Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Reflectors

Pages: 1 | 2 | 3 | 4 | (show all)
Jeff Morgan
Postmaster
*****

Reged: 09/28/03

Loc: Prescott, AZ
Re: Planet scope decision new [Re: Gray]
      #5618730 - 01/12/13 10:14 AM

Quote:

Jeff, that is an excellent observation and yes the planets do not reach zenith at my location, more like what you guessed, at most 75 degrees. I do have a badder mpcc and an at ff as coma correctors, but have only used the badder yet with good results. With the truss design I would need a tracking platform and I do not wish to go that route at this time. I was looking around and if I actually wanted a 6" F8 newt, I would have to buy an Orion dob and put rings on it for around $300. I'm not sure I want to do that, but it is an option. Looking at a set of rotating rings, they will run me $450 for an 8" set. I've never used any before and wonder if they are worth it. I'm thinking my 8" should be tested out first, then flocked, fanned, and maybe a new spider with a set of Parallax rings. This is off topic but I would also like a instrument on a alt/az mount for comet scanning. I'm thinking either a 10" dob or a set of big bino's on a good mount, also need a good chair. Plant scope is almost concluded here with me. Thanks again Jeff!




I didn't know your exact latitude, so it was kind of a WAG. It doesn't matter whether it is 70, 75, or 80 degrees though. The planet only hits that elevation for 1-2 hours per 24 hours and due to diurnal and seasonal motion that will likely occur when you are not able to look (like during the day!) And even then Worst Case it is quite close to standing eyeball height for the average person. To make that a limiting factor in your scope selection doesn't make a lot of sense.

OTOH, comet sweeping is whole different animal where the shorter Newt would serve you better by virtue of covering more square degrees. It's a productivity thing, not an optical thing. Not to dash your hopes, but in this day and age automated searches discover most things like comets. But then again, you could be the one ....

Tracking is worthwhile. With patience you might score some deals on the used market. But consider that you need rings, the eq mount, and a balance rail. I think you would be hard-pressed to accomplish all of this for less than $1000 - the cost of a new Tom Osypowski Compact platform. True it will add 6-8" in height to whatever you place on it, but it is a very easy piece of equipment to live with. Years ago I wrote a review on it which you will find here. And getting back to the whole zenith thing, an equatorial platform does help alleviate some of the clumsiness associated with Dobson's Hole.

Edited by Jeff Morgan (01/12/13 10:34 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gray
scholastic sledgehammer
*****

Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Jeff Morgan]
      #5619157 - 01/12/13 02:16 PM

Sorry Jon, I had to goto bed, it was ~6am here on the east coast. I use a GSO laser type, that came with my old Z12. It seems to be aligned, I haven't tried barlowing it though. Maybe I should get a better tool? I've read that pro's do use Howie's tools. Do you think that a set of rotating rings would be worth the expenditure for me? I'm sure you've probably used them before.

Jeff, I gather from your writings that an EQ platform mounted Dob is the way to go for planet viewing. So my question is, do you think the 8" F9 truss dob would be a better scope for viewing than my 8"F5? That setup would run me $2k new with shipping and above and beyond what I would want to spend. But, it never hurts to know as much as possible in that realm. I think I should keep my spider after reading some on curved spiders, but fan and flock for sure. What do you folks think of buying a 6"F8 dob from Orion? I have a set of rings already. I would like to have a long focus newt but I am unsure if the difference between F5 & F6 would be really noticeable.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Planet scope decision new [Re: Gray]
      #5619395 - 01/12/13 04:32 PM

Quote:


Sorry Jon, I had to goto bed, it was ~6am here on the east coast. I use a GSO laser type, that came with my old Z12. It seems to be aligned, I haven't tried barlowing it though. Maybe I should get a better tool? I've read that pro's do use Howie's tools. Do you think that a set of rotating rings would be worth the expenditure for me? I'm sure you've probably used them before.




Graham:

Have you actually tested your collimator by rotating it in the focuser and watching the dot on the primary mirror? Just about every collimtor that came with a Dob I have ever seen is badly out of collimation.

