Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Sharpstar 61 EDPH II APO Chromatic Abberation?

  • Please log in to reply
117 replies to this topic

#26 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 7,042
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 11 October 2020 - 02:38 PM

About 60 exposures, 1 minute, unguided, unmodded DSLR Canon 800D.

 

no filters.



#27 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 7,042
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 11 October 2020 - 02:43 PM

This is a jpg , one the the 60, untouched and higly enlarged.(i Always take RAW + JPG)

 

The photo above is stacked off course, but the jpg here is(cut out of a brighter star) untouched and comes straight from the camera.

Attached Thumbnails

  • 61edph.JPG

Edited by F.Meiresonne, 11 October 2020 - 03:04 PM.

  • j.gardavsky likes this

#28 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 7,042
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 11 October 2020 - 02:53 PM

I finally had the opportunity to setup everything and start testing the go-to, which seems to work relatively well. However, my photos of the Pleiades have these purple halos around them and I can't help but wonder if I got a dud scope, or if it really matters and I can edit this out and correct at a later point. I posted here because I want to know if this is specifically a fault with the telescope and I do not have any eye pieces to just pop into the scope to check myself.

This is just a 30 second exposure and it seems to be visible in other stars, not red ones or orange ones, but blue ones specifically.

Very disturbing picture. I don't think it should look like this...see my picture of M35, made by the doublet version of this scope. IMO something is not right with the scope...



#29 mmalik

mmalik

    DSLR camera modifications

  • *****
  • Vendors
  • Posts: 11,855
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 11 October 2020 - 04:37 PM

See below a picture taken with the doublet version...

Let's be clear; doublet version of what? I presume it is not Sharpstar 61 EDPH II; if not then let's not confuse the matter. Regards


Edited by mmalik, 11 October 2020 - 04:38 PM.


#30 Barologuy

Barologuy

    Vostok 1

  • -----
  • topic starter
  • Posts: 101
  • Joined: 28 Jul 2020

Posted 11 October 2020 - 05:49 PM

I messaged Sharpstar and I'm waiting to hear back. I'll keep you updated!

#31 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 7,042
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 12 October 2020 - 12:59 AM

Let's be clear; doublet version of what? I presume it is not Sharpstar 61 EDPH II; if not then let's not confuse the matter. Regards

No it is the sharpstar 61 mm EDPH version 1. A doublet. Only very recently Sharpstar came out with a triplet version. Same FF/FR, same F, same outfit

 

That is why I cannot understand the doublet seems to give better views that the triplet here. You should expect just the opposite.


Edited by F.Meiresonne, 12 October 2020 - 01:01 AM.

  • leviathan likes this

#32 mmalik

mmalik

    DSLR camera modifications

  • *****
  • Vendors
  • Posts: 11,855
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 12 October 2020 - 01:18 AM

Thanks for clarifying; I didn't know. Regardless, they are two different sopes/designs. Agree with your assessment though. Regards


Edited by mmalik, 12 October 2020 - 01:33 AM.


#33 anat

anat

    iAstroHub 3

  • *****
  • Vendors
  • Posts: 1,112
  • Joined: 03 Jun 2004

Posted 16 October 2020 - 08:02 PM

I messaged Sharpstar and I'm waiting to hear back. I'll keep you updated!

Any words from Sharpstar on this issue?

Sent from my SM-N960F using Tapatalk
  • SwissCheese likes this

#34 Barologuy

Barologuy

    Vostok 1

  • -----
  • topic starter
  • Posts: 101
  • Joined: 28 Jul 2020

Posted 16 October 2020 - 09:39 PM

No word from Sharpstar.

It could be related to the fact that I have a larger scope mounted on top of that may be causing the lens problems, but when I stack them generally the purple rings go away and it seems to go away as the weather chills down.

Not sure what that means though.

#35 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 7,042
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 17 October 2020 - 09:00 AM

How do you focus?



#36 Barologuy

Barologuy

    Vostok 1

  • -----
  • topic starter
  • Posts: 101
  • Joined: 28 Jul 2020

Posted 17 October 2020 - 09:28 AM

How do you focus?



Typically I have a DSLR connected and then I focus as best as possible using camera features, then I place a Bahtinov mask over the OTA to make the final adjustments, usually while on max camera "zoom" on the image.

And I refocus when I slew to a new object.

#37 andysea

andysea

    Aurora

  • *****
  • Posts: 4,686
  • Joined: 03 Sep 2010
  • Loc: Seattle, WA

Posted 17 October 2020 - 06:48 PM

I agree with what others have said. It looks like CA.  I might have missed it but did you try the same target without the focal reducer?

That would be the first step to troubleshoot the system. You will get field curvature but that is expected without a corrector.

Make sure that you have some of the bright stars in the center of the image.



