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

Best way to focus Jupiter?

  • Please log in to reply
5 replies to this topic

#1 REC

REC

    Voyager 1

  • *****
  • topic starter
  • Posts: 11482
  • Joined: 20 Oct 2010
  • Loc: NC

Posted 05 September 2019 - 10:57 AM

Jupiter is a low contrast planet and I find it harder to get the best focus for detail. I find that if I just focus on a moon close by the planet, then that the best it will be to view the entire globe. I find Saturn not as difficult to get the sharpest view. Maybe I should just start on Saturn and then swing over to nearby Jupiter and not touch the focus knob?

 

Lately I have just been using my C102 that has a 10:1 Crayford focuser with the fine focus knob. Using around 100-125x on them.

 

Anyone else have a good method?



#2 scadvice

scadvice

    Apollo

  • *****
  • Vendors
  • Posts: 1368
  • Joined: 20 Feb 2018
  • Loc: Lodi, California

Posted 05 September 2019 - 11:11 AM

I focus on a star field nearby as a starting point then move to the planet.

 

I have a motorized focus which helps as I can note the focus position number and always go back to if I later play with the focus knob or the temperature changes significantly. This allows me to adjust always from the same starting point rather than hunting back and forth. Further, I can note down another or any position I think is focused and still sample around that point without losing these focus references to do comparisons.



#3 Mike G.

Mike G.

    Surveyor 1

  • *****
  • Posts: 1537
  • Joined: 17 Jun 2013
  • Loc: Oberlin, Ohio

Posted 05 September 2019 - 11:17 AM

I do the same thing - use one of Jupiter's moon to get the best focus.  my eyes are quite astigmatic (even with correction) so bright objects like Jupiter always end up flared unless I use a filter (Baader neodymium typically) to dim it down to a reasonable level for my eyes.  Saturn gives some nice aspects to use for fine focus like the Cassini division or just the edge of the rings.  most focusers have a lock screw that you can tighten down after fine focus and just leave it there after you are satisfied you have the best focus for conditions.

 

the Baader filter will also increase contrast on Jupiter's belts - you might want to give it a try.


  • REC and vtornado like this

#4 vtornado

vtornado

    Vanguard

  • *****
  • Posts: 2039
  • Joined: 22 Jan 2016
  • Loc: Northern Illinois

Posted 05 September 2019 - 12:18 PM

I use the moons because I can get them to resolve to tiny disks if I'm in focus.

Sometimes focus goes in an out because of turbulence.

If there are no moons, I use the planet edge and get that as sharp/defined as I can.

 

What kind of mount do you have for your C102?

Do anything you can to stabilize it, so you can focus without jiggling the tube.

Balance it well,

use vibration suppression pads or view from grass/dirt not a driveway or deck

weight reduction you can replace the dew shield with a foam one, don't use a finder, use 1.25 inch, light weight eyepieces. If you have a killer mount, then this is not applicable to you.


Edited by vtornado, 05 September 2019 - 12:25 PM.

  • REC likes this

#5 REC

REC

    Voyager 1

  • *****
  • topic starter
  • Posts: 11482
  • Joined: 20 Oct 2010
  • Loc: NC

Posted 05 September 2019 - 01:34 PM

I do the same thing - use one of Jupiter's moon to get the best focus.  my eyes are quite astigmatic (even with correction) so bright objects like Jupiter always end up flared unless I use a filter (Baader neodymium typically) to dim it down to a reasonable level for my eyes.  Saturn gives some nice aspects to use for fine focus like the Cassini division or just the edge of the rings.  most focusers have a lock screw that you can tighten down after fine focus and just leave it there after you are satisfied you have the best focus for conditions.

 

the Baader filter will also increase contrast on Jupiter's belts - you might want to give it a try.

I do use the Baader filter, it helps on my AR scope. Cassini and ring edge is a good idea too! Then swing over to Jove.



#6 REC

REC

    Voyager 1

  • *****
  • topic starter
  • Posts: 11482
  • Joined: 20 Oct 2010
  • Loc: NC

Posted 05 September 2019 - 01:37 PM

I use the moons because I can get them to resolve to tiny disks if I'm in focus.

Sometimes focus goes in an out because of turbulence.

If there are no moons, I use the planet edge and get that as sharp/defined as I can.

 

What kind of mount do you have for your C102?

Do anything you can to stabilize it, so you can focus without jiggling the tube.

Balance it well,

use vibration suppression pads or view from grass/dirt not a driveway or deck

weight reduction you can replace the dew shield with a foam one, don't use a finder, use 1.25 inch, light weight eyepieces. If you have a killer mount, then this is not applicable to you.

I have a pretty sturdy AZ mount for it. I'll move the scope from the patio to the lawn, forgot about that! I do use a foam dew shield. Extends about 6 inches from the one on it.




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