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Sharpstar 61 EDPH II APO Chromatic Abberation?

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#151 UKalwayscloudy

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Posted 05 May 2021 - 08:27 AM

TSRED279 arrived this morning and I have done a crude initial test with some fixed spacers that gave me 74mm Backfocus with my aps-c Hypercam 26c attached. Just been doing some daytime work and am very pleased so far. In particular illumination is flat, to the eye, into the corners so I believe TS claim that it is good to 30mm.

Using the 2in plug fit for now and will see if I can set up a screw fit. Will report back when I've had a chance to play on a proper target.


Edited by UKalwayscloudy, 05 May 2021 - 08:41 AM.

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#152 UKalwayscloudy

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Posted 06 May 2021 - 07:38 AM

TSRED279 update:

 

The M54 thread on the 2in scope plug of the reducer is easily adapted to the M63 thread on the scope with the TS adapter with the rotator built in (the TS part "CAA", which I happened to have from another project), so I now have a secure screw fit with rotation. I did a full frame illumination test on my Nikon Z6 and the results are good - there is the vignetting you might expect from a T2 link but it is really only in the deep corners. Vignetting is minimal to the eye on a 24mm x 24mm square let alone DX or APS-C, so this all come down to the radius at which the correction of star shapes deteriorates. Pic of FX flat frame shown. Just need a clear night now. (Any banding on the pic is just jpeg compression artefacts)

Attached Thumbnails

  • TSFX2.jpg

Edited by UKalwayscloudy, 06 May 2021 - 07:41 AM.

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#153 leemajors

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Posted 06 May 2021 - 01:32 PM

TSRED279 arrived this morning and I have done a crude initial test with some fixed spacers that gave me 74mm Backfocus with my aps-c Hypercam 26c attached. Just been doing some daytime work and am very pleased so far. In particular illumination is flat, to the eye, into the corners so I believe TS claim that it is good to 30mm.

Using the 2in plug fit for now and will see if I can set up a screw fit. Will report back when I've had a chance to play on a proper target.

I used about 71.5mm spacing as thats what the TS table seemed to show.


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#154 UKalwayscloudy

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Posted 06 May 2021 - 02:44 PM

Yep I did a similar extrapolation and thought 71.5 was about right with a 1mm thickness filter in place for a 335mm OTA. I need to rummage through my spacer box to nail it down. I won’t make any inferences about star shape quality till I have that sorted.

#155 timmbottoni

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Posted 06 May 2021 - 03:17 PM

Thanks for this interesting discussion. The big question I think is whether these images are representative of all samples or not.

 

I am a huge fan of WO products, and have been for a while, so probably at least somewhat biased, and am always a bit reluctant to believe marketing claims from most vendors. 

I am also a huge fan of Trevor Jones, as he has produced some very helpful and informative videos.

 

I have the WO ZS61 original (FPL53 doublet) and original 1x flattener, and I can attest to the fact that I don't see CA in my images like this.  I have been following the new 2nd version of the WO ZS61 and .8x reducer flattener and I have not seen CA in those images either.  My original review thread is still available if you are interested. https://www.cloudyni...utions-welcome/

 

I'm not saying that to brag, but instead to offer it up for informative purposes and comparison. 



#156 premk19

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Posted 06 May 2021 - 03:26 PM

Thanks for this interesting discussion. The big question I think is whether these images are representative of all samples or not.

 

I am a huge fan of WO products, and have been for a while, so probably at least somewhat biased, and am always a bit reluctant to believe marketing claims from most vendors. 

I am also a huge fan of Trevor Jones, as he has produced some very helpful and informative videos.

 

I have the WO ZS61 original (FPL53 doublet) and original 1x flattener, and I can attest to the fact that I don't see CA in my images like this.  I have been following the new 2nd version of the WO ZS61 and .8x reducer flattener and I have not seen CA in those images either.  My original review thread is still available if you are interested. https://www.cloudyni...utions-welcome/

 

I'm not saying that to brag, but instead to offer it up for informative purposes and comparison. 

Totally different scopes, so not a like for like comparison.


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#157 EasyQuest

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Posted 06 May 2021 - 03:54 PM

TSRED279 update:

 

The M54 thread on the 2in scope plug of the reducer is easily adapted to the M63 thread on the scope with the TS adapter with the rotator built in (the TS part "CAA", which I happened to have from another project), so I now have a secure screw fit with rotation. I did a full frame illumination test on my Nikon Z6 and the results are good - there is the vignetting you might expect from a T2 link but it is really only in the deep corners. Vignetting is minimal to the eye on a 24mm x 24mm square let alone DX or APS-C, so this all come down to the radius at which the correction of star shapes deteriorates. Pic of FX flat frame shown. Just need a clear night now. (Any banding on the pic is just jpeg compression artefacts)

If this turns out really nicely with low or no CA. I am going to try this setup on my Radian Raptor 61, which is base on the Sharpstar 61 EDPHII. I will also try my Apex ED-S Reducer on my scope and see if CA is there.


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#158 leemajors

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Posted 06 May 2021 - 04:39 PM

Thanks for this interesting discussion. The big question I think is whether these images are representative of all samples or not.

 

I am a huge fan of WO products, and have been for a while, so probably at least somewhat biased, and am always a bit reluctant to believe marketing claims from most vendors. 

I am also a huge fan of Trevor Jones, as he has produced some very helpful and informative videos.

 

I have the WO ZS61 original (FPL53 doublet) and original 1x flattener, and I can attest to the fact that I don't see CA in my images like this.  I have been following the new 2nd version of the WO ZS61 and .8x reducer flattener and I have not seen CA in those images either.  My original review thread is still available if you are interested. https://www.cloudyni...utions-welcome/

 

I'm not saying that to brag, but instead to offer it up for informative purposes and comparison. 

I tried a zs61 plus my tsred279 reducer prior purchasing the sharpstar, yest it had better colour correction, but i couldnt get round stars into the corners with any combination of reducer flattener or spacing. The sharpstar plus the matched reducer on the other hand gave  me perfectly round stars into the corners but with the blue fringing. Ive also looked at getting a redcat, but after looking at nearly every redcat image on astrobin, they nearly all showed + shaped stars in the corners.

Fringing is fixable with the cls filter but star shapes arent so for the moment im sticking with the sharpstar.



#159 leemajors

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Posted 06 May 2021 - 04:48 PM

If this turns out really nicely with low or no CA. I am going to try this setup on my Radian Raptor 61, which is base on the Sharpstar 61 EDPHII. I will also try my Apex ED-S Reducer on my scope and see if CA is there.

I will be interested to see your results, i tried contributing to the Raptor thread but kept getting getting told the raptor doesnt show fringing, even though i can see it in 9 out of 10 raptor images. Im 99.9% sure they have the exact same optics, numerous sources have confirmed this, yet when i try to explain this i was treated like i was either delusional or trying to run the raptor down. Was then told that mentioning the sharpstar at all was hijacking the thread, so i simply posted a link to this thread then that post was removed along with a PM that it wasnt allowed to link to other threads . No idea whats going on but i was simply trying to help. I may start a new thread about both version of the scope and see how that goes LOL


Edited by leemajors, 06 May 2021 - 04:49 PM.


#160 EasyQuest

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Posted 06 May 2021 - 08:20 PM

I will be interested to see your results, i tried contributing to the Raptor thread but kept getting getting told the raptor doesnt show fringing, even though i can see it in 9 out of 10 raptor images. Im 99.9% sure they have the exact same optics, numerous sources have confirmed this, yet when i try to explain this i was treated like i was either delusional or trying to run the raptor down. Was then told that mentioning the sharpstar at all was hijacking the thread, so i simply posted a link to this thread then that post was removed along with a PM that it wasnt allowed to link to other threads . No idea whats going on but i was simply trying to help. I may start a new thread about both version of the scope and see how that goes LOL

The Radian Raptor 61 has CA for sure, here is M8 and M20 filter-less on a ZWO ASI 2600MC. So it is the same as the Sharpstar 61 EDPHII. I will try again with the Apex ED-S Reducer. Note the photo I edit some of the CA out but it is obvious in the middle of M8.

Attached Thumbnails

  • CN - M8 and M20.jpg

Edited by EasyQuest, 06 May 2021 - 08:21 PM.

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#161 timmbottoni

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Posted 06 May 2021 - 08:55 PM

I tried a zs61 plus my tsred279 reducer prior purchasing the sharpstar, yest it had better colour correction, but i couldnt get round stars into the corners with any combination of reducer flattener or spacing. The sharpstar plus the matched reducer on the other hand gave  me perfectly round stars into the corners but with the blue fringing. Ive also looked at getting a redcat, but after looking at nearly every redcat image on astrobin, they nearly all showed + shaped stars in the corners.

Fringing is fixable with the cls filter but star shapes arent so for the moment im sticking with the sharpstar.

Interesting comparisons.  I get round stars out of both my ZS61 and RedCat51, as well as undetectable CA. I am hardly a expert at astrophotography with my light pollution, and old unmodified Canon 60D.   But I have fun with both.

I think each person has to decide what is important to them and what meets their needs, but my concern is in the marketing of a scope claiming to be Apochromatic when the output of photos indicates that it has way more CA then others in the same category, all classified and sold as APO.   Glad you are pointing out that you recognize that CA is clearly visible, as it lets others know how to evaluate whether it will meet their needs or not. 

 

Clear skies!

 

Timm


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#162 bits

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Posted 06 May 2021 - 09:35 PM

I will be interested to see your results, i tried contributing to the Raptor thread but kept getting getting told the raptor doesnt show fringing, even though i can see it in 9 out of 10 raptor images. Im 99.9% sure they have the exact same optics, numerous sources have confirmed this, yet when i try to explain this i was treated like i was either delusional or trying to run the raptor down. Was then told that mentioning the sharpstar at all was hijacking the thread, so i simply posted a link to this thread then that post was removed along with a PM that it wasnt allowed to link to other threads . No idea whats going on but i was simply trying to help. I may start a new thread about both version of the scope and see how that goes LOL

Lee good sir, that's not what happened at all.

People were just sharing their experiences, which still isn't enough for you.  You are on an undeterred mission here to prove something to yourself.  It's not like the same people aren't in both these threads. 



#163 UKalwayscloudy

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Posted 07 May 2021 - 04:24 AM

https://www.youtube....h?v=jHiGG9a3l84

 

I am not going to comment.



#164 leemajors

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Posted 07 May 2021 - 05:13 PM

Lee good sir, that's not what happened at all.

People were just sharing their experiences, which still isn't enough for you.  You are on an undeterred mission here to prove something to yourself.  It's not like the same people aren't in both these threads. 

The way i see it i was only sharing experiences too, yet my comments get deleted for no reason except i shared a link to this thread, even though people have been sharing to other threads on CN forever. I have no mission as i have no reason do be on one, i dont own the Raptor and no need to buy one as i already own the sharpstar. Of course some of the same people are in both threads, but in this thread there is no opposition to anything ive said and only thanks for doing the tests and research. Yet in the Raptor thread ive been told im wrong several times and that ive miss identified CA in the Raptor images even though the person who said that was a self proclaimed beginner while ive 25 years experience in imaging.

The fact you felt you needed to say im on a mission instantly makes me think you are on a mission too!

now this comment will probably get deleted just for defending myself. 

Back to the subject I have a further test session planned on the next clear night, i plan to test different spacings of the dedicated reducer, as there is a small possibility that the reducer may perform better in regards to colour correction if we diverge from the recommended 55mm, if so this could explain why a couple of raptor and sharpstar owners havent noticed CA while most have. If not then it could be there is some variation in the manufacturing of the reducer. Sharpstar actually told me 6 months ago that they are possibly going to produce and improved version of the reducer that better matches the triplet verion of the scope, as the existing reducer was developed for the MK1 sharpstar doublet. They just then carried it over to the mk2 and the raptor.

lee



#165 leemajors

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Posted 07 May 2021 - 05:23 PM

https://www.youtube....h?v=jHiGG9a3l84

 

I am not going to comment.

Shame they only tested in narrowband, they posted another video last week before they had to return the scope listing their likes and dislikes after 4 months of use. I really like their videos generally but a triplet ought  to be tested in broadband for colour correction as thats the reason people buy triplets, so a real shame they didnt mention colour correction as part of their review. They certainly got an amazing narrowband image or Orion with it though.  
 


Edited by leemajors, 07 May 2021 - 05:25 PM.


#166 TareqPhoto

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Posted 07 May 2021 - 07:23 PM

Shame they only tested in narrowband, they posted another video last week before they had to return the scope listing their likes and dislikes after 4 months of use. I really like their videos generally but a triplet ought  to be tested in broadband for colour correction as thats the reason people buy triplets, so a real shame they didnt mention colour correction as part of their review. They certainly got an amazing narrowband image or Orion with it though.  
 

And i always ask people to show me broadband results either from RGB filters or OSC if they use refractors, so that i can see if it is good enough, and i like if they show with less processing to color correction, otherwise if everything can be corrected by processing then a triplet idea is also useless here.


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#167 UKalwayscloudy

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Posted 13 May 2021 - 10:13 AM

I used about 71.5mm spacing as thats what the TS table seemed to show.

My new spacer arrived and I am at 72mm calibrated to include the effect of a 2.5mm IDAS filter. So just need a clear night now! Daytime test photos look good corner to corner on trees. 



#168 chanrobi

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Posted 09 June 2021 - 10:03 AM

Well thanks.  You know, Trevor has had a pretty long reputation as a reputable astrophotographer so it was hard not to at least give a look at the scope. I'm a veteran in astrophotography and have used 5+ scopes over the years.  In recent years, I have moved more towards a portable setup that I can take with me all over the world in my traveling.  So, this radian seemed to fit in a nice niche for that purpose.  I didn't just blindly buy on hype.  But I expected more from OPT and Trevor.  Alas, that trust was misplaced.  

I respect the guy for making cool videos. However if you look at EVERYTHING he posts, the clickbait titles, and almost complete lack of real information (look at this scope!, this mount! it's good! type reviews).

 

It's clear the objective is just to gain as much popularity to make MONEY. Accurate and informative reviews are obviously not the primary objective of any of his videos. And if it is, it's just a byproduct.

 

Go look at any "review" or article on equipment on his site, it reads like any other spam website when you search for "product xyz review".

It's always, GREAT PRODUCT!! Almost as if it was make from a boilerplate template...



#169 TareqPhoto

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Posted 09 June 2021 - 04:40 PM

I respect the guy for making cool videos. However if you look at EVERYTHING he posts, the clickbait titles, and almost complete lack of real information (look at this scope!, this mount! it's good! type reviews).

 

It's clear the objective is just to gain as much popularity to make MONEY. Accurate and informative reviews are obviously not the primary objective of any of his videos. And if it is, it's just a byproduct.

 

Go look at any "review" or article on equipment on his site, it reads like any other spam website when you search for "product xyz review".

It's always, GREAT PRODUCT!! Almost as if it was make from a boilerplate template...

At the beginning when i was watching him in 2017 i was saying this guy is the one i must follow to learn, but in 2018 suddenly i lost the interest in him completely and i felt his videos turned from reviews and tutoring into promotions and Ads more, so i felt like he is now into getting more likes and more ads for his gain, and i already learnt somewhere else and i have no interest in so many items he is reviewing, but because he became popular at some point i didn't want to point out about his lately approach as many are still watching him and liking his videos, so be it for them and good luck for him.



#170 UKalwayscloudy

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Posted 11 June 2021 - 05:45 AM

Just started to try out the TSRED 279 on the 61EDPHII. I was using the new IDAS NBZ on this occasion so not necessarily a great test of broadband CA, but I was pleased with the results. I will keep testing. 

Attached Thumbnails

  • NGC6992smaller.jpg



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