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

ED APO 127mm f/7,5 FCD-100 vs APM 140 SD?

  • Please log in to reply
11 replies to this topic

#1 fedele

fedele

    Messenger

  • -----
  • topic starter
  • Posts: 400
  • Joined: 07 Jan 2021

Posted 07 December 2021 - 03:35 AM

everything  you think about

 

thanks



#2 MT4

MT4

    Apollo

  • *****
  • Posts: 1,109
  • Joined: 05 Jun 2021
  • Loc: Tokyo, JP

Posted 07 December 2021 - 03:41 AM

I've very recently had to make a similar decision and eventually decided to go with the APM 140:

https://www.cloudyni...tics-125mm-f78/


  • Jon_Doh and 25585 like this

#3 25585

25585

    James Webb Space Telescope

  • *****
  • Posts: 15,316
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the SW UK. 51°N

Posted 07 December 2021 - 12:39 PM

everything  you think about

 

thanks

What is your current scope & mount?



#4 DeanD

DeanD

    Viking 1

  • *****
  • Posts: 591
  • Joined: 05 May 2018
  • Loc: South Australia

Posted 07 December 2021 - 06:36 PM

Size does matter if you are looking to get maximum brightness and detail in DSO's, but all three of those scopes will give excellent views with minimal CA. If you are thinking of imaging then there are many other factors to take into account: the main one I suspect being a photography adequate mount, which would need to be able to cope with roughly twice the weight of the scope and equipment and which could easily cost more than any of those scopes.

 

For general viewing I would look to the 140, while being aware of the potential difficulties for carrying and mounting a large scope (although you can get away with a less capable mount if it is just for viewing).

 

All the best,

 

Dean



#5 Jeffmar

Jeffmar

    Surveyor 1

  • -----
  • Posts: 1,646
  • Joined: 18 Mar 2012
  • Loc: salt lake city, utah

Posted 07 December 2021 - 09:49 PM

If your mount isn’t as robust as you would like consider the Explore Scientific ED127 carbon fiber. I think it’s about 5 pounds less than the same scope in aluminum. I don’t know how much the APM weighs but I would guess it is more than the regular ES ED127. I am very happy with the performance of my ED127 scope. It is light, has no false color, works incredibly well for astrophotography, and it isn’t a bad visual scope. I have it on a heavy mount so I can even image in light to moderate winds. 

 

I replaced the focuser with a Starlight brand unit. The stock focuser worked fine but it had barely two inches of travel and I had to screw on and off spacers to go from visual to photo mode. 


Edited by Jeffmar, 07 December 2021 - 09:52 PM.

  • Castor likes this

#6 junomike

junomike

    ISS

  • *****
  • Administrators
  • Posts: 22,012
  • Joined: 07 Sep 2009
  • Loc: Ontario

Posted 11 December 2021 - 10:25 AM

I'd expect the ES 127 to be a little better CA corrected, however this may not be as critical to some as the extra 13mm Aperture.....And Visa-Versa...



#7 thesubwaypusher

thesubwaypusher

    Apollo

  • *****
  • Posts: 1,120
  • Joined: 08 Jul 2004
  • Loc: New York City

Posted 11 December 2021 - 12:59 PM

Hi:

 

Obviously from the picture, I have enjoyed both the Esprit 150 and the APM simultaneously, so I was able to compare them directly. You are not interested in the 150, so I will only say that I really liked the 140 for its contrast- disliked it for its imperfect field and slight CA, and ultimately kept the Esprit, which was perfect in those areas. The 3.7" focuser on the 140 was a dream. Not a Feather Touch, but still excellent.

 

The ES 127ED FCD100:

 

The (upgraded) focuser on the ES is nothing like the unit on the APM, but still quite good.

 

The 13mm difference would not be perceptible enough to notice, BUT that disparity may be noted when coupled with the one less element on the 140, determined by your skies.

 

***Depending on your level of experience, your tolerance for false color and an imperfect field (as far as progressive flatness off the center axis) is what may make the difference. The ES is very impressive in these areas. It is more geared, I discovered almost immediately, to satiate the more experienced eye.

 

Lastly, if you care about esthetics, or how striking the two telescopes look in person, I would say they are even.

 

Good luck on your decision,

 

Chris

 

 

Attached Thumbnails

  • 1.jpg

  • Castor likes this

#8 Tank

Tank

    Skylab

  • *****
  • Posts: 4,397
  • Joined: 27 Jul 2009
  • Loc: Stoney Creek, Ontario, CANADA

Posted 11 December 2021 - 06:39 PM

Both are food scopes
127 will be better CA corrected
127 will be lighter

140 will go deeper
140 will cool down faster

My vote go for aperture unless you cant handle it
  • Jon_Doh likes this

#9 fred1871

fred1871

    Surveyor 1

  • -----
  • Posts: 1,973
  • Joined: 22 Mar 2009
  • Loc: Australia

Posted 11 December 2021 - 09:40 PM

@thesubwaypusher - is the "imperfect field" only the "progressive [lack of] flatness off the center axis"?

 

Apart from (presumably slight) CA, is the curvature of field the full extent of the problem, or are there other issues as well? Thanks for any further information.



#10 thesubwaypusher

thesubwaypusher

    Apollo

  • *****
  • Posts: 1,120
  • Joined: 08 Jul 2004
  • Loc: New York City

Posted 11 December 2021 - 10:18 PM

@thesubwaypusher - is the "imperfect field" only the "progressive [lack of] flatness off the center axis"?

 

Apart from (presumably slight) CA, is the curvature of field the full extent of the problem, or are there other issues as well? Thanks for any further information.

 

Hi Fred-

 

That's why they push a field flattener with that scope which I am sure works great. But the logic there then becomes, Why not just buy a triplet to begin with? I only recall that issue, which would be expected with a doublet. I would have dealt with it if I didn't find the Esprit in Astromart when I got home from purchasing the 140. Because the view in the APM is excellent. For a while. But once you get something better and do your own little shootout, it's all over for the loser. Unless you wish to take size and weight into consideration to negate the results of the comparison.

 

Yes, slight color. 

 

Chris


Edited by thesubwaypusher, 11 December 2021 - 10:22 PM.


#11 MT4

MT4

    Apollo

  • *****
  • Posts: 1,109
  • Joined: 05 Jun 2021
  • Loc: Tokyo, JP

Posted 11 December 2021 - 11:43 PM

OP has gone very quiet.  Wondering if a decision has been reached.



#12 thesubwaypusher

thesubwaypusher

    Apollo

  • *****
  • Posts: 1,120
  • Joined: 08 Jul 2004
  • Loc: New York City

Posted 12 December 2021 - 04:26 AM

Forgot about him!




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