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which c5 or should I go 127 mak?

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23 replies to this topic

#1 vtornado

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Posted 30 November 2018 - 09:52 PM

Hello all of you out there in cat land!

 

I want to join the party and buy a small cat for quick peeks,

on a light mount.

 

I only buy used scopes, because I try them out and if they aren't keepers, I sell them

back for about what I paid.

 

There are a whole lot of c5's out there.  orange ones, black ones, white ones, blue ones.

I know that color does not do anything, but it does reflect a generation. 

Are there any of these generations I should look at more seriously or ones I should avoid?

If I buy an orange tube from the 70's or 80's do I have to worry about mirror reflectivity

given that this scope is now nearly 50 years old?

 

Does the variation in quality from scope to scope outweigh the differences in the generations of this scope?

 

I think??? I would prefer the c5 due to the wider field,  lighter weight and faster cool down.

But my main targets are planets, so should I focus on the mak?   Is planetary performance in the mak

noticably better?  Or again is it a scope to scope variation?

 

Thanks for your help.

VT.


Edited by vtornado, 30 November 2018 - 09:54 PM.


#2 barbie

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Posted 30 November 2018 - 10:35 PM

I would go with the 5"Mak.  I've had a couple of these and they are excellent for planetary.  There was no variation in quality between the ones that I owned.  Either the Orion or Skywatcher would be better than a C5 for planets, for which you don't need a wide field of view.  The 5" Mak also has a smaller secondary which will be better for planetary contrast.



#3 SeattleScott

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Posted 30 November 2018 - 10:56 PM

Logically I would lean towards the Mak. The advantages of the SCT in terms of lighter weight and faster cool down (albeit largely myth and now irrelevant thanks to Reflectix) are not really significant at 5” aperture. I did spend some time with an ETX 125 at a star party and was impressed. Haven’t used a C5.

Scott
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#4 jallbery

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Posted 01 December 2018 - 02:01 AM

I bought a used Orion Apex 127 (Synta-- should be optically identical to SkyWatcher and Celestron 127mm Maks) to use on a  4/5SE mount.   I then came across a great deal on a used recent issue C5, so I bought it as well.   I decided the C5 was the keeper.  Here is why:

  • The C5 weighs significantly less than the Apex 127 and is more compact.
  • Due to the lighter weight and shorter moment arm, the C5 is more stable on the 4/5SE mount.
  • The two scopes put up very similar views.   The Mak did not seem to have any advantage.  Maybe the Mak's slight advantage of a smaller obstruction is offset by the fact that the C5 actually has a larger aperture (the Mak has an undersized primary that reduces the effective aperture).
  • The Apex had an annoying tendency to have flares from bright stars just outside the field of view.  The C5 (unlike my C6) was delightfully free of these annoyances.    A due shield or flocking can help correct this though.
  • Use of SCT threads means compatibility with a host of options for larger SCTs (although you can get a SCT thread adapter for the Mak, though.

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#5 Eddgie

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Posted 01 December 2018 - 08:12 AM

I would go with the C5.

 

  • There are several issues with the 127 MCT.  Many of these are not working at the advertised aperture and are commonly working at 120mm vs the 127 mm for the C5
  • The secondary obstruction in most of these 127mm MCTs is no smaller than in a C5
  • The optical quality of the 127s varies perhaps more than on C5s

You don't have to take my word on the last two..  Here is a link that shows a bunch of tests for various MCTs and the quality is all over the map.   By comparison, C5s actually look to me to be typically better.  Chances of getting a bad one actually seem to be worse with the MCT to me.  Look at the variation in these:

 

http://teleskop-spez...-teleskope.html

 

I would recommend a later C5 (XLT Coatings).

