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

New telescope: Bresser Messier AR-102 f/4.5

  • Please log in to reply
297 replies to this topic

#76 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 07 May 2017 - 01:47 AM

 

 

Interesting although when I chose "Canada" as my location, the website added the appropriate shipping cost but didn't subtract the VAT?

 

Mike

You have to click to continue on with the checkout after that. It will then update to the non-VAT price.

 

Hi.

 

Has yours been delivered yet?

 

Me? No I haven't ordered it. I want to, but I don't have the luxury of even throwing a couple hundred dollars around willy nilly. I wish. That is, not unless I don't go with my other planned scope upgrade at this time.



#77 rogeriomagellan

rogeriomagellan

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,814
  • Joined: 13 Oct 2016

Posted 07 May 2017 - 09:52 AM

 

 

 

Interesting although when I chose "Canada" as my location, the website added the appropriate shipping cost but didn't subtract the VAT?

 

Mike

You have to click to continue on with the checkout after that. It will then update to the non-VAT price.

 

Hi.

 

Has yours been delivered yet?

 

Me? No I haven't ordered it. I want to, but I don't have the luxury of even throwing a couple hundred dollars around willy nilly. I wish. That is, not unless I don't go with my other planned scope upgrade at this time.

 

Oh, I see. Have you managed to take a look at the raw picture of M13 available on the AR-102XS web page yet?

 

https://www.bresser....tical-Tube.html


Edited by rogeriomagellan, 07 May 2017 - 09:53 AM.


#78 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 07 May 2017 - 10:56 AM

Yeah I saw it.



#79 junomike

junomike

    Hubble

  • *****
  • Moderators
  • Posts: 19,511
  • Joined: 07 Sep 2009
  • Loc: Ontario

Posted 07 May 2017 - 03:40 PM

Yeah I saw it.

I just viewed it also.  I'm no Imager but the FC seems to star just out from M13 itself.

The CA on the other hand isnt' too bad although I wouldn't expect it to be on such a dim target.

 

Mike



#80 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 07 May 2017 - 06:36 PM

I actually find the coma much more noticeable in that image than any CA. I don't really any CA actually.



#81 Astrojensen

Astrojensen

    Voyager 1

  • *****
  • Posts: 13,260
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 08 May 2017 - 02:19 AM

I actually find the coma much more noticeable in that image than any CA. I don't really any CA actually.

It's not coma, it's a combination of off-axis astigmatism and field curvature. The scope was deliberately used without a flattener, to assess its "raw" performance. 

 

 

Clear skies!

Thomas, Denmark


  • paul and rogeriomagellan like this

#82 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 08 May 2017 - 11:16 AM

I though field curvature had to do with things on the outer edge not coming into focus? I guess I wouldn't really know, the only only scope I've ever looking through is my long-ish achro, which has little to none of either. *shrug* Still, if that's the scope's actual colour correction, then I think it's actually pretty **** good.


Edited by Gofr, 08 May 2017 - 11:16 AM.


#83 Peter Besenbruch

Peter Besenbruch

    Fly Me to the Moon

  • *****
  • Posts: 7,318
  • Joined: 21 Aug 2014
  • Loc: Oahu

Posted 08 May 2017 - 01:01 PM

I though field curvature had to do with things on the outer edge not coming into focus?

Not exactly. You can focus the edge of the field when dealing with field curvature, but the center goes out of focus when you do. If you can't focus the edge at all, you are dealing with other issues, like edge astigmatism.


  • Sarkikos likes this

#84 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 08 May 2017 - 01:56 PM

 

I though field curvature had to do with things on the outer edge not coming into focus?

Not exactly. You can focus the edge of the field when dealing with field curvature, but the center goes out of focus when you do. If you can't focus the edge at all, you are dealing with other issues, like edge astigmatism.

 

 

Ah yes, I was aware of that. I wasn't quite clear. My point is it looked like coma since the stars at the edge had trails and I've only ever heard of such a phenomena occurring with coma. My only scope being a longer achro, coma and FC haven't been issues I've seen myself and is easy to mistake for other aberrations, as that picture shows. Still, I think it's overall pretty good and I still want one. I need to email TS if they're gonna have any in stock soon. They usually have better prices than astro market, and with my tanking Canadian dollar, need every bit of savings I can get.



#85 T1R2

T1R2

    Mercury-Atlas

  • -----
  • Posts: 2,922
  • Joined: 11 Jun 2013
  • Loc: NeverWhere, 35*N

Posted 08 May 2017 - 03:42 PM

I dont think coma is inherent to refractors, the lenses and air spacing take care of that, I think I just read that recently somewhere.its easy to misjudge astigmatism for coma, but they are different



#86 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 08 May 2017 - 04:28 PM

I dont think coma is inherent to refractors, the lenses and air spacing take care of that, I think I just read that recently somewhere.its easy to misjudge astigmatism for coma, but they are different


That's right, which is why I found it extra odd.

