Affordable, Lightweight Observing Scope for a CEM25ec

[stringB]

I'm in the process of upgrading my imaging rig and have a very new/nice CEM25ec leftover that I could possibly sell. However, My Astrograph that I AM selling, although fantastic for imaging is not large enough to do any observing of value. I'm getting a RASA8 so there will be NO observing at all with that. I was thinking of setting up a modest observing rig that's lightweight and affordable for the wife/kids to enjoy while I’m imaging (boring to them).  I have already started a meager collection of eyepieces and a nice 2” diagonal so at least a 2” focuser is a must. I would have no intention of imaging with this rig. The mount weighs only 4.7kg so I’d like to leave it rigged by the garage door and just walk out with scope mount and tripod. The mount is rated for a 12.3kg load. I want more than an 80mm refractor. Perhaps a Skymax 150 or similar. An inexpensive Newtonian comes to mind. I would like to load the CEM25 down with the best bang for the money without going way too far over the load rating of the mount and my back. I would use the built in polar scope and hand controller GoTo only. Teach the kids etc. Thank you in advance for helping an observing newb out.

Edited October 30, 2020 by stringB

[jonathan]

Perhaps a simple refractor could be an option, something like the Skywatcher Evostar 120.  Minimal maintenance, 2" focuser, easy to handle.

On the reflector side perhapse the Skywatcher 150P, it's probably the biggest you could reasonably manage already attached to a mount.  No diagonal required, easy to collimate, forgiving.

 

Edited October 31, 2020 by jonathan

[Alan64]

A short-focus Newtonian and a long-focus Maksutov are at the extremes; the Newtonian for low-to-medium powers and wider views of the sky, and the Maksutov for medium-to high powers with a narrow(er) view of the sky.

Newtonian... https://www.bhphotovideo.com/c/product/468744-USA/Vixen_Optics_2604_R130Sf_5_1_130mm_Reflector_Telescope.html

You won't need a 2" diagonal, or a diagonal at all, with a Newtonian.

Maksutov... https://www.bhphotovideo.com/c/product/1141693-REG/sky_watcher_s11520_127mm_maksutov_cassegrain_ota.html

That make and model comes with a 2" visual-back, and a 2" diagonal to boot.

There is also this economical yet very good ED-refractor to consider...

https://www.astronomics.com/astro-tech-at102ed-4-f-7-ed-refractor-ota.html

[stringB]

I seemed to make a big deal about the 2" visual. Yes, Id sure prefer it. However, In my price range I don't want to rule out choices like the C6 because they have a 1.25" visual. I like some of the choices already mentioned here for the money. I love the Astro Tech stuff considering the price.  I'm adding an Astro Tech 1.25 dielectric diagonal to my visual kit so I now can go either way

[Alan64]

A 6" Schmidt(C6) is lighter in weight compared to a 6" Maksutov(Skymax 150), but the secondary-obstruction of the Schmidt is larger than that of the Maksutov.  Albeit, a 6" Maksutov takes longer to acclimate, and due to its thicker correcting-plate, or meniscus.  All telescopes require acclimation before observing can begin; refractors the quickest, Maksutovs the slowest.  However, of all the mirrored designs of telescopes, a Maksutov does come closest to simulating the performance of an ED or apochromatic refractor.

Here's a comparison of the obstructions between a C5 f/10 Schmidt(left) and my own 127mm f/15 Maksutov(right)...

A telescope's secondary-obstruction is akin to a cataract of the human eye, which reduces sharpness and contrast.

This is the Maksutov I have... https://www.bhphotovideo.com/c/product/1291487-REG/explore_scientific_fl_mc1271900tn_firstlight_127mm_f_15_alt_az.html

The Orion and Sky-Watcher 127mm f/12 Maksutovs have an effective aperture somewhat less than advertised; approximately 118-120mm.  The ES(US) and Bresser(Europe) 127mm f/15 Maksutovs are at a full 127mm, and with somewhat smaller obstructions, which is why I chose an ES over the former. 