As far as rotating rings, my 12.5 inch came with them. I bought a set of Antares ball bearing rings for my 8 inch F/5, they worked but they were heavy and quite frankly, ugly...

So, with a little time, a few tools and an extra ring, I did some grinding, replaced the felt on the stock rings with bondable Teflon, added some Teflon to take the thrust. I sold the Antares rings, these are just as good, lighter and look better...

Rotating "Wilcox Rings" with Teflon

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gray
scholastic sledgehammer
*****

Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Jon Isaacs]
      #5619454 - 01/12/13 05:03 PM

Jon, I have not tried that method of testing, and can not believe I didn't think of that! I checked it against the wall in my kitchen...Seems the better test would be your suggested method. Thanks for the aesthetic review of your rotating rings. I will save that cash and attempt the Wilcox build instead! Looks good there. My laser does have adjustment screws if it's out. I appreciate you. Thanks

Post Extras: Print Post   Remind Me!   Notify Moderator  
azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Planet scope decision new [Re: Jon Isaacs]
      #5619461 - 01/12/13 05:08 PM

There is a difference between f/6 and f/5 in that the secondary needs to be larger than the f/6 scope and this doesn't help planetary contrasts too its easier to collimate the f/6 than an f/5 .

I'd personally rather have a 6" f/8 than an 8" f/5 . Sure it's just one fstop but one too many for me. It's a personal taste thing too. I've never been a fan of reflectors faster than f6. The 6" f/8 will provide excellent diffraction patterns with no coma and planetary images with refractor-like quality. I've never had a view at f/5 that could be called refractor like.

Some folks are content at f/4. A lot matters about how tolerant you are of the faster reflector issues. I am no fan. Love my 6" sct though despite the large CO.

Pete


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Planet scope decision new [Re: azure1961p]
      #5619639 - 01/12/13 06:52 PM

Quote:

I'd personally rather have a 6" f/8 than an 8" f/5 . Sure it's just one fstop but one too many for me. It's a personal taste thing too. I've never been a fan of reflectors faster than f6. The 6" f/8 will provide excellent diffraction patterns with no coma and planetary images with refractor-like quality. I've never had a view at f/5 that could be called refractor like.





A few thoughts:

My collection includes both an RV-6 (6 inch f/8) as well as an 8 inch F/5 an 10 inch F/5 and a few others. It does take more care and effort to get the good views with an F/5 Newtonian but with the right eyepieces and a coma corrector, nearly perfect views are possible. Some might call them "refractor-like" but I avoid that comparison because refractors have their own set of issues.

At 200x, the diffraction limited field of view of 8 inch F/5 is about 31 degrees AFoV, on a driven mount, this is more than sufficient to avoid the effects of coma.

I have directly never compared the 8 inch F/5 to the 6 inch F/8, my sense is that the 8 inch provides somewhat more detailed views of Jupiter. The 10 inch F/5 is definitely the best of that bunch.

The way I look at it, getting the good planetary views with a Newtonian begins with excellent seeing. You can't see it if it isn't there. Next comes preparing the scope. A great mirror that is not collimated or has thermal issues is not going to perform.

Graham has an 8 inch F/5, I suggest learning how to get the most out of what Graham already has and then decide where to go from there.

Jon

Edited by Jon Isaacs (01/12/13 11:46 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Planet scope decision new [Re: Jon Isaacs]
      #5619853 - 01/12/13 09:40 PM

Agreed Jon.

With risk of beating a topic into the ground, ill just reiterate I just got through installing a boundary fan along with the rear blowing fan and that has really really made a nice difference. Till now the Galilean moons have been the test bed in observing the reduction in flare. The rear blowing fan reduces it by a whopping half while the boundary fan proves to be more subtle but just as real in reducing the halved flaring to half of that.

The full time fan was something I finally started doing a year ago while the added boundary fan was something not even a few weeks ago. I had no idea how much flaring was NOT the sky but in the scope itself.

