I got problems

[Kevdan]

Hi all,

Last night was a great night, clear as anything, But I was sadly dissapointed, I started out looking at Saturn and thats where it ended, All I could see was a double image as if Saturn had split in two, with one of them slightly below the other, I checked collimation and this appears just as it was when I set it a week ago and the same as the picture of a collimated scope in astrobaby's guide. My heart sunk as I started to think that the mirrors were cracked,So in the early hours this morning I took out the primary and secondary mirrors to inspect them and nothing. So what could be the problem, I can still only think that it must be collimation but as I said earlier it appears to be ok.

This is similar to how it looks, This is the pic of Astrobaby's 200p and my 150p looks very similar.

Kev

[Moonshane]

hi Kev

was the image like Saturn split down the middle with one bit further down than the other or like two identical Saturns one above the other?

was the scope cooled for at least half an hour before observing? If the former, check your eyepieces as this may be the cause or if the latter, it could be cooling or possibly collimation.

[banner001]

like moonshane said, tube currents can cause an image to be 'smeared' in a direction looking like you have a main image, then a fainter one and so on...how long did you cool the scope for?

[Kevdan]

Hi Guys,

Scope is kept in the shed and was bought into the garden about 8:30ish It's easier to set up in daylight and I didnt start to use it till after10:00, I was a bit gutted as I have made my own Bhartov mask so I could do some imaging but never got that far,

The image was of Saturn with another Saturn pasted on top but very slightly out say 5% - 10% lower than the other but as bright and as big.

Kev.

[kniclander]

to me your collimation looks a bit out - particularly the secondary is quite clearly off-centre (it should appear as around circle in the middle of the primary). Not sure if that would give you the "double effect" but might be worth a tweak to start with.

[Kevdan]

Hi,

Thats not my picture, its the pic from astrobaby's guide to collimation but my scope pic is very similar to this.

Kev

[kniclander]

but that's a pic of an uncollimated scope, right?

[Kevdan]

Hi,

No, the write up at theside of the pic says this "This is an actual photograph taken through a Cheshire and shows a near perfect collimation pattern for a fast (f5) Newtonian. It is in fact my own Sky-Watcher 200P"

Here are a couple of pics of my own scope , they arent brilliant but it shows that collimation isnt that bad.

the first is with no cheshire in.

Kev.

[Doc]

Looking at your photos I think the primary is not exactly under the secondary, so you need to tilt or slightly adjust your secondary mirror.

[valleyman]

Looks like the secondery is out, there should be 3 tags visible and I can only see 2 in the top left picture.

[swamp thing]

Looking at your photos I think the primary is not exactly under the secondary, so you need to tilt or slightly adjust your secondary mirror.

I would agree with Doc, looks like your secondary needs a tweak.

Regards Steve

[Doc]

Can see the crescent that is the image of the primary in the secondary, it needs to be concentric all the way round, also as valleyman states you are missing a mirror clip, by tilting the secondary you should see all three clips.

[kniclander]

Hi,

No, the write up at theside of the pic says this "This is an actual photograph taken through a Cheshire and shows a near perfect collimation pattern for a fast (f5) Newtonian. It is in fact my own Sky-Watcher 200P"

Kev.

i have now officially retired from givng collimation advice

good luck!

[swamp thing]

i have now officially retired from givng collimation advice

good luck!

LOL!

Steve

[Kevdan]

Hi,

Ok so here are the latest pics.

Kev.

[Freff]

The thin orange cresent of the primary is clear in the last images. It needs a tweak.

[mdstuart]

But its not bad enough to cause a double image..

I presume you are not looking through a double glazed window or sky light..

Have you tried a few eyepieces?

Do you get the same effect on bright stars?

Mark

[x6gas]

Hmmm. Sorry, but I'm not sure that poor collimaton could cause the effect you are reporting.

Just to get a few more silly questions out of the way, did you try more than one eyepiece and if so did you see the same effect? Similarly, if you were using a Barlow or any other optical element at that end of the scope did you try without?

It sounds to me more like a double image from some kind of refraction and that would point to the EP end of the 'scope.

Cheers, Ian

[x6gas]

Ha, ha, Mark beat me to it!

[Moonshane]

sometimes when observing I see a slight shift in the image and this is generally seeing, sometimes being a bit out of focus or a combo of both. not so much a double image but more 'atmospheric shimmer'. this is inevitable at highish powers and is part of planetary observing. I am not an imager but expect that taking numerous webcam images is what avoids this ending in the resulting final image?

[paul mc c]

I remember once looking at Jupiter and the view was terrible,proper boiling,looking at the moon the view was very sharp.i couldnt understand the difference in the two views,until i realised that a house 5 doors away had thier central heating on and it was the heat coming out of thier flue that was the problem,20 mins later when Jupiter had moved the view was fine....just a thought!

[SlipperySquid]

It doesn't look to me like a collimation problem mate, I've had worse ad don't get double images. More than likely like has already been stated it's at the eyepiece end

What magnification where you going for? what do stars look like in say a 25mm/15mm eyepiece?

Matt.

[virtualpilot45]

I've got the same scope and I've had the 'double vision' when the focus isn't quite on. Focussing better has always worked with me however!

[lw24]

I've had exactly the same problem Kevdan, however it was with my ST120 Refractor.

The solution was simple, but it had me worried for a while! T'was as following:

I screwed my fringe killer filter into my diagonal, however the thread on my diagonal isn't very good, and what happened, is that the filter slipped out of the thread, so that it was loose. It only covered up half the view. This gave me a double Saturn. I solved it pretty quickly, by luck more than anything, but it had me worried.

I doubt this is the same as you, unless you were using a filter.

Clear Skies

[Kevdan]

a house 5 doors away had thier central heating on and it was the heat coming out of thier flue !

Im a commercial heating engineer and have enough of boilers and heaters at work dont say they are going to do me at home as well LOL.

Ok, I had the same images when I used my 26mm and my 9mm also with my webcam.

Daftest thing is I was going to use my home made bahtov mask but it never got to that.

Kev.