Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Luna and Planetary Scope (visual)

This topic has been archived. This means that you cannot reply to this topic.
50 replies to this topic

#1 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 29 March 2016 - 07:24 PM

I am currently looking for a 100% visual scope for quick Luna and planetary views from my heavily light polluted back yard.

At the moment I have my eye set on a Tak FC100DF. Triplets may have better colour correction but they're far more front heavy and take considerably longer to cool down.

I will probably end up hitting the second hand market. With this in mind, is this the best path to go down? I had at first considered a good 8" F/6 newt but that'll take even longer to cool down, like, a LOT longer.

Thoughts?

Edited by AtmosFearIC, 29 March 2016 - 09:07 PM.


#2 tomjones

tomjones

    Viking 1

  • *****
  • Posts: 706
  • Joined: 25 Jan 2011

Posted 29 March 2016 - 08:35 PM

6" f/8-10 reflector and if you get a quality mirror can be as good as a cheapo 6" lens like apm edapo.



#3 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 29 March 2016 - 09:22 PM

Orion UK make a 6" F/8 with a 1/10 Wave system. How long would something like this take to acclimatise?

Just to further explain what I am looking for. I have a 130mm triplet refractor that I use for imaging, this takes about half an hour to go through the polar alignment routine. While it is doing its 9 minute sky models I plan on doing some planetary stuff.

Or maybe one night it is only going to be clear for a little while, want a scope that I can set up, make a cup of coffee and then get to observations.

From the research I have done so far it appears that a smallish doublet refractor is where this excels at, especially in regards to cool down times.

#4 george tatsis

george tatsis

    Apollo

  • *****
  • Posts: 1,437
  • Joined: 20 Nov 2008

Posted 29 March 2016 - 10:43 PM

Orion UK make a 6" F/8 with a 1/10 Wave system. How long would something like this take to acclimatise?

 

I used to have an Orion UK 6" f/11  1/10 and after I'd installed a small mirror fan, the telescope could reach thermal equilibrium in less than 30'. Even better, keep it in an unheated garage , shed,  or something and it's good to go.

 

George



#5 Erik Bakker

Erik Bakker

    Cosmos

  • *****
  • Moderators
  • Posts: 9,326
  • Joined: 10 Aug 2006

Posted 30 March 2016 - 01:09 AM

The FC100 is the perfect scope for your intended use and much more. Order now and enjoy ASAP!



#6 SeattleScott

SeattleScott

    Voyager 1

  • *****
  • Posts: 11,311
  • Joined: 14 Oct 2011

Posted 30 March 2016 - 01:50 AM

My experience with 4" doublets is it takes about 15 min for the objective to cool, but 30 for a 2" diagonal. By comparison my 10 OrionUK reflector takes 30-45 min to cool, without using the fan. The 6" model would probably cool about as fast as a refractor with a 2" diagonal. Maybe faster with the fan. Of course the frac can still win if you use a 1.25" diagonal. 

 

Apo pro refractors really seem ideal for lunar/planetary in multiple ways. Clear aperture, fast cool down, lack of collimation issues, you view thru the back of a long tube so body heat doesn't affect the view, etc. problem is the design doesn't scale well to larger apertures. But I recently did a shoot out with my Vixen 103ed versus my iOptron 150 Mak with very nice optics, and it was pretty much a tie on the Moon. The Mak probably won by a nose, but then it took longer to cool. So there may not be a big difference between a 4" premium Apo and a 6" scope. Obviously the OO should be nice optically, like mine, with a smaller CO than the Mak. So it would probably best a premium 4" Apo if you got it collimated just so, and it will be rated for more mag. It just isn't as convenient to pull out as my 9lb Vixen, nor would it be as good for wide fields. And I doubt the OO would win by much. For me convenience won, small planetary scopes that I don't need to collimate.

 

Obviously I do have the 10" OO but I really got that for DSO at dark skies.

