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Equipment Discussions >> Reflectors

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Gray
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Reged: 01/31/11

Loc: Hixson, TN
Planet scope decision
      #5614492 - 01/09/13 08:58 PM

I am looking for a good planet scope in my price range of $1000 and under, preferably under...

So far I'm seeing three scopes, but want the best choice of the three but I have neither seen or used any. They are:

1) Parks 6" F/8 Newt
2) IOptron 150mm F/12 Mak
3) Skywatcher 100mm F/9 ED frac

Of the three which is the best buy? I live about 5 miles north of the city in South-Eastern Tennessee. My skies are decent when it's clear. I would like a very nice performer on Saturn, Jupiter, Mars and the Moon. Solar option is not that important to me. I do understand that the Mak would take a long time to cool down. I have an Atlas mount that would handle all of these scopes. I think I'm leaning towards the Parks newt for now. Can any of you fine gentlemen offer me some sound advice? Thank you


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Mr. Marbles
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Reged: 04/23/05

Loc: Saratoga Springs, NY
Re: Planet scope decision new [Re: Gray]
      #5614528 - 01/09/13 09:19 PM

I haven't used any of those 3 telescopes, but I would go with the Parks as well. Aperture is king on planets, contrary to what some may tell you. I had an FS-102 and I never found it be a great planetary scope. Don't get me wrong, it provided aesthetically pleasing images but the detail was not there. And that's a world class 4-inch APO. I don't know how the Mak-Cass will stack up against the Parks. F/8 is nice for a Newtonian, generous diffraction-limited field.

Edited by Mr. Marbles (01/09/13 09:21 PM)


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Gray
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Mr. Marbles]
      #5614533 - 01/09/13 09:24 PM

Thanks for the input Mr. Marbles. I read Jon Issacs say that Parks was out of business although their website is still up? It would be nice to view before you buy lol.

Edited by Gray (01/09/13 09:50 PM)


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Achernar
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Re: Planet scope decision new [Re: Gray]
      #5614538 - 01/09/13 09:27 PM

Of the three, I would probably opt for the 6-inch F/8 Newtonian. Choice number two would be the Mak. Both would be very good planetary telescopes, but the Newtonian would cool down faster. The Mak would be more portable and can be used easily for astronomical imaging too, not to mention no need to collimate or wash the mirrors. I have had a 6-inch F/8 for 30 years, and I still use it for lunar and planetary observing. From a dark site, I have hunted down a lot of DSO's too with it. You can find a 6-inch F/8 OTA or build one for your Atlas EQ mount, they are common.

Taras


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Gray
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Achernar]
      #5614549 - 01/09/13 09:39 PM

Taras, Thanks for pointing a few advantages out on the Mak, with portability and collimation in mind. An hour of cool down time is no biggie to me. If Parks is indeed out of business, I only really have 2 choices left. Btw, I throughly enjoyed your homepage. Very nicely put together with a wealth of information from just a few minutes glance. Thank you sir.

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careysub
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Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Planet scope decision new [Re: Gray]
      #5614550 - 01/09/13 09:40 PM

Duplicate post appearing. Weird.

Edited by careysub (01/09/13 09:41 PM)


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careysub
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Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Planet scope decision new [Re: Gray]
      #5614551 - 01/09/13 09:40 PM

If you are really, really looking for a planet-optimized telescope, and are willing to go the full $1000, then you might take a look at this:

http://www.optcorp.com/product.aspx?pid=67-12025

It is an 8" F/9 with a 15.6% central obstruction.


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Gray
scholastic sledgehammer
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: careysub]
      #5614564 - 01/09/13 09:46 PM

Careysub, Thanks, I have looked at that scope as well but did not put it in my line up because I would rather use my mount for tracking. The dob does look attractive, but I'm wondering how comfortable the view would be with 60" of focal length? I'd rather sit if possible. Thanks for bringing that to the table though!

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zipthelipp
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Reged: 09/10/12

Loc: Bayside NY
Re: Planet scope decision new [Re: Gray]
      #5614579 - 01/09/13 09:59 PM

Skywatcher 100mm F/9 ED frac
I think I'm going to get the ES152 doublet and get a fringe filter to view planets.