Anyway something to consider.

Good luck Graham!

Pete


Post Extras: Print Post   Remind Me!   Notify Moderator  
dpwoos
Pooh-Bah
*****

Reged: 10/18/06

Loc: United States
Re: Planet scope decision new [Re: Jon Isaacs]
      #5620012 - 01/12/13 11:26 PM

One way to think about it is that it is best to use and learn from the 8" f/5, so that one can answer the question for oneself or at least ask narrowly targeted questions. I hope I'm not being too critical, but I do wonder if sometimes the best response to broad questions like this isn't to suggest spending more time observing, including if possible observing with others, and then coming back and telling everyone here why such and such piece of gear isn't working for this or that, and asking for suggestions on how to overcome those deficiencies.

Some years ago I was assisting in a wood shop class at a K-6 school, and the teacher told me to make sure that the kids asked me a question before I assisted them, and (most importantly) that "help me" is not a question. A moment of enlightenment that I have never forgotten.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jeff Morgan
Postmaster
*****

Reged: 09/28/03

Loc: Prescott, AZ
Re: Planet scope decision new [Re: Gray]
      #5620110 - 01/13/13 01:48 AM

Quote:

Jeff, I gather from your writings that an EQ platform mounted Dob is the way to go for planet viewing. So my question is, do you think the 8" F9 truss dob would be a better scope for viewing than my 8"F5? That setup would run me $2k new with shipping and above and beyond what I would want to spend. But, it never hurts to know as much as possible in that realm. I think I should keep my spider after reading some on curved spiders, but fan and flock for sure. What do you folks think of buying a 6"F8 dob from Orion? I have a set of rings already. I would like to have a long focus newt but I am unsure if the difference between F5 & F6 would be really noticeable.




German Equatorials are just not friendly to Newtonians. It's a size and mass thing. And equatorials in general require tilted mounts, which means off-center loads that need to be balanced. Extra weight to balance. Extra weight to make the mount stiff enough to hold the scope and the counterweight. An alt-az mount keeps the loads centered over the mount, leading to greater stability with far less mass. Figure out a way to make it track (like a platform or ServoCAT) and you have the best of both worlds.

If planetary is truly your main interest, longer focus will serve you better:

- Simple eyepieces like Orthos, Plossls, Brandons, RKE's (and a few others) are favored by the hard-core planetary crowd for good reasons. And they perform great at longer focal ratios, not so great at f/5;

- You can buy these eyepiece types at high quality levels for not a lot of money. The faster scopes require more corrected (and costly) glass;

- You get greater image scale at longer focal ratios before you have to resort to barlows. This is important because it keeps the glass count down, and simple eyepiece designs have limited eye relief in the shorter focal lengths; and

- Then there is a the whole collimation thing. It is the number one performance killer, and it is more forgiving at longer focal ratios.

It occurred to me that instead of fixating on this Orion scope, you should find yourself a Criterion RV6. It's the 6" f/8 scope you've been wanting, and it has an equatorial mount. They go used for perhaps $300. While I am a skeptic of mass-market mirrors the RV6 has a great track record and I suspect your odds of getting a fine optic are much better than with the Orion.

Perhaps you could talk Jon out of his


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Planet scope decision new [Re: Jeff Morgan]
      #5620185 - 01/13/13 04:54 AM

Quote:


It occurred to me that instead of fixating on this Orion scope, you should find yourself a Criterion RV6. It's the 6" f/8 scope you've been wanting, and it has an equatorial mount. They go used for perhaps $300. While I am a skeptic of mass-market mirrors the RV6 has a great track record and I suspect your odds of getting a fine optic are much better than with the Orion.




And yet Jon find that his 8inch F/5 provides at least as good an image as his RV-6...

So often the focus is on the equipment, slow scope, fast scope, big scope, little scope, 1 element eyepieces or 7 element eyepieces. You gotta buy this, can't live without that. These are things were can argue all day and all night. Jeff has his preferences, the things that work for him, I have mine, the things that work for me. I am not going to argue what works best in terms of equipment.