 

Scott



#7 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 30 March 2016 - 05:24 AM

My experience with 4" doublets is it takes about 15 min for the objective to cool, but 30 for a 2" diagonal. By comparison my 10 OrionUK reflector takes 30-45 min to cool, without using the fan. The 6" model would probably cool about as fast as a refractor with a 2" diagonal. Maybe faster with the fan. Of course the frac can still win if you use a 1.25" diagonal. 

 

Apo pro refractors really seem ideal for lunar/planetary in multiple ways. Clear aperture, fast cool down, lack of collimation issues, you view thru the back of a long tube so body heat doesn't affect the view, etc. problem is the design doesn't scale well to larger apertures. But I recently did a shoot out with my Vixen 103ed versus my iOptron 150 Mak with very nice optics, and it was pretty much a tie on the Moon. The Mak probably won by a nose, but then it took longer to cool. So there may not be a big difference between a 4" premium Apo and a 6" scope. Obviously the OO should be nice optically, like mine, with a smaller CO than the Mak. So it would probably best a premium 4" Apo if you got it collimated just so, and it will be rated for more mag. It just isn't as convenient to pull out as my 9lb Vixen, nor would it be as good for wide fields. And I doubt the OO would win by much. For me convenience won, small planetary scopes that I don't need to collimate.

 

Obviously I do have the 10" OO but I really got that for DSO at dark skies.

 

Scott

Thanks for that Scott, still nudging me in the Tak direction. I have an Orion 12" GoTo Dob which I have for those times that I head up to my dark site. That thing takes like two hours to cool down though and is more sensitive to collimation being nearer to F/4. The truss is pretty solid though which is a big bonus over the last 16" Meade Lightbridge that I had.

 

The portability of a 4" refractor is wonderful and I would prefer to not have to deal with collimation and optical degradation over time (not that reiodizing the mirror every 10 years? is a big issue). I guess the Tak will take wide field better and also Bino Viewers which I don't yet own.



#8 Hesiod

Hesiod

    Aurora

  • *****
  • Posts: 4,722
  • Joined: 13 Jan 2013

Posted 30 March 2016 - 06:53 AM

The FC can be ready in about 30' (with a delta of 25°C between storage and outside), a 1.25" prism diagonal will be ready in the same amount of time

As a planetary scope it is good as any 10cm may be (but if you are used to your 12" the first impact may be estranging, even more if you are thinking to a 8" as a viable alternative); it is very pleasant too when observing from dark sites, for wide field swoops (which can be done even with 1.25" eyepieces due to the short f.l.).

 

As a dedicated planetary scope, the DC version may save you some money without any loss; if you desire to employ even 2" stuff, the DF is ready out of the box.

Due to the short f.l., the DF ability to get a binoviewer into focus without any focal amplifier is totally useless for planetary observations, and in any case I deem highly advisable a low-power GPC/OCS/etc...even for low-power views

 

Last, despite being advertised as "small" and "light", to get the best results I do not advise to get a mount smaller than a Great-Polaris sized one (T-sky or Twilight2 for alt/az)



#9 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 30 March 2016 - 07:34 AM

The 12" is new and I have only ever used it once and the collimation wasn't flash hot, setting up at midnight without a laser ;)

 

Pretty much all of my planetary viewing so far has been from a 10" SCT which has never been remotely close to cooled but have done some Luna with a SW 100ED I used to own. It gave sharper view than the SCT due to cooling.

 

I'd go the DF over the DC so that I can use 2" stuff.

 

Still considering whether to go alt/az or not but at this stage I will be using an old HEQ5, pre Synscan so it just has the stepper motors.



#10 Cliff C

Cliff C

    Mariner 2

  • *****
  • Posts: 240
  • Joined: 11 Feb 2009

Posted 30 March 2016 - 08:20 AM

Unless your leaving your 130mm scope set up on the tripod with cameras attached why not buy an alt/az mount for the 130mm?