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george golitzin
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Reged: 02/24/06

Re: Planet scope decision new [Re: Mr. Marbles]
      #5614584 - 01/09/13 10:02 PM

Quote:

I haven't used any of those 3 telescopes, but I would go with the Parks as well. Aperture is king on planets, contrary to what some may tell you. I had an FS-102 and I never found it be a great planetary scope. Don't get me wrong, it provided aesthetically pleasing images but the detail was not there. And that's a world class 4-inch APO. I don't know how the Mak-Cass will stack up against the Parks. F/8 is nice for a Newtonian, generous diffraction-limited field.




I agree. I also think that 6 inches is where it just starts to get interesting. I had a 6-inch Intes mak that was wonderful on Saturn, perhaps less so on Jupiter: that is, fine, high-contrast detail was great, whereas low-contrast stuff was harmed a bit by the CO. If you can find an 8-inch f/6 Newt OTA for your mount, one with a good mirror, I would go with that, provided you have a way to rotate the tube. And don't be afraid to buy used.


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Jon Isaacs
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Loc: San Diego and Boulevard, CA
Re: Planet scope decision new [Re: george golitzin]
      #5614608 - 01/09/13 10:24 PM

Quote:


I agree. I also think that 6 inches is where it just starts to get interesting. I had a 6-inch Intes mak that was wonderful on Saturn, perhaps less so on Jupiter: that is, fine, high-contrast detail was great, whereas low-contrast stuff was harmed a bit by the CO. If you can find an 8-inch f/6 Newt OTA for your mount, one with a good mirror, I would go with that, provided you have a way to rotate the tube. And don't be afraid to buy used.




I see that Gray/Graham already has an 8 inch F/5 Newtonian as well as an Atlas Mount. I suspect that this is at least as good and probably a better planetary scope than any of the three smaller scopes. I can see two ways to proceed. First would be a longer focal length 8 inch such as George suggests. The second would be to make sure the 8 inch F/5 has good mirrors, have both tested and reworked/replaced as needed.

The Skywatcher 100mm F/9 ED has the virtue that it will cool down much quicker than the others so it would be a reasonable choice for shorter sessions and sessions when there is not enough time to allow the others to reach thermal equilibrium.

Besides, everyone needs a decent 4 inch refractor, that's just how life is.

Jon Isaacs


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dpwoos
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Re: Planet scope decision new [Re: Jon Isaacs]
      #5614636 - 01/09/13 10:43 PM

I agree - it would be good to know why the 8" f/5 is not a satisfactory "planetary" scope. There are some folks in our club who make this distinction, but in my experience it is not very useful. If a scope has good optics then it is good (for everything, including planets, and within the limits of the aperture), and if not then it is not much good (for anything).

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Gray
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: dpwoos]
      #5614975 - 01/10/13 07:30 AM

Wow folks, didn't think I hear all that. I'm embarrassed to say my new atlas is a closet queen since I bought it. I have had the 8" out once but not on a EQ 6 mount (another closet queenie). The time I had that newt out, I checked my finder on Jupiter and about burned my eye out with how bright it was. I also read the f/5 newt should work well if the mirror has been made right. I'm getting that maybe I don't need another scope I agree with that thought, but inferno, it's been cloudy for a week and a half & rain for the next four days. I guess I'm gonna have to call Parks & ask them if they are open. Btw, I wouldn't buy an ES AR152 frac and look at anything but the Milky Way . Thanks fellow folks.

Edited by Gray (01/10/13 07:31 AM)


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Ed D
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Re: Planet scope decision new [Re: Gray]
      #5614996 - 01/10/13 07:54 AM

My suggestion would be taking the Chino mirrors (primary and secondary) out of the 8" f/5 and either replace it with a good custom one, or have it figured and coated by one of the reputable firms or individuals. Don't get hung up obsessing about the secondary size and central obstruction. As long as it's about 20% or less it's fine, as are 4 vane spiders. You already have a Moonlite focuser, which I assume is two speed, which makes it easy to achieve good focus at high mags in the f/5. I want to add that flocking my tube helped immensely, as did adding a fan to control the boudary layer.

Ed D

Edited by Ed D (01/10/13 08:15 AM)


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Gray
scholastic sledgehammer
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Ed D]
      #5615071 - 01/10/13 08:55 AM

Ed D, that's an interesting idea. I haven't actually found pricing for such a thing except getting a re-coat job done which was under $100 for an 8" I think... It seems the practical solution is to get the newt out and do some tests before making any purchases. I've been manly concentrated in using imaging equipment thus far after a bad experience with an ES AR152 refractor and selling my Z12 dob. I thank you for your input, that is also an excellent option although I'm still leaning towards a longer focus instrument. I will definitely make note of that.

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dpwoos
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Re: Planet scope decision new [Re: Gray]
      #5615099 - 01/10/13 09:15 AM

Our club has an excellent 14" f/4.7 dob (mirror refigured by club member) and its performance on planets is great. I think this idea of a long focus "planetary" scope is from a time when it was really hard to find an excellent "fast" mirror. These days, f/4.7 is not considered to be very fast at all, and much faster (and much larger) mirrors are readily available. If coma is bothersome to you then a Paracorr really does the job.

Edited by dpwoos (01/10/13 09:44 AM)


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Jon Isaacs
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Re: Planet scope decision new [Re: Gray]
      #5615107 - 01/10/13 09:23 AM Attachment (17 downloads)

Quote:

Ed D, that's an interesting idea. I haven't actually found pricing for such a thing except getting a re-coat job done which was under $100 for an 8" I think... It seems the practical solution is to get the newt out and do some tests before making any purchases. I've been manly concentrated in using imaging equipment thus far after a bad experience with an ES AR152 refractor and selling my Z12 dob. I thank you for your input, that is also an excellent option although I'm still leaning towards a longer focus instrument. I will definitely make note of that.




Graham:

A few random thoughts/observations:

- The most important factor in getting the good planetary views, is the seeing... it takes a stable atmosphere, excellent seeing.

- Preparation of the scope is also critical. Thermal equilibrium, actively cooling the scope, these are the biggies. Setting the scope outside for an hour or two doesn't get it, a good quality, vibration free fan cooling the mirror and the scope is most important. Collimation needs to be spot on.

- Aperture is important, focal ratio is of much lesser importance. I have a fair number of telescopes and consider my old 12.5 inch F/6 Equatorially mounted Newtonian my best planetary scope but I rarely use it because it is massive (around 300 lbs) and requires a ladder. Instead, when I want the good planetary views, I generally use my generic 10 year old, 10 inch F/5 Dobsonian that has been small modifications to optimize it for higher magnifications. This includes a custom Floyd Blue fan, a modern GSO Crayford and reworking the bearings with Ebony Star-Teflon. I wear gloves to help control my body heat and on an excellent night, this scope is capable of 800x when splitting double stars.

With your 8 inch F/5, I would recommend a fan, Floyd recently made one for my 8 inch F/5, and making sure it is properly collimated. Since it will be on a tracking mount a Paracorr is not needed but "rotating rings" are a necessity, they make it so much easier to view comfortably.

Jon


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george golitzin
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Re: Planet scope decision new [Re: Jon Isaacs]
      #5615396 - 01/10/13 12:07 PM

Quote:


I see that Gray/Graham already has an 8 inch F/5 Newtonian as well as an Atlas Mount. I suspect that this is at least as good and probably a better planetary scope than any of the three smaller scopes. I can see two ways to proceed. First would be a longer focal length 8 inch such as George suggests. The second would be to make sure the 8 inch F/5 has good mirrors, have both tested and reworked/replaced as needed.

The Skywatcher 100mm F/9 ED has the virtue that it will cool down much quicker than the others...Besides, everyone needs a decent 4 inch refractor, that's just how life is.

Jon Isaacs




Ah, I didn't see the 8-inch f/5 in the signature. Yes that would be better--if the optics are good, such a newt is capable of outstanding planetary views.

But I find a long focus 4-inch refractor, while fun to look through, basically useless by comparison. Just not enough light for the planets--you're down to 0.5 mm at just 200 power--and no wider a view than the 8-inch f/5. At this point, my only uses (visually) for a refractor, as opposed to a larger newt, are 1. birds 2. solar, and 3. extreme widefield. For that, I'm perfectly happy with my 80ED.


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rflinn68
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Loc: Arkansas
Re: Planet scope decision new [Re: george golitzin]
      #5615813 - 01/10/13 04:13 PM

The 8" f/5 newt you already have would be my choice followed by the 4" ED. I myself wouldnt even consider the iOptron 6" Mak. The one I looked through didnt impress me at all.

Of the scopes I own the Orion 10" newt puts up the best planetary images after doing the modifications. Listen to Jon about the collimation and thermal equalibrium being extremely important for planetary views. I came very close to selling this scope and now I am so glad I didnt! I did the mods (Destiny 3 vane curved spider, Protostar flockboard, and Antares Optics secondary) all at once so I cant say which helped the most but they all helped to improve the scope immensely. The addition of binoviewers has also helped improve my views on planets and doubles.