Anyway, the CA looks to be well controlled in their sample shot. I wonder if that's the ED at work or some sort of post processing that was done on the image. An earlier review seemed to suggest it was no better than a pure achromat.
  • T1R2 likes this

#87 rogeriomagellan

rogeriomagellan

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,814
  • Joined: 13 Oct 2016

Posted 08 May 2017 - 07:48 PM

 

I dont think coma is inherent to refractors, the lenses and air spacing take care of that, I think I just read that recently somewhere.its easy to misjudge astigmatism for coma, but they are different


That's right, which is why I found it extra odd.

Anyway, the CA looks to be well controlled in their sample shot. I wonder if that's the ED at work or some sort of post processing that was done on the image. An earlier review seemed to suggest it was no better than a pure achromat.

 

As far as I know, there was no post processing.



#88 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 08 May 2017 - 08:26 PM


I dont think coma is inherent to refractors, the lenses and air spacing take care of that, I think I just read that recently somewhere.its easy to misjudge astigmatism for coma, but they are different

That's right, which is why I found it extra odd.

Anyway, the CA looks to be well controlled in their sample shot. I wonder if that's the ED at work or some sort of post processing that was done on the image. An earlier review seemed to suggest it was no better than a pure achromat.
As far as I know, there was no post processing.

That's actually pretty good if that's a raw photo.

#89 Astrojensen

Astrojensen

    Voyager 1

  • *****
  • Posts: 13,260
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 09 May 2017 - 12:09 AM

It IS a raw photo!! Post processing was left out on purpose, to show what you can do with this scope with no experience in image processing, no field flattener, etc. Just the scope, mount and camera.

 

 

Clear skies!

Thomas, Denmark


  • T1R2, Gofr and rogeriomagellan like this

#90 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 09 May 2017 - 12:35 AM

Well if that is a raw photo, then I think it seems to be a pretty fantastic setup. I'm really gonna have to mull this one over.


  • rogeriomagellan likes this

#91 T1R2

T1R2

    Mercury-Atlas

  • -----
  • Posts: 2,922
  • Joined: 11 Jun 2013
  • Loc: NeverWhere, 35*N

Posted 09 May 2017 - 01:07 AM

yep, I may have to add this scope to my ever growing list of "I wants"


  • rogeriomagellan likes this

#92 Mitrovarr

Mitrovarr

    Gemini

  • -----
  • Posts: 3,045
  • Joined: 12 Sep 2004
  • Loc: Boise, Idaho

Posted 09 May 2017 - 01:22 AM

That's pretty cool. I'm impressed by the lack of CA in that image. Hopefully the CA correction is better than that earlier report (that said it was about on par with a regular F/5 achro) suggested.

 

It obviously needs a field flattener for photography, but so would anything in that aperture and speed.



#93 marcus_z

marcus_z

    Messenger

  • -----
  • Posts: 402
  • Joined: 02 Jan 2016
  • Loc: SE Germany

Posted 09 May 2017 - 01:57 AM

That's pretty cool. I'm impressed by the lack of CA in that image. Hopefully the CA correction is better than that earlier report (that said it was about on par with a regular F/5 achro) suggested.

 

It obviously needs a field flattener for photography, but so would anything in that aperture and speed.

That picture can be delusive because it lacks bright stars. It gets interesting when something like M45 is in the picture. Also note the Galaxy in the background that can be barely noticed in this 30+ min exposure.



#94 rogeriomagellan

rogeriomagellan

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,814
  • Joined: 13 Oct 2016

Posted 09 May 2017 - 07:57 AM

 

That's pretty cool. I'm impressed by the lack of CA in that image. Hopefully the CA correction is better than that earlier report (that said it was about on par with a regular F/5 achro) suggested.

 

It obviously needs a field flattener for photography, but so would anything in that aperture and speed.

That picture can be delusive because it lacks bright stars. It gets interesting when something like M45 is in the picture. Also note the Galaxy in the background that can be barely noticed in this 30+ min exposure.

 

For only visual use, I guess that people can be surprised. A little sharper view with eyepieces?



#95 coopman

coopman

    Fly Me to the Moon

  • *****
  • Posts: 6,502
  • Joined: 23 Apr 2006
  • Loc: South Louisiana

Posted 10 May 2017 - 07:50 PM

Is purple a color choice for the OTA?

#96 rogeriomagellan

rogeriomagellan

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,814
  • Joined: 13 Oct 2016

Posted 10 May 2017 - 09:54 PM

 

That's pretty cool. I'm impressed by the lack of CA in that image. Hopefully the CA correction is better than that earlier report (that said it was about on par with a regular F/5 achro) suggested.

 

It obviously needs a field flattener for photography, but so would anything in that aperture and speed.

That picture can be delusive because it lacks bright stars. It gets interesting when something like M45 is in the picture. Also note the Galaxy in the background that can be barely noticed in this 30+ min exposure.

 

Hi, Marcus.

 

M45 would be a very nice target. Last week I got in touch with the guy who took that picture and I urged him to take one of M31. I hope that a few others are posted pretty soon there.



