Scope dilemma...

[Patbloke]

OK folks I am about to order a Celestron Nexstar 6SE for many reasons - portability, Goto and budget... but before I do I have a simple question -

I have the use of a Skwatcher 200p, so will the nexstar 6SE give me better, the same or lesser views? I ask as although the primary mirror is smaller the focal length is greater...

Also some reviews are very flattering of the nexstar...

Here we go....☺

[ronin]

Lesser. The aperture is simply less, you are collecting just over half the light of the 8"..

[Moonshane]

^{tracking will give you a big bonus when looking at higher power. personally I am biased toward dobs andI tend to agree the views through the dob will be better than the SCT but the reasons you mention buying the SCT are nothing to do with the actual views I suppose. they may actually complement each other as the dob will be great at wider fields and the SCT for higher power planetary etc. optically, I'd be surprised if the dob is not better.}

[Patbloke]

Lesser. The aperture is simply less, you are collecting just over half the light of the 8"..

Thanks for that which I understand... However what I'm struggling with is that If the 6SE has a greater focal length, will I not be able to get greater magnification? albeit that I will not have as much light gathered... 

[Moonshane]

magnification is really governed by 1) atmosphere and 2) aperture 3) optical quality. more aperture allows more magnification in theory but always governed by atmospheric conditions. better optical quality also allows more magnification but again often restricted by 1) and 2).

the dob wins on aperture and probably optical quality but don't underestimate the value of tracking at high powers. not essential but really helps to concentrate (and sketch if appropriate).

[CodnorPaul]

I don't understand why the dob wins on optic quality - my experience of looking through various manufacturers dobs vs my SCT is my SCT wins hands down on optic quality. The dob advantage to me is price and getting a big mirror - not giving better views

[swamp thing]

I don't understand why the dob wins on optic quality - my experience of looking through various manufacturers dobs vs my SCT is my SCT wins hands down on optic quality. The dob advantage to me is price and getting a big mirror - not giving better views

You aren't convincing me.

[Patbloke]

^{tracking will give you a big bonus when looking at higher power. personally I am biased toward dobs andI tend to agree the views through the dob will be better than the SCT but the reasons you mention buying the SCT are nothing to do with the actual views I suppose. they may actually complement each other as the dob will be great at wider fields and the SCT for higher power planetary etc. optically, I'd be surprised if the dob is not better.}

Ah yes interesting maybe that's it Moonshane... the SCT WILL have greater power (more mag?) If I buy it I'll see you at the Peaks to discuss! 

[tich]

I've got an 6"SCT & yes it gives fantastic views on planets & a few DSO's but you are restricted with the mag mainly due to conditions as stated plus the FOV, I also had an 8" newt (F5) & now have a 10" Newt (F4.7) & both have given me much superior views than the SCT.

 

[CodnorPaul]

I've got an 6"SCT & yes it gives fantastic views on planets & a few DSO's but you are restricted with the mag mainly due to conditions as stated plus the FOV, I also had an 8" newt (F5) & now have a 10" Newt (F4.7) & both have given me much superior views than the SCT.

I will keep fighting the SCT corner here...again not my experience. I have compared my 8sct to a 10 reflector and it held its own on DSO, and gives sharper views on planets. I can't say the reflectors were collimated well, don't know, but my SCT is. I would not swap my SCT for a reflector unless going for a 16" dob+

[swamp thing]

I will keep fighting the SCT corner here...again not my experience. I have compared my 8sct to a 10 reflector and it held its own on DSO, and gives sharper views on planets. I can't say the reflectors were collimated well, don't know, but my SCT is. I would not swap my SCT for a reflector unless going for a 16" dob+

You're still not convincing me. What you've just said goes against the laws of optics too.

[RikM]

I have compared my 150p to my friends C6 a few times and there really isn't anything in it. A 200p is a very noticeable step up from a 150p so I would have to assume a 200p to beat a C6 by the same margin. Certainly my 250px does.

Magnification is more or less a false argument. Either scope can give the same magnification, it just requires a different eyepiece. With my range of scopes I find that the larger aperture allows a higher magnification to be used, up to the limit imposed by the atmosphere.

[CodnorPaul]

You're still not convincing me. What you've just said goes against the laws of optics too.

What I said is held its own, not beat...

[swamp thing]

How do you interpret "held its own?"

Meaning, as good, is what I would say, and that's not possible I'm afraid.

[CodnorPaul]

How do you interpret "held its own?"

Meaning, as good, is what I would say, and that's not possible I'm afraid.

No - in same league, not a big difference given the aperture

[swamp thing]

No - in same league, not a big difference given the aperture

Your 8" SCT is "in the same league" as an 8" Dob. Not a 10"

I've used some very nice 8" SCT over the years, can they natch a 10" NO.

I don't even need to look through your 8" scope to know my 10" will out perform it on every thing I look at because the laws of optics say so.

A 10" will go deeper on deep sky and out resolve it on planets. I'm afraid that's the laws of optics for you.

Even a pretty average 10" mirror will wipe the floor with a very good 8" mirror.

[ollypenrice]

The focal length of the scope alone isn't very important. It is the effective focal length (that of scope and EP) which matters.

The issues concerning SCT versus Newtonian optics are various. The SCT was intended to reduce coma, and it does. Bernhard Schmidt called his invention the Coma Free Reflector. It was his friend Walter Baader who, after Schmidt's death, pushed for the SCT designation to honour him. A Newt needs a coma corrector to be coma free. On the other hand the SCT usually has a larger secondary obstruction, which reduces contrast, and the extra glass of the corrector makes for more scatter. But then, on the other other hand, the corrector eliminates diff spikes. And so on and on.   In my view pure Newtonian optics are better than SCT optics of the same aperture for visual observing. 

Olly

[cotterless45]

I think a trap that a lot of folk fall in is to start looking at scopes, when they should be considering what targets they spend the most time observing. There is no "do it all" scope. I expect there are other considerations such as portability and ease of use.

I've only looked through a Mak once, it was quite good on planets, but I was told that the fov was quite narrow.

For the most satisfying general use it's very hard to beat an 8" Dob. Especially if you are restricted by poor skies. The ota has a focal length of 1200 compared to the 1500mm of the Nexstar6.

You will find your highest magnification will be restricted by seeing conditions. Most nights up to x200 is about it and x300 if exceptional. You'll need tracking to keep up , or a fast arm !

Perhaps a compromise is a SW GOTO Dob, with a seat for comfortable viewing. This will give you good views of a range of targets and quite handy to transport when collapsed. Certainly if all my Newts, mounts and heavens forbid , refractors disappeared one night , I'd be considering a 10" GOTO Dob.

I think that your choice may also depend of you want to dabble or go deeper into observing and imaging.

It's very much like recommending which car to get to anyone on the forum.

Possibly the very best way is to have a look through your weapon of choice. Certainly something which folk here will let you do at star parties under

Clear skies,

Nick.

[tich]

Last year I had both my 8" Newt & 6" SCT set up & I was observing Saturn last year, whilst both scopes were giving good views the 8" was clearly brighter & had a better contrast. Both scopes were using Hyperion eyepieces so there was no advantage with either of them. I like the SCT for its portability, size & even it's planetary imaging capabilities but on the fainter stuff the 8" wins, the 10" is even better as was proved when observing M76 as I couldn't see it with the 8" but with the 10" it was clearly visible which surprised me as I didn't think that a couple of inches would make a lot of difference, how wrong was I.

[LeeB]

Pat , i've pm' ed you with more detail but I agree with the school that says apeture wins, a well collimated newt will do what a cat can but with better contrast at the same aperture, an 8 is an 8 full stop, the only slight addative is a good fract will help a little with no central obstruction but in my opinion a six will still not match a well set up 8 newt. I love the view through my six inch but if I want detail I go for the big gun every time.

A longer focal length newt will help detail on planets, but normally only because its more likely to be well collimated, the central obstruction is smaller and its easier on eyepieces.

[Tinker1947]

I will go with the Reflector giving better views than the SCT, having a 10" Reflector and a C11.........

[Sandraj]

Thinking aloud here, would it be more beneficial for the OP to go with the 8SE instead for portability and tracking instead of the 6SE? How would the 8SE compare?

[RikM]

The 8SE is a very nice telescope and will give views as good as a 200p in a quite convenient package.

[Sandraj]

The 8SE is a very nice telescope and will give views as good as a 200p in a quite convenient package.

Thats cool then as I may well be tempted now in getting one. 

[Patbloke]

Ladies and Gentlemen after seeking your advice and much reflection (see what I did there) I am proud to announce I am the proud owner of an 'amazing condition' Celestron C8 SGT XLT on Advance GT mount with Nexstar controller (thanks for the tip off Lee) I did have to make a one hundred and twenty mile return trip, but it was more than worth it!

I'm sorry everyone you know this will mean a few more weeks of cloud don't you?

The weird thing is I have ended up with an 8 inch and a mount and tripod that appears to be bigger and heavier than my EQ5... You have to laugh as my original intention was to get a quick easily portable scope to put in the car and disappear to a dark site. This is a beauty, and looks so clean, and judging by the clarity of the brickwork on the house up the road, looks real sharp.  Can't wait to try her, I'll let you know how she performs and get some pics on here soon...

Clear skies everyone!