#38 Barologuy

Barologuy

    Vostok 1

  • -----
  • topic starter
  • Posts: 101
  • Joined: 28 Jul 2020

Posted 18 October 2020 - 01:28 AM

I agree with what others have said. It looks like CA. I might have missed it but did you try the same target without the focal reducer?
That would be the first step to troubleshoot the system. You will get field curvature but that is expected without a corrector.
Make sure that you have some of the bright stars in the center of the image.


I did not try it without a focal reducer, I'll update this next time I have clear skies. Lots of smoke right now, the Colorado fires are about 5 miles from my house!

#39 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 7,042
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 18 October 2020 - 05:03 AM

I agree with what others have said. It looks like CA.  I might have missed it but did you try the same target without the focal reducer?

That would be the first step to troubleshoot the system. You will get field curvature but that is expected without a corrector.

Make sure that you have some of the bright stars in the center of the image.

That would be indeed a good test

 

Or shoot the moon, when she is bright, to see i you get purple or yellow rims....


Edited by F.Meiresonne, 18 October 2020 - 05:05 AM.


#40 alphatripleplus

alphatripleplus

    World Controller

  • *****
  • Moderators
  • Posts: 121,748
  • Joined: 09 Mar 2012
  • Loc: Georgia

Posted 18 October 2020 - 10:10 AM

Stay safe with those fires nearby! I am also curious  to see what the results are without the reducer.



#41 byang

byang

    Lift Off

  • -----
  • Posts: 13
  • Joined: 13 Jun 2014
  • Loc: Singapore

Posted 24 October 2020 - 10:21 PM

No word from Sharpstar.

It could be related to the fact that I have a larger scope mounted on top of that may be causing the lens problems, but when I stack them generally the purple rings go away and it seems to go away as the weather chills down.

Not sure what that means though.

It is almost 2 weeks. Have u gotten a reply from Sharpstar?



#42 Barologuy

Barologuy

    Vostok 1

  • -----
  • topic starter
  • Posts: 101
  • Joined: 28 Jul 2020

Posted 24 October 2020 - 11:37 PM

It is almost 2 weeks. Have u gotten a reply from Sharpstar?


I have still not gotten a reply from Sharpstar regarding the CA.

I'll also note that viewing without the Reducer and Flattener, and removing all other equipment made no difference, the stars are still purple.

Edited by Barologuy, 24 October 2020 - 11:39 PM.


#43 byang

byang

    Lift Off

  • -----
  • Posts: 13
  • Joined: 13 Jun 2014
  • Loc: Singapore

Posted 25 October 2020 - 08:36 PM

I have still not gotten a reply from Sharpstar regarding the CA.

I'll also note that viewing without the Reducer and Flattener, and removing all other equipment made no difference, the stars are still purple.

Thanks for the update. Do u mean that the same was observed when the scope was used for visual?

 

I have gotten same day response from Sharpstar when I sent them an enquiry in July: sales@sharpstar-optics.com. Was it the same email that u sent to? You may want to email them again and ask if they have received your earlier email and are studying the problem, and to provide a date where you may possibly hear from them on the outcome. Giving them the serial number of your scope or QC report may also be useful for the investigation at their end. Just a suggestion :-)



#44 Barologuy

Barologuy

    Vostok 1

  • -----
  • topic starter
  • Posts: 101
  • Joined: 28 Jul 2020

Posted 26 October 2020 - 11:53 PM

Thanks for the update. Do u mean that the same was observed when the scope was used for visual?

 

I have gotten same day response from Sharpstar when I sent them an enquiry in July: sales@sharpstar-optics.com. Was it the same email that u sent to? You may want to email them again and ask if they have received your earlier email and are studying the problem, and to provide a date where you may possibly hear from them on the outcome. Giving them the serial number of your scope or QC report may also be useful for the investigation at their end. Just a suggestion :-)

I am reaching out through my vendor and I will hopefully know more later this week.



#45 leemajors

leemajors

    Sputnik

  • -----
  • Posts: 44
  • Joined: 11 Feb 2013

Posted 18 November 2020 - 10:25 PM

This is very helpful thread, I purchased the sharpstar EDPH II last week and coincidentally my first light image was also of M45.

Although the stars were nice and round into the corners of the frame I was very disappointed to see large amounts of blu/purple fringing on the brightest stars, considering I purchased specifically as it is a triplet. I was Using an Idas LP2 filter which has built in UV/IR cut & also tried a standard Baader UV/IR filter. some form of UV?ir filter is a must with all refractors, but neither of these seemed to help

On further test tonight I decided to remove the reducer and found the fringing was almost completely absent and quite satisfactory, put the reducer back on and the fringing was back.Ive just sent Sharpstar a FB message, they normally have replied to me the same day in the past.