 

C5 has these advantages:

 

  • Lighter and more compact
  • Wider field of view
  • Focal reducer available
  • Common size treads on rear port making it possible to use a wider variety of attachments
  • Better for binoviewing (though it will not work at full aperture in any configuration I have tried, though you can get 125mm of aperture)

Don't be influenced by the coolade that MCTs are always better than SCTs.  It simply is not true.  If the quality is not extremely high (on either of these types) and the secondary (including the blockage from the baffle which is often quite large) is no smaller, the performance won't really be discernably better than a similar sized SCT with equal secondary and aperture.   

 

As for quality, again, the quality of these scope will be influenced more by sample to sample variation than by generation.  I have been looking at bench tests for SCTs for 15 years and done star testing on perhaps two dozen SCTs and the quality is inconsistent.   Some are quite excellent, most are good, and some are barely diffraction limited.   It can be a roll of the dice.

 

(oh, and yes I have owned two C5s and two 127MCTs.   I preferred the C5 for exactly the reasons I mentioned.  Of the four scopes, one of the C5s had a slight turned edge and did not have quite the same contrast as the 127 I had at that time.  The second C5 had excellent optics and the second MCT had so-so optics.  Just the way these scopes are..)


Edited by Eddgie, 01 December 2018 - 08:16 AM.

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#6 Brent Campbell

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Posted 01 December 2018 - 09:05 AM

I have never used one but occasionally a c6 comes up for sale.  It’s going to be more expensive than a c5 but they have a good reputation.


Edited by Brent Campbell, 01 December 2018 - 09:26 AM.

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#7 Erik Bakker

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Posted 01 December 2018 - 10:48 AM

Jallbery and Eddgie are spot on waytogo.gif

 

An older C5 that comes out well in the sample variation can also be an excellent choice.

 

I have a black fork mounted Super C5 from around 1983 and find it a superb sample with great optics. The coatings are still going strong after all these years.


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#8 Eddgie

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Posted 01 December 2018 - 12:22 PM

And neither of these scopes is going to be a match for your 102ED on planets.   

 

In fact, none of these are going to give you anything you don't already have.

 

If you just want another telescope to add to your collection, pick one or the other and try it out.  If you don't like it, sell it.   

 

Me?  I think you already have more small telescopes than you need, but I am not you, and you seem to enjoy having a lot of small telescopes, so deciding on what else to add should just be a matter of picking the one you think you would enjoy more.


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#9 vtornado

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Posted 01 December 2018 - 05:40 PM

Hi Eddgie, I greatly respect your opinion on these things.

Your answers are couched in science yet have a good sense of practicality.

 

I want to get a cat for the following reasons.

I go on vacation to an orange zone once a year.

I don't have enough room in the car for a big mount.

Last year I brought my ST80 on a photo tripod  In an orange zone it does not perform that great.  The sky is still to bright for milky way sweeping, and this scope has too much

CA to use at high power.

I  also have to hike about a mile

to get out of the immediate glare of town to a baseball field.  So I have to carry the scope too.

 

I bought an ares 130 f/5 on  a whim from a member here, and it is a little bigger than

I thought.  But it is still an awesome scope, I don't know if I can lug this 1 mile. 

 

I'm thinking the c5 is the most scope I can fit in the car, mount easily, and carry for a mile,

and not have CA, and not break the bank on a small apo.

 

My other purpose, Is I love helping people in this hobby.  I have no CAT scopes, so I want

to own one so I can give hands on advice.

 

I have found a celestron xlt 127  sct 8 miles from me for $220.  I think I am going to pick it up.

 

BTW The herd is going to thin soon.

Thanks for your help.

VT


Edited by vtornado, 01 December 2018 - 10:00 PM.

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#10 erin

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Posted 01 December 2018 - 06:58 PM

Hi VT,

 

Good luck with the 127 xlt! I have only heard good things about it. 

 

Erin


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#11 Jon Isaacs

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Posted 02 December 2018 - 03:59 AM

I have found a celestron xlt 127  sct 8 miles from me for $220.  I think I am going to pick it up.

 

 

No better way to figure this out than to buy one and try it.   I have owned three C-5s of varying vintages, an ETX-125 (original) and an Orion Starmax 127.  They all had 40% Central obstructions.  Orion states that the "secondary mirror obstruction" was 39mm.. A clever dodge around the fact that secondary baffle is 48mm... 

 

My experiences agree with Eddgies.  I bought the first one for a similar purpose to yours but it just never worked for me.  A 130mm F/5 Newtonian with a 2 inch focuser, is somewhat larger but not overly so and does a good of imitating a fast 4 inch apo.

 

Jon


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#12 vtornado

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Posted 02 December 2018 - 01:45 PM

Hi Jon,

 

The baffle is plastic and simply glued to the corrector in these Mak's.   I fixed a friends mak where the baffle had fallen off.   Silicone glue worked wonders. So I think and adventurous tinkerer could experiment with a new baffle.  It would be interesting to 3d print a new one that is smaller and see how the image is.  Would a smaller baffle clip the light cone coming off the primary?  Or is it just a oversight in the design of these. 

Maybe someone smarter than I could do a ray trace to determine the minimum sized baffle.

On that thought maybe I could do that ...  Been 40 years since I did one of these.

 

I have a 130mm f/5 newt (AWB) visually and price wise it is awesome.  With the dob mount,

It weighs in kind of heavy.  15 lbs.  Great for carrying out in the yard, or 300 feet from the car,

but a little heavy to lug a mile.   Plus there is no table for me at my site, which either means

I need to lay on the ground with it, or bring a milk crate or two to put it on.

 

I think the c5 might work on a photo tripod, with a reasonable head and pan handle.


Edited by vtornado, 02 December 2018 - 01:54 PM.


#13 Eric63

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Posted 02 December 2018 - 03:29 PM

If this is for travel, then keep it small, light and simple. I think a C5 would be best for that. I can't imagine that the view would be much different between a C5 and a 127Mak. Otherwise the 130F5 is a better all around scope.

For traveling I use my BT-70-45 binoculars and a C90. Both use a the same light photo tripod.

Eric
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#14 Cometeer

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Posted 02 December 2018 - 04:30 PM

I'm a bit late to the party. I was in your situation not too long ago. I needed a scope that I could easily take on my carry-on luggage when flying. Initially, I was deciding between a 127mm mak and a 80mm apo. I ended up choosing the 80mm apo since it would be easier to track with on a manual alt-az mount. After a year of use, I found the focal length just didn't cut it for planetary and smaller DSO's.

 

I then picked up a white C5+ that was listed locally. After some comparisons, I ultimately chose to take the C5 over the 127mm mak for the following reasons:

- C5 is more compact and lighter.

- C5 is easily paired with a focal reducer for a shorter focal length (makes it more versatile). The mak needs several adapters to use a focal reducer.

- my C5 is optically excellent and easily held its ground to the mak. 

- it's true that a C5 would need collimation, but I collimated mine 5 months ago and haven't had to touch it since. If collimated correctly, the collimation will hold for a long time.

 

As for mounts, I used a Stellarvue M1 at first. Works great, but I needed tracking for times I do outreach, so I upgraded to the Skywatcher AZ-GTI. Though, if you are looking for something simple, portable, and convenient to use, I would recommend a Stellarvue M1V on a sturdy camera tripod.

 

There is a difference between different generations of the C5. The first picture is of my white tube C5+. These were known to be quite good. Notice the dark interior baffling. The second picture is of a black tube C5 (I'm not sure of the serial number so it could've come earlier or after). The interior baffling is very reflective.

 

Notice the entire baffle is not very reflective.

IMG_0971.JPG

 

Baffle here is very shiny.

IMG_0968.JPG

 

There was a noticeable difference in contrast between the C5's, especially during daytime use. The poorly baffled one put up very washed out images. I never owned a newer C5 (post 2000s), but I would point the scope at the bright blue sky and take a look through the rear. If you notice the baffle to be reflective, I would line the inside of the baffle with flocking paper.

 

This is my current C5 setup. I was able to source a case that's provided with the newer spotter series and modify it to my liking.

IMG_0504.jpg

 

 

 

 

 

 

 

 

 


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#15 vtornado

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Posted 03 December 2018 - 12:38 PM

Thank you all for your help.smile.gif

 

One post that Eddgie made on a different thread was interesting ...

Both the Mak, and the SCT both have a spherical mirror, probably being made in the same factory.

 

So now the important difference is comparing the manufacturing accuracy of the ashpheric sct corrector, vs spherical mct corrector.  Maybe the mct corrector is easier to make ergo better?   But they have been making the sct corrector for decades, they have automated tools.

 

It was also pointed out that one driving force for the MCT design was that in the mid 20th century

The ashperical sct corrector plate was difficult to make.

 

Additionally the published MCT spot size is a fib, since it does not include the baffle, which makes the spot about the same as the SCT spot.

 

The synta maks are also shown to be operating at 120mm not 127.  (13% brighter maybe discernable)

 

So with all that being  said in the  MCT vs SCT decision,  probably there is more to do with the samples being compared than differences in intrinsic design performance.

 

So because of a slightly wider field, lighter weight, quicker cool down, and sct rear port convience I chose the SCT. 

 

After picking it up, I can definitely tote it a mile to my observation site.  Now I just need

a very light head for a photo tripod.

 

I purchased a local used c5 xlt blue/white tube.

I will check the baffle for shineyness.  Thx cometeer.

I have had two clear nights in November, I don't know when I will get out to test it out.

 

VT


Edited by vtornado, 03 December 2018 - 12:40 PM.

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#16 AlienRatDog

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Posted 03 December 2018 - 01:58 PM

I know I’m late to this game but I recommend the C5, I have a 127mm mak, it isn’t bad, it’s just a tad heavier than I like.

#17 Conaxian

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Posted 03 December 2018 - 03:31 PM

Yeah, I'm late, too.

Nobody mentions the difference in cost.. Those C5s cost $599 while the maks can be had for $400.

That $199 can get you a nice Lumicon 2" enhanced, double-pass collimated diagonal and a decent 1 1/4" Celestron prism diagonal, both of which can be used on all non-SCT scopes you may have.

Easier to make= less costly.  Then there's the accessories- the mak comes with a vixen dovetail and a straight through 6X30 finder mounted well off the tube.. These items make for even more savings in actual use. 

Throw in another $66 with the $599 you were going to spend, and you can get a 150mm Sky-Watcher mak.

https://www.amazon.c...k/dp/B00Z4HX18M

If aperture rules, then the $66 would not be wasted.

-just sayin'.


Edited by Conaxian, 03 December 2018 - 03:44 PM.


#18 AlienRatDog

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Posted 03 December 2018 - 03:40 PM

Yeah, I'm late, too.
Nobody mentions the difference in cost.. Those C5s cost $599 while the maks can be had for $400.
That $199 can get you a nice Lumicon 2" enhanced, double-pass collimated diagonal and a decent 1 1/4" Celestron prism diagonal, both of which can be used on all non-SCT scopes you may have.
Easier to make= less costly.
Throw in another $66 with the $599 you were going to spend, and you can get a 150mm Sky-Watcher mak.
https://www.amazon.c...k/dp/B00Z4HX18M
If aperture rules, then the $66 would not be wasted.
-just sayin'.


You can get the C5 spotting scope from Amazon for $474, it blows my mind that it costs more than a C6! If I was buying new, the Nexstar 5SE is on sale for $599.

#19 Conaxian

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Posted 03 December 2018 - 04:02 PM

I did not know that. I looked around, considered them, but every store I checked had them at $599. I stand corrected.

$474 is a lot more acceptable price. It comes with a dovetail too. Not bad.


Edited by Conaxian, 03 December 2018 - 04:04 PM.


#20 jallbery

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Posted 03 December 2018 - 04:30 PM

Note that the $475 C5 spotting scope comes with a nicer finder and a much nicer case than what is provided with the $389 Apex 127.  It also comes with a lifetime warranty.

 

But you can get a c6 XLT for $400.  That's a heck of a deal.  No case or lifetime warranty, though.


Edited by jallbery, 03 December 2018 - 09:25 PM.

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#21 gfstallin

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Posted 02 March 2019 - 11:45 PM

I'm very late to the game. Tomorrow I am going to check out a Nexstar 5SE "used 4 times" for $200. This, along with my ED80 should put me in portability heaven. I'm crossing my fingers...

 

George



#22 photoracer18

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Posted 04 March 2019 - 04:16 PM

Personally if I was going for just a C5 OTA I would pick one of the spotting scope/telephoto versions as from my experience of owning several and working for a dealer for a time I think on average they have better optics. Especially the C5-750 F6 versions although not for everyone with their larger CO. I also prefer the older models that came with the shiny metal focusing knob over the black painted or plastic knobbed versions. Sort of like the C-9.25 models where the preferred version (pre- Edge HD) is generally the first gen with the metal focuser and digital counter because it more closely matches the original prototype from Vixen. All that being said I currently own a black C-5 F10 (shiny metal focuser) that was off the GEM model. Its not bad. I originally bought it to put on an old Nexstar 5 mount I still own but it has the wrong screw holes for that.

If you can find a telephoto C5 with the original case that is about as portable a setup as you can get. And yes I agree that except for weight issues an MCT might be better. I prefer fixed optics Maks to moving primary ones because the element separation is always at the max correction point. Don't think anyone makes any small ones like that anymore. Probably why mine is the Orion Argonaut 150 (Intes MK67). Too heavy for real portability however but right on the borderline. That's why at 71 my portable scopes are the TMB 80 SS triplet and a LOMO Astele 95 MCT.

 

You should be able to get a used C5 for no more than $200-$250 in my book. I mostly never buy new either. But I am also on the lookout for previously owned scopes that were never actually used. You would be surprised at what you can find. I previously bought a TEC140 like that years ago and the current AT115EDT I have was bought new by someone who was going to get back into astronomy but never did and I got it unused for $900 with hard-case, rings, and dovetail. Since I have done a lot of repairs in the past I look for things like that also.



#23 Jond105

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Posted 12 April 2019 - 01:02 AM

Thank you all for your help.smile.gif

 

One post that Eddgie made on a different thread was interesting ...

Both the Mak, and the SCT both have a spherical mirror, probably being made in the same factory.

 

So now the important difference is comparing the manufacturing accuracy of the ashpheric sct corrector, vs spherical mct corrector.  Maybe the mct corrector is easier to make ergo better?   But they have been making the sct corrector for decades, they have automated tools.

 

It was also pointed out that one driving force for the MCT design was that in the mid 20th century

The ashperical sct corrector plate was difficult to make.

 

Additionally the published MCT spot size is a fib, since it does not include the baffle, which makes the spot about the same as the SCT spot.

 

The synta maks are also shown to be operating at 120mm not 127.  (13% brighter maybe discernable)

 

So with all that being  said in the  MCT vs SCT decision,  probably there is more to do with the samples being compared than differences in intrinsic design performance.

 

So because of a slightly wider field, lighter weight, quicker cool down, and sct rear port convience I chose the SCT. 

 

After picking it up, I can definitely tote it a mile to my observation site.  Now I just need

a very light head for a photo tripod.

 

I purchased a local used c5 xlt blue/white tube.

I will check the baffle for shineyness.  Thx cometeer.

I have had two clear nights in November, I don't know when I will get out to test it out.

 

VT

How are you liking it? I’m thinking I’m joining the Cat party as well, probably with the 6” mak though, but over all how do you like the design?



#24 vtornado

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Posted 19 July 2019 - 12:17 PM

Sorry Jond, did not see this.   I like the C5.  It compares well to the view of a 100ed, and 130 f5, the portability is awesome

it fits in a school backpack.  




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