Focusing on Jupiter

[Ger]

Hi all

After been woken by some New Years revellers I decided to take out my telescope and to take a look at Jupiter. Having picked up Jupiter this morning and a couple of days ago I was looking to see if someone can let me know based on my telescope what my expectations should be. I am using a Skywatcher Skyhawk 1145p along with. 25mm, 10mm and a 2 x Barlow.

I have been using the 10mm but Jupiter is currently not to dissimilar to a nice star, and no I have not mistaken a star for Jupiter. I am looking forward to been able to getting some good experience under my belt when the moon is visible but it the meantime I was wondering what tips people might be able to provide,

 

thank you

 

Ger 

[cloudsweeper]

Jupiter is unmistakable - a clear disc, larger than a star, with at least two cloud belts visible (probably grey).  The other strong clue is that its Galilean moons are often in evidence right by it - sometimes four, sometimes fewer - and very often in a straight line with Jupiter itself.  Seeing the moons as sharp points of light is a good guide to being in focus when looking at the planet.   

Start at your lowest mag (x20), then increase it to your max (x100).  The view might get a little "fuzzier" at the higher end, depending on conditions.  Magnification isn't everything - sharp, pleasing views are often seen at low mag.

Doug.

 

[ronin]

Jupiter will never be big, none of the planets are, we however expect them to be.

I think your scope is 1000mm focal length, if I recall it is sort of long and thin - which is good. If it is not long and thin then say so as that could be the problem.

Find Jupiter with the 25mm which gives 40x, then try the 10mm which gives 100x. Problem here is the scope is a starter one and 100x is getting towards the max it will or should deliver easily. Going to suggest you try the 25mm and the barlow - do not expect great things but at 80x it might be better overall. The barlow and the 10mm eyepiece are genarally not great.

If neither the 10mm or the barlow+25mm work then it is likely going to be go buy (borrow) a 12mm plossl. I have no idea where in the Dublin area you could get one.

Jupiter is OK down at 60x, so 80x with a 12mm (single or combination) should be usable if the result is fairly sharp. You want sharp not necessarily big. I have seen Jupiter well at 40x in a small achro refractor, then looked at it through a 14" SCT under what I would describe as identical conditions on consequitive nights. The 14" view was awful. So do not get the idea that more is better.

[Ger]

43 minutes ago, cloudsweeper said:

Jupiter is unmistakable - a clear disc, larger than a star, with at least two cloud belts visible (probably grey).  The other strong clue is that its Galilean moons are often in evidence right by it - sometimes four, sometimes fewer - and very often in a straight line with Jupiter itself.  Seeing the moons as sharp points of light is a good guide to being in focus when looking at the planet.   

Start at your lowest mag (x20), then increase it to your max (x100).  The view might get a little "fuzzier" at the higher end, depending on conditions.  Magnification isn't everything - sharp, pleasing views are often seen at low mag.

Doug.

 

thank you very much Doug 

[Ger]

8 minutes ago, ronin said:

Jupiter will never be big, none of the planets are, we however expect them to be.

I think your scope is 1000mm focal length, if I recall it is sort of long and thin - which is good. If it is not long and thin then say so as that could be the problem.

Find Jupiter with the 25mm which gives 40x, then try the 10mm which gives 100x. Problem here is the scope is a starter one and 100x is getting towards the max it will or should deliver easily. Going to suggest you try the 25mm and the barlow - do not expect great things but at 80x it might be better overall. The barlow and the 10mm eyepiece are genarally not great.

If neither the 10mm or the barlow+25mm work then it is likely going to be go buy (borrow) a 12mm plossl. I have no idea where in the Dublin area you could get one.

Jupiter is OK down at 60x, so 80x with a 12mm (single or combination) should be usable if the result is fairly sharp. You want sharp not necessarily big. I have seen Jupiter well at 40x in a small achro refractor, then looked at it through a 14" SCT under what I would describe as identical conditions on consequitive nights. The 14" view was awful. So do not get the idea that more is better.

thank you ronin 

[ronin]

Problem is getting to be that the manufacturers give out 2 eyepieces and they are reducing the quality of them. Used to be 2 plossl's, then then dropped to 2 MA's now it is Huygens and Ramsdens. I am sure one day it will be a small positive singlet in them. Galileo used a small negative singlet.

I keep thinking that is they supplied say a 15mm plossl and just one reasonable item then people would be happier. However if they did that then eventually they go back to supplying a single MA then a single Huygen/Ramsden. All in the purpsoe of saving them money.

Even the kits are doing that now, they used to be a kit of 4 plossl's, I notice now that there is often one plossl then it is Huygens.

Have seen it said but oddly you can expect to end up with a collection of eyepieces for a scope that are close to the cost of the scope. 5 plossl's at say £25 each come to £125. If you get/have a better scope then you tend to think of beter eyepieces are greater individual cost.

I always find this one about right:

http://bigtelescope.blogspot.co.uk/2015/02/christmas-and-telescopes-how-to-avoid.html

Another is this site for similar:

http://www.deepskywatch.com/Articles/what-can-i-see-through-telescope.html

Is your scope sort of long and thin ?? BAsically is the tube about 800-900mm long ??

[Ger]

hi Ronin. thank you again for all the info. the focal length is actually only 500 mm. Will this affect the type of eyepiece I should consider

[John]

1 hour ago, Ger said:

hi Ronin. thank you again for all the info. the focal length is actually only 500 mm. Will this affect the type of eyepiece I should consider

If you use the 2x barlow lens with the 10mm eyepiece you will get 100x magnification which will show Jupiter quite nicely with your scope. Planets are never going to appear large in the eyepiece to be honest, not even the mighty Jupiter.

[Charic]

.........Just woken and took the scope out! Did it cool properly?
Is it collimated and Star tested to ensure the airy disk/rings are concentric.
Were you bleary eyed from sleep?
Were the seeing  conditions sufficient for observation.
Are you expecting too much from the scope?

I owned a not too dissimilar telescope, the Celestron 127EQ and the images of Jupiter were not spectacular, in-fact the 127EQ was not spectacular for anything except the Moon or terrestrial observations!

My present scope provides so much more, on just about everything, it even shows Jupiters surface detail, but conditions must be perfect, and when they are, Jupiter is stunning.
I live under the jetstream up here (feels like it!) hence all the s... weather I get, but there are many times where I just wish Jupiter could have better focus, yet the scope is ok, its setup to the best I can manage, no! its not the scope,  the issue is  down to the seeing and turbulence above me. The only real issue I  have with this scope, and is still on the back burner for upgrading, my image of Jupiter is still small, I wish it was twice the size, but upgrading seems to be the answer, but with that comes additional problems, so still  mulling things over!

Go back to basics, check and double check you scope is properly setup, ensure the conditions are good and try again. Always start with the longest focal length eyepiece, slowly working up to the shortest focal length which  provides a satisfactory image, any longer in focal length may reduce the image quality you expect! There's more to it than just jumping  say from a 12mm to a 6mm, its not just a doubling of power, but contrast, resolution, field are all affected one way or another.

Earths Moon will look fine through your scope, in-fact the Moon should look stunning, but expect somewhat less when looking further towards the Planets. 

[Ger]

57 minutes ago, Charic said:

.........Just woken and took the scope out! Did it cool properly?
Is it collimated and Star tested to ensure the airy disk/rings are concentric.
Were you bleary eyed from sleep?
Were the seeing  conditions sufficient for observation.
Are you expecting too much from the scope?

I owned a not too dissimilar telescope, the Celestron 127EQ and the images of Jupiter were not spectacular, in-fact the 127EQ was not spectacular for anything except the Moon or terrestrial observations!

My present scope provides so much more, on just about everything, it even shows Jupiters surface detail, but conditions must be perfect, and when they are, Jupiter is stunning.
I live under the jetstream up here (feels like it!) hence all the s... weather I get, but there are many times where I just wish Jupiter could have better focus, yet the scope is ok, its setup to the best I can manage, no! its not the scope,  the issue is  down to the seeing and turbulence above me. The only real issue I  have with this scope, and is still on the back burner for upgrading, my image of Jupiter is still small, I wish it was twice the size, but upgrading seems to be the answer, but with that comes additional problems, so still  mulling things over!

Go back to basics, check and double check you scope is properly setup, ensure the conditions are good and try again. Always start with the longest focal length eyepiece, slowly working up to the shortest focal length which  provides a satisfactory image, any longer in focal length may reduce the image quality you expect! There's more to it than just jumping  say from a 12mm to a 6mm, its not just a doubling of power, but contrast, resolution, field are all affected one way or another.

Earths Moon will look fine through your scope, in-fact the Moon should look stunning, but expect somewhat less when looking further towards the Planets. 

Thanks for the detailed reply. All the conditions were good including been in the garden for some time, however I think there is a small issue with my set up that needs more time ( and patience ) on my part.

[Charic]

Just keep at it, It  takes time, understanding and a little experience.