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Jeff Morgan
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Re: Planet scope decision new [Re: careysub]
      #5615836 - 01/10/13 04:26 PM

Quote:

If you are really, really looking for a planet-optimized telescope, and are willing to go the full $1000, then you might take a look at this:

http://www.optcorp.com/product.aspx?pid=67-12025

It is an 8" F/9 with a 15.6% central obstruction.




Of course I would just take the money and build my own scope - but limited to commercial choices I would have voted for #1 or #2. Then I followed the link in your post. I would take the larger and longer mirror in a heartbeat! Grab a few good orthos and a barlow, good to go.

Just bear in mind that a a mass-market optic is a *BLEEP*-shoot. Long mirrors are easier to make well than short ones, but a mass-producer can always screw that up too.


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Gray
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: george golitzin]
      #5615958 - 01/10/13 05:57 PM Attachment (25 downloads)

George, I see you have canceled the refractor due to the lack of aperture. I am interested in a good planetary telescope, that may double as an imager but not particularly at this time. I feel I may agree with you on this and thusly take it off my list.

Ed D's suggestion of having the mirror tested and if warranted re-figured and re-coated is another good idea. I looked for about 30 minutes of where I could send my mirrors too ,and how much I would be looking at, but I seem to have hit a road block due to the small size of the mirror. I found one source that would re-test and re-work my mirrors for around 450$~.

My Moonlight is only a single speed focuser, and I think I can keep it that way all things considered

Mr. Issacs, I thank you for your commentary with generous thoughts and ideas that are more important to the subject than just buy another scope and be done with it! I agree 100% with you that I should at-least have a fan on my scope and have read proofs that they can make a huge difference. That will be my first step. I will need to find a supplier for that accessory (on the cheap if possible).
So it seems I'm at the point first and foremost to actually test this scope of mine first and see how it preforms before making any further telescope purchases, which is responsible sounding enough to me . I pulled a post from the achieves about the Parks AV8 system but found no real help here. http://www.cloudynights.com/ubbarchive/showflat.php/Cat/0/Number/1319195/page... One comment about half way down (may be a mis quote) says that an 8"F5 is more of a "general observing" type telescope than a planetary. That kinda talk suckers me into believing a long focus newt is the way to go, and not just a 6" but an 8" just like the AV8 (8" F6). So, I have three options now with the refractor being removed henceforth.

1) Run tests on what I have now with a fan installed to determine if I have a general observing scope or better.
2) If not send mirrors off for reworking in hopes of a better wave rating.
3) Look into either the 6" or 8" F8/F6 Parks Newt's as a better alternative. Or lastly, check into the Ioptron 150mm Mak instead.

If I could remove the Mak from the list I would. Cool down time is not too critical although tube currents would be, but how it would compare to the Parks 6" newt should determine if it stays or goes. Any more thoughts in line with my rambling is very much appreciated!

Edited by Gray (01/10/13 06:06 PM)


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Gray
scholastic sledgehammer
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: Gray]
      #5616007 - 01/10/13 06:24 PM

I forgot to mention that I have taken note of the upgrades suggested by rflinn68! Awesome advice, thank you sir. Also, I agree with you too Jeff, If I had the time and I should one day, I would just attempt my first mirror project!

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Jon Isaacs
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Re: Planet scope decision new [Re: Gray]
      #5616147 - 01/10/13 07:44 PM

Quote:

I will need to find a supplier for that accessory (on the cheap if possible).




I tried making my own fans but I never really was able to eliminate the vibration. I recommend Floyd Blue's fans, they are simple, effective and free of vibration. I have 4 of them, the most recent is for my 8 inch F/5 and I also have my 10 inch f/5, my 12.5 inch F/4.06 and my 12.5 inch F/6 fitted with Floyd's fan.

Blue Sky Accessories: Floyd Blue, Blueman

If I recall correctly, they're about $35.

Jon


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dpwoos
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Re: Planet scope decision new [Re: Jon Isaacs]
      #5616522 - 01/10/13 11:55 PM

Our 6" f/8 flex mirror dob has, out of necessity, a fan that blows across the face of the mirror. That worked so well that now all of our newts have fans that blow across the face. We mount the fan(s) on the same 1/2" neoprene rubber that we use for our flex cells, and I have never detected any vibration. We use good quality pc cooling fans with filters.

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Gray
scholastic sledgehammer
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Reged: 01/31/11

Loc: Hixson, TN
Re: Planet scope decision new [Re: dpwoos]
      #5617205 - 01/11/13 12:38 PM

Thanks for the fan help Jon & dpwoos. I'm thinking it would be a bit difficult to cut a hole in the side of a metal ota, so more than likely for now I will just install one on the back of the mirror.
I've been looking into what actually constitutes a good planetary scope or more so optimizing a scope for planetary viewing. It seems some agree that focal ratio is not important in reflectors but central obstruction is. Seeing, optics ,and thermal issues being the most critical. Still, I see posts from older gentlemen wishing they still had a long focus newt from the days past. Those kinda comments I can empathize with and appreciate as good as gold. I've taken all this into account and still am lusting after a long focus newt "optimized" for plants. I guess I'm looking at a 6" f8 long tube newt preferably with a curved spider, dual speed focuser, fans, and flocking. If there is any other scope out there that would be better at observing Jupiter and so on, I sure would like to know. I haven't read a good thing once about Ioptron's 6" Mak yet, so the axe must come down on it too. lol

Edited by Gray (01/11/13 12:39 PM)


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azure1961p
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Re: Planet scope decision new [Re: Jeff Morgan]
      #5617232 - 01/11/13 12:52 PM

I'd personally get that 8" f/9 truss dob by Optcorp. Nothing in your want list could touch it. Too the mount would be much easier on you than the PARKS. At anyrate Id go with the 6" f/8 or the 8" f/9 both will yield very high definition in good seeing. The only thing I've seen outdo the 8" f/9 was a 10" f/7 Cave and another one bring a Parks and a Celestron C11. Not a Meade10" SCT nor 8" SCT. Those have been my experiences anyway.

Oh and collimating is NOT the bother it is with short scopes. It still matters to be sure but the disaster factor is lessened.

Pete

Edited by azure1961p (01/11/13 01:02 PM)


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Gray
scholastic sledgehammer
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Re: Planet scope decision new [Re: azure1961p]
      #5617325 - 01/11/13 01:56 PM

Pete, the only problem I'd have with that 8" F9 Dob is the tracking platform I'd have to buy. I really don't have space for that type of thing right now. Don't get me wrong though, I'd love to look through that instrument, but chasing a planet back and forth gets old.

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dpwoos
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Re: Planet scope decision new [Re: Gray]
      #5617404 - 01/11/13 02:51 PM

Not to say that you aren't entitled to your own likes/dislikes etc., but whenever someone posts that they have difficulties tracking with a dob I have to wonder if they have ever given this a chance with a properly constructed mount, with minimal stiction. Many, many folks find tracking planets at high powers not to be that big a deal, and so maybe this is worth a rethink?

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Starman1
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Re: Planet scope decision new [Re: Gray]
      #5617405 - 01/11/13 02:51 PM

The three "C"s of observing:
--Collimation. If you're not real certain on this one, getting good tools (e.g. Catseye or Glatter) can make the difference. Adequate collimation is OK but excellent collimation is required for small planetary details.
--Cooling. No 8" will cool by itself to ambient temperature if the temperature is falling during the night. At best, it will take 3 hours or more before heat issues disappear from the images. Active cooling is mandatory.
One rear fan will cut the period of cooling to 1/3 of what it would be without the fan. This is critical for planetary observations.
--Conditions. Seeing, mostly, and transparency. Seeing is the Biggie. I have seen nights where my 12.5" was aperture-limited and the images unbelievable. In those conditions, I've seen Jupiter with as much detail as a really good photograph. No, better, because what I saw was sharply focused and photos never are.

