Is my collimation out?

[Stargazer33]

Hi,

I have finally been able to get out and do some observing over the last couple of nights, due to finally having clear skies!

I have managed to find M13 and M57 although neither of them were very clear in my Skymax 102mm Mak/Cass at quite high mag.

Last night I was trying to find M29 and was having great difficulty. Whilst I was centring on gamma Cygni I noticed that the star had concentric rings around it which were broken at intermittent intervals. No matter how I changed the focus I couldn't get rid of these lines.

Thinking about it at work today I was wondering, is the collimation of my scope out? I know Mak/Cass scopes are good at holding collimation but It seems that my views are never as clear as other people seem to get.

I have tried to do the star test and have even done it with an LED light held behind a piece of card with a pin [removed word] hole in it at about 30' away and that seems to be okay to me. Not too sure though if it is pinched in at one side or not.

I guess my question is: should I take it to my local astro store and ask them to check the collimation for me?

Any thoughts/suggestions would be gratefully received.

Bryan

[Steve Ward]

I'm guessing that if you had Concentric rings then the colli is fine , what you were seeing were the effects of the atmosphere.

The seeing was dreadful here last night , I didn't even bother setting up.

[NGC 1502]

Hi Bryan, as post #2, sounds like collimation is ok. The fact that you mention intermittent broken rings

says that the seeing was poor. Poor seeing (turbulent atmosphere) is common on nights after a hot day, as

all that stored up heat in the ground & buildings dissipates into the sky.

M29 is about 1.5 degrees south of Gamma Cyg ( Sadr ) it is quite tiny, and as it lies within the Milky Way

can become lost to the eye. It looks like this http://www.astronomy-pictures.com/2004-05/ST-7-M29.htm

The brighter stars in the centre are M29, the image shows many more background stars than visually.

Your 102 Mak will show it easily, I get a nice view through my 70mm refractor.

Regards, Ed.

[Stargazer33]

Thanks guys!

I guess I am just expecting too much! Especially after not being able to get out for an outrageous number of months due to bad weather/clouds.

That has taken a load of my mind...and saved me a trip to the astro shop and probably some money too!

Bryan

[JamesF]

Maks don't tend to go out of collimation very easily unless they've been treated fairly carelessly. They're not that hard to collimate yourself though, should you need to. A couple of allen keys and a large bag of patience are the main tools required.

James

[Moonshane]

I presume that your scope will produce airy rings (given the small exit pupils at higher powers) and it therefore sounds normal to me. when observing doubles I really like the effect and feel it makes for lovely visual images.

[Stargazer33]

I presume that your scope will produce airy rings (given the small exit pupils at higher powers) and it therefore sounds normal to me. when observing doubles I really like the effect and feel it makes for lovely visual images.

I was trying to see the double, double in Lyre last night but couldn't see it. I found a couple of doubles (or what looked like doubles to me) at 180x mag, but nothing that looked like a double, double.

Should I be able to split the double stars with my scope at these mags and see four star?

A couple of allen keys and a large bag of patience are the main tools required.

James

Unfortunately I have less than an ants armpit full of patience!

Bryan

[Moonshane]

you should be able to split the double double well at that magnification. if you have an optical finder then point this at Vega and the double double is the single double obvious to the north approx currently (i.e. left if facing east as I normally do). look in your scope and each component of this single double splits again into four stars.

[JamesF]

The seeing here was not at all good last night. If it were the same further east that may well have been a contributory factor?

James

[Stargazer33]

Thanks!

I think I was looking at the wrong double, going back and looking at the star map - 'Turn Left at Orion'.

I also thought I had captured the Dumbell nebula too, although it didn't look anything like the sketch in TLaO. Again going back to the book I think I got that wrong too and hadn't gone far enough and was actually looking at M27!

I really must try and get myself to a dark site!

Looks like tonight is going to be out due to the weather forecast - still the stars aren't going anywhere (I know the Universe is expanding so they are actually going somewhere, but you know what I mean! ).

Thanks again for all your help guys!

Bryan

[JamesF]

M27 *is* the dumbell nebula. You might possibly mistake it for M57, perhaps?

James

[Stargazer33]

Ha! Just testing! I meant M71. I was looking at the wrong page as I was typing - what can I say, I'm a man and can't do two things at the same time!

I started from Altair and went 'up' in my eyepiece and I think I reached M71 (in between Gamma and Delta Sagittae). I didn't realise this object was there and stopped searching as soon as I saw a fuzzy blob thinking it was M27.

Bryan