My point is that the important things, the things that make the big differences are the seeing and the preparation of the equipment, there is no need to spend money to get better views, better views are possible with the existing equipment. The first step is work on getting the best possible views with what one already has... It is the least expensive, the most instructive and can yield major improvements.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jeff Morgan
Postmaster
*****

Reged: 09/28/03

Loc: Prescott, AZ
Re: Planet scope decision new [Re: Jon Isaacs]
      #5620333 - 01/13/13 09:12 AM

I recall reading an article about Walter Scott Houston where one evening someone had told Scotty that he wanted to discover a comet. His response was something to the effect of "well why are you inside now?"

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Planet scope decision new [Re: Jeff Morgan]
      #5620510 - 01/13/13 10:54 AM

Quote:

I recall reading an article about Walter Scott Houston where one evening someone had told Scotty that he wanted to discover a comet. His response was something to the effect of "well why are you inside now?"






The all time greatest bicycle racer is Eddy Merckx, his professional career lasted 10 years, in that 10 years, he won 525 races, more than one per week... When asked about his secret:

"Ride Lots"

For me:

"The more you look, the more you see."

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Chucky
sage
*****

Reged: 04/16/10

Loc: Dublin, Ohio
Re: Planet scope decision new [Re: Jon Isaacs]
      #5621117 - 01/13/13 04:03 PM

"If you keep running, you'll get something" - Richard Petty....200 Nascar wins.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jeff Morgan
Postmaster
*****

Reged: 09/28/03

Loc: Prescott, AZ
Re: Planet scope decision new [Re: Chucky]
      #5621284 - 01/13/13 05:28 PM

"Even the blind squirrel finds an occasional acorn" - Author Unknown

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Planet scope decision new [Re: Chucky]
      #5621503 - 01/13/13 07:39 PM

Quote:

"If you keep running, you'll get something" - Richard Petty....200 Nascar wins.




Richard Petty: A Blind Squirrel Win

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gray
scholastic sledgehammer
*****

Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Jon Isaacs]
      #5621562 - 01/13/13 08:15 PM

Thanks folks. I get the hint from long ago. I need to get out and take a look first. I should get my chance this weekend. It has been raining everyday for 2 weeks straight so far. Rain in the forecast for the next 3 days too. It's raining heavily now...

I've still been considering another scope though I think I'm a nut for collecting telescopes and equipment. Considering my time available, being that I never get a night off and school will be starting up later this week, I'm wondering if I would be better off with a smaller instrument with quicker cool down time and less fuss. Only one person has suggested the 100mm frac in my club with the same question asked, I get great feedback from you guys, not so much from them. I'm definitely going with Jon & Don's advice for my current scope. A tracking platform would be nice for a larger dob, but I just don't want to spend the money right now. Limiting myself to $1K. A man that works everyday needs a hot-tub too if possible.

So, until then my plans are to keep what I have, flock and fan the 8"F5 for sure. Mounting a side fan for breaking up the boundary layer is very tempting maybe worthwhile depending on how good of a fan I install on the back, blowing on the back of the primary. I think. So, I will keep looking and get back with you folks on this when I have made some progress. I think you all have given me more than enough information to help me along, and like always I appreciate all of your suggestions and feedback more than you will probably know. Oh yeah, King Richard was happiest when Mopar was dominating the track with the 426 race Hemi under the hood, Bill France was NOT lol. Always did love Chrysler products myself.

Edited by Gray (01/13/13 08:32 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Planet scope decision new [Re: Gray]
      #5621667 - 01/13/13 08:58 PM

Quote:

I've still been considering another scope though I think I'm a nut for collecting telescopes and equipment. Considering my time available, being that I never get a night off and school will be starting up later this week, I'm wondering if I would be better off with a smaller instrument with quicker cool down time and less fuss. Only one person has suggested the 100mm frac in my club with the same question asked, I get great feedback from you guys, not so much from them.




