Getting the best out of Jupiter with a large Newtonian

[Mr Spock]

When you hear people say they can't see detail, or colours, on Jupiter, it's usually because the planet is too bright. All that brightness washes everything away. This is especially true of large Newtonians like my 12".

The refractor is fine. At only 100mm the image isn't that bright. In fact, it could do with being a bit brighter. Except with Venus. That is really bright so I use a variable polariser to get the brightness where I want it!

I do the same with the 12" on Jupiter. But aren't variable polarisers fiddly? After all, they are fitted to the nosepiece of the eyepiece and so are down in the draw tube where you cant reach. Easy in a refractor, you just put one piece of the polariser on the diagonal and the other on the eyepiece. Then it's as simple as rotating the eyepiece until you get the right brightness.

For my 12" Newtonian, which doesn't need a diagonal, I have a different solution. Thankfully my LVW eyepieces are dual fit 1.25" and 2". In 2" they need a 35mm extension tube to reach focus as they reach deeper into the draw tube than they do with a 2" to 1.25" adapter. This means I can attach one part of a 2"  polariser to the extension tube, and one part of a 1.25" polariser to the eyepiece.

Here's what I mean:

Here's what they look like together:

For a scope the size of a 12", once you have the brightness turned down a little, Jupiter offers up a wealth of detail - and colour. The GRS last night for example, was a lovely rich salmon pink colour. Very easy to see, with the separation between the GRS and the belt a clean crisp white. There was even a hint of darkness in the GRS' centre. The 100mm was pretty good, but somehow that gap looked a bit 'dirty' and the GRS was greyish-red.

 

 

[Ratlet]

I use this method with my Dob, but with a 1.25" sized eyepiece.  The 2" Polariser screws onto the 2" to 1.25" Reducer.  I bought a 1.25" Variable polariser filer and a 2" Polarising filter to keep costs down an flexibility high.

I say it every time filters and planets come up, but I also stack a yellow and "Moon & Skyglow" filter for planetary.  I find it cuts the brightness and helps me distinguish the colours a bit better at the cost of a yellow cast on the view.  Works well on Jupiter/Saturn/Mars (I find it gives an Voyager era feel to the view).  I don't find it palatable at all on the moon though.

But Mr Spock's tips for the VPF turned it from a permanent drawer dweller into an indispensable part of my kit.

[Mr Spock]

For Venus I add in a #47 violet filter. It brings out cloud detail.

[RobertI]

Interesting post, I was recently viewing Jupiter in the C8 with BVs and thought that more, or at least different detail was apparent when thin clouds rolled across, so perhaps a VPF might help and also reveal more colour.

Edit: actually do you need a VPF if you are using a diagonal, doesn’t the diagonal polarise the light so you only need one polarising filter?

Edited December 29, 2024 by RobertI

[great white]

Nice idea, although I don’t think my 2” adapter is threaded. 
 

I’ll have to check it out….

[PeterStudz]

This is a brilliant tip-tip that I don’t know about! 

Interesting…  I can use the 1.25” extension tube on my SkyWatcher 200p Dob (these focusers need one) to do this as it has a filter thread too. That means I only need the one filter, although the eyepiece sticks up a bit it shouldn’t mater for the convenience. 

Edited December 29, 2024 by PeterStudz

[Tiny Clanger]

1 hour ago, great white said:

Nice idea, although I don’t think my 2” adapter is threaded. 
 

My 250p Skyliner's adaptor is not threaded for filters, I checked when I bought it, but as the 'scope is second hand it might not be standard issue.

[great white]

31 minutes ago, Tiny Clanger said:

My 250p Skyliner's adaptor is not threaded for filters, I checked when I bought it, but as the 'scope is second hand it might not be standard issue.

Just checked the included 2" adapter with the Skywathcher 10" dob.

Threaded!

Sources are kind of limited around here, so amazon turned up a 2" polarizer to give it a try.

"LUŽID Brass 2" Variable Polarizing Eyepiece"

Supposedly schott glass, brass rings.

It will be good enough for my uses.

Will be nice to have a variable polarizer without having to remove the eyepiece all the time.

 

 

[SCANS]

Brilliant idea! Thanks for this tip 😀

[Paz]

This is a good point. As well as straight ahead dimming, I'll use colour filters to dim the view as well as filtering to a colour, and larger apertures allow more possibilities with this.

[SCANS]

Turns out that my Baader double polarizer doesn't come apart. I suppose that's a good thing, but my idea of simply adding a 1.25" single will actually require a 2" single as well. Not a big deal, but glad I did a bit of research before forcing my double to separate.

[Ed in UK]

Funnily enough this is an idea that I've had in mind for a couple of weeks after reading others saying that they saw more detail in Jupiter if viewed through a thin cloud layer.

The polarizer idea popped into my head and I did give it a try last night. As already mentioned, it is a bit fiddley but it did knock down the light and reveal Jupiter in a more comfortable viewing light.

Need to work on it a little as I found the polarizer kept misting up every time I handled it. Hands too warm....🤣

Thanks for the guidance, every little helps. 🙂

[great white]

My 2” polarizer showed up today. I excitedly grabbed the case holding my lenses, filters, adapters etc and pulled out the 2” barrel.

Tried to thread in the 2” polarizer and was just gutted. They’re both 2”, but the polarized ring diameter is just a bit to big to even fit in the threaded end of the adapter:

 

Just one of the perils of fitting parts from different manufacturers. I start thinking about possibly turning the polarizer ring down in the lathe, maybe taping the polarizer to the barrel and about the return process to send it back. Turning the barrel over in my hands I notice it has a small land at its base:

 

hmmm, could I be that lucky? I try and drop one part of the 2” polarizer into the 2” barrel and:

 

Genius! It drops right in place! Sits there nice and square.

Now I can put in the 1.25” adapter:

 

and turn the 1.25” eyepiece to vary the polarization.

Theres always a solution to every problem. You just have to find it….:)

Edited January 7 by great white

[Jim Franklin]

@Mr Spock

Michael, nice posts and useful, I have often used a Moon filter with Jupiter when I use the LX200 12" and a pollution filter with the LX90 8" to dampen down the brightness to get detail, I have never been sure these were the best solutions but they sort of nworked. I have a variable polarising filter that runs from ND0 to ND8 so I think I may give that a go, theoretically, it should tune to give the best of both world. 

[JOC]

I've got a polariser for Tammy (600mm camera lens).  I wonder how much detail I'd see through just the camera on it's tripod.  IIRC apparent 'magnification is FL mm/apperture mm 

Canon website says Aperture is expressed in f-stops. Confusingly, the f-number is not the actual size of the aperture, but has an inverse relationship to it:          aperture diameter = focal length (f) divided by f-number

it hits F 6.3 at 600mm

So apperture must be 600/6.3 = 95mm

So that gives me 600/95 = Only approx 6.3x magnification which is a little disappointing to blow things up enough to see things like moons and GRS.  Perhaps that explains why I've always dropped the camera into the focusser and messed about taking afocal photos.

[Ratlet]

A bit of weirdness.  I've tried this a couple times with the 102ED with my 2" SV223 diagonal and was gifted some of the worst views I've ever hard of Jupiter and Mars.  Truly awful.  It was like it had a combination of astigmatism and a colour cast, going from yellow to blue as you swept round the polariser. Setup was the 2" Polariser on the diagonal nose and the 1.25" on the eyepiece.

Did some testing today and it turns out, at least with this particular diagonal that it just doesn't work.  I held the filters ahead and behind the digonal and looked through by eye and sure enough, as soon as you introduce the diagonal the image goes to wonk.  It doesn't even fully dim.  Remove the digonal and it works as intended.

I've solved the issue by fitting the 2" filter to the 2" to 1.25" reducer (I added a spacer as well, the SV215 zoom is long and I have a fear of double stacking a filter and forgetting to remove the 2" filter.

Not sure if anyone else has had a similar issue or can enlighten me as to why this happens?  Might be something to do with the mirror being dielectric coating?

[IB20]

Had the 8” out from about 4pm today and by the time I came to use it, it had formed a slight condensate on the mirror. Gave some of the best views of Jupiter I’ve ever had with a reflector. 😅

Completely removed the diffraction spikes which distract my eye no end. For the first time I could see huge amounts of detail in both colour and bands/zones. 

It was horrible to look through on the moon however. 

[Mr Spock]

15 minutes ago, IB20 said:

Completely removed the diffraction spikes which distract my eye no end.

Thanks to the polariser I don't see them at all. For a long time I couldn't figure out what people were talking about as I couldn't see them!