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Planet scope decision

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#1 Gray

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Posted 09 January 2013 - 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 :bow:

#2 Mr. Marbles

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Posted 09 January 2013 - 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.

#3 Gray

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Posted 09 January 2013 - 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.

#4 Achernar

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Posted 09 January 2013 - 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

#5 Gray

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Posted 09 January 2013 - 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.

#6 careysub

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Posted 09 January 2013 - 09:40 PM

Duplicate post appearing. Weird.

#7 careysub

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Posted 09 January 2013 - 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.c...px?pid=67-12025

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

#8 Gray

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Posted 09 January 2013 - 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!

#9 zipthelipp

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Posted 09 January 2013 - 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.

#10 george golitzin

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Posted 09 January 2013 - 10:02 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.


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.

#11 Jon Isaacs

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Posted 09 January 2013 - 10:24 PM

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

#12 dpwoos

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Posted 09 January 2013 - 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).

#13 Gray

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Posted 10 January 2013 - 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 :smashpc: :whistle:. Thanks fellow folks.

#14 Ed D

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Posted 10 January 2013 - 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

#15 Gray

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Posted 10 January 2013 - 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.

#16 dpwoos

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Posted 10 January 2013 - 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.

#17 Jon Isaacs

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Posted 10 January 2013 - 09:23 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.


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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#18 george golitzin

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Posted 10 January 2013 - 12:07 PM

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.

#19 rflinn68

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Posted 10 January 2013 - 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.

#20 Jeff Morgan

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Posted 10 January 2013 - 04:26 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.c...px?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.

#21 Gray

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Posted 10 January 2013 - 05:57 PM

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.cloudynig...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!

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#22 Gray

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Posted 10 January 2013 - 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!

#23 Jon Isaacs

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Posted 10 January 2013 - 07:44 PM

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

#24 dpwoos

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Posted 10 January 2013 - 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.

#25 Gray

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Posted 11 January 2013 - 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






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