16 replies to this topic

[GKA]

Just finished  watching Ed Ting's video about these two sct's.

Ed said in the video that it seems that the Edge has some lextra lenses in the back , while the ordinary one don't.

 

I know that the Edge is better at astrophotography , but how big will the diffrences be using a hyperstar , does the hyperstar equal the diffrenses out?

The reason i ask is that i have a Celestron 6" se  that i plan to put a hyperstar on to check what effects it will have on my light pollution , and if succsessful , i might go bigger.

 

Does anyone have any experiences with this ?

 

Thanks 

[slepage]

When using the hyperstar the light is not going through the baffle tube, so it does not matter if it is the edge (with the rear lens element) or if it is the standard version without the rear element. 

 

I think that you should expect that the wider field of view from the hyperstar is going to make the light pollution issue seem worse not better.

 

Steve

Edited by slepage, 06 May 2024 - 05:10 PM.

[Cpk133]

The primary mirror locks would be the only difference using Hyper but I’m not an imager so I’ll defer to those that know better.

[carolinaskies]

Just finished  watching Ed Ting's video about these two sct's.

Ed said in the video that it seems that the Edge has some lextra lenses in the back , while the ordinary one don't.

 

I know that the Edge is better at astrophotography , but how big will the diffrences be using a hyperstar , does the hyperstar equal the diffrenses out?

The reason i ask is that i have a Celestron 6" se  that i plan to put a hyperstar on to check what effects it will have on my light pollution , and if succsessful , i might go bigger.

 

Does anyone have any experiences with this ?

 

Thanks 

Hyperstar only utilizes the corrector and primary mirror, the secondary is removed so light is transmitted through Hyperstar out the front of the telescope to the camera. In this scenario an edge has no advantage over an XLT.  The Edge is only more advantageous if you are using a very large camera sensor of at least APS-C or larger where curvature starts to come into play. 

Hyperstar is at F/2 speed which increases the signal to noise ratio making a faster telescope more ideal than a slower focal ratio telescope.   Skyglow is uniform when stacking successive images which is why EAA is a great method for light polluted skies, and the faster you can gather data the less effect skyglow has on the image.  With and F/10 or even F/7 telescope it takes about 6x as long exposure to gather the same signal as an F/2.  Light pollution is not point source but broad gradient of light from horizon toward the zenith.  As successive images are taken that gradient % of noise reduces vs real signal of the target.  

Compare this hyperstar video on YT... https://youtu.be/Ogx...sslmBkfRR&t=304  showing the Horsehead at F/2 as a single image vs https://youtu.be/5rU...lMFeHeQA&t=1627  an 8" at F/6.3.  

 

[charles.tremblay.darveau]

With the regular 8” you can also get the Starizona reducer which I’ll argue is even better than the celestron one (less CA)

[Echolight]

With the regular 8” you can also get the Starizona reducer which I’ll argue is even better than the celestron one (less CA)

Then there is also the Alan Gee Telecompressor from Baader.

 

I've read a bit about people stacking reducers on the back. I wonder if anyone has stacked one behind an Alan Gee Telecompressor.

[charles.tremblay.darveau]

I didn’t hear great things about the Alan Gee reducer. I would be curious to see results. The Starizona one is absolutely amazing. The only thing I don’t like about it is that it uses compression locks

[GKA]

When using the hyperstar the light is not going through the baffle tube, so it does not matter if it is the edge (with the rear lens element) or if it is the standard version without the rear element. 

 

I think that you should expect that the wider field of view from the hyperstar is going to make the light pollution issue seem worse not better.

 

Steve

I was hoping it would be the other way around , since you can use very short exposures ?

[GKA]

Hyperstar only utilizes the corrector and primary mirror, the secondary is removed so light is transmitted through Hyperstar out the front of the telescope to the camera. In this scenario an edge has no advantage over an XLT.  The Edge is only more advantageous if you are using a very large camera sensor of at least APS-C or larger where curvature starts to come into play. 

