  • -----
  • Posts: 48
  • Joined: 22 Apr 2013
  • Loc: Pennsylvania

Posted 24 April 2013 - 11:20 AM

I'm no expert on the HyperStar, but it seems fair to say that it is a "crude" system in the sense that it is a improvised system--meaning that the designers of SCTs never intended that a camera should replace the secondary mirror, and therefore did not take this into account when designing the corrector plate. However, that does not mean that it doesn't work--there have been many improvised systems which have worked well, or at least well enough to accomplish the intended task. As someone else mentioned, every telescope is a compromise...

The only non-improvised system I know of which is nearly as fast as HyperStar is a Takahashi hyperbolic astrograph for $5400. But the Takahashi aperture is only 180mm and it's pretty much a one-trick-pony. Part of the appeal of HyperStar is being able to reconfigure an F/10 telescope as an F/2 astrograph as needed, while spending a lot less than $5400...

Cheers, Keith

#22 bilgebay

bilgebay

    Skylab

  • *****
  • Moderators
  • Posts: 4114
  • Joined: 06 Nov 2008
  • Loc: Turkiye - Istanbul and Marmaris

Posted 24 April 2013 - 11:35 AM

How about alignment? Do you expect everybody to go through the same process as you did?



I am not expecting anything Alph. I am only addressing what Mike considers as issues with this system, which, as an actual user, I know that they are not.

My effort to align the optical axis of my C11 Edge was/is an attempt to reach perfection. The system was still useable even before I aligned everything and remember, what i aligned had nothing to do with the Hyperstar lens, it was the secondary and corrector plate to the primary which is an essential parameter even for visual work.

I have bought a multipoint laser collimation tool from Hotech after discussing the possibilty to use this device to optically align all the components of a SCT+Hyperstar system with David. David is willing to invest into this area. The result will be more elegant and we will be sure of aligning the optical axis rather than having to rely on some mechanical properties to support my previous method. Of course, this laser is not cheap but still justifiable.

Lastly, i will really appreciate your sharing the wealth of knowledge you seem to have rather than hitting with negative comments and running. My shooting or not shooting with Hyperstar has no relevance in this context.

#23 Starhawk

Starhawk

    Space Ranger

  • *****
  • Posts: 5489
  • Joined: 16 Sep 2008
  • Loc: Tucson, Arizona

Posted 24 April 2013 - 01:42 PM

No stretch, here.

The Mt. Lemmon system is at f/2, now. The lens set for it is about 16" across. The corrector with spherical primary on an SCT already correct for spherical aberration in an SCT. That's why these literally are the same type of system. And it's not a coincidence the same guy designed all of them.

-Rich

The original design came from the 60" scope on Mount Lemmon. The scope was originally a cassegrain and got a new front end built to allow deep sky searches for asteroids.


To be fair, that was a classical Cass with a paraboloid mirror at F/4 or thereabouts. All that would be required to switch to prime focus would be removal of the secondary and addition of a coma corrector. Takahashi offered a convertable classical Cass/Newt for years. Converting an SCT with a spherical F/2 primary is much more of a compromise and definitely not the same design.

It's OK to like Hyperstar but let's remain realistic. ;)



#24 Alph

Alph

    Surveyor 1

  • -----
  • Posts: 1755
  • Joined: 23 Nov 2006
  • Loc: Melmac

Posted 24 April 2013 - 02:01 PM

My shooting or not shooting with Hyperstar has no relevance in this
context.


The point is that many hyperstar owners move on to other telescopes quite quickly including you :grin:. They don’t want to deal with alignment issues every single imaging session. Also the hyperstar f/2 optics has additional inherent shortcomings like vignetting, poor narrowband efficiency, focusing issues, diffraction artifacts caused by cables/camera profile and bloated stars.

I have bought a multipoint laser collimation tool from Hotech after discussing the possibilty to use this device to optically align all the components of a SCT+Hyperstar system with David. David is willing to invest into this area. The result will be more elegant and we will be sure of aligning the optical axis rather than having to rely on some mechanical properties to support my previous method. Of course, this laser is not cheap but still justifiable.



I pointed out to David Ho few years ago that the ACT collimator could be used to align the Hyperstar. I had a number of discussions with him about it. He has been very slow in embracing the Hyperstar. I could not convince him to make a mounted mirror that could be threaded on the Hyperstar. Once I even tried to setup a meeting between Starizona and Hotech at a local show, nothing came out of it. Starizona showed very little interest. Personally, I have used the ACT collimator with a blue filter a couple of times to align my 14” HS with mixed results. Squaring the ACT collimator to the SCT is not repeatable.

I think f/2 is simply too fast for narrowband filters and micro-lenses, f/3 would be better, but that's too slow for Starizona (talked to them about it, no plans for Hyperion Hyperstar)

#25 Starhawk

Starhawk

    Space Ranger

  • *****
  • Posts: 5489
  • Joined: 16 Sep 2008
  • Loc: Tucson, Arizona

Posted 25 April 2013 - 12:00 AM

Micro lenses work at f/1.4. The narrowband filters work, though they can produce unusual flares on bright stars.

Actually, I wonder what the limits are for driving existing hyperstar variants with different primary mirrors. Of course, getting an f/2 parabola isn't trivial.

-Rich






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics