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Hi all

I recently brought a celestron 6 se to replace my 10" dob and have to say I am happy with the celestron as a whole. However I have now seen a celestron nexstar 8 and was considering swapping it for my 6 se.

Now firstly I know there was a fair bit of difference between the brightness of objects between my ol 10" and the 6 se, will there be a big difference between the 6 and the 8?

also the 8 is the older (silver) version. Is there much difference, such as lense coatings, or is it just the tripod. I am a bit worried about swapping to the older style if it is not as good as the SE.

as always any help or views are welcome

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I very much doubt that you'd find any difference at all between generations. In competing for business the two main SCT makers have to keep inventing new acronyms for minor refinements but don't expect to see any really significant improvements!

Olly

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One thing you will notice, specially at high magnification is the fact that the SE mount that holds the 6 inch scope is far stable than the one holding the 8 inch scope. This is because the 8 inch scope is a tad too heavy for the mount and this shows up at high magnification, which you will want to use considering the fact that the 8 inch takes in 76% more light and can go to high powers. I'd say if you were to buy the 8SE, please do, keep the SE mount for camping trips etc, and also buy a sturdy EQ mount like the EQ5 or HEQ5 for it. No modifications are necessary on the 8 inch scope and it can therefore be swapped between two mounts by the turn of the lock screw.

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thanks for the reply. This is my main problem with the change, the tripod on the 8 is different with rectangle legs which looks a lot less stable than the tripod on my SE model.

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I think the 1st generation Nexstar mounts (sounds like the C8 you are considering is one of these) had aluminum tripod legs which are not as stable as the later steel tubed ones which came in with the Nexstar 5i and 8i and were continued with the SE series. The GOTO functionality of the original Nextstar mount is more limited in terms of alignment options and the number of objects in the database as well.

Here is a review comparing the Nexstar 8 and 8i models which might be of interest:

http://www.cloudynig...php?item_id=658

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John thank you for linking that reveiw, was exactly what I was looking for! Think i shall keep my 6 se for now, as it appear to have a better mount and features. Might well go down the route of trying to find just a 8" OTA, therefore allowing me to interchange the two.

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or for the step up in light grasp your thinking of go for the 9.25, but you will need a mount to go with it

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Remember, the Nexstar 8i and Nexstar 8 does not have 3 stars SkyAlign mode or removable OTA. Vixen dovetail system was introduced in the orange 8SE.

Since you already have a Nexstar 6SE, you can just sell the C6 OTA and replace it with a C8 OTA. 6SE and 8SE shares the same mount, the only different is the OTA. The Vixen dovetail system in the SE is one of the biggest improvement over the previous generations of Nexstar scopes.

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I upgraded from 6SE to 8SE and have not regretted it.

Points to bear in mind:

  • It is the same mount and tripod, and (as has been stated) it pushes the SE mount to the limit. You notice it especially when there is any sort of breeze, particularly if you make a nice long dew shield (which I did).
  • It is significantly heavier for carrying in and out - not to the point where I can't, but it was the first thing I noticed when I set it up. The 6SE was an easy carry in comparison (I keep the OTA on the mount and carry it as one lump, but you could easily carry them in two bits.)
  • Probably the most significant problem I have encountered is that because the tube is bigger (longer), you are very limited with altitude. Anything above about 50 degrees and you are likely to start running the OTA into the mount. For this reason I will be upgrading to a good EQ mount in a month or so, which will totally solve the problem.

So, in summary, my thoughts are I like the OTA and image quality, but don't think the mount is really up to the job and a decent EQ mount is going to add quite a bit to the price.

HTH

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  • Probably the most significant problem I have encountered is that because the tube is bigger (longer), you are very limited with altitude. Anything above about 50 degrees and you are likely to start running the OTA into the mount.

I don't really understand that point, surely the star diagonal solves any such problem... I have the 8SE and the OTA has never run into the mount :confused:

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The focal lengths are slightly different too aren't they?

c6 is 1500mm and the c8 2000mm ish.

So for a given EP, the magnification will be slightly different too.

Cheers

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I don't really understand that point, surely the star diagonal solves any such problem... I have the 8SE and the OTA has never run into the mount :confused:

He means when you try looking up close to the zenith, the star diagonal will possibly hit the mount (the hatch where the AA batteries go). It always will on mine since I fitted a Baader Steeltrack focuser, in fact I stopped using the original goto mount because it was just too weedy for the upgrades I fitted.

The 8SE is a great compact scope that you can fit a lot to - there are accessory screws all around the back plastic collar, no modifications are necessary if you buy the right accessories - but the mount does need to be swapped for a beefy AZ or EQ.

I have kept my original 8SE mount and am now planning to buy a C6 to go on it for some grab and go goto astronomy, the 8SE was a bit too heavy and a bit too wobbly to qualify for that title, and I like to try new things. :)

Edited by jonathan

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Following on from all of the above, I upgraded my 6SE with the ota from an 8SE and it's a neat upgrade path. It is pushing the mount though a bit more, but gentle movements on the focus knob and not setting up on a hard surface can make a big difference to the vibration from the extra weight. The 8 gives the mount a bit of a Dob hole though :D even with the tube slid all the way up.

The 8 has a lot to offer though - 90% more light gathering area than the 6, which is great for DSOs - but planetary wise I've had both tubes out a couple of times now and struggled to really tell them apart on Saturn (British weather!) The 6 has a lot to offer :cool:

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I don't really understand that point, surely the star diagonal solves any such problem... I have the 8SE and the OTA has never run into the mount :confused:

I've never encountered this problem with my 8se. It would happen if you placed the OTA too far back on the dovetail. I happily observe up to zenith.

Edited by LukeSkywatcher

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I have been told by the good chaps at FLO that a C6 is still excellent for planets and moon, it's probably just the faint DSOs where the 8SE will really help.

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Thanks for all the help guys. Where would be the best place to by a 8" OTA? I have tried looking for one secondhand but it seems they never come up.

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Astrobuysell is a good place to start http://www.astrobuys...uk/propview.php

The C8 otas do come up occasionally, but their higher price point new makes them less popular than your common garden Dob, and therefore less churn on the used market. Either that or everyone loves 'em :)

Don't underestimate your C6 though... It'll show you plenty :cool:

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If you are going to mount a C8 / 8SE onto the Celestron 6SE mount, consider buying the suppression pads as well to reduce the vibration when focusing.

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Steve, before you buy I just thought I would add this, I did not notice much difference between my old 6SE and the 8SE I tried out, that's why I opted for the 925, the 6 SE is surprisingly impressive for its size :smiley:

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Steve,

This is a comparison I did when I upgraded from 6SE to 8SE. Ignore the quality of the images - single frames taken at different times under different conditions - but will give you some idea of the difference in image-size using the same ep/barlow combinations on the two scopes.

HTH

post-4846-0-20264000-1373343002_thumb.jp

  • Like 2

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thank you for the imput guys. looking at the images I will certainly look out for a 8" OTA. but until then I am very happy with the 6, I was really worried that going from a 10" dob to a 6" I would not see as much. However I would say the 6 gives a much clearer view, especially of saturn

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Just an update.... I did it! At the weekend I took a 2 1/2 hour trip to pick up a C8 xlt. The C8 had a revelation Crayford focuser, dew shield and camera mount. I feel I got it for a bargain at £310 + £40 petrol.

I have since sold my C6 ota for £280 and focuser £70. Although I had to buy a visual back and diagonal (£38 together), so all in all The upgrade to a C8 + few shield cost £38!!!!!

Just need clear skies now!

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