Looking For a Different Setup

[Ozman]

I only power my goto mounts with a 12v automotive jump starter box. AAs will only power reliably for a short time (if that) and will inevitably cause all kinds of weird issues as they lose power.

I believe one of the Omni scopes on the CG4 is likely the best option for you. The 150 may be the best one for you, it would not be for me. I would opt for one of the refractors for a variety of reasons both visual and photographical.

[Baskevo]

I only power my goto mounts with a 12v automotive jump starter box. AAs will only power reliably for a short time (if that) and will inevitably cause all kinds of weird issues as they lose power.

I believe one of the Omni scopes on the CG4 is likely the best option for you. The 150 may be the best one for you, it would not be for me. I would opt for one of the refractors for a variety of reasons both visual and photographical.

Is this what you are talking about Ozman? This comes with the EQ mount too. What are some advantages/disadvantages of this scope compared to the 130 SLT?

[Sky Tinker]

Yes, that's the kit of which Ozman made merry mention. With a Newtonian on an equatorial, during the mount's revolutions, the focusser will end up in different positions. Many use a Newtonian that way, but they simply loosen the tube-rings slightly and rotate the tube, and the focusser, to a more comfortable position. Some also add a third tube-ring to the tube only, not the mount, right behind the front ring, and to act as a brake in keeping the tube from sliding out; also to keep the rings permanently loosened for quicker adjustments of the tube. Teflon pads are utilised within the DIY project...

https://www.cloudynights.com/ubbthreads ... etails.jpg

Parks Optical, of California, was in business from the mid-1950s up to the mid-2000s or so. They equipped their better Newtonians with rotating rings, with ball-bearings...



That particular kit sold for about $3000 towards the end. Then, John Dobson had come along some time before with his simple "Dobsonian" alt-azimuth mount, which eventually put Parks out of business. Incidentally, before they did fold up, I had ordered a customised 8" f/5 from them...




They didn't offer an 8" f/6 OTA among their regular line-up. I had called them one day, and asked for an f/5, and they obliged. However, to this day, I've yet to observe with it. It will need a Dobson mount made for it beforehand, and in future.

Equatorial mounts in general, no matter the telescope mounted thereupon, are for observing objects for longer spans of time; not for flitting from one object to that in the space of 15 minutes or so. It is also easiest to star-hop with an equatorial.

Then, there's this 4" f/10 refractor kit of the "Onmi XLT" series... https://optcorp.com/products/celestron- ... cope-21088

Yes, only 4" in aperture, true, but an unobstructed aperture. A 6" f/5 Newtonian, as within the other kit, simulates a 5" f/6 apochromatic-refractor, if the Newtonian is collimated spot-on.

The world of equipmental astonomy can be just as fascinating as the objects observed with them.

[Sky Tinker]

They didn't offer an 8" f/6 OTA among their regular line-up.

My bad, they DID in fact offer an 8" f/6 OTA, regularly, but I had wanted an f/5.

[Arctic]

In general I would recommend sticking with your new scope for awhile as you learn the ropes of visual astronomy. Then I would consider upgrading to an 8" or 10" Dob which will reveal more detail on the planets such as Cassini's division. Keep in mind that poor seeing will reduce the amount of details you can see on the planets.

Also, consider getting a pair of 7x50 binoculars. They will reveal a surprising amount of objects and can help you identify things you want to observe in your scope.

Most of all, good luck!

-Michael in Northern California

Excellent advice...

[Ozman]

I only power my goto mounts with a 12v automotive jump starter box. AAs will only power reliably for a short time (if that) and will inevitably cause all kinds of weird issues as they lose power.

I believe one of the Omni scopes on the CG4 is likely the best option for you. The 150 may be the best one for you, it would not be for me. I would opt for one of the refractors for a variety of reasons both visual and photographical.

Is this what you are talking about Ozman? This comes with the EQ mount too. What are some advantages/disadvantages of this scope compared to the 130 SLT?

Yes that is it. Compared to the 130SLT, the scope has more aperture which is a bonus for visual observing, not much advantage for imaging but neither will bring a DSLR to focus. The difference in mounts is HUGE! The only advantage the SLT has is the goto. The CG4 is WAY sturdier (the vibration issues are gone), it will track much smoother, and it is an equatorial mount which will allow for much, MUCH longer exposure times. The SLT can support 10-12 pounds, but has issues with weights like these as you have already found. The CG4 is solid with 20 pounds on it, there is just no comparison.

But I would go with the 120mm Omni refractor on the CG4 over the 150mm reflector. Sharper optics, no worries with collimation, the EP doesn't end up in awkward positions, and the scope will bring a DSLR to focus, a DSLR will give a much wider field than a small chip CMOS imager and will do a better job on most DSOs at a cheaper price, and you can use the DSLR regularly during the day, a CMOS imager only works attached to a scope. With a DSLR alone (no scope) on the CG4, you can do a LOT of wide field DSO imaging and can really push the exposure time limits because of the very short focal length of the DSLR lens alone.

[Baskevo]

Ozman, you are just too awesome man. Thank you.

Just to clarify:

120 mm omni refractor (comes with EQ mount) - https://www.highpointscientific.com/tel ... cope-21090
Orion EQ-3M single-axis telescope drive (to track objects for long exposure) - https://www.telescope.com/Orion/Orion-E ... word=07829

And then eventually when I buy a DSLR camera, I will be able to get some decent pictures? If I go with this setup, should I keep my Celestron eyepiece kit? this one -

And I'll still be able to look at planets and DSO's, but I'll just have to find them myself to be able to start tracking them, right?

You are the best Ozman!

[Ozman]

Yes that is the scope and the motor drive. With a DSLR you will be able to get good pictures of DSOs. Planetary pictures will be possible, but you really need a different scope and camera to get what most people consider good pictures. You need more focal length and a camera with a small chip shooting video to do it really well. The scope also has some CA (chromatic aberration) that will show up quite quickly doing planetary imaging, but it shows much less on most DSOs and you can deal with that using filters and in post processing (you'll have to learn all about that with any imaging).

You will have very good views of the planets and will see MANY DSOs (remember the darker the location the more DSOs you will see). You will have to find the targets yourself and then you can easily track it manually just by turning the RA knob or can track automatically by attaching the motor. You will have to polar align the mount, which is very easy to do for visual use. It is a little more difficult to align it for imaging as it must be much more precise. You will have to learn to do a drift alignment (not hard but it is a little lengthy) and will need a reticle eyepiece for the precise alignment.

It's a toss up on the eyepiece kit. You may want to return it if you can, you can certainly get better performing eyepieces. But there are some things in there that can provide good service, and the hard case is nice to have. Some of the stuff in there you will rarely use and some of the stuff you may find useless.

The 32mm EP is a good one and will give you the widest possible view in the 1.25" format (but the scope will also take 2" EPs), the 17mm, 13mm, and 8mm also are good, with the 8mm being your highest power EP for regular use in the f/8 scope. The 6mm will be useful, but only on occasions of really good seeing, you'll find it's just too much on many occasions and you'll go back to the 8mm. The Barlow is OK (not great) but it's not really all that useful in this kit with this scope. It turns the 32mm into a 16mm, you've got a 17mm. It turns the 17mm into a 8.5mm, you have an 8mm. It turns the 13mm into a 6.5mm, you've got a 6mm. It turns the 8mm into a 4mm and conditions will have to be PERFECT which MAY happen once or twice a year, but the Barlow it self is questionable as to whether it will support that much power. It turns the 6mm into a 3mm which you will NEVER use.

The moon filter is useful, the rest of them, not so much. Most of us put them away and forget we have them.

If you don't have too much money into the EP kit, I would probably keep it. If you can return in for a considerable amount, I would instead invest that cash in a few better EPs and build on that later. One thing to consider, for most of us, scopes come and go, but good performing quality eyepieces are always kept, and if kept well will last a lifetime.

[ARock]

If you are planning to do AP with this setup, you might want to look at ONSTEP for motor drives.
https://onstep.groups.io/g/main

For long exposure AP, you would need guiding and thus drive motors (both RA and DEC) capable of being used for guiding. Without guiding you will be limited to < 1 min exposures.

ONSTEP is a DIY solution but it has a good community behind it.

[Ozman]

If you are planning to do AP with this setup, you might want to look at ONSTEP for motor drives.
https://onstep.groups.io/g/main

For long exposure AP, you would need guiding and thus drive motors (both RA and DEC) capable of being used for guiding. Without guiding you will be limited to < 1 min exposures.

ONSTEP is a DIY solution but it has a good community behind it.

With a good drift alignment, I could get up to 2 minute exposures unguided on the CG4 imaging at 700mm. I don't think it would be a stretch to expect 90 second exposures imaging at 1000mm, although there may be several unusable exposures. I've seen 3 minute exposures using a short DSLR lens doing some very impressive wide field shots. The determining factor will be the precision of the polar alignment.

Of course configuring the mount for guiding would greatly lengthen the exposure potential, but on a shoestring budget, a LOT of things can be done without it.

[ARock]

Of course configuring the mount for guiding would greatly lengthen the exposure potential, but on a shoestring budget, a LOT of things can be done without it.

These days guiding can be done on a shoestring budget too, if you are willing to do some DIY.
$60 Guide scope + $40 security webcam + webcam adapter. Some have used camera lenses with adapters instead of a guide scope.

A DIY motor solution for a RA only guiding would be under $50 (some soldering required).
https://forum.arduino.cc/index.php?topic=245679.0

I have not priced ONSTEP lately, but it might be around the price of the Orion Single Axis motor drive with a lot more features. Here is a link of someone starting on such a setup if anyone wants to ask about prices.
http://www.astronomyforum.net/telescope ... mount.html

There is a certain amount of DIY ness as in every minimalist setup, but ONSTEP is quite established there days, and takes away the headache of software compatibility with the existing tool chains.

[Baskevo]

Can you guys give me a run down on why exactly the single axis motor I linked above would not give me more than 1 minute exposure? I'm a little confused by that part. What exactly does the motor do, if not give the star in field of view for the purpose of long exposures?

I have been looking up videos on EQ mounts -- they look complicated but like a lot of fun! I was surprised to find that the GoTo mount took away a bit of fun of trying to find stuff yourself in the sky, and the EQ mount seems more rewarding as it will give me a lot to learn.

I have also been practicing stacking and processing images I've been able to catch of Andromeda with my iPhone (really, really fuzzy images lol). I got photoshop for free from my school, and downloaded Lynkeos to play around. I was able to turn out some not ridiculously terrible images of Saturn and Andromeda (mostly just blurs and fuzzy's). I'm excited to try it with this new mount and to learn.

I think I am going to return the eyepiece kit. I do like the box, too, but it was pretty pricy for stuff I can probably buy individually for the same price. You can buy just the box for a 1/3 of the price.

[ARock]

Can you guys give me a run down on why exactly the single axis motor I linked above would not give me more than 1 minute exposure? I'm a little confused by that part. What exactly does the motor do, if not give the star in field of view for the purpose of long exposures?

For AP you need very very good accuracy of the motion by the motor drive. The accuracy needed increases with the length of your exposure and also depends on the image scale of your setup (which is why as Ozman says a camera with a lower focal length lens mounted on your CG4 would get longer expsoures more easily). Such accuracy would need deadly accurate polar alignment, perfect balance of the scope and very accurate gears on your mount. Reality is less precise than this, so you need autoguiding to make corrections to your motor drive using another guide scope and guide camera and software which controls your motor.
Here are some good videos on AP. Look in particular at the autoguiding one.
https://www.youtube.com/channel/UCx_N3K ... -NyKRugXmw

Lunar/Planetary AP needs less exposure and can be done without a very accurate tracking mount. The tools/workflow for lunar/planetary AP are different from that of DSOs.

[Sky Tinker]

Telescope kits from overseas manufacturers are well known in not matching the telescope to the mount properly. The Celestron 102mm f/10 refractor is supported well enough for visual-use upon a CG-4(EQ-3), and at 9.5 lbs. The 120mm f8 however weighs 12.5 lbs...

https://www.highpointscientific.com/cel ... -21090-ota

But it's not just the weight, but the weight in tandem with the length of the refractor. This is my 4" refractor mounted onto my CG-4...



...but my 4" refractor is a porker, like a prize-winning hog from the county fair, and weighs about the same as that Celestron 4.7" refractor. Longer refractors are just that, long. There is a condition called the moment-arm effect that one encounters when under-mounting a refractor. If you were to grab the back end of my refractor there on that CG-4, and pull it sideways just a bit, then let go, it would vibrate like a tuning-fork until it stopped moving. Quite frankly, I wish the scale in equatorials sold in the marketplace would ascend from an EQ-2 directly to an EQ-5, and with an EQ-3 never to seen again. I bought that CG-4(EQ-3) back in 2012, and when I didn't know any better. These are EQ5-class equatorial mounts, which would support the 120mm f/8 refractor quite well...

https://www.telescope.com/Orion/Orion-S ... p/9829.uts
https://www.telescope.com/Orion/Meade-L ... 114955.uts

...and many other telescopes that might be had in future, up to an 8" Schmidt if not larger; also an 8" f/5 Newtonian, but that may be pushing it. Either one would be the only equatorial you'd ever need, most likely, and much more versatile than an EQ-3. Also, the shipping weight of an EQ-5 is only about 5 lbs. more than that of an EQ-3; a bag of sugar extra, in other words.

Dual motor-drives are available for either one here in the U.S., and a go-to upgrade kit for the Orion EQ-5 even. There are single, RA-only, motor-drives available, but one would need to be sourced from Canada perhaps, or Europe; for example...

https://www.teleskop-express.de/shop/pr ... ndset.html

Once both packages arrive, the refractor would mount onto its "match made in heaven" in a matter of seconds.

After all, a house(telescope) is only as strong as its foundation(mount).

[Baskevo]

wait... I thought the CG-4 supported 20 lbs. You're saying I would still get vibrations with the Omni XLT 120 refractor?

I'd really rather not spend an extra 300 dollars on a better mount. Can I buy the scope and mount separately?

[JayTee]

If you need to reference mount payload capacities, you can refer to this post and the spreadsheet link therein.
viewtopic.php?f=54&t=1041

Cheers,
JT

[Ozman]

wait... I thought the CG-4 supported 20 lbs. You're saying I would still get vibrations with the Omni XLT 120 refractor?

I'd really rather not spend an extra 300 dollars on a better mount. Can I buy the scope and mount separately?

The CG4 is rated for 20 pounds and is quite a sturdy mount for the money. And yes, you can buy the mount and scope separately (most of us do).

You have to consider not only weight but also the length of the scope. With the 120mm f/8 refractor (1000mm focal length), the mount will hold it very well for visual observing, when you touch the scope to focus there will be a second or two of vibration which dampens very quickly, but this is much, much less than the vibration associated with your 130SLT and will track WAY smoother than the SLT.

For astrophotography (AP), you have to cut the weight capacity rating in half (or close) or you will overload the mount (AP must be very precise, it's more than keeping the target in the field of view, it's keeping it precisely in the same exact place in that field of view). So the AP capacity of the CG4 is about 10-13 pounds and the 120mm scope is pushing that. This is NOT an ideal set up and will require some effort. And as others have noted, you can get more appropriate gear and/or get more gear to upgrade this mount (a dual axis drive is better to have than a single axis drive and of course cost more), but I was trying to point to an option that WILL do at least some of what you state you want to do and stay somewhat close to your stated budget.

As to the length of your possible exposures on the CG4 unguided with a single axis drive, this all depends on the accuracy of your polar alignment (VERY CRUCIAL), the focal length you are imaging at, and any actual physical errors in the mount (these are mass produced mounts and not fine tuned hand crafted instruments, some error is inherent).
Any error is multiplied by longer focal length, so the shorter you image at the easier it is and the longer you can image.

I could reliably get 90 seconds and sometimes 2 minutes imaging at 700mm on the CG4 before noticing trails, but this was with a meticulous drift alignment. You may find that 1 minute is all you can get and that is IF you do a good alignment, or you may be able to get into the 90 second range. Or you may decide to get a shorter scope that is easier to work with, but unless it is an APO or ED scope (which costs) it will have more CA and you have to be careful there as it will build in a longer exposure to levels hard to deal with. F/8 is not great for imaging, but it does help to offset some of that CA.

[Sky Tinker]

wait... I thought the CG-4 supported 20 lbs. You're saying I would still get vibrations with the Omni XLT 120 refractor?

I'd really rather not spend an extra 300 dollars on a better mount. Can I buy the scope and mount separately?

Here are the links again...

The 120mm f/8 OTA only... https://www.highpointscientific.com/cel ... -21090-ota

...and either one of these EQ5-class mounts...

https://www.telescope.com/Orion/Orion-S ... p/9829.uts
https://www.telescope.com/Orion/Meade-L ... 114955.uts

The Meade would match the colour-scheme of the OTA. The Orion would allow for maintaining a lower, less conspicuous profile whilst out at night; although some don't like black mounts, as one may be more prone to bumping into it or tripping over it in the darkness.

$560(lowest price) for the 120mm/CG-4 kit, or $700 to $730 for the blue-plate special; $140 to $170 extra rather for that. You will need to decide if the extra cost will be worth it, and in the long run. If you plan to dabble in taking photos and what-not, you'll be better off with an EQ-5.

A 5" f/8 refractor is different from a 6" f/5 Newtonian, or a 6" f/10 Schmidt. The refractor is long, the other two are shorter. In order to keep the false-colour when viewing brighter objects down to a minimum, the refractor, an achromat, must be longer. That 120mm f/8 refractor is over a yard in length. Google or Yahoo! "telescope moment arm effect" for more information.

CG-4 load-capacity information... https://www.cloudynights.com/topic/2605 ... -capacity/

[Baskevo]

Okay. So I think I want to do the 120mm f/8 with one of those EQ5-class mounts, and a dual-axis motor. So this will allow me to see some detail in Saturn and Jupiter (not for photos), and be able to learn AP later on with, like, 130 second exposures(?) when I buy a DSLR

(just a quick reminder, I'm in a light polluted area).

I really appreciate all of the advice guys. I understand that this is a very expensive and time consuming hobby. I am loving it so far. the last few nights I've really enjoyed just getting shots with my iPhone (they are getting better), and it's totally addicting. I'm really excited to start learning this.

Especially Ozman, seriously, thank you!!

[Ozman]

The EQ-5 class mounts are even more versatile and opens up even more than the CG4 is capable of, it's money well spent if you go that way. Everything, whether visual or AP, is tied to the mount. The better the mount, the better the performance, PERIOD.