That's one comprehensive piece of kit. Though I think you are doubling up having both a Cheshire and a Laser collimator - still, fun to try both.
Actually, no! A laser is only part of a good collimation setup. A good cheshire should be part of every setup, especially with a solid tube newtonian as a laser cannot effectively align the secondary.
Actually, no! A laser is only part of a good collimation setup. A good cheshire should be part of every setup, especially with a solid tube newtonian as a laser cannot effectively align the secondary.
Malcolm
Hi Malcolm,
I was assuming the secondary was correctly placed, but point taken.
I used a sight tube for my secondary, and a Cheshire ever since. I did pick up a cheap laser collimator on Ebay, but have never gotten around to using it. The one thing that I never did fathom was the thing called an Autocollimator that used to be sold as a set with the Cheshire by one company. The guy who owned it couldn't make head nor tails of the instructions, he lent it to me, and I couldn't make any sense of it either.
Cheers,
Renato
The one thing that I never did fathom was the thing called an Autocollimator that used to be sold as a set with the Cheshire by one company. The guy who owned it couldn't make head nor tails of the instructions, he lent it to me, and I couldn't make any sense of it either.
Scroll down and download instructions for LightPipe/SightTube & Autocollimator. Page 6 describes theory behind autocollimator.
Also refer to table at top of above web page. The autocollimator is a highly sensitive device for precise collimation and used after collimation with a less sensitive device.
I spoke with Alex before getting collimation tools. He said he had both, Chesire was better for secondary, laser more convenient for primary, when batteries die (if that happens), which it happened to him, it was good to have the Chesire. Since they were both 'cheap' rather than the most expensive stuff, he said to get both, learn both, good education before going and spending who knows what $$$ on something I don't even understand how works.
Only thing I forgot is a star map. In fact, I don't even know how to read one.
Plenty of time for maps. At least you have something interesting to look at tonight if the weather is kind to you, the lunar eclipse could be a nice first light.
Aside from that, Jupiter is still pretty visible and easy to find (the very bright object more or less due north (I am assuming you are in Australia) and maybe 30 degrees up from the horizon just on dark. The moon is, well, the moon! And Mars is up in the east on dark and will be not too far above the moon and is reasonably easy to find.
A tip for finding planets if you are not aware of it, they scintilate (Twinkle) a lot less than the stars so look for the steadiest looking objects. And they will always be in the reigion around the celestial equator (The line from east to west that is above the horizon by the same angle as your latitude)
Venus is also well up the sky before sunrise if you happen to be up at a silly time in the morning. I have a morning jog as many mornings a week as I can manage and have to leave for work at 7AM so I am well and truly running in the dark, Venus tempts me to be late to work and get the scope out instead, I have usually observed it in the evenings when it is trailing the sun and after the heat of the day it is not much of a target. I keep meaning to have a look in the morning.
At least that gives you some fairly easy targets to pot to get used to the scope.
Scroll down and download instructions for LightPipe/SightTube & Autocollimator. Page 6 describes theory behind autocollimator.
Also refer to table at top of above web page. The autocollimator is a highly sensitive device for precise collimation and used after collimation with a less sensitive device.
Thanks, those instructions are a lot better than those we were looking at back in the 90s.
I had no idea that what was meant to be adjusted was the secondary mirror.
Regards,
Renato
Thanks, those instructions are a lot better than those we were looking at back in the 90s.
I had no idea that what was meant to be adjusted was the secondary mirror.
Regards,
Renato
The autocollimator is a wonderful tool with the proper knowledge; however, it has to be of top quality. Not all autocollimators on the market (and there are only few choices) are equal.
Unfortunately, the autocollimator instructions provided in astrosystems documentation is incorrect. Even the theory behind the autocollimator described in the same documentation is incorrect.
The autocollimator is used for both secondary and primary axial alignment. You can refer to Vic Menard's CDP procedure for the proper method to use an autocollimator with a single central pupil http://www.catseyecollimation.com/vicsCDP.html
I have written extensively about the autocollimator theory. Here is a link. Most of the info inside the link is academic and is not a required knowledge to use the autocollimator.
The autocollimator is a wonderful tool with the proper knowledge; however, it has to be of top quality. Not all autocollimators on the market (and there are only few choices) are equal.
Unfortunately, the autocollimator instructions provided in astrosystems documentation is incorrect. Even the theory behind the autocollimator described in the same documentation is incorrect.
The autocollimator is used for both secondary and primary axial alignment. You can refer to Vic Menard's CDP procedure for the proper method to use an autocollimator with a single central pupil http://www.catseyecollimation.com/vicsCDP.html
I have written extensively about the autocollimator theory. Here is a link. Most of the info inside the link is academic and is not a required knowledge to use the autocollimator.
Thanks very much Jason,
Very interesting. I'd been thinking of ordering one till I read what you just wrote.
Here is my question for you. I have a truss dobsonian which I have to assemble every time I use it. And every time, I have to use a Cheshire to make adjustments to get the little dark spot dead centre into the middle of the annulus in the middle of my primary. The more concentric the spot is in the annulus, the better the image.
Is it worth getting an autocollimator - other than for checking that something isn't slightly out with the secondary mirror (I was never that confident using the cross-haired sighting tube that I initially used)? Is it something I could get collimation right with in a minute or two after assembling and using the Cheshire? Or is it going to take another half hour of fiddling around?
Thanks for any assistance you can give me on this intriguing issue.
Regards,
Renato
Thanks very much Jason,
Very interesting. I'd been thinking of ordering one till I read what you just wrote.
Here is my question for you. I have a truss dobsonian which I have to assemble every time I use it. And every time, I have to use a Cheshire to make adjustments to get the little dark spot dead centre into the middle of the annulus in the middle of my primary. The more concentric the spot is in the annulus, the better the image.
Is it worth getting an autocollimator - other than for checking that something isn't slightly out with the secondary mirror (I was never that confident using the cross-haired sighting tube that I initially used)? Is it something I could get collimation right with in a minute or two after assembling and using the Cheshire? Or is it going to take another half hour of fiddling around?
Thanks for any assistance you can give me on this intriguing issue.
Regards,
Renato
I use my cats eye cheshire and autocollimator every night i setup, I also have the sight tube but I only use that when I take the secondary out of the scope. I have found them to be accurate and easy to use, and when I have all the reflections lined up I know that the collimation is perfect!
good deal
now you can look at nebulas,galaxies and maybe if your lucky you might catch a supernova exploding.you've got apeture,a lot more than some people who like refractors who have to put up with small light gathering power.
I use my cats eye cheshire and autocollimator every night i setup, I also have the sight tube but I only use that when I take the secondary out of the scope. I have found them to be accurate and easy to use, and when I have all the reflections lined up I know that the collimation is perfect!
Much appreciated, thanks.
To George - sorry about this digression in your thread about your marvellous looking new telescope.
To George - sorry about this digression in your thread about your marvellous looking new telescope.
Regards,
Renato
It is ok. I tend to do it as well on other peoples posts because something there was relevant to what I was thinking and rather than start a new thread, since it was mentioned, i get it sorted in the thread I read it in. All good
I saw saturn tonight between the clouds and 5 (might of been 4?) moons. WOW!
It is 'very' small looking compare to the monitor screen, like not even 1 inch in size. More like 5-10mm, but it was nice!
