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A Larger Dob or TEC APO180FL?

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#1 Peter Natscher

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Posted 25 December 2010 - 09:23 PM

Seasons Greetings and a Fabulous 2011 to All at the Refractors Forum! Do something different in 2011!!

My 24" Starmaster Dob is sold and shipping out after New Year's. I've given up anything larger due to caring for my back's health. I've done my observing with large Dob's for 15 years and now I'm looking for a new way to observe -- a different way with a new kind of telescope, hopefully with smaller pieces to carry. Would a mid-sized APO do this for me? I am initially thinking about a new and "smaller" 20" F/3.3 Starmaster GoTo with all quartz optics, quick cool-down time, lower eyepiece height -- and this choice would allow me to sit in my adjustable observing chair at the eyepiece at all telescope elevations -- really cool! But, my other big choice is the TEC APO180FL on a AP900GTO mount. I like to observe everything from the Moon, planets (daytime and night), double stars, nebula, and DSO's. I have the budget for either of these superb telescopes but they are totally different from each other in what they will allow me to see. I'm used to aperture (18"-24") but am tiring of the large Dob boxes and mirror/cell weight to set up -- not to mention the usual optics collimation time. The TEC 180 on a GEM will provide contrasty views, better focus, more acceptable nights of observing than the 20" Dob will, plus no more collimation or mirror thermal issues. The TEC 180 will be available with this spring's run only while any Starmaster Dob can be ordered at anytime should I end up missing the larger aperture. I'm currently obsessed with my thoughts about the sharper views, better contrast, overall a better optical system with the TEC -- seeing the diffraction rings around stars at 300x that a Dob just doesn't show. Which telescope should I choose for my next few years of observing? :confused:

#2 oxygen

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Posted 25 December 2010 - 09:59 PM

WIN WIN

But if you have had the big dobs and looking for something new go with the TEC 180. If you could set it up permanently set up time will be nothing compared to a 20" dob, almost as simple as turn it on and start observing. Sounds like you are likely leaning towards the TEC so i say give it a go.

#3 Mel M

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Posted 25 December 2010 - 10:38 PM

How much time do you usually spend on set-up and collimation? Do you like the large mak-newts?

#4 blueman

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Posted 25 December 2010 - 11:03 PM

The TEC 180 is a great scope that gives as good a view as any refractor that I have ever used.
However, a 7" APO will not give a view that compares to a 20-24" DOB. Aperture does rule when you are trying to see dim objects, so if you like faint fuzzies, the 180 will not perform like you are use to seeing.
The 180 will deliver sharpe images, double stars and planets that will be very pleasing.
The weight of the 180 is not too heavy, but it is not 20 lbs either. The AP900 and the scope will add up to a bit, but it will be several pieces.
Blueman

#5 David Pavlich

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Posted 25 December 2010 - 11:24 PM

I think Floyd said it best. I can't add to it. However, if imaging has ever crossed your mind, the big TEC on the AP mount would be loads of fun!

David

#6 johnnyha

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Posted 25 December 2010 - 11:43 PM

How about spicing it up and adding a Mewlon 250 to the mix? :grin:

#7 Ziggy943

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Posted 26 December 2010 - 12:35 AM

As you stated above they are at different ends of the telescope spectrum. They are each great representatives. DSO objects no doubt will not be as bright and globulars not as well resolved. Not by a long shot. For planets and double stars you may not be giving up as much and gaining a lot of convenience. The AP 900 mount was my mount of choice for the 160 TEC. The 180, as pictured by Blueman, is also a good fit for the 900.

Tough choice. You can't go wrong either way. It only takes me 15 minutes to set up my 160 on the 900. All of the components travel easily in a minivan. Big dobs, IMHO, are more work, but they're worth it if DSO's remain you top priority.

#8 Alan A.

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Posted 26 December 2010 - 12:50 AM

I think the way to go would be to get the 20" scope and keep a 5-6" refractor as well. That way, depending on your time and energy, as well as your target list for the night you can pick your weapon. On a night of so so seeing and transparency and less available time - set up the refractor. On good steady nights when you have more time available - set up the dob. Thats my 2 cents.

#9 gillmj24

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Posted 26 December 2010 - 05:24 AM

It's not quite a huge dob in size but a ~40lb refractor and it's required mount isn't exactly easy on the back either. Just don't hurt your back and drop the scope, you'll love it once it's set up though.

#10 alrosm

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Posted 26 December 2010 - 05:37 AM

My feeling is that you need to use the tec before you buy it to make sure the loss of aperture is not gonna be a problem for you.
The Tec will be great for astrophotography.

#11 Erik Bakker

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Posted 26 December 2010 - 07:31 AM

Hi Peter,

I think for visual observing the TEC FL180 will be a very rewarding scope. For my taste, it is too massive to haul around with it's mount to dark sites. So if you can mount it (semi)permanently, it would be my first choice along with a 4" APO for grab and go and easy travel to dark sites for widefield and general observing. For the moon, doubles and planets the FL180 will rule at home.

CS,

Erik

#12 Jon Isaacs

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Posted 26 December 2010 - 07:47 AM

I think the way to go would be to get the 20" scope and keep a 5-6" refractor as well. That way, depending on your time and energy, as well as your target list for the night you can pick your weapon. On a night of so so seeing and transparency and less available time - set up the refractor. On good steady nights when you have more time available - set up the dob. Thats my 2 cents.


This makes good sense to me. A 7 inch refractor on a serious EQ mount is not such an easy setup, I am not sure how much easier it would be than compact 20 inch. The difference between a 5 inch and a 7 inch apo of course is real but the 5 inch is quite manageable by comparison.

Once one is accustomed to having some serious aperture, giving it up may be more difficult than it seems at first. It is one thing to be viewing faint fuzzies with a relatively small scope knowing that a big one is there if need needed but if the smaller scope is all you have, then it just might be frustrating.

Multiple scopes are the ticket, it's just a question of which ones.

Jon

#13 skybsd

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Posted 26 December 2010 - 08:27 AM

My feeling is that you need to use the tec before you buy it to make sure the loss of aperture is not gonna be a problem for you.
The Tec will be great for astrophotography.


I'd wholeheartedly agree with this sentiment, really.

Not on the same scale of aperture shock as you are venturing, but if the difference between my C-14 and SV105-F6.2 is anything to go by, the difference in what you see and can see at the eyepiece is massive.

This IS your money we're talking about here, so I'd reckon that its only prudent to find a way to "see" for yourself what this difference represents, in order for you to be sure that you're going to be satisfied with such a change.

Regards,

skybsd

#14 Peter Natscher

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Posted 26 December 2010 - 11:41 AM

How about spicing it up and adding a Mewlon 250 to the mix? :grin:


I had a 10" Mak F/14 and the focal length was too long for my observing tastes. I like the idea of a F/7 scope to get wide fields (1.5-1.9 deg.) yet high enough APO lens quality to get high-power planetary views, also. The 180 would be very versatile. My experience observing thru other's Maks and APOs says that the APO has better contrast.

#15 Peter Natscher

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Posted 26 December 2010 - 11:47 AM

How much time do you usually spend on set-up and collimation? Do you like the large mak-newts?


It's only 20 minutes for set up of a 20" Dob and another 5-15 minutes collimating. I'm fast with this procedure out at a site since basic collimation is done beforehand in my garage. I usually observe away from home on paved parking lots meeting up with my group at dark site locations. The residual heat radiating off of the pavement 'til midnight affects Dob's performance greatly. Sometimes, much of the night is lost to a mirror that doesn't cool properly and you get sub-par views no matter what aperture you have. A refractor mounted 60" high up on a pedestal doesn't get the parking lot heat effect. Refractors get to be used earlier on in the evening with better performance.

#16 Peter Natscher

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Posted 26 December 2010 - 11:53 AM

The TEC 180 is a great scope that gives as good a view as any refractor that I have ever used.
However, a 7" APO will not give a view that compares to a 20-24" DOB. Aperture does rule when you are trying to see dim objects, so if you like faint fuzzies, the 180 will not perform like you are use to seeing.

The 180 will deliver sharpe images, double stars and planets that will be very pleasing.
The weight of the 180 is not too heavy, but it is not 20 lbs either. The AP900 and the scope will add up to a bit, but it will be several pieces.
Blueman


You are right about a 20"ers light gathering benefit over a 180mm scope. Even with my past 10" Mak, views of Saturn were superb up to mid-powers, but once it was pushed over 300X, Saturn faded too much eliminating any more detail to be seen. OTOH, my 20" F/4.2 Dob (Zambuto) provided bright detailed views of Saturn up to 600X when the seeing permitted and the mirror was fully equilibrated.

#17 Peter Natscher

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Posted 26 December 2010 - 11:59 AM

I think the way to go would be to get the 20" scope and keep a 5-6" refractor as well. That way, depending on your time and energy, as well as your target list for the night you can pick your weapon. On a night of so so seeing and transparency and less available time - set up the refractor. On good steady nights when you have more time available - set up the dob. Thats my 2 cents.


In my observing experience over the past 15 years, I was never able to forecast how good the seeing was going to be before driving out to a dark sky site here in central California. Many times, the sky's afternoon appearance and weather forecasts looked marginal but it turned out very good for everyone after sunset while we were all set up for the evening. You get out with your best equipment each time hoping for the best weather conditions.

#18 Peter Natscher

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Posted 26 December 2010 - 12:09 PM

I think the way to go would be to get the 20" scope and keep a 5-6" refractor as well. That way, depending on your time and energy, as well as your target list for the night you can pick your weapon. On a night of so so seeing and transparency and less available time - set up the refractor. On good steady nights when you have more time available - set up the dob. Thats my 2 cents.


This makes good sense to me. A 7 inch refractor on a serious EQ mount is not such an easy setup, I am not sure how much easier it would be than compact 20 inch. The difference between a 5 inch and a 7 inch apo of course is real but the 5 inch is quite manageable by comparison.