Graham:

Personally I am not a nut for collecting telescopes and equipment... It's true that I have more than 20 telescopes spread out over two houses and garages but I need them all...

As far as a useful acquisition, I say yes to the Skywatcher 100mm F/9 apo that you were initially considering. In terms of sheer capability, it will not provide the same planetary views a larger scope might. That is a larger scope that is collimated, cooled and setup. But the less fuss and fast cool down mean that you will use it when you wouldn't use a large scope so in that sense, it will provide better planetary views because you will be using it more frequently.

My 4 inch apo gets a lot of use... probably more than any other scope. It makes a good companion for larger scopes, I set them up side by side and it makes a great grab and go scope.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gray
scholastic sledgehammer
*****

Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Jon Isaacs]
      #5633788 - 01/20/13 07:02 PM

Friday night I got to test out my atlas with the newt for the first time. Setup was very easy with the new mount. I didn't know the thing even had a built illuminated polar finder and it was a little weird looking into it with a light red hue painted across the sky. I think the finder is close, but I wasn't sure if I should rotate the mount to align the big dipper up in the reticle. I did it anyway and it was good enough for visual. I collimated the newt at the beginning with the laser, rotating it in the focuser to see if it moved any. It did not that I could tell. I knew going from 70 degrees inside to 29 degrees outside would take a long time to cool down, especially with no fans installed yet. In the meantime I commanded the mount to swing to M42, M81, M1, and finally rested on Jupiter. All of the objects were centered perfectly, but not near as bright as the 12" dob once showed them. Still they were there.

The seeing was excellent, but it was cold as Dante's Inferno. I rolled the focus out and noticed the heat waves rolling off the mirror, and took mental note of what it looked like. I rechecked every 30 minutes until finally after 1.5 hours the tube was frosted over and the mirror seemed stabilized. I changed out a 32mm ep and dropped in a 6mm LER AT eyepiece with a 2" ED barlow to take a peek. It didn't look that great, so I rechecked collimation and it was off. I re-did the collimation and peered again with decent results. There was a large bright diffraction spike center of the planet, which was a little annoying. I could see the GRS, and four cloud bands but no detail within the bands themselves. The color wasn't as rich as I would have liked to see either. Even at 330x, the planet wasn't big enough for me either. I've been chasing a good view of Jupiter since I started in this hobby about 7 years ago and haven't satisfied my need yet...
I was observing over my roof top but not close enough to see blurring from the heat coming of the roof. Collimation is picky on this scope for sure and the mirrors must have shifted during slewing. It's got a decent mirror in it and to tell the truth I bought this scope to image with other than an AT 8" IN. I wanted more focal length. I think the scope will do well for that purpose and it does do decent on DSO's although I didn't give it enough time because I had to head to work at 2am.
I have been looking into the other reflectors, particularly the 6" spot maks and the 150mm iOptron mak, but can't really find a decent review of either, except the 127mm Orion Mak, it seems to have good reviews. I'm still set on flocking the newt and after the lengthy thread on thermal issues next door, I think I'll be just adding one rear fan for now, although I have some ideas if I can find some really small fans. A dual speed focuser would be nice, but what to do with the brand newt Moonlite I wonder?? I bet if I had more magnification I could have used it Friday night. I need a big picture to scrutinize not a small marble.
I'm glad I got out and gave the new stuff a whirl. I'm wanting to start imaging again especially since M1 is high in the sky and I've never shot it before. The Atlas was well worth the money, so was the newt. I looked at a 10" newt from Orion but it maybe to heavy for the new mount idk. I need a planet scope (mirror type with or without lens) that will please me and allow observing double stars, planets and maybe a new interest in Spectroscopy. I just ate supper and all the blood left my head, sorry for the rambling.

Edited by Gray (01/20/13 07:12 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
dpwoos
Pooh-Bah
*****

Reged: 10/18/06

Loc: United States
Re: Planet scope decision new [Re: Gray]
      #5634686 - 01/21/13 10:42 AM

Quote:

I could see the GRS, and four cloud bands but no detail within the bands themselves. The color wasn't as rich as I would have liked to see either. Even at 330x, the planet wasn't big enough for me either. I've been chasing a good view of Jupiter since I started in this hobby about 7 years ago and haven't satisfied my need yet...




I think that you may have hit up against the capabilities of your optics. I would observe with your local astro club, and see what the best scopes are getting compared to yours. Assuming everything is working right, this will give you a good idea of how you are doing.

So far as the apparent size of Jupiter goes, that is a function of magnification and unless your seeing is unusually good you simply aren't going to frequently do better than 300X and be productive. However, there is nothing to say that you can't use more magnification than that, if you are ok with seeing what appears to be a fuzzier image - i.e. bigger but no more detail. In fact, I think that you might find that the magnifications you are currently using will satisfy you if you can achieve more detail at those magnifications. However, this is personal preference thing and so only you can decide.

There is always the possibility that planetary visual observing is simply not going to do it for you, but I wouldn't rule it out until you have seen what a known top-notch scope can provide.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Planet scope decision new [Re: dpwoos]
      #5635098 - 01/21/13 02:32 PM

At 330X, Jupiter, average size 45", would appear to be 4.125 degrees across (simple math).
Since the full moon, to the naked eye, is approximately 1/2 degree, that means the image of Jupiter is 8-1/4X as wide as the full moon to the naked eye and has 68X the area!!!
That's HUGE!
Yet, the comment that Jupiter doesn't appear large enough is one I've heard for years.

Why is that?
1) Newbies in the hobby have been inundated with Hubble and fly-by spacecraft photos, some of them printed full-page and larger than any image could possibly appear from the Earth. Let's call it "stacking the deck" against the observer. It also means amateurs are led to believe the full technicolor images are the norm and, of course, they are not.
2) Newbies are not aware that the planets are among the smallest objects in the sky. They think that because they are bright, they must appear large in a telescope. The average star cluster is close to the size of the Full Moon, while the planets are, at best, the size of a crater on the Moon.
3) resolution of very small details takes aperture more than it does magnification. I see more on Jupiter at 140X in my 12.5" than 300X in my 5" Maksutov. Beginners often have smaller apertures, so they're disappointed at the lack of detail they see.
4) There is no "context" to the image, so the actual size of the image they view appears small because it is not seen against any familiar background or horizon. At 330X, the image of Jupiter is pretty close to as half as large as the entire bowl of the Big Dipper. Next time you're out, look at how big that is and wonder how you could possible say that's not big enough. It really doesn't need to be that big to see huge amounts of detail on the planet, so the reason people say it's not large enough isn't really related to the actual size they're seeing.
5) The variability of seeing conditions is something only experience in viewing can teach you. Once you see what near-perfect seeing can reveal, you know that the poor image quality you're experiencing has nothing to do with optics or magnification--it's the atmosphere. I've seen nights so poor the 12.5" can basically see two bands on Jupiter--at any magnification. And I've seen nights where a 456X image was clear and sharp and white swirls within a salmon-colored GRS were distinctly visible. It's all in viewing a lot of times or for a lot of time in one sitting to catch the moments when the seeing is as good as it can be.

I'm surprised that after 7 years that Gray hasn't caught one of those nights yet. I was super-impressed with the image of Jupiter in my 4.25" reflector back in 1963. But then, I had no Hubble pictures or fly-by photos to compare it to, either. I realize now that I didn't really see all that much, but it impressed the heck out of a 12 year old boy to be able to see bands and the GRS at all!

For every planetary observer, read up about and do everything you can to collimate well and cool the scope's optics to ambient temperature. It may mean practicing collimation and installing fans, but since you can't do a whole lot about seeing, you might as well optimize the things you CAN control.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | (show all)


Extra information
7 registered and 22 anonymous users are browsing this forum.

Moderator:  ausastronomer, Knuklhdastrnmr, Phillip Creed, JayinUT 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 4053

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics