27 replies to this topic

[Harold88]

Hello!

In my quest to search the night sky I have a dilemma.

Currently I have 3 telescopes, one 10 inch dobsobian, one 4 inch f7 Ed and one small C90.

I am using mostly the F7 for balcony astronomy and I am thinking to add another telescope that will be able to do what my F7 can't and that is enough magnification on planets and also take a binoviewer without any modifications of the tube.

I am thinking of putting the F7 on a skytee type of mount tougher with a catadioptric telescope.

I have read and read and read for the last week's but I'm still not sure about what I should go for.

The options I see are those:
Skymax 150 or 180
A C6 or C8
A classic Cassegreain 6 or 8 inches.

The budget is also somehow tied.
The cheapest option in Europe right now is a classic Cassegreain which costs around 500$.
6 inches make is around 800$ , C6 is 1000
180 make is around 1200$ and the cheapest C8 from Celestron is around 1400$.

I am open to any suggestions.

[mrowlands]

I think you would be disappointed with a 6 inch obstructed scope compared to the 4 inch refractor.  Even an 8 inch will have to be well thermally acclimated to beat the refractor, and the "seeing" will have to be decent.  At least that's been my experience.

 

An 8 inch will allow you to use more magnification at a respectable exit pupil.

 

Mike R.

[Harold88]

So even for planetary the jump from my 4 inch refractor to a 6 inch obstructed reflector is not going to wow me?

I should aim for at least a skymax 180?

Edited by Harold88, 17 July 2024 - 09:20 AM.

[vtornado]

For planets, I thought a 4 inch ED was was rougly equivalent to a 5 inch Mak.   So I doubt that going to a 6 inch CAT would wow you.  It would be an incremental step up.

 

I would go with the skymax 180 or an 8 inch SCT.  There are lots of used C8's floating around , at least in the states.  I have never looked through a 180 Mak, so the recommendation  it is just based upon aperture.  I know they are quite heavy.

 

My sky tee can handle a heavy tube 20 lbs.  I'm unsure about two scopes???

 

Be aware that depending upon where you live cats have to be insulated/cooled and may require dew remediation.

[Harold88]

Be aware that depending upon where you live cats have to be insulated/cooled and may require dew remediation.

Well summer's are torrid and winter's are usually cold 🙂

[Jon Isaacs]

Well summer's are torrid and winter's are usually cold

Insulation seems to manage the thermal issues of SCTs and Maks.. 

 

For most purposes, your 10 inch Dob is a good companion for your 4 inch F/7... It is your interest in binoviewing which makes the Cassegrain of interest..  But they have long focal lengths so they will not provide a wider field of view than the Dob used with an OCA.

 

Jon

[Harold88]

Unfortunately I am not able to do balcony astronomy with my dobsobian, I have to go outside the city and very rarely I am able to do this.
If I would have lived somewhere near the city, in a house with large enough yard, I would have used only the dobsobian and a pair of binoculars but unfortunately this is not the case.

[jhwilmes]

That makes a lot more sense. Usually an 8-10 inch reflector is considered a good complement to a 4" refractor. I am guessing being more compact and able to mount makes it easier for the balcony. I would stick with one of the larger options you listed (skymax 180, 8" Cass, C8), though I don't know enough as to which of those scopes is best for your needs.

[Harold88]

I don't know enough as to which of those scopes is best for your needs.

I am very curious about the difference in price between a Classic Cassegreain and a SCT, why is a SCT 50% more expensive?

Edited by Harold88, 18 July 2024 - 01:56 PM.

[sevenofnine]

The 6" Mak will likely fit on the same mount as your 4" refractor. That could be a consideration for balcony use. The scope's long focal length and sharpness makes it excellent for planetary use IMO 

[Brent Campbell]

I have a 4 inch f7 like you, a 10 inch DoB, and an 8 inch c8.  I am considering retiring my c8 next year -  want to see how my 10 inch dob does on planets.  The reason is that I am considering this is that an 8 inch sct can be heavier than a 10 inch dob due to the size of the mount, the dob has a wider fov, and the dob is actually more ergonomic than an sct.  

 

Scts are not all that convienient when you look at the sum of the parts needed to make them complete.  The 4 inch f7 is 80 to 90 percent of the c8 depending on conditions, and it’s a whole lot easier to mover around.   The c8 requires a dew shield, mount ( in my case a very heavy ultima fork mount), tripod, diagonal.  Focusers on most c8 s are nothing to get excited about ( I replaced mine with a fethertouch upgrade).   You may up spending a bunch of money for a scope that is sort of meh compared to your dob.
 

I would look through a c8 before purchasing.  In this case a star party visit will either confirm your plan, or you’ll be thanking me for saving you money.

Edited by Brent Campbell, 18 July 2024 - 06:28 PM.

[Echolight]

Buy used.

[Echolight]

I think you would be disappointed with a 6 inch obstructed scope compared to the 4 inch refractor.  Even an 8 inch will have to be well thermally acclimated to beat the refractor, and the "seeing" will have to be decent.  At least that's been my experience.

 

An 8 inch will allow you to use more magnification at a respectable exit pupil.

 

Mike R.

Depends what you mean by beat.

 

An 8 inch will show nebula and globular clusters, as well as fine detail on the Moon in ways that a 4 inch just can't.

 

Of course all these will take a hit with binoviewers. 

I didn't really take that into account.

Edited by Echolight, 18 July 2024 - 08:41 PM.

[Spikey131]

This is what I do.  Since 2017.  A great combination.

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[Echolight]

This really belongs in the cats and casses forum instead of reflectors.

Or maybe the binoviewers forum if you're dead set on that.

 

You'd likely get more response on the scopes you are looking at.

 

Me, I'm a fan of the C8 for a little big scope.

Compact, lightweight, closed tube, and plenty of light gathering.

I bought mine used. It's now 24 years old.

But I've never used binoviewers. Instead, I use a reducer corrector and a Baader 2 inch diagonal sans nosepiece or visual back to get 105mm backspace behind the reducer.

Gets 1.8 degrees with a 28 PWA and goes 400x on the Moon. Sucks up nebulosity like a vacuum.

 

For me, a C8 on a manual alt az mount is way lighter with more ergonomic view than a 10 inch dob.

 

Zenith

 

Mid elevations

 

Or low over the horizon

 

are all equally easy to look at.

 

This gets used about 5:1 over my 10 inch dob. Just easier in every way.

[dnrmilspec]

I agree with echolight.  The 8" scope will be the top performer of your choices.  Here is a bit of a long answer.

 

I don't know what your mount is now or what you are considering.  I do know that sufficient capacity and tracking will be important for you from your balcony for a couple of reasons.  The first is that you are in a city and next to a building.  You will have to contend with disturbances in seeing from a variety of sources in addition to the natural ones.  Spending more time at the eyepiece is the best way to experience moments of good seeing that will reveal exciting planetary detail to you.  The second is that you will want to use much higher magnification which will make manual tracking more difficult and, at best, annoying. 

 

The 8" SCT will outperform both the 7" Mak (by a little) and the 4" refractor (by a lot).  I have owned 5" and 7" Maks.  They are lovely scopes.  The moon through either is a joy to behold.  A well collimated and equipped 8" SCT is better.  Physics is annoying sometimes.  Not that you could go wrong with either.  Suffice it to say that both the SCT and larger Maks require a really nice mount.  Something in the AVX class would be good if the budget allows.  But a less expensive used tracking mount, with or without goto, is important IMO.  A used AZ/EQ5 would be really cool.  Your proposed SkyTee2 would be good provided you enjoy using the alt/az knobs. 

 

There is a lot of debate about Classical Cassagrains and SCTs.  The SCTs are easier to mount and most say better corrected though for planetary this is not such a big deal.

 

So given your choices and being kind to your budget. I would look for a used 8" SCT on some kind of a tracking mount.  Given used prices, that should give you very good bang for your buck. The 8SE Celestron will do a good job for you if you want new.

 

You have a 10" Dob so you know what a larger scope can do. 

 

I think the thing to keep in mind is that this will not be your last telescope.  If you do not like what you get, changing will not be a hassle.  Whatever you get enjoy it. 

[Harold88]

 

I don't know what your mount is now or what you are considering.  I do know that sufficient capacity and tracking will be important for you from your balcony for a couple of reasons. 

 

Curently I have my f7 on a Twilight I AZ on a steel tripod. It's a nice mount for the money, I don't really have any complains.

 

I also have an AZ Gti which I am able to put it on a omegon titania 600 tripod. Here my little future project is to use this combo with my little C90 mak purely as a tracking device, to be able to find the celestial objects faster and keep the rest of the scopes manually driven.

[Harold88]

This is what I do.  Since 2017.  A great combination.

Looks awsome but I think that kind of mount is way above my budget and to be honest I preffer to firstly build myself a nice collection of eyepices before spending so much on a mount.

Edited by Harold88, 19 July 2024 - 01:39 AM.

[balcon3]

I agree with the others who recommend an 8-inch Cassegrain style telescope to complement your 4-inch refractor. I have a Mewlon 180c to complement my 80mm f7 ED refractor, and the pairing works very well. The refractor for wide views, the 180c for planets, globular clusters, and other objects that benefit from magnification. Planets in the the 180mm scope look awesome. I don't think an obstructed 6-inch scope will provide a significant upgrade from your unobstructed 4-inch refractor. I would go for 180mm minimum. Binoviewing setup is easy with a Cassegrain/SCT.

 

One other possibility that I will just throw out there for discussion is a 5-inch refractor. I've never owned one so I am not necessarily recommending it. But I have seen comments to the effect that it is a signficant step up from 4-inches, particularly on planets. You would need a different mount since the Twilight I won't be able to handle it.

 

The ability to see details on planets is highly dependent on seeing. If you live under the jet stream or in a place where the seeing rarely gets above 200x, you may not often be able to benefit from the higher magnifications that an 8-inch scope will allow.

[Harold88]

One other possibility that I will just throw out there for discussion is a 5-inch refractor. I've never owned one so I am not necessarily recommending it. But I have seen comments to the effect that it is a signficant step up from 4-inches, particularly on planets. You would need a different mount since the Twilight I won't be able to handle it.

 

I have taught about it but ,  from what I have read, whilst you can get away by using some cheaper ED glass for a 4 inch f7, when you are going 5 inch or above, this isn't viable anymore. So for a 5 inch refractor only a true apo should be considered or a long focal refractor but that is a very large and heavy beast so it's not really for me.

 

There are some nice light weight carbon apos, like the AP 127/952 triplet from Explore Scientific, made with FCD 100 glass, but the price makes me cry.

 

Also I don't think it works with a bino without a barlow.

[Echolight]

Looks awsome but I think that kind of mount is way above my budget and to be honest I preffer to firstly build myself a nice collection of eyepices before spending so much on a mount.

Forget binoviewers then. A good one ain't cheap, and you have to have twice as many eyepieces.

[mrowlands]

A friend has/had an Omegon Twinmaster which I think is the same as the SkyTee.  He used a C9.25 and a 90 or 100mm refractor and it was pretty solid.  However, that was using while sitting down.  I can see where it might not be as solid if the tripod legs are extended for observing standing up.

 

I think the 180 MCT will be a nice step up, especially for planets.  So will the 8" SCT, and due to it's wider field and slightly more aperture, will be more versatile for deep space.

 

Mike R.

[Bomber Bob]

Buy used.

That's what I did.  Like you, I already had an 8" F6 Newtonian, but can't use it right now.  Instead, for less than $300, I got a 1986 C8:

 

 

On a balcony, the tripod EQ kit could be too crowded to use.  I also have a pedestal EQ & a hefty AZ option:

 

[Harold88]

for less than $300, I got a 1986 C8:

 

 

I have never seen such prices, USA is something different, you cannot compare it to Europe, you people are buying and selling way more compared to the rest of the world.

[Bomber Bob]

I have never seen such prices, USA is something different, you cannot compare it to Europe, you people are buying and selling way more compared to the rest of the world.

I bought my excellent condition C8 on ZEN Marketplace -- Japan's eBay.  It was originally an SP-C8, and still had the hardware to attach to the Super Polaris.  I removed all that, and put hinged rings on it -- makes it easier to swap between mounts.

 

FYI:  AFAIK, ZEN will ship to Europe...

Edited by Bomber Bob, 19 July 2024 - 11:46 AM.