A 5"/127mm Maksutov is the sweet-spot among the varying apertures of the design; not too large, nor too small, just right rather.  A 127mm would acclimate faster than a 150mm, and would be lighter in weight of course. 

Both Schmidts and Maksutovs are for seeing objects up close, which is what a telescope is for in the first place.  Else, one would use their eyes or a pair of binoculars.  A Maksutov, in particular, is like a microscope, but for the sky.  In addition, the majority of deep-sky objects are small, and will fit within the view through a Maksutov at the lowest power(59x, for the ES).

Celestron does offer a focal-reducer for their C-series Schmidts, shortening the focal-ratio from f/10 to f/6.3.  Such enables somewhat lower powers and somewhat wider views.  Maksutovs may make use of such as well.  But in the end, I would think that both types of telescopes perform best at their native configurations; f/10, f/12, and f/15.

Edited November 1, 2020 by Alan64

[jonathan]

3 hours ago, stringB said:

I seemed to make a big deal about the 2" visual. Yes, Id sure prefer it. However, In my price range I don't want to rule out choices like the C6 because they have a 1.25" visual. I like some of the choices already mentioned here for the money. I love the Astro Tech stuff considering the price.  I'm adding an Astro Tech 1.25 dielectric diagonal to my visual kit so I now can go either way

2" diagonals are easily converted to 1.25" with a simple insert, in fact I think most 2" diagonals probably come with such an adaptor (mine certainly did) or they are readily available and cheap.  I would advise trying to buy such things that have a brass compression ring as this will be nicer for your eyepieces and other equipment that slots into them.

In my experience there are actually not that many 2" eyepieces, usually it's ultra-wide field or highly specialised ones that probably require a specialised scope to make proper use of them.  I think I only own one 2" eyepiece.

[stringB]

The 2" visual is about more than the diagonal. I have other 2" items I would like to use in the image(visual) train. (more on that later) I think the CEM25 would handle the Skymax150. That's on the short list of possibles. I just saw the Stellalyra 6". It seems to check off a few boxes too. What does the group think? 

Edited November 1, 2020 by stringB

[johninderby]

Loving my new StellaLyra  6” Classical Cassegrain. Using as my grab’n’go planetray scope. Compared to a mak no dewing and much quicker cooldown, fixed primary so no mirror flop and a proper Crayford focuser.  Great build quality. 👍🏻

The. Classical Cassegrain is great for visual and lunar / planetary imaging. The RC is better for DSO imaging.

I have upgraded the focuser to a Baader Steeltrack but the standard focuser is certainly usable.

Edited November 1, 2020 by johninderby

[stringB]

NICE!

I would indeed want the CC. Does the Stellalyra 6" have enough backfocus to accommodate the following (hand-me-down) visual train?

EDIT: Eyepiece, 2" Astro Tech  dielectric mirror diagonal, ZWO 2" filter drawer (21mm).   I'd like to use a left over ASI120mm Mini and WO Uniguide 32mm guidescope. I'm  doing GoTo, plate solving and polar aligning with an ASIAIRPro120mm/Skysafari but I'm not guiding with it in this proposed rig.

Edited November 1, 2020 by stringB

[johninderby]

It does have lots of back focus. Specs say 150mm of backfocus beyond the focuser.

[lenscap]

On 30/10/2020 at 01:28, stringB said:

The mount weighs only 4.7kg so I’d like to leave it rigged by the garage door and just walk out with scope mount and tripod.

CEM25                      4.7 kg

1.5" tripod                5 kg   (2" is 8 kg)

150p     about          5  kg  

Counterweight say   5 kg

 

Total about 20kg and very top-heavy.   Could you lift it?    Sure, but I wouldn't call it lightweight.

Would an SCT on an Alt/Az goto be more portable?

[stringB]

Quick answer is NO. I was removing the counterweight with my Askar Fra400  but it was so light that I could practically  run it with nothing but the CW bar. (of course I didn't) It was also safe when I set it down without the CW long enough to install it. The entire kit was only a 11kg carry to the backyard.

When I started this visual carry kit idea I was thinking of a C6 or the 127. Without the CW the entire kit weighs about 14kg. Then aperture fever set in. Now I'm up to 20kg with the 150. I can lift 20kg but not when it's so awkward and valuable. I'm not sure it would be safe without the CW until it was installed. The jury is still out on this idea... Imaging rigs can be very lightweight but a visual kit will have to be very underpowered to remain an easy carry. That's why I'm asking for ideas. I like the SCT on an Alt/Az goto mounts for a family kit but the whole point of this idea is to find a use for the unused CEM25ec. Shipping costs have made selling it, giving it away and it's a month old.

[stringB]

Im in the US so I ordered the Orion CC6. Thanks for everyone that contributed to this topic. I learned a lot from you as I always do.

[johninderby]

3 hours ago, stringB said:

Im in the US so I ordered the Orion CC6. Thanks for everyone that contributed to this topic. I learned a lot from you as I always do.

Look forward to hearing how you get on with it. 👍🏻

Edited November 2, 2020 by johninderby

[stringB]

Somewhere along the way "Affordable, Lightweight" became this monster. I'm up to 16.7 kg without the CW so I'll be breaking this down to carry it. However everything is mounted/wired to the scope so all I have to do is balance and power it up. Even though the CC is not designed for imaging, I can't resist setting this up for mono planetary imaging. With the Baader flip mirror I can go visual or imaging (or a combination of both) with the flip on a knob I can also utilize the ASIAIRPRO's Polar Alignment, GoTo ,Plate Solving and Autofocus even when observing.  I hope for this to be a very flexible kit. Attached is a Photoshop kludge of what I hope to build .

 

 

Edited November 4, 2020 by stringB
photo had gotten in middle of text

[Alan64]

Congratulations on the classical-Cassegrain.  I've suggested it in the past to others, but I didn't know if you'd go for it, and there you have it.

You can image with the telescope.  It's just that it will require more precise tracking.

[stringB]

10 hours ago, Alan64 said:

It's just that it will require more precise tracking.

Thank you for you input on this,Alan. I may not have much observing experience but I hope to have great tracking with the ASIAIRPRO and an OAG. It's funny how my imaging mind works... This lasted as a "observing only" rig for about a week.

[stringB]

@johninderby and others who have upgraded the Stellalyra CC 6  to the Baader Steeltrack. Until someone comes up with a EAF clutch. (you listening ZWO?), I will never touch the fine-tune knob as mine will be locked down to a ZWO EAF Autofocuser with no freewheel clutch. I must use autofocus, the ASIAIRPRO  on-screen controls(UGH) or the EAF remote to focus. I will also have manual  Baader fine-tune focus controls at the Eyepiece.

Do you think I would benefit much from the Steeltrack upgrade,  if I'm only as good as the resolution of the EAF? 

[johninderby]

The Steeltrack is a much stronger and more stable focuser that will handle a lot more weight than the stock focuser withoit slipping. Also less problems with sagging when you add weight to it.

Edited November 4, 2020 by johninderby

[stringB]

6 hours ago, johninderby said:

The Steeltrack is a much stronger and more stable focuser that will handle a lot more weight than the stock focuser withoit slipping. Also less problems with sagging when you add weight to it.

Hmmm. Sounds worth it then. With all of the weight I'm planning to put on it the Steeltrack will probably put less stress on the EAF.

This is the new adapter that I had selected to Attach the Steeltrack to the OTA. Will this work?

https://agenaastro.com/baader-m90-adapter-bds-diamond-steeltrack-rt-focuser-2957283.html

I saw a post somewhere about a "new" Steeltrack with ClickLock could you please give me the model number for the newest Steeltrack that will work with the CC? I want to make sure I get this right.

Edited November 4, 2020 by stringB
Additional question.

[Alan64]

4 hours ago, stringB said:

Hmmm. Sounds worth it then. With all of the weight I'm planning to put on it the Steeltrack will probably put less stress on the EAF.

This is the new adapter that I had selected to Attach the Steeltrack to the OTA. Will this work?

https://agenaastro.com/baader-m90-adapter-bds-diamond-steeltrack-rt-focuser-2957283.html

I saw a post somewhere about a "new" Steeltrack with ClickLock could you please give me the model number for the newest Steeltrack that will work with the CC? I want to make sure I get this right.

The AA listing mentions a GSO RC(Ritchey-Chretien), which appears identical on the outside to a GSO classical-Cassegrain.  So much so that vendors have mistakenly included an image of a GSO RC within listings for a GSO CC.

GSO manufactures the Orion CC, incidentally.  But you would need to research that further.

Then...

Despite a CC not have having a corrector-plate, like a SCT or MCT which are prone to dew, I strongly suggest that you get a dew-shield for your CC.  There's an excellent possibility that a shield for a C6 SCT will fit...

https://farpointastro.com/shop/farpoint-dew-shield-celestron-6se-sct/

Shipping is free.

The one for the C5 SCT fits my ES/Bresser 5" Maksutov like a glove...

However, it's best to wait until the telescope arrives, then to measure the diameter of the CC where the dew-shield will be attached, then go from there.  The outside diameter of a C6 is 7.1" or 181mm there at the front.

Don't think for a moment that dew, moisture, cannot reach both mirrors within a CC.  An ounce of prevention...so it is said.

[stringB]

Alan, I very appreciative/ interested in your reply and I will look over all that you have said but this is very important.

Is the Orion version of the CC6 possibly inferior to the Stellalyra CC6? I thought It was the exact same scope with the same manufacturer. I know that Orion does not have the best reputation in some cases but I was looking for affordable.  Should I just wait for FLO to get some Stellalyra CC6's  back in stock... It's the same price... In your opinion that is.

[johninderby]

Have never needed a dewshield for my 6” and 8” CCs. Been so dewey that water was running off the outside of the OTA yet zero dewing up of the secondary. All depends on your local conditions though. 

I wouldn't get a dew shield unless you do experience dewing.

They do make secondary heaters for the RC version but not the CC yet.

EDIT:

As far as I know the Orion and StellaLyra versions are identical.

Edited November 5, 2020 by johninderby

[Alan64]

20 minutes ago, stringB said:

Alan, I very appreciative/ interested in your reply and I will look over all that you have said but this is very important.

Is the Orion version of the CC6 possibly inferior to the Stellalyra CC6? I thought It was the exact same scope with the same manufacturer. I know that Orion does not have the best reputation in some cases but I was looking for affordable.  Should I just wait for FLO to get some Stellalyra CC6's  back in stock... It's the same price... In your opinion that is.

The Stellalyra, Orion, GSO, and TS are all manufactured by GSO.  Orion manufactures nothing.  Synta, GSO, et al manufactures all Orion products.

I live just 25 miles south of Memphis, north of you.  We both live in a humid, subtropical climate-zone...

On February 6th, 2016, I took my 6" f/5 Newtonian out for a look-see.  To my horror, the telescope began to frost(frozen dew) over.  It covered the mirrors, even the primary...

I then took an afocal-shot of the Moon, through an eyepiece, at right.

In that you live farther south, you may find that you'll need an electrical, heated dew-shield even.

[stringB]

Living in the muggy south and set up by the pond in my backyard.I am usually a believer in dew protection both active and passive. I guess I did think that the CC would not be as prone as most designs. Heck I don't know enough to know where to put a heater strap on a cc. LOL I suppose at the bottom where the mirror is but I've never seen one equipped with either a dew shield or dew strap. I've purchased this design and I really know nothing about it except what you guys have said so far. I'm all ears.

Edited November 5, 2020 by stringB