Collimation and cooling are within your control. Conditions are not, but there are some lessons to be learned:
--never observe an object directly above a roof top. Heat from the roof will rise and distort the image.
--seeing conditions are often best at 2 times of night: right at twilight in the evening when the heat of the sun is removed from the atmosphere; and between midnight and dawn when the atmosphere has settled into strata of temperature gradients.
--try not to sit with your warm legs directly below a steel tube. You will see heat signatures in the images. It helps to flock the tube internally. This won't slow the cooling of the tube, but it will reduce the heat images from warm legs under the tube, and it will help reduce tube currents as the steel tube loses its heat into the interior.
--resist the temptation to look at an object below 30 degrees altitude. At 30 degrees, you are looking through literally twice as much air as at the zenith, and the extra air will always show more turbulence and scintillation. Of course, with Venus and Mercury, this rule doesn't work, but for exterior planets, this is a good rule to follow.
--the center of a valley usually has steadier air than the periphery (where air is either rising or falling). I went from the center of West LA, where seeing was spectacularly good, to a mountainside above LA. Now I see good seeing one or two nights a year. If it has to be a mountainside, make it one facing the wind, not the "alee" side. a steady laminar flow over your site is much better than the turbulence after the air rolls over some form of obstruction. In a city, try to set up on the upwind side of a building for the same reason.
--look at the weather maps. 2-3 days after a front passes, the air gets calmer and more stagnant. If the pressure isobars are close together, seeing will suffer.
--check out the jet stream position. If it's overhead (+/- 50 miles), you won't get good seeing. If it's a long way away from overhead, you might.
--check out the high altitude wind speed. If it's dead calm or if it's really fast, you won't get good seeing. If it's steady and not too fast, the air flow may be quite laminar and good seeing will result.
If you learn to anticipate good seeing conditions, you will be rewarded with a lot more episodes of fantastic planetary images.

Prevent stray light from entering the bottom of the eyepiece bya adding about an 8-10" extension to the side of the tube opposite the focuser. This will improve contrast (like flocking does to the interior) by keeping direct light from the sky out of the bottom of the eyepiece in the focuser. It can be quite simple--even black construction paper or cardboard.

Last, I don't see anything wrong with an 8" f/5 on an EQ mount for planetary viewing. Of the scopes you mentioned, the Parks isn't available, the 6" Mak is nice but it'll be a gamble that you get a really superb one optically (and cooldown is WORSE than your 8" newt.). And the Skywatcher refractor is too small to show you the small details the 8" can (the 8" will resolve details 1/2 the size).


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Gray
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Re: Planet scope decision new [Re: Starman1]
      #5617510 - 01/11/13 04:01 PM

dpwoos, I did have a Z12, and after a couple of observing sessions during decent seeing, I grew uncomfortable constantly bringing the planet back only too be able to observe the object for maybe a second in the sweet spot. I don't discount what others can do or have been able to do, I'm just saying it's not for me. I appreciate your thoughts.

Don, so glad you stopped in to enlighten me further! I gather from what you say that Parks is no longer in business, even though their site is up and current? Now then it looks as if I should just upgrade my newt with fans, flocking, and I'm wondering what you guys think of a curved spider? 3 or 4 vane. I was thinking 3, for my 8" even though they are expensive at $94 from Jim at Scopestuff. I'm also wondering if I should replace the secondary or keep it. What would you suggest I upgrade my scope with altogether, for optimizing it for planets is a better question of questions. Or would another scope be a better option? Thank you Starman

Edited by Gray (01/11/13 04:03 PM)


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Starman1
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Re: Planet scope decision new [Re: Gray]
      #5617531 - 01/11/13 04:14 PM

Quote:

I gather from what you say that Parks is no longer in business, even though their site is up and current? Now then it looks as if I should just upgrade my newt with fans, flocking, and I'm wondering what you guys think of a curved spider? 3 or 4 vane. I was thinking 3, for my 8" even though they are expensive at $94 from Jim at Scopestuff. I'm also wondering if I should replace the secondary or keep it. What would you suggest I upgrade my scope with altogether, for optimizing it for planets is a better question of questions. Or would another scope be a better option? Thank you Starman



Parks' website is pre-paid but there is no one currently working there.
If you do a curved spider, be aware that most of them are not collimationally stable. Try the ones that look like )-( as in this site (go down the page--the pic is on the right):http://www.obsessiontelescopes.com/telescopes/12.5/index.php
That design does not appear to sag as you point lower.
Might as well keep your secondary.

If you upgrade the scope but keep it possible to use your mounts, an 8" f/6-f/7 would still work and the secondary would be a little smaller.
An f/9 would be getting somewhat heavy and too big a wind sail, not to mention having an inconvenient eyepiece position for comfortable viewing.
Frankly, by today's standards, f/5 is long. Imaging scopes are typically f/3-f/4.

And, as long as your scope tracks, you'll not need a coma corrector at f/5.


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rflinn68
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Re: Planet scope decision new [Re: Gray]
      #5617539 - 01/11/13 04:19 PM

The Destiny 3 vane curved spider worked very well for me. I went ahead and did the flockboard from Protostar and put on a new 1/20 ptv Antares Optics secondary at the same time. My collimation holds just as good or better than it did before with the factory spider. The Destiny that I bought was about the same price but it also came with collimation thumb screws. Not sure if Jims do or not. I also got lucky with Antares Optics! I ordered the 1/15 ptv 2.6" secondary for my 10" and they were out of that one and out of the 1/18 so they shipped me a 1/20 mirror for the same price of a 1/15. Very good people to deal with for sure! Like I said before, I almost sold my scope but now I am so glad I didnt. I'm still wanting to get a big dob (16"+) and will start saving for it soon but I am quite happy now with my 10" for the time being.

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rflinn68
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Re: Planet scope decision new [Re: rflinn68]
      #5617569 - 01/11/13 04:35 PM

I just checked and the thumbscrews are an option at ScopeStuff. I bought the Large from Destiny for $99 and they were standard. The Large 3 vane is $109 at ScopeStuff and the thumbscrews are extra. The medium 3 vane is $94. A medium now from Destiny is $69.95 but you'll need to see what options are included with it.

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Gray
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Re: Planet scope decision new [Re: rflinn68]
      #5617574 - 01/11/13 04:39 PM

Thanks rflinn68!

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Gray
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Re: Planet scope decision new [Re: Gray]
      #5617903 - 01/11/13 07:59 PM

I really appreciate all you fine fellows who have offered to help me with this interesting decision. It is fascinating to think of all the possibilities and humbling when I see how much money the good things cost. I hope others will read this and learn a bit from what I've seen wrote so many times before. I've learned quite a bit from all of this and am very thankful to you all. I'll end this thread with that.

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Jeff Morgan
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Re: Planet scope decision new [Re: Starman1]
      #5618083 - 01/11/13 09:55 PM

Quote:


If you upgrade the scope but keep it possible to use your mounts, an 8" f/6-f/7 would still work and the secondary would be a little smaller.
An f/9 would be getting somewhat heavy and too big a wind sail, not to mention having an inconvenient eyepiece position for comfortable viewing.
Frankly, by today's standards, f/5 is long. Imaging scopes are typically f/3-f/4.

And, as long as your scope tracks, you'll not need a coma corrector at f/5.





Rebuilding a commercial dob allows one to spread the money over time. Doesn't help resale though. The economics aren't that compelling, at that point DIY starts making a lot of sense. 50/50 call on that, there is a lot of value in being able to get into the game now vs. months from now.

The 8" f/9 in the link was a truss design, it's performance in the wind likely is reasonable. It would have a zenith eyepiece height of 72" (give or take a few, depending upon the build). The OP was interested in planets, and listed his location as Tennessee. Not much chance of a planet finding it's way to the zenith from that latitude. Close (perhaps 75 degrees elevation), but not quite. Might even be quite comfortable for someone of average height. (Then again, the OP could be short.)

If planetary is your thing, look at what the more prolific ALPO observers such as Troiani, Parker, and Beisch are using - Large Newtonians in the f/6 to f/7 range. First emphasis on aperture, second emphasis on long. I doubt many (or any) of them are sub f/5, even for planetary imaging. Especially for planetary imaging where image scale is desired.

Edited by Jeff Morgan (01/11/13 10:17 PM)


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Gray
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Re: Planet scope decision new [Re: Jeff Morgan]
      #5618501 - 01/12/13 06:24 AM

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!

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Jon Isaacs
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Re: Planet scope decision new [Re: Gray]
      #5618520 - 01/12/13 06:52 AM

Graham:

A few thoughts:

- For correcting coma at planetary magnifications, the Paracorr is the one. It is my understanding that the MPCC adds spherical aberration and is basically for astrophotography.

- All total summed effect of all the modifications you can do will be small in comparison to just making sure that your current scope is perfectly collimated and thermally stable. The first step IMHO, is doing the small things which make big differences in getting your current scope to perform it's best.

- When you listen to old timers, you are listening to people who have memories of how things used to be rather than how they are today. Back in the old days, there were no coma correctors, eyepieces had problems with fast mirrors, and fast mirrors were generally not well made. The world has changed...

Jon Isaacs


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Gray
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Re: Planet scope decision new [Re: Jon Isaacs]
      #5618527 - 01/12/13 07:15 AM

LOL, wow, never would've expected that comment! Thanks for that tid bit on the coma correctors too. Paracorr, check. I do have a laser and a Cheshire but maybe I should look into better tools. I will check them out. I'll do further reading about rotating rings before I decide on them too. Fans are a biggie and I will also read what I should do there. I appreciate your thoughts Jon.

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Jon Isaacs
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Re: Planet scope decision new [Re: Gray]
      #5618547 - 01/12/13 07:43 AM

Quote:

I do have a laser and a Cheshire but maybe I should look into better tools.




A good laser is a good tool.. What laser are you using and are you Barlowing it to adjust the primary.

Jon


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Jeff Morgan
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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)


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Gray
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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.


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Jon Isaacs
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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


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Gray
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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

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azure1961p
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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


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Jon Isaacs
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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)


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azure1961p
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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


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dpwoos
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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.


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Jeff Morgan
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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


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Jon Isaacs
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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


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Jeff Morgan
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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?"

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Jon Isaacs
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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


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Chucky
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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.

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Jeff Morgan
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Re: Planet scope decision new [Re: Chucky]
      #5621284 - 01/13/13 05:28 PM

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

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Jon Isaacs
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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


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Gray
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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)


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Jon Isaacs
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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


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Gray
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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)


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dpwoos
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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.


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Starman1
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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.


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Gray
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Re: Planet scope decision new [Re: Starman1]
      #5635227 - 01/21/13 03:40 PM Attachment (29 downloads)

Maybe you guys are right. I haven't really had anything decent in 7 years to observe with until now. I just wanna make sure y'all understand what kinda scale I was seeing. Don you make it sound like it was huge, but I saw different unless my barlow wasn't working right. I'm putting a pic on here that a fellow took with his 14" SCT Friday night. If you stand back 3 feet from the screen, that's about how big Jupiter was and how much detail I saw in the 8". If that looks right to you then I'll settle down.

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tomharri
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Re: Planet scope decision new [Re: Gray]
      #5635256 - 01/21/13 03:56 PM

That's about what I saw last nite in my 8"f/5 newtdob. Along the equator could see a little more of the 'festoons', and all the dark bands were a little more 'sharper' more clearly defined edges. Plus could only go to a 5mm lens=200x. So a little less than average seeing for around here.

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Starman1
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Re: Planet scope decision new [Re: Gray]
      #5635419 - 01/21/13 05:39 PM

Your drawing on my monitor was 1" across a circle of 36" radius (which has a diameter of 72", which is a circumference of approximately 226"), with the eye sitting at the center of the circle.

Each inch of the circumference of 226" is an angular change of 360/226 = 1.59 degrees, with the eye at 36" away.
Actually, at 330X, Jupiter was about 4.13 degrees wide (apparent), or about the same as your drawing at (rounding off) the distance of 14" from the screen.

If you saw that much detail, you were doing pretty good. That indicates your seeing was average or above average.

People consistently underestimate the size of Mars and Jupiter in their scopes, but rarely underestimate Saturn. Perhaps the appearance of the rings is the reason, but I think it's for the reasons I mentioned, with Seeing conditions and Expectations being the primary ones.


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Gray
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Re: Planet scope decision new [Re: Starman1]
      #5666321 - 02/07/13 12:32 AM

Well folks, I'm a little embarrassed to say that I neglected to buy anything discussed above. I went out of my way and ordered a 108mm ED iOptron Versa with a WO CF dielectric diagonal yesterday from OPT. It's an F6.1 ED scope with 660mm of FL using FPL51 glass. No where near a planet scope, but I intend on using the 8" F5 for that. I learned quite a bit from this post, and even ventured into automated focusing, but rested in widefield viewing and better resolution imaging with my DSI3. It's F-ratio & FL is what I have been looking for with my little camera. Just wanted to put that in here. Thanks again for all your help!

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Jeff Morgan
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Re: Planet scope decision new [Re: Gray]
      #5666727 - 02/07/13 09:52 AM

Quote:

Well folks, I'm a little embarrassed to say that I neglected to buy anything discussed above. I went out of my way and ordered a 108mm ED iOptron Versa with a WO CF dielectric diagonal yesterday from OPT. It's an F6.1 ED scope with 660mm of FL using FPL51 glass. No where near a planet scope, but I intend on using the 8" F5 for that. I learned quite a bit from this post, and even ventured into automated focusing, but rested in widefield viewing and better resolution imaging with my DSI3. It's F-ratio & FL is what I have been looking for with my little camera. Just wanted to put that in here. Thanks again for all your help!




Fear not, it will do nicely for you and there is always another telescope around the corner.


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