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Mak vs refractor observe Jupiter

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#26 Matt Looby

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Posted 05 July 2021 - 03:12 PM

Mak vs frac for planets...

 

The issue here is chromatic aberration at play.  Looking at your signature, smiles233, you will not be gaining anything by getting a refractor that your Maks, or your 8SE for that matter, are not already providing you.  If anything you will be introducing chromatic aberration unless you start looking at ED refractors to help control this, and this means much bigger $$$.  An achromatic refractor will be a significant step backwards from your current scopes because of this aspect.

 

And on a Voyager 2 mount, a 4" refractor will begin to test your patience as it will start wobbling every time you touch it - a 4" refractor at high magnification on such a mount is not a great combination.  While you have a 100mm Mak, its smaller, more compact size means less moment issues are at play compared to a long tube.

 

I certainly understand your frustration with poor seeing conditions.  I have the same problem where I live.  And like you I have a variety of telescopes.  Larger apertures are more affected by poor seeing - something you may already be aware of (I am assuming because of your question).  In all honesty, the only two  things I can recommend to you:

 

1,  Patience.  I know it is not much, but there is nothing more you can do.  A different scope won't help you.

2,  Adapt your viewing.  If seeing conditions are not much chop, then you need to adapt to the conditions.  If you can't max out the magnification then your only option is to drop the magnification.

 

My preferred scope at home is a 9" Mak, and for many years before that it was a C8 (like your 8SE).  And being plagued with poor seeing I have no choice but to adapt my planed session to suit the conditions.  OK, I can't max out the magnification, then the only two options I have are either drop the magnification and work with that or pack up.  I do have an ED80 refractor that I could use instead, and it is a nice scope, but I don't use it all that much.  And if I had a smaller Mak or SCT I wouldn't use it any more than I do the refractor.  And an ED80 still shows a small amount of chromatic aberration that my 9" Mak doesn't.

 

Most nights I pull out the Mak (or the C8), the most I can push it to is around 250X, and I am happy to work with that when it comes to the Moon and planets.  If seeing doesn't allow for 100X I will normally do something else.  The smaller scopes I have I use for other applications.

 

When it comes to the planets, aperture is the only route.  You already have that with your 8SE.  You already know the differences between your 8SE and your smaller Maks.  A refractor is not going to help you if seeing is the problem.

 

What a shorter focal length refractor will do is provide you with a rich field scope if you look at an f/5 instrument.  A 4" f/5 or 5" f/5 frac with a nice 2" 30mm eyepiece will provide you with a delightful situation that will very nicely compliment the high magnification beasties you already have.  I LOVE my modest 4" f/5 achromat - a stonking good RFT smile.gif  I know its high magnification shortcomings, so I use it to its strengths waytogo.gif  I keep the magnification right down with this scope, and with an 80° 30mm eyepiece this little scope gives me a 5° true field of view - HUGE!!!  It cost me little and it is a low magnification monster!

 

The sketch below is of the Eta Carina complex that I did with this modest 4" f/5 achro - a view none of my other scopes can provide!

 

Alex.

 

 

Question, did you render the lunar formations  entirely at the eyepiece?

Really you are able to draw DSOs like that at the eyepiece? Your are are quit capableble to render the limb like nobody

I have ever run across.  Interesting thanks for sharing.

 

Matt



#27 maroubra_boy

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Posted 05 July 2021 - 04:39 PM

Question, did you render the lunar formations  entirely at the eyepiece?

Really you are able to draw DSOs like that at the eyepiece? Your are are quit capableble to render the limb like nobody

I have ever run across.  Interesting thanks for sharing.

 

Matt

Hi Matt,

 

Q1,  Yes.  Here is a little video of me doing one of my sketches at the eyepiece, the whole two hour process in 2minutes 45 seconds:

 

https://www.youtube....GUhlvYb8vc&t=7s

 

Q2,  Yes.  Here is a second video, this time done by a friend of mine during the Queensland Astrofest where there were a couple of hundred people as my witness laugh.gif  If you look closely you will even see a meteor flash between the flagpole and tree beside it at the 21 second mark:

 

https://www.youtube....h?v=i13Goy7_7-U

 

The differences between the two is I use a dim orange light to do my DSO sketches, but a brilliant white head lamp for the Moon - there is no dark adaptation with the Moon...  And the technique for DSO's is a very subtle one, where I am effectively dry painting, using brushes to apply soft pastel dust, but with the Moon while I am using the exact same soft pastels, their application is a brutal one - there is nothing subtle about the Moon lol.gif  It is not uncommon for me to go through a whole soft pastel pencil with a sketch of the Moon.  

 

Alex.

Attached Thumbnails

  • Sketch mosaic.jpg

Edited by maroubra_boy, 05 July 2021 - 04:46 PM.

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#28 nibiru711

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Posted 05 July 2021 - 05:40 PM

There were patchy clouds last night but at 2:30 am I had my 127mm maksutov out observing Jupiter for about 20 minutes and it look so much better than previous views with it. I figure it needs Jupiter to be higher up in the sky in order to look good. I could see up to six bands at times plus a couple of festoons plus the whiter features look better than with my dobsonians although I didn't use either one last night. Later on around 4 am I took my orion 70mm refractor out to look at the planets. It look better than ever on Juipter and Saturn. I could see 4 bands at times on Jupiter and on Saturn I could see the upper cloud band be a darker color than bottom with 7mm celestron ex cel ed. Although it didn't get rid of the chromatic abberation with the ed 7mm it did help out with it on Jupiter and Saturn. It appears that ed glass eyepieces do help with the chromatic aberation with achromats but it doesn't get rid of it totally.



#29 Matt Looby

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Posted 06 July 2021 - 12:41 AM

Hi Matt,

 

Q1,  Yes.  Here is a little video of me doing one of my sketches at the eyepiece, the whole two hour process in 2minutes 45 seconds:

 

https://www.youtube....GUhlvYb8vc&t=7s

 

Q2,  Yes.  Here is a second video, this time done by a friend of mine during the Queensland Astrofest where there were a couple of hundred people as my witness laugh.gif  If you look closely you will even see a meteor flash between the flagpole and tree beside it at the 21 second mark:

 

https://www.youtube....h?v=i13Goy7_7-U

 

The differences between the two is I use a dim orange light to do my DSO sketches, but a brilliant white head lamp for the Moon - there is no dark adaptation with the Moon...  And the technique for DSO's is a very subtle one, where I am effectively dry painting, using brushes to apply soft pastel dust, but with the Moon while I am using the exact same soft pastels, their application is a brutal one - there is nothing subtle about the Moon lol.gif  It is not uncommon for me to go through a whole soft pastel pencil with a sketch of the Moon.  

 

Alex.

Thanks Alex, I shall watch your vids.  

Attached Thumbnails

  • med_gallery_922_3553_1407435886_3106.jpg

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#30 luxo II

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Posted 16 July 2021 - 10:25 PM

Question, did you render the lunar formations  entirely at the eyepiece?

Matt yes he does, Alex is quite a fine astro artist. He's also pretty versatile when it comes to being prepared to work with what the seeing allows, and choosing a scope accordingly.



#31 REC

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Posted 18 July 2021 - 02:57 PM

I recently sold my XT8 when I upgraded to a 12" Dob.

 

I just added an Astro Tech 102ED which I use on an Explore Scientific TW1 mount which  I believe is similar to the voyager mount. 

https://www.astronom...ractor-ota.html

https://www.astronom...1.html?___SID=U

 

bottom line is that aperture wins.  My best views of planets were with my 8" Dob and now my 12" Dob.  My 5" Mak does a good job but the Dobs blow it away.  

 

I expect the new 4" ED refractor will be similar to the 5" Mak.  I have not tried this new, less than 3 weeks old, scope on a planet yet. 

Ed, you sure have built up a nice array of scopes in such a short time! Good for you. The AT 102 is a winner and you should think next about adding a binoviewer to your collection. I have found that they are superb for moon and planets. May to be found in the used depeartment. First choice would be a used DenkII with a power switch. I have the WO BV around $200 with 2 EP's and a 1.6x barlow. Many to choose from under $200 used.



#32 nibiru711

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Posted 19 July 2021 - 06:42 PM

I got a used Orion poro prism diagonal to use on both the 127mm maksutov and 70mm refractor and it helped out with brightness and clarity.


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