Hyperstar is at F/2 speed which increases the signal to noise ratio making a faster telescope more ideal than a slower focal ratio telescope.   Skyglow is uniform when stacking successive images which is why EAA is a great method for light polluted skies, and the faster you can gather data the less effect skyglow has on the image.  With and F/10 or even F/7 telescope it takes about 6x as long exposure to gather the same signal as an F/2.  Light pollution is not point source but broad gradient of light from horizon toward the zenith.  As successive images are taken that gradient % of noise reduces vs real signal of the target.  

Compare this hyperstar video on YT... https://youtu.be/Ogx...sslmBkfRR&t=304  showing the Horsehead at F/2 as a single image vs https://youtu.be/5rU...lMFeHeQA&t=1627  an 8" at F/6.3.  

 

That was sort of what i was hoping for , i guess i will be buying the hyperstar to check this out.

I'm in bortle 6/7 and are using narrowband filters now , but with this years lousy weather in mind , it would be great to be able to collect much data in a short period of time.

[charles.tremblay.darveau]

I was hoping it would be the other way around , since you can use very short exposures ?

Hyperstar will speed up data acquisition no matter light polluted or not. What longer acquisition does is that it flattens out the shot noise from the light pollution which can then be better subtracted. More photons, less shot noise.

 

You may need to reduce the subs length to make sure the histogram is not over-saturated.

[KTAZ]

I didn’t hear great things about the Alan Gee reducer. I would be curious to see results. The Starizona one is absolutely amazing. The only thing I don’t like about it is that it uses compression locks

Which is a concern for serious imagers.

[charles.tremblay.darveau]

Which is a concern for serious imagers.

So are the Chromatic aberration introduced by the edge 0.7 reducer, can't win them all either way .

[RichA]

So are the Chromatic aberration introduced by the edge 0.7 reducer, can't win them all either way .

Very good question as the old f/6.3 unit does add some.

[Echolight]

Maybe I'll double stack some .63 reducers on my C5 or C6, slap a four thirds on the back, and see what happens 

[slepage]

I was hoping it would be the other way around , since you can use very short exposures ?

The sensor does not discriminate in the source of light and as such, the light being pulled in from the stars at a faster rate will be match by the amount of light being pulled in from the light pollution, so you will not see any advantage in your goal of reducing the amount of light pollution moving to the hyperstar.  What could make moving to the hyperstar worse is the fact that light pollution is generally brighter near the horizon and gradually reduces as you move toward zenith.  With the larger field of view using the hyperstar, your field will now include a larger part of the sky that is lower in altitude thus showing a relatively greater amount of light pollution in that part of the frame.

 

Steve 

Edited by slepage, 08 May 2024 - 09:57 AM.

[Echolight]

The sensor does not discriminate in the source of light and as such, the light being pulled in from the stars at a faster rate will be match by the amount of light being pulled in from the light pollution, so you will not see any advantage in your goal of reducing the amount of light pollution moving to the hyperstar.  What could make moving to the hyperstar worse is the fact that light pollution is generally brighter near the horizon and gradually reduces as you move toward zenith.  With the larger field of view using the hyperstar, your field will now include a larger part of the sky that is lower in altitude thus showing a relatively greater amount of light pollution in that part of the frame.

 

Steve 

My sky is much brighter on the north side of zenith than the south. I never look below about 70 or 80 degrees to the north.

[carolinaskies]

The sensor does not discriminate in the source of light and as such, the light being pulled in from the stars at a faster rate will be match by the amount of light being pulled in from the light pollution, so you will not see any advantage in your goal of reducing the amount of light pollution moving to the hyperstar.  What could make moving to the hyperstar worse is the fact that light pollution is generally brighter near the horizon and gradually reduces as you move toward zenith.  With the larger field of view using the hyperstar, your field will now include a larger part of the sky that is lower in altitude thus showing a relatively greater amount of light pollution in that part of the frame.

 

Steve 

Except the source of light pollution is factored out first in setting the gain then in successive stacking.  For longer focal lengths gain cannot be dropped efficiently like it can with a Hyperstar.  This can of course be further enhanced with some of the newer LP filters too.  

The key still remains that a Hyperstar can image even diffuse targets much faster than conventional longer focal lengths.  Cuiv the Lazy Geek who lives in Tokyo has proven the ease of Hyperstar many times over in his videos.