You will need a mount for your second scope anyway. If you do not do too much astrophotograpy you could leave the 130mm on tha alt/az mount, carefully carry it outside in one pass to let it aclimate or keep it in a case and bring put the scope out in its open case 15-30 minutes before you observe.

For the ultimate in portable, quick set up scopes how about a Televue 85? A friend of mine has a Tak 78 and it is a fantastic scope. These 80mm'ish scopes are nice and short making them easy to get out the door. I still have my 70mm TV Pronto on an upswing head connected to a camera tripod. It takes only one hand to get out the door for quick peeks. The only downside to the Pronto is the color correction. Both the Tak 78 and the TV-85 have excellent color correction.



#11 stevenwav

stevenwav

    Viking 1

  • *****
  • Posts: 735
  • Joined: 06 Feb 2012

Posted 30 March 2016 - 08:50 AM

The new TAK FC100DL -f/9 is what you want. I just had first light with mine last night - AWESOME. Are you in Melbourne FL or AU?



#12 Eddgie

Eddgie

    ISS

  • *****
  • Posts: 27,522
  • Joined: 01 Feb 2006

Posted 30 March 2016 - 09:27 AM

 

My experience with 4" doublets is it takes about 15 min for the objective to cool, but 30 for a 2" diagonal. By comparison my 10 OrionUK reflector takes 30-45 min to cool, without using the fan. The 6" model would probably cool about as fast as a refractor with a 2" diagonal. Maybe faster with the fan. Of course the frac can still win if you use a 1.25" diagonal. 

 

Apo pro refractors really seem ideal for lunar/planetary in multiple ways. Clear aperture, fast cool down, lack of collimation issues, you view thru the back of a long tube so body heat doesn't affect the view, etc. problem is the design doesn't scale well to larger apertures. But I recently did a shoot out with my Vixen 103ed versus my iOptron 150 Mak with very nice optics, and it was pretty much a tie on the Moon. The Mak probably won by a nose, but then it took longer to cool. So there may not be a big difference between a 4" premium Apo and a 6" scope. Obviously the OO should be nice optically, like mine, with a smaller CO than the Mak. So it would probably best a premium 4" Apo if you got it collimated just so, and it will be rated for more mag. It just isn't as convenient to pull out as my 9lb Vixen, nor would it be as good for wide fields. And I doubt the OO would win by much. For me convenience won, small planetary scopes that I don't need to collimate.

 

Obviously I do have the 10" OO but I really got that for DSO at dark skies.

 

Scott

Thanks for that Scott, still nudging me in the Tak direction. I have an Orion 12" GoTo Dob which I have for those times that I head up to my dark site. That thing takes like two hours to cool down though and is more sensitive to collimation being nearer to F/4. The truss is pretty solid though which is a big bonus over the last 16" Meade Lightbridge that I had.

 

The portability of a 4" refractor is wonderful and I would prefer to not have to deal with collimation and optical degradation over time (not that reiodizing the mirror every 10 years? is a big issue). I guess the Tak will take wide field better and also Bino Viewers which I don't yet own.

 

 

 

Have you considered boundary layer fans for the 12"?  With boundary layer scrubbing, there is no cool down.  You get full resolution views within 30 seconds.

 

If planetary is a major part of your observing, you won't find a refractor you can afford that will beat a 12" dob with great mirrors, and if your mirrors are not great, for less than the cost of a larger Apo, you can have someone make your mirrors great.  My 12" dob has given me planetary views I never saw with my 6" Apo.

 

http://www.skyandtel...NewtThermal.pdf

 

 

Has anyone ever seen coating etching in an Apo from dew?  I have.   All scopes have their issues including refractors.  My AP suffered such damage, and Roland Christan said it would cost thousands to repair it because he would have to make new tools to strip it and then recoat it.. He basically said that it was not worth doing.   Not that it hurt the performance, but it was a major hit on resale.

 

Coatings damage.jpg

 

 

And modern silicon dioxide over-coated aluminium used on mirrors will last decades.  SiOis pretty standard on mirrors today, and with this coatings, mirrors will last decades (and perhaps longer).


Edited by Eddgie, 30 March 2016 - 09:55 AM.


#13 Astrojensen

Astrojensen

    Voyager 1

  • *****
  • Posts: 13,949
  • Joined: 05 Oct 2008

Posted 30 March 2016 - 02:34 PM

I am currently experimenting with a 4" high-end triplet apochromat and a 6" f/8 newtonian, specifically as planetary scopes. I am super impressed with the newtonian. It *always* shows more than the apochromat, even in poor seeing and in very good seeing, it pulls far ahead in terms of brightness and resolved details. It costs less than $300 as new, while the apo is over $4000 as new... 

 

I am NOT seeing a strong tendency to more stable images in the refractor, if I take some precautions when I use the newtonian. I am using a dew shield from a C8 to extend the tube of the newtonian and this alone seems to do wonders in keeping my body heat and breath out of the light path. I also insulate the top of the tube, so it doesn't get colder than the air and can't radiate heat away to the universe. The only reason the seeing seems a bit worse in the newtonian is because it actually has 50% better resolution and 100% more light, so I tend to want to use it at higher magnifications than the refractor. When I use the same medium magnifications, for example 100x - 120x, the image is equally sharp and stable. At higher magnifications, 150x - 250x, the refractor SEEMS more stable, because it resolves less than the newtonian, but the newtonian is vastly outperforming it then in terms of details and contrast. The difference is NOT slight. 

 

This doesn't mean I don't love refractors. I have lots of them and have no plans to stop using them.

 

 

Clear skies!
Thomas, Denmark 



#14 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 30 March 2016 - 07:05 PM

At the moment I have my imaging setup on a modified EQ6 Pro running EQMOD, I just happen to have and old HEQ5 laying around for visual purposes. I have an ASA DDM60 on the way to replace the EQ6.

The TV85 certainly is a nice scope and was on my short list as I was thinking about keeping below 90mm as a grab and go. Ultimately I decided to go with that little extra aperture to stave off wanting more :)

I am in Melbourne AU Steve, way down South :)

Taking cooling out of the 12" doesn't interest me, lugging a 12" dob outside, setting it up and all that just isn't going to happen for a half hour observing session. It's the reason I want a small scope for quick city viewing.

A quality 6" F/8 newt is going to be cheaper than a quality 4" doublet but the price between the two isn't enough to bother me. It's all weighing up between what is going to give the best view for what is going to be the easiest to use and get the most use. With the greatest emphasis on the last part.

#15 Astrojensen

Astrojensen

    Voyager 1

  • *****
  • Posts: 13,949
  • Joined: 05 Oct 2008

Posted 31 March 2016 - 02:46 AM

 

A quality 6" F/8 newt is going to be cheaper than a quality 4" doublet but the price between the two isn't enough to bother me. It's all weighing up between what is going to give the best view for what is going to be the easiest to use and get the most use. With the greatest emphasis on the last part.

If that is the case, a lightweight 4" doublet on a relatively lightweight mount sounds just like the right choice. 

 

 

Clear skies!

Thomas, Denmark



#16 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 91,288
  • Joined: 16 Jun 2004

Posted 31 March 2016 - 03:00 AM

 

 

A quality 6" F/8 newt is going to be cheaper than a quality 4" doublet but the price between the two isn't enough to bother me. It's all weighing up between what is going to give the best view for what is going to be the easiest to use and get the most use. With the greatest emphasis on the last part.

If that is the case, a lightweight 4" doublet on a relatively lightweight mount sounds just like the right choice. 

 

 

Clear skies!

Thomas, Denmark

 

 

Another consideration might be one of the 120mm Skywatcher ED doublets.  

 

Jon



#17 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 31 March 2016 - 04:06 AM

Tak:
- On the larger side but still grab and go, kinda airline portable not that I have any current plans on taking anything other than a pair of 10x50 binos on a flight.
- Cools marginally faster (15 minutes?).
- No need for collimation unless something seriously goes wrong.
- Fluorite, for its seemingly magical properties :p
- Less maintenance.

 

Orion Optics UK:
- Would not consider it grab and go, not unless compared to my 12" dob anyway  Still small and light.
- Cool down is a bit longer but not substantial (20-30 minutes?).
- Has 2.25x light grasp.
- Has better resolution.
- At F/8 collimation is very forgiving.
- Not fluorite but still good quality optics.

 

I am still nudging a bit more over to the Tak at the moment. It is considerably more expensive but it is more portable if I want to take somewhere other than my back yard, has better resale value (not that I am planning on selling either of them). Has the "But it is a Takahashi" draw to it  Has a nice chunk of protected fluorite.

 

Ultimately though, is it worth spending that bit extra? Especially when on paper a good newt with a small secondary (~22% on this one) should out perform.

It is this quandary which has me wanting to head to the Tak Party next weekend to view through a whole row of them!



#18 dweller25

dweller25

    Vanguard

  • -----
  • Posts: 2,247
  • Joined: 30 Aug 2007

Posted 31 March 2016 - 04:35 AM

I think you want to own a Tak ??? so go for the TSA120



#19 SeattleScott

SeattleScott

    Voyager 1

  • *****
  • Posts: 11,311
  • Joined: 14 Oct 2011

Posted 31 March 2016 - 05:04 AM

Just to complicate things a bit, the appeal of the Vixen 103 to me was largely its low weight. At 9lbs it pairs nicely with my $200 AZ4 alt az, which weighs 18 lbs. So it really is grab and go. Granted it isn't a Tak and it probably isn't fluorite but it should be very similar in performance while being more convenient. Just a thought. I suspect the Tak is a better seller but the people who get the vixen are folks who want near Tak performance with near Skywatcher weight.

 

Scott



#20 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 31 March 2016 - 05:16 AM

I think you want to own a Tak ??? so go for the TSA120

 

You may indeed be right there, still want to make the most practical decision though. I suppose I am trying to find a reason to talk myself out of a Tak :p The TSA, although better colour corrected... Being a triplet is pretty front heavy and takes a fair bit longer to cool down.

 

 

 

 

Another consideration might be one of the 120mm Skywatcher ED doublets.  

 

Jon

I actually owned an ED100 F/9 until about a month ago. Although it performed really well, it couldn't be pushed excessively. Not to the same point that a better corrected doublet or long focal length reflector can.

 

 

Just to complicate things a bit, the appeal of the Vixen 103 to me was largely its low weight. At 9lbs it pairs nicely with my $200 AZ4 alt az, which weighs 18 lbs. So it really is grab and go. Granted it isn't a Tak and it probably isn't fluorite but it should be very similar in performance while being more convenient. Just a thought. I suspect the Tak is a better seller but the people who get the vixen are folks who want near Tak performance with near Skywatcher weight.

 

Scott

 

At this stage I am planning on sticking with the HEQ5 but I may end up moving to a T-Rex or something in the future, who knows. The Vixen is another one to research I suppose :)



#21 Hesiod

Hesiod

    Aurora

  • *****
  • Posts: 4,722
  • Joined: 13 Jan 2013

Posted 31 March 2016 - 06:30 AM

Being ca 70 cm long* I do not think the FC100 may be deemed "airline portable".

These small refractors show highly contrasted views, and can equalize or even outmatch a lot of larger telescopes if the seeing is acting as bottleneck (IME they are at their best when the maximum resolution is around 1 arcsec, i.e. 52Or can be split, but Zeta Boo can not).

If you have a seeing that consistently allows details close to 0.5< arcsec to be resolved, a 4" could turn rather disappointing, no matter how good it may be.

If you observe from sites haunted by a not so good seeing*, and most of times even 1 arcesc details (e.g. solar granulation, the 5 largest among Plato's craterlets, etc..) fail to be noticed, a fine, quick 4" refractor may gift you a lot of pleasant nights.

 

EDIT

I have no direct experience of the AX103, but the vendor from which purchased the FC offered me it as a viable alternative for visual, and probably a better astrograph than the Tak

 

 

*larger telescopes will always show the same details, but in such cases the telescope with the better contrast will do it more easily (and quite often ,with the most pleasant look); the larger telescope may look a bit fuzzier because of the atmospheric flickering, allowing for instant pop up and sudden disappear of those smallest details the smaller one can not resolve

 

 

 

 

 

 

 

*may be shortened by unscrewing the dewshield and focuser, but in such case you will have to get some plugs to protect both ends.


Edited by Hesiod, 31 March 2016 - 06:34 AM.


#22 bobhen

bobhen

    Fly Me to the Moon

  • *****
  • Posts: 5,059
  • Joined: 25 Jun 2005

Posted 31 March 2016 - 08:05 AM

If you can afford the Tak TSA 120 get it. The OTA is 13 pounds. Yes a little front heavy but add a 2” diagonal and a finder and that helps – believe me it’s not that bad.

 

Cooling will take a little longer than a doublet but again we are not talking about a lot of time here and (unlike mirror scopes) the scope is usable at mid power even while it is acclimating. And (unlike mirror scopes) once acclimated you don’t have to worry about reforming heat plumes if temperatures drop.

 

The TSA 120 is a noticeable step up from 100 mm; “exceptionally” sharp, and very portable on a CG5 or EQ5 type mount or on many alt/az mounts for an even quicker set up.

 

I have owned a TSA 120 for the past 6 years and it is a remarkable telescope.

 

If the 120 is outside of your budget or portability requirments, for your stated needs, I would get the Tak 100 refractor and put it on a nice alt/az mount. You will enjoy the no-hassle portability and the plug-and-play ergonomics of the refactor and of course the killer Takahashi optic.

 

Bob



#23 james7ca

james7ca

    Cosmos

  • *****
  • Posts: 9,426
  • Joined: 21 May 2011

Posted 31 March 2016 - 06:39 PM

I know that this is a refractor forum, but for lunar and planetary work I'd go for a mirrored system (SCT or Newtonian). Much more bang for the buck and since you say you will be working from your backyard you shouldn't have any problem keeping such a system collimated and ready to use after a short cool down. However, if you were planning on traveling with your scope then a four inch or smaller refractor might serve you better. IMO, the main advantages of a refractor are robust portability (below a certain objective size) and wide-field viewing/photography.

 

Even something like a 6" SCT ($600) would be a great planetary/lunar scope and would be easier to handle/transport out to the backyard than just about any refractor of similar performance.



#24 AtmosFearIC

AtmosFearIC

    Apollo

  • -----
  • topic starter
  • Posts: 1,254
  • Joined: 10 Dec 2015

Posted 31 March 2016 - 08:16 PM

It is a scope that will largely be used from home because that's where I am most of the time :p
Definitely going to travel though, maybe weekends away or when I go to my dark site. Need something to use while the behemoth is cooling down! Plus, I am not really wanting to burn a hole in my retina when using a 12" F/4.5 and looking at the moon hehe

#25 james7ca

james7ca

    Cosmos

  • *****
  • Posts: 9,426
  • Joined: 21 May 2011

Posted 31 March 2016 - 09:43 PM

One issue to consider is your age. As your eyes get older you'll probably have more of a problem with small exit pupils when using high magnifications. This means that a 6" scope working at 200X will probably give you a more stable and better view with "old" eyes than will a 4" working at that same magnification. Even if both are resolving the same features the view with the larger aperture will likely be better (because the exit pupil at the eyepiece will be larger). This is another reason why a reflector with a larger aperture versus a smaller refractor will work better for some users. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics