Buying advice Celestron c5+

[Rambi]

Hi guys

This is my first post so i might start with saying hi from Norway.

I have never ever even looked thru a telescope and for the last couple months got a huge urge to start this hobby.

Seeing that i have no idea about telescopes besides what i read over the past weeks i would like some advice here, as the title states i have a Celestron c5+ (i think) on sale not far from where i live and are considering having a look at it.

Is there something to look out for with this particular telescope?

[Luna-tic]

If the price is right, I'd say go for it. The picture shows an alt-az mount with a wedge; the wedge makes it into an equatorial mount. Google for good descriptions of mount types, and the benefits/downsides to each one.

The C5 is a Schmidt-Cassegrain design, a type of catadioptric telescope. This means it uses both mirrors and lenses in the design, where a Newtonian uses mirrors, and a refractor uses lenses. The focal ratio of a Schmidt-Cassegrain is typically f/10,  and the focal length of the C5 is 1250mm, fairly long for the actual length of the scope. SCT's are compact-for-aperture, and great for looking at the Moon or planets, less so for some deep space objects because the field of view can be too narrow to see certain objects in their entirety. The focal length of 1250mm gives you a range of about 30x to 250x depending on your eyepiece selection. The compact size makes them pretty easy to carry around and set up. C5's are sold as spotting scopes (for birding and target checking), and are fairly robust. The corrector plate (clear lens in the front) can be broken if it gets hit, and the secondary mirror in the corrector's center can get out of alignment. This isn't a failing of the C5 inparticular, just a trait of Schmidt-Cassegrains in general. The mirror is easily realigned and is expected to need alignment (called collimation) from time to time, for optimum optical performance.

I own two Schmidt-Cassegrain telescopes, a 6" and an 8", and love them. They gather quite a bit of light and give a nice, bright image, and are great general purpose telescopes.

[Rambi]

18 minutes ago, Luna-tic said:

If the price is right, I'd say go for it. The picture shows an alt-az mount with a wedge; the wedge makes it into an equatorial mount. Google for good descriptions of mount types, and the benefits/downsides to each one.

The C5 is a Schmidt-Cassegrain design, a type of catadioptric telescope. This means it uses both mirrors and lenses in the design, where a Newtonian uses mirrors, and a refractor uses lenses. The focal ratio of a Schmidt-Cassegrain is typically f/10,  and the focal length of the C5 is 1250mm, fairly long for the actual length of the scope. SCT's are compact-for-aperture, and great for looking at the Moon or planets, less so for some deep space objects because the field of view can be too narrow to see certain objects in their entirety. The focal length of 1250mm gives you a range of about 30x to 250x depending on your eyepiece selection. The compact size makes them pretty easy to carry around and set up. C5's are sold as spotting scopes (for birding and target checking), and are fairly robust. The corrector plate (clear lens in the front) can be broken if it gets hit, and the secondary mirror in the corrector's center can get out of alignment. This isn't a failing of the C5 inparticular, just a trait of Schmidt-Cassegrains in general. The mirror is easily realigned and is expected to need alignment (called collimation) from time to time, for optimum optical performance.

I own two Schmidt-Cassegrain telescopes, a 6" and an 8", and love them. They gather quite a bit of light and give a nice, bright image, and are great general purpose telescopes.

Thank you for the input.
The price is around 150 so it's a nice starting price for a person in my situation, I also like the formfactor so that i will actually use it "tiny apartment and car".

Im known to go all in unfortunately but this time i'm trying to hold back and get something cheap to begin with.

I learnt collimation and how to use equatorial mount (in theory), so i hopefully won't have too much of a trouble with that. 

The corrector plate is easy enough to spot damages on but is there a way to check the main mirror for defaults thru the eyepiece or is this done by inspecting it thru the corrector plate? Seeing the mount is motor driven it's important to check for play in the drive i guess, also this went out of production in 98 so i reckon spare parts aren't even worth looking for.

[happy-kat]

Hi

Unless you are 100% sure of the quality I would not use that solar filter (I think that might be what it is on the bench) better to be safe then badly damage eye sight.

There is an erect image (I assume) 45 degree diagonal on that bench and a more comfortable 90 degree one for night use. You will be able to see the main mirror I think when just looking down from the front, dust is fine I doubt there will be no dust but fungus not so good but I imagine that would be unlikely to find. Hopefully you will get a knowledgeable reply as I am just thinking practically.

If the mount head can be moved manually by hand then perhaps if the price is right it is not essential the motor work.

[Luna-tic]

46 minutes ago, Rambi said:

 

The corrector plate is easy enough to spot damages on but is there a way to check the main mirror for defaults thru the eyepiece or is this done by inspecting it thru the corrector plate? Seeing the mount is motor driven it's important to check for play in the drive i guess, also this went out of production in 98 so i reckon spare parts aren't even worth looking for.

If the corrector is clean, you should be able to inspect the mirror through the front of the scope.. If the scope has never been opened, the mirror should be in good shape. 

[Rambi]

Good stuff here, thanks guys!

[Ben the Ignorant]

Hello, Rambi.

I own a C5+, it has been mine for many years, and never stopped working fine. To inspect the optics, just look from the front, you'll see the main mirror and the secondary reflected on it. The plate is indeed exposed to shocks, but there is a solution.

 

The photo you show has the scope mounted upside down with the finder under the diagonal, this is how it's supposed to be oriented:

And the C5+ has an equatorial wedge, as you see between the scope base and the homemade tripod. The lateral rail on the tube was designed to attach a camera but I use it for a sliding counterweight, a must with some modern eyepieces that were unconceivably heavy at the time the C5+ was designed. Check that the motor works, it should make only a gentle whirring sound, and a rechargeable 9V battery should last 14 hours in continuous functioning, I tested that.

 

Bumping the plate is a real risk, so I made a dewshield from several layers of thick drawing paper (painted black inside). It's rigid enough, absords and later rejects dew, looks ugly, projects far enough up front to kill all stray light, and protects the plate against bumps, the most likely being an elbow strike when the scope sits behind you:

I need to make a permanent dewshield with an improved material, and rigid enough to accept the cap, the component on the table that happy-kat mistook for a solar filter. Having to remove the dewshield to attach the cap is a useless hassle. The dewshield needs to be 20 cm long to intercept all stray light (from real-world testing).

 

In this interferometer comparo, see how the C5 is in the same league as an Astro-Physics triplet, a Vixen (rebranded Celestron C70) fluorite apo, and another expensive high-end refractor, the Tele Vue Genesis. To confirm the greatness of the result, two were tested, and performed the same:

 

My personal C5+ is very sharp, especially on the Moon and Mars, but the lower-contrast planet Jupiter shows more colors in my 80mm triplet apo. Saturn is in-between. When the optics are well-centered, star images are very small and very regular. It resolves the brightest globulars easily. 250x keeps it sharp on the Moon, but 190x is more reasonable for other planets because they are not so starkly black on white.

Finally, the C5+ sports a single-layer coating on the plate, but high reflectivity multi-coatings on both mirrors.

[Cosmic Geoff]

Buy it if the price is right; there seem to be plenty of accessories. Make sure that the mount drives are actually working. If they are not, you may be faced with a large expense to replace the mount with a more modern one.  You may need to collimate the telescope, which needs a clear head and a steady hand but is something you can do yourself. When I bought my used C8 the collimation was totally out.

[Rambi]

"Buy it if the price is right"
This came up a couple times above, The follow up question then becomes, what price is right for this if its in good working condition?

I'm going to have a look at it tomorrow, just bought a battery just incase its depleted when i arrive (2h drive).

 

[martinl]

If “150” is the price in GBPs then I’d say it’s more than right. If the mirrors look ok (some dust is fine, aluminium coating flaking off is not) then go for it. I’m guessing the Norwegian market is much like the Swedish - not a lot of choice. I’d buy a C5+ for £150 if available locally, even if I didn’t really need it. The C5+ is a classic.

If you buy it, read up on collimating SCTs. It’s simple, and can easily make the difference between a marginal scope and a great one!

[Mr niall]

Yes if it’s £150 or there abouts I’d say definitely go for it, sounds like a great deal.

[fozzybear]

21 hours ago, happy-kat said:

Unless you are 100% sure of the quality I would not use that solar filter (I think that might be what it is on the bench) better to be safe then badly damage eye sight.

I have a c5 and it is the scope cover made from metal not a solar filter

[Rambi]

Hmm, just noticed that i clicked the "+" believing that it gave rep when it infact was for multi quoting, how do i give rep? 

Want to show that i appreciate the help that im getting.

[Rambi]

ah, gotcha

[Rambi]

39 minutes ago, martinl said:

If “150” is the price in GBPs then I’d say it’s more than right. If the mirrors look ok (some dust is fine, aluminium coating flaking off is not) then go for it. I’m guessing the Norwegian market is much like the Swedish - not a lot of choice. I’d buy a C5+ for £150 if available locally, even if I didn’t really need it. The C5+ is a classic.

If you buy it, read up on collimating SCTs. It’s simple, and can easily make the difference between a marginal scope and a great one!

I'm a fellow swede actually, just ended up across the border.
And yes the prices seem to be quite similar between Norway/Sweden, In fact for once Norway actually seems cheaper when it comes to this hobby.

Have a look at finn.no it seems to be a lot more than on blocket.se that im guessing you are looking at, its spelled stjernekikkert (telescope) in Norway.

[fozzybear]

If i'm not mistaken it also looks like there is a hard storage case in your 2nd picture lower right hand side to store the scope maybe an original celestron? I might be wrong but a bonus...

Andy

[Rambi]

3 minutes ago, fozzybear said:

If i'm not mistaken it also looks like there is a hard storage case in your 2nd picture lower right hand side to store the scope maybe an original celestron? I might be wrong but a bonus...

Andy

That's correct, i did deliberately not share all pictures due to that his house was in the picture where the case was clearly visible, it's also a pic on the corrector plate from a few meters away that as far as i can see shows it to be "ok", but you never really know before you are there in person. The seller do not know that i shared the pics so best to be at least somewhat respectful how i use them. 

[martinl]

9 minutes ago, Rambi said:

I'm a fellow swede actually, just ended up across the border.
And yes the prices seem to be quite similar between Norway/Sweden, In fact for once Norway actually seems cheaper when it comes to this hobby.

Have a look at finn.no it seems to be a lot more than on blocket.se that im guessing you are looking at, its spelled stjernekikkert (telescope) in Norway.

Blocket.se is a joke. There are however some sites in Sweden with more informed users/sellers/buyers. Astronet.se is one, another is Astropixlar köp och sälj on Facebook. The traffic is quite low though. 

For small items (eyepieces etc) postage is quite reasonable from the UK, so either SGL or http://www.astrobuysell.com/uk/ are good places to buy from.

I’ll have a look at finn.no. Thanks!

[Rambi]

59 minutes ago, martinl said:

Blocket.se is a joke. There are however some sites in Sweden with more informed users/sellers/buyers. Astronet.se is one, another is Astropixlar köp och sälj on Facebook. The traffic is quite low though. 

For small items (eyepieces etc) postage is quite reasonable from the UK, so either SGL or http://www.astrobuysell.com/uk/ are good places to buy from.

I’ll have a look at finn.no. Thanks!

No, thank you.

eyepieces and accessories is what's next on the list (if i buy the telescope that is).

[Cosmic Geoff]

14 hours ago, Rambi said:

eyepieces and accessories is what's next on the list (if i buy the telescope that is).

There seem to be plenty eyepieces in the picture, and a C5 does not need fancy eyepieces so you may not need to buy more.

For guidance, a new C5 OTA costs around 500 euros and a C5 SE GoTo around 800 euros. If the asking price is 150 Euros, even if the mount is no good this looks like a steal.

[Ben the Ignorant]

4 hours ago, Cosmic Geoff said:

There seem to be plenty eyepieces in the picture, and a C5 does not need fancy eyepieces so you may not need to buy more.

Since replacing the stock plastic-frame prism diagonal with a metal-frame mirror my C5 can hold 100° and 82° eyepieces. The sliding counterweight I attached to the lateral rail is enough for the 82's but the 100's require more, I am thinking of a collar counterweight that will be constantly attached at the front, right behind the dewshield. This will make the scope heavier but no prob, the motor is the same as for an 8" tube and twin-arms fork.

[Rambi]

Sweet, a C5+ is now standing in my living room.

It was in great condition, one owner, bought it for him and his children 20 years ago, Used it a handful times and then left it standing unused.

So yeah, im happy. Snapped the finderscope mount during transport though, on closer inspection it was already dmg at the area were it snapped so it was due i guess. Epoxing it now.

Telescope came with loads of adapters that i have no idea what it is, link; https://imgur.com/a/ewCg6

Also a bit confused with the wedge, I was expecting latitude numbers on it but instead it looks like regular degree numbers instead, probably just me that misunderstood the whole EQ concept.

[martinl]

Looks great!

The numbers on the wedge ARE latitudes. Just set it to your latitude and aim the arm towards Polaris.

You got an excellent set of eyepieces as well. These Celestron “Halloween” Plössls are well regarded, a bit of collectors’ items. The Ortho should also be very good. The Ultima barlow is excellent - I have the same one. 

I don’t know what the adaptors are for. If they have 42mm threads they are probably T2 adaptors, useful for photography to get the spacing right. You can safely forget them for now. 

The only addition I would recommend is some kind of red dot / reticle finder, perhaps a Rigel Quickfinder or a Celestron StarPointer Pro. It makes it a lot easer to find things. 

[Rambi]

3 minutes ago, martinl said:

Looks great!

The numbers on the wedge ARE latitudes. Just set it to your latitude and aim the arm towards Polaris.

But, it only goes to 45, im at 59, Im clearly stupid in some way now but i can't see how i will get this scale to work.

5 minutes ago, martinl said:

You got an excellent set of eyepieces as well. These Celestron “Halloween” Plössls are well regarded, a bit of collectors’ items. The Ortho should also be very good. The Ultima barlow is excellent - I have the same one. 

I don’t know what the adaptors are for. If they have 42mm threads they are probably T2 adaptors, useful for photography to get the spacing right. You can safely forget them for now. 

The only addition I would recommend is some kind of red dot / reticle finder, perhaps a Rigel Quickfinder or a Celestron StarPointer Pro. It makes it a lot easer to find things. 

Glad to hear, I basically had no idea what i came home with. 

[Rambi]

3 minutes ago, Rambi said:

But, it only goes to 45, im at 59, Im clearly stupid in some way now but i can't see how i will get this scale to work.

Nvm, looks like it clocks out at 60 just where the screw ends so i'm just inside.