Star test, Arcturus, Celestron NexStar 5SE XLT

[pseudorandomly]

Regarding the astigmatism discussion here: jkt8012 is correct; astigmatism manifests itself as a 90 degree flip, not a 180 degree flip. The central hole does appear slightly oval, but you have to be careful about judging that from a processed video image; software might have stretched the image to conform to a particular aspect ratio. I'd tweak the collimation more precisely before trying to judge that, so it's easy to tell if the bright rings are oval by the same amount as the dark hole.

[mateuszlee]

aren't they a bit of egg shape ?

[jkt8012]

ahlberto is not correct about the astigmatism. Although the pattern is oval it does not flip 90 degrees on either side of focus which is the characteristic of astigmatism. This oval pattern could be due to unequal air density in the tube. However , he is correct about the scope needing collimation. The shadow of the secondary is not centered. .

[ahlberto]

@jkt8012 No,youre wrong.The image flips 180º (not 90º...) as you can see in the video.Its a bad C5 sample and the optics are faulty and completely astigmatic.Its a pitty but the SCTs are usualy very good.

[buija1]

super

[ahlberto]

The scope is astigmatic and is very descolimated

[CumputerPhysiscsLab]

@ahlberto How could you see that?

[ahlberto]

@CumputerPhysiscsLab Hi.The descolimation is obvious and the oval shape of the dougnout denounces a optic with astigmatism

[SaturnAndItsRings]

The Nexstar SE series are great scopes! I have a 6se myself =)

[tim71pos]

It's not well collimated, too far over to the 3 to 5 o'clock position. You want to collimate it at the breakout point which you see at 1:52. See the article "SCT collimation under adverse circumstances" on Astromart.

It's a great demonstration though for newbies. Thanks for posting it.

[igotmail2]

Impressive presentation and demonstration! Great optics! Well done! Thank you!

[krisDM3000]

Looking good! But the NexStar has a tracking mount right? When you don't have a tracking mount it's easier to do that test on Polaris.

[CumputerPhysiscsLab]

@krisDM3000 Yes, it has a mount. Thanks!

[J122BO55]

@CumputerPhysiscsLab how much would i have to pay for an telescope like this one?

[CumputerPhysiscsLab]

@J122BO55 Celestron C5 costs around 500 US$