#97 jring

jring

    Messenger

  • -----
  • Posts: 458
  • Joined: 23 Sep 2016

Posted 11 May 2017 - 11:15 AM

That's pretty cool. I'm impressed by the lack of CA in that image. Hopefully the CA correction is better than that earlier report (that said it was about on par with a regular F/5 achro) suggested.

Hi,

 

the german forum thread has developed a bit - Tommy Nawratil has taken his example apart, found an adjustable but plastic lens mount and ground down a spacer a bit to remove some SA...

 

before:

 

http://forum.astrono...alt#Post1281736

 

after:

 

http://forum.astrono...alt#Post1282069

 

and then measured the secondary spectrum for the 102/460 and an SW 102/500.

 

http://forum.astrono...alt#Post1282390

 

As can be seen the result is comparable to the f5 FH and Gerd Duering did some rough doublet designs for FK61 and cheap CGEM partner glasses - all were better by a huge margin.

 

http://forum.astrono...alt#Post1282398

 

Here is the values for some existing refractors, achros and apos alike...

 

http://forum.astrono...alt#Post1283036

 

Everybody has to draw their own conclusions from this - but I would not buy the scope for the ED glass but rather for as a 4" richfield FH with a nice focusser.

 

Joachim


  • Sarkikos likes this

#98 rogeriomagellan

rogeriomagellan

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,814
  • Joined: 13 Oct 2016

Posted 11 May 2017 - 11:30 AM

 

That's pretty cool. I'm impressed by the lack of CA in that image. Hopefully the CA correction is better than that earlier report (that said it was about on par with a regular F/5 achro) suggested.

Hi,

 

the german forum thread has developed a bit - Tommy Nawratil has taken his example apart, found an adjustable but plastic lens mount and ground down a spacer a bit to remove some SA...

 

before:

 

http://forum.astrono...alt#Post1281736

 

after:

 

http://forum.astrono...alt#Post1282069

 

and then measured the secondary spectrum for the 102/460 and an SW 102/500.

 

http://forum.astrono...alt#Post1282390

 

As can be seen the result is comparable to the f5 FH and Gerd Duering did some rough doublet designs for FK61 and cheap CGEM partner glasses - all were better by a huge margin.

 

http://forum.astrono...alt#Post1282398

 

Here is the values for some existing refractors, achros and apos alike...

 

http://forum.astrono...alt#Post1283036

 

Everybody has to draw their own conclusions from this - but I would not buy the scope for the ED glass but rather for as a 4" richfield FH with a nice focusser.

 

Joachim

 

Hi, Joachim.

 

In your post above, you wrote:

 

"Tommy Nawratil has taken his example apart, found an adjustable but plastic lens mount and ground down a spacer a bit to remove some SA".

 

Coud you tell me what SA stands for?



#99 Gofr

Gofr

    Viking 1

  • -----
  • Posts: 531
  • Joined: 01 Aug 2016
  • Loc: Canada

Posted 11 May 2017 - 02:25 PM

 

 

That's pretty cool. I'm impressed by the lack of CA in that image. Hopefully the CA correction is better than that earlier report (that said it was about on par with a regular F/5 achro) suggested.

Hi,

 

the german forum thread has developed a bit - Tommy Nawratil has taken his example apart, found an adjustable but plastic lens mount and ground down a spacer a bit to remove some SA...

 

before:

 

http://forum.astrono...alt#Post1281736

 

after:

 

http://forum.astrono...alt#Post1282069

 

and then measured the secondary spectrum for the 102/460 and an SW 102/500.

 

http://forum.astrono...alt#Post1282390

 

As can be seen the result is comparable to the f5 FH and Gerd Duering did some rough doublet designs for FK61 and cheap CGEM partner glasses - all were better by a huge margin.

 

http://forum.astrono...alt#Post1282398

 

Here is the values for some existing refractors, achros and apos alike...

 

http://forum.astrono...alt#Post1283036

 

Everybody has to draw their own conclusions from this - but I would not buy the scope for the ED glass but rather for as a 4" richfield FH with a nice focusser.

 

Joachim

 

Hi, Joachim.

 

In your post above, you wrote:

 

"Tommy Nawratil has taken his example apart, found an adjustable but plastic lens mount and ground down a spacer a bit to remove some SA".

 

Coud you tell me what SA stands for?

 

Spherical Aberration



#100 Vondragonnoggin

Vondragonnoggin

    Cosmos

  • *****
  • Posts: 8,619
  • Joined: 21 Feb 2010
  • Loc: Southern CA, USA

Posted 11 May 2017 - 02:40 PM

Just saw this thread - want!

 

this would be perfect as an in between my 120ST and AT72ED and F/4.5 would be awesome for my Night Vision eyepieces. Wonder if Markus can get this to me? 

 

Not listed on APM website yet.


Edited by Vondragonnoggin, 11 May 2017 - 02:44 PM.

  • Sarkikos likes this


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