Once one is accustomed to having some serious aperture, giving it up may be more difficult than it seems at first. It is one thing to be viewing faint fuzzies with a relatively small scope knowing that a big one is there if need needed but if the smaller scope is all you have, then it just might be frustrating.

Multiple scopes are the ticket, it's just a question of which ones.

Jon


I'm getting that returning feeling again that it's best to have two telescopes: go with the 20" F/3.3 all quartz fast cooling Dob (Starmaster FX-Q) to satisfy my deep sky observing at a dark site and get a smaller TEC 140 or 160 on a smaller than AP900 mount (AP Mach 1?) for at home observing in brighter skies where I can enjoy the planets and Moon. Yuri, of TEC, is making a 180FL run this spring so I had to think about the 180 now. Buying a TEC140 or 160 gives me time since these runs haven't been announced yet. The 20" Dob can be ordered now.

#19 Ziggy943

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Posted 26 December 2010 - 12:22 PM

A 7 inch refractor on a serious EQ mount is not such an easy setup, ...

Jon


IMHO the 180 on a AP900 mount would be an easy set up. One person can easily handle all of the parts, no tools required. The telescope can be set up in 15 minutes. You can't get away from all work if it is to be a portable telescope.

#20 Peter Natscher

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Posted 26 December 2010 - 12:38 PM


A 7 inch refractor on a serious EQ mount is not such an easy setup, ...

Jon


IMHO the 180 on a AP900 mount would be an easy set up. One person can easily handle all of the parts, no tools required. The telescope can be set up in 15 minutes. You can't get away from all work if it is to be a portable telescope.


I know setting up a mid-sized refractor (160-180) on a AP900 mount and 60" pedestal would take the same amount of time and effort as setting up a 20" Starmaster Dob. I've set up similar telescopes before. I think the 180, 900 mount and 60" pedestal would take less space in my SUV than the 20" Starmaster. The heaviest parts of both telescopes are: AP 900GTO at 50lbs., AP 60" pedestal at 50lbs., TEC180 at 37lbs, and the Starmaster Dob 20" F/3.3 mirror & cell are 48lbs. None of these weights alone are prohibitive to me.

#21 Peter Natscher

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Posted 26 December 2010 - 12:41 PM

Hi Peter,

I think for visual observing the TEC FL180 will be a very rewarding scope. For my taste, it is too massive to haul around with it's mount to dark sites. So if you can mount it (semi)permanently, it would be my first choice along with a 4" APO for grab and go and easy travel to dark sites for widefield and general observing. For the moon, doubles and planets the FL180 will rule at home.

CS,

Erik


One reason for my desire to get a refractor is to enjoy daytime planetary observing along with visual-filtered solar observing. A Dob isn't good for this. A 140 or 160 would work fine for this.

#22 Aquatone

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Posted 26 December 2010 - 12:42 PM

I used to own a 180 mounted on an AP900 but I would not call it an "easy" setup by one person. Manageable yes, but not easy. It is not so much the weight, it is the long movement arm of the telescope and the *height you have to lift* a very expensive instrument onto the mount. You are probably going to be lifting to the level of your head at least. For this size telescope the pier needs to be at least 50" high and ideally more if you are not going to be crouching down when looking at zenith objects.

Personally, I came to realize that 160mm is really the sweet spot size for a refractors when it comes to reasonable aperture, viewing comfort, portability, and ease of setup. Of course if you are 6"3" and a power lifter you may disagree!

Chris

#23 blueman

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Posted 26 December 2010 - 12:57 PM

Here is what the TEC 180 on an AP mount looks like. It is not small and it was not that easy to hang it either, but doable by one person. Providing you are tall enough that you are not making a big reach. I am 5'10" for perspective.
Blueman

Attached Thumbnails

  • 4272619-180-Tec-&-Me-W.jpg


#24 Eddgie

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Posted 26 December 2010 - 01:07 PM

I have a 6" f/8 APO that only weighs about 30 lbs complete with Telrad, 2" diagonal, and 31mm Nagler.

While it is not as hard to get into the saddle as my C14 is, the fact is that it has to be mounted HIGHER than the C14. The extra height means that you are lifting the entire weight over your shoulder to mount it.

It is not all THAT easy on one's back to be lifting 40+ pounds 6 feet in the air. Remember, you have to put rings and a dovetail on it. This all adds up.

The extra one inch of aperture you are going to get between a 6" refractor and a 7.1" refractor is not going to set the world on fire.

But it sounds like you WANT a 7" APO, so if we get to vote on it, I think you should get exactly what you want.


#25 kevin M13

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Posted 26 December 2010 - 01:11 PM

I like the idea of a F/7 scope to get wide fields (1.5-1.9 deg.) yet high enough APO lens quality to get high-power planetary views, also. The 180 would be very versatile. My experience observing thru other's Maks and APOs says that the APO has better contrast.


If you really like wide fields, I think this is the key place the refractor wins hands down. I always liked the deep sky capture of my modest dob, but I never could get used to the coma. The paracorr only helps a little.

Exciting times for you! Good luck.

Kevin


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