I wonder if they upgraded the reducer at same time as they switched the scope from goblet to Triplet, or if its the same one used for both. it arrived in a separate box so its possible our reducer came from older batch than the scope?

Ive found a work around solution is to image through an Astronomik CLS ccd filter which has  a very strong blue cut built in ( it blocks all blue light below 450nm) I consider this a hack though as I used to use that with cheap doublets, didn't expect to need it with a triplet.

Here are some example images.

Attached Thumbnails

  • Screenshot 2020-11-19 at 02.34.53 copy.jpg
  • Screenshot 2020-11-17 at 13.34.51 copy.jpg


#46 anat

anat

    iAstroHub 3

  • *****
  • Vendors
  • Posts: 1,112
  • Joined: 03 Jun 2004

Posted 19 November 2020 - 12:54 AM

I had the similar color fringing with my 61 edph II + ASI533mc + Astrodon L filter. 



#47 leemajors

leemajors

    Sputnik

  • -----
  • Posts: 44
  • Joined: 11 Feb 2013

Posted 19 November 2020 - 04:26 AM

yes I saw on the previous page, what did you do about it?

 

Lee


  • anat likes this

#48 Barologuy

Barologuy

    Vostok 1

  • -----
  • topic starter
  • Posts: 101
  • Joined: 28 Jul 2020

Posted 19 November 2020 - 01:54 PM

So, my experience has been... Absentee. I reached out to Sharpstar (Twice) and didn't hear back about the CA. I called my dealer, and emailed the dealer the photos explaining the situation after they stated they would forward them on to the owner of the company, if I remember correctly. That was on October 26. I called them again on November 2, and got no answer regarding it. The "forwarded" email hadn't even been sent.

I'm going to call them again next week, but overall I'm just going to deal with the CA and purchase a refractor with better optics some time in the future.

It's just disappointing to deal with it at all at the magnitude it is, being that it's a triplet.

I enjoy the images I've processed, but if I had to review the scope based solely on the CA, I'd say save your money and get something with more product support and a good track record. It's a good scope but it seems like after me being on here a couple months now, some people get good ones, others get duds. It's removable, sure. Will it make me buy a different 61mm or similar? Nope. I just think there needs to be less chromatic abberation surrounding the terms "triplet" or "Apochromatic".

There shouldn't be any, especially with an uncropped, non pixel peeping image.

Just my opinion.

Edited by Barologuy, 19 November 2020 - 01:55 PM.


#49 leemajors

leemajors

    Sputnik

  • -----
  • Posts: 44
  • Joined: 11 Feb 2013

Posted 20 November 2020 - 05:08 AM

Sharpstar always reply to me on FB within a few mins depending o the time of day with the time difference.

I sent them my findings and linked to this thread, though they just said thank you, and if not happy return to the dealer.

Lee



#50 KenChiangMai

KenChiangMai

    Lift Off

  • -----
  • Posts: 3
  • Joined: 22 Nov 2020

Posted 22 November 2020 - 01:30 PM

So, my experience has been... Absentee. I reached out to Sharpstar (Twice) and didn't hear back about the CA. I called my dealer, and emailed the dealer the photos explaining the situation after they stated they would forward them on to the owner of the company, if I remember correctly. That was on October 26. I called them again on November 2, and got no answer regarding it. The "forwarded" email hadn't even been sent.

I'm going to call them again next week, but overall I'm just going to deal with the CA and purchase a refractor with better optics some time in the future.

It's just disappointing to deal with it at all at the magnitude it is, being that it's a triplet.

I enjoy the images I've processed, but if I had to review the scope based solely on the CA, I'd say save your money and get something with more product support and a good track record. It's a good scope but it seems like after me being on here a couple months now, some people get good ones, others get duds. It's removable, sure. Will it make me buy a different 61mm or similar? Nope. I just think there needs to be less chromatic abberation surrounding the terms "triplet" or "Apochromatic".

There shouldn't be any, especially with an uncropped, non pixel peeping image.

Just my opinion.

It might be best to try contacting them on facebook. They are visible to all on that platform, and if they don't reply, that would be noted by all who read the post.

 

I've been strongly considering purchase of the 61EDPH II, and I must say that at this point, you've pretty much talked me out of it. I futs around with a Tamron 70-300 zoom on a Sony a7r ii. It's a pretty nice lens, though not perfect, and especially since there's no field flattener. Not fast at all, at f/6.3 at 300mm. The thing is, looking at the pics here and reading all the comments, I'm not seeing the 61EDPH II as being much of an upgrade, if at all. Sure... Your edges might be better/flatter, but I can live with just the center. :) Better, perhaps, to spend less money on actually purchasing PixInsight. After all, I will never be a pro at this stuff, whatever "pro" might mean.

 

Thank you.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics