SteveE
sage
Reged: 12/05/07
Posts: 281
Loc: La Louisiane
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I've become very interested in planetary observing. Jupiter this past season has been a challenge and a lot of fun. I'll be sorry to see it move too far west later in the season. I'm using an Orion XT10 f/4.7 and a C8 f/10. Skies are typically humid and of average seeing. I can't often magnify beyond 120X.
At useful magnifications the views through the XT10 are too bright and the views through the C8 lack the detail that I've seen in the XT10 when I can magnify enough to dim the image. I frequently use them side by side and it is clear to me that the XT10 has the greatest potential. My question is would I be better off with a scope that offers me optimal exit pupils in the range of magnifications I'm more likely to use? The XT10 is too bright from 120X on down. Maybe an 8" f/7 or so would narrow the exit pupils in my useful magnification range and give me the detail I want but without drowning it out with brightness?
So let me know, is my thinking clear here or are there other factors I've not yet learned? Someone mentioned using a mask but it seems to me that I would lose a lot of aperture that way or increase the central obstruction percentage depending on how I mask it. Thanks.
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SteveE
Obsession 18 f/4.5; CPC 1100/Hyperstar/Mallincam; some backyard stuff and binoculars
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brianb11213
Carpal Tunnel
Reged: 02/25/09
Posts: 2076
Loc: 55.215N 6.554W
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If glare is a problem, try a good quality neutral density or Moon filter. A green tinted Moon filter will increase the contrast on Jupiter as well as reducing the glare.
Reducing aperture rarely does any good, in my experience. And, when it is effective, it's because the seeing is so bad that you can see very little detail anyway.
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Sarkikos
Pooh-Bah
Reged: 12/18/07
Posts: 1036
Loc: Suburban Maryland
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Steve,
Whatever you do, don't reduce your aperture. You paid for that aperture, why would you want to reduce it? You reduce the aperture, you reduce resolving power as well as the brightness of the image. What you need to reduce is just the brightness of the image. Yes, use a filter on bright objects like the Moon or Jupiter. Green filters are good for observing the Great Red Spot and bands on Jupiter. Try #58 or #56.
Clear Skies,
Mike
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Celestron 10" f5 Newt on 1stBase (DSO)
Zhumell 8" f6 Newt, Bosma 6" f12 MCT (NSO)
6" f5 Newt, 130ST, 4.5" f4.4 Ball w/GLP, ST80 w/Crayford (RFTs)
C4-R (NSO/DS)
90mm f13 MCT (Luna/DS)
SkyMaster 25x100, 15x70
Zhumell 20x80
Barska XWA 10x50, 8x40
OptiView LPR 10x50
Const View 2.3x40
BV-125C
CG5, 2 drv / CG4, 2 drv, wood legs, ScopeStuff saddle / CG3, 1 drv
SV AZ / 501HDV on Bogen 055XB / P+ on Oberwerk
QuikFinder, Telrad
Orion Dynamo Pro 12, Dew-Not
Have GLP and not afraid to use it!
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cavefrog
sage
Reged: 11/11/08
Posts: 449
Loc: loozyanna
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I vote for using 2 polarizing filters together. just like being used on the moon. tightening one in the eyepiece, and leaving the other loose, one can adjust the amount of light desired by twisting the eyepiece in the focuser. and yes i agree with Mike. do not reduce your aperture, for the same reasons he has stated.
Theo
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I am only an egg
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skyward_eyes
Carpal Tunnel
Reged: 12/12/06
Posts: 2100
Loc: Arizona
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Yes the filters would help. I found the sweet spot for planetary observing is my 16" f/4.5 with Swazye primary. But there are times where I wish I had a filter to tone things down.
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www.skywardeyes.webs.com
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starrancher
professor emeritus
Reged: 06/09/09
Posts: 574
Loc: Northern Arizona
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Filters are the ticket here . I find planets being too bright for my liking & toning down the brightness brings out the surface detail . Stopping down aperture is counterproductive as it stops down resolution . Green is great for Jupiter , Yellow & Blue as well as Green all work good on Saturn . Red is the ticket to Mars . I also use a Dark Red for Venus & Mercury that IMO is better that the Violet so called Venus filter .
Just my  s' worth .
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LXD75 AR5
LXD75 SN8
Series 4000 Plossls
Misc. other stuff
Fort Rock , Az .
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Orthos
member
Reged: 09/11/07
Posts: 12
Loc: Texas
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I was trying to see the GRS last night with my XT10. I had cooled it for over an hour, then collimated with my new Hotech laser collimator. The seeing was average according to cleardarksky.com. While I was very pleased with my image of jupiter, I still couldn't see the GRS even though Stellarium showed the GRS facing us.
I used my Orion polarizing moon filter because it was very bright even at 150X. Still no go on the GRS. I used to have a blue filter but didn't think much of it. Sounds like a green filter may help me.
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Orion XT10 Dobsonian
32mm, 20mm, 8mm Televue Plossls w/Televue Barlow
Hotech laser collimator and cheshire
Oberwerk 11 X 56 binos
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Dean Norris
sage
Reged: 11/05/08
Posts: 423
Loc: Santa Cruz, Ca
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I've been using an apodizing mask on my 10" newt with good results. The mask is easy to make,and is inexpensive as well. I have found that it improves contrast on Jupiter, Mars and Venus. Here's a photo of mine.
Steady Skies, Dean
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1971 10" Cave Newtonian F/6
MoonLite CR Focuser Telrad Finder 8x50 finder
TV 40mm, 32, 20, 7.4, Meade 6mm, UO 5mm, Meade 2x Barlow
7x50 Binoculars
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Thierrys
journeyman
Reged: 11/08/08
Posts: 32
Loc: Mru, Indian Ocean
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Quote:
I still couldn't see the GRS even though Stellarium showed the GRS facing us.
Stellarium isn't accurate at showing the GRS position.
Use the Sky and Telescope website instead.
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5" Meade ETX-125
Coronado PST
10x50 Nikon Action Extreme
10x50 Nikon Action
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starrancher
professor emeritus
Reged: 06/09/09
Posts: 574
Loc: Northern Arizona
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Thierry's is correct as Stellarium is not accurate for the red Spot rotation . It is pretty darn accurate for the Jovian Moon rotation & reliable there but not for the Red Spot .
Red spot was at meridian last night at about 8:30 PST .
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LXD75 AR5
LXD75 SN8
Series 4000 Plossls
Misc. other stuff
Fort Rock , Az .
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Orthos
member
Reged: 09/11/07
Posts: 12
Loc: Texas
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That explains it. It wasn't visible when I was looking last night. I'm thinking about getting Skytools 3. Is that accurate for Jupiter? Thanks for the info.
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Orion XT10 Dobsonian
32mm, 20mm, 8mm Televue Plossls w/Televue Barlow
Hotech laser collimator and cheshire
Oberwerk 11 X 56 binos
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SteveE
sage
Reged: 12/05/07
Posts: 281
Loc: La Louisiane
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Orthos, try the freeware app "Jupiter 2." I've found it to be reliable the several times I've used it. It has a couple of other features you might be interested in.
I'll try the variable polarizing filter tonight. I've used it before and haven't been satisfied but I have to admit that I'm not patient in taking the time to seat the eyepiece, view, unseat it, adjust, reseat it, etc.. The last time I tried I didn't like the color it gave. I love it for the moon, not for Jupiter. I'll try again.
Thanks for all your responses. I guess this means that none of you think a more "planetary" dob would make a difference such as an 8" f/7 as I mentioned before? Off axis in the XT10 on Jupiter is not impressive for me so far. I'm wondering if on-axis isn't as sharp as it could be as well and whether a slower scope couldn't handle that.
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SteveE
Obsession 18 f/4.5; CPC 1100/Hyperstar/Mallincam; some backyard stuff and binoculars
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SteveE
sage
Reged: 12/05/07
Posts: 281
Loc: La Louisiane
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Quote:
If glare is a problem, try a good quality neutral density or Moon filter.
Brian, could you suggest a quality filter manufacturer?
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SteveE
Obsession 18 f/4.5; CPC 1100/Hyperstar/Mallincam; some backyard stuff and binoculars
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starrancher
professor emeritus
Reged: 06/09/09
Posts: 574
Loc: Northern Arizona
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I just print out the GRS transit schedule for the year off S & T . It is always at hand with the rest of my gear & at a glance , I know when the transit is . 
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LXD75 AR5
LXD75 SN8
Series 4000 Plossls
Misc. other stuff
Fort Rock , Az .
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SteveE
sage
Reged: 12/05/07
Posts: 281
Loc: La Louisiane
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...And Orthos, I wasn't trying to steer you away from Skytools! I have it and it's a great program! Here's a quote from ST3 for tonight concerning Jupiter:
"Look for the Great Red Spot until about 19:50, when it will exit on the western limb. Also look for Europa to emerge from Jupiter's shadow at 20:16 and Callisto in transit from 18:01 to 22:47."
Times are CST. The freeware app "Jupiter 2" will map the GRS for you and give you more specific, minute-to-minute information.
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SteveE
Obsession 18 f/4.5; CPC 1100/Hyperstar/Mallincam; some backyard stuff and binoculars
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Sarkikos
Pooh-Bah
Reged: 12/18/07
Posts: 1036
Loc: Suburban Maryland
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I use Planet Vistas to track what Jupiter, the other planets, and the Moon are up to. It is s free download from skyhound.com. You can install Planet Vistas as your computer background. It is not good for planning, but it's great for grab-n-go observation opportunities. Now it's telling me that the GRS is about to disappear around the side of Jupiter.
By the way, one problem with trying to see the Great Red Spot, is that it is no longer Great nor Red, though it's still a Spot. It should be renamed the NSGPS: the Not So Great Pink Spot. Often it is easier to locate by looking for a brighter or darker ring around it, especially where it juts into the SEB (South Equatorial Belt).
Mike
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Celestron 10" f5 Newt on 1stBase (DSO)
Zhumell 8" f6 Newt, Bosma 6" f12 MCT (NSO)
6" f5 Newt, 130ST, 4.5" f4.4 Ball w/GLP, ST80 w/Crayford (RFTs)
C4-R (NSO/DS)
90mm f13 MCT (Luna/DS)
SkyMaster 25x100, 15x70
Zhumell 20x80
Barska XWA 10x50, 8x40
OptiView LPR 10x50
Const View 2.3x40
BV-125C
CG5, 2 drv / CG4, 2 drv, wood legs, ScopeStuff saddle / CG3, 1 drv
SV AZ / 501HDV on Bogen 055XB / P+ on Oberwerk
QuikFinder, Telrad
Orion Dynamo Pro 12, Dew-Not
Have GLP and not afraid to use it!
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starrancher
professor emeritus
Reged: 06/09/09
Posts: 574
Loc: Northern Arizona
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Funny , I viewed the most awesome Red Spot transit just a couple months ago . Although it does come & go in the depth of its' color & intensity great views can still be had as IMO good seeing has more to do with it . The dark barge in the Red Spots' wake this year is a very noticeable feature .
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LXD75 AR5
LXD75 SN8
Series 4000 Plossls
Misc. other stuff
Fort Rock , Az .
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brianb11213
Carpal Tunnel
Reged: 02/25/09
Posts: 2076
Loc: 55.215N 6.554W
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Quote:
could you suggest a quality filter manufacturer?
Baader are good value; Astronomik & Astrodon (in increasing quality). Generic Chinese filters are better avoided unless you can try before you buy.
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rookie
scholastic sledgehammer
Reged: 01/14/06
Posts: 873
Loc: St. Petersburg, FL
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Steve,
I've tried several filters for viewing Jupiter. I have the wheel of colored filters from Orion, but never liked any of them. By far, the best one for me has been the SkyGlow filter. It brings out much more contrast in the bands and adds definition to the GRS.
Sometimes this topic comes up in CN and I never read about another person using the SkyGlow filter for that purpose. Don't know if it's just something people don't consider or if it's my particular preference. I'd like to hear the opinions of others.
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SV
Scope: Celestron CPC8
Binoculars: Garrett GT80~45, Fujinon 16x70, Regals 10x42, Ultima 9x63, Nikon AE 8x40
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starrancher
professor emeritus
Reged: 06/09/09
Posts: 574
Loc: Northern Arizona
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Quote:
Steve,
I've tried several filters for viewing Jupiter. I have the wheel of colored filters from Orion, but never liked any of them. By far, the best one for me has been the SkyGlow filter. It brings out much more contrast in the bands and adds definition to the GRS.
Sometimes this topic comes up in CN and I never read about another person using the SkyGlow filter for that purpose. Don't know if it's just something people don't consider or if it's my particular preference. I'd like to hear the opinions of others.
An observing buddy of mine has the Lumicon deep sky filter (broadband) , pretty much a Sky Glow (broadband) & it is also his favorite filter for Jupiter . I have viewed Jupiter several times through his Celestron C6 SCT with this filter & do agree that it works very nicely for Jupiter . This I have also read in articles & I believe one by David K. regarding this filter .
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LXD75 AR5
LXD75 SN8
Series 4000 Plossls
Misc. other stuff
Fort Rock , Az .
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