The Official Astronomy Thread

[Crusader]

Kalvaer has it spot on. The easiest way to test is actually to just rotate it in the focuser, although focuses slop could also play a role. Mine is way out that's why I only use it with a barlow.

As an aside, my Technopro has shipped! Excellent service from them since it's within 12 hours of placing the order.

 

[marine1]

Guys this aint happening. I cannot seem to focus just with eye pieces on Venus. I can just see a light, very blur. Tried using all my eye pieces.

 

[marine1]

I wonder if my scope is out of alignment if that is possible??
Using this:
http://shop.technopro.co.za/skywatcher-sk127makeq3-maksutovcassegrain-5-p-879.html

 

[Kalvaer]

How low down was venus? It can appear very blurry if the conditions are bad as well. It is after all a very very bright ball.

I've only been able to see venus in a "half moon" type phase by looking with the rods of my eyes. Never direct

 

[marine1]

Thats exactly how I saw it through the scope.

 

[Crusader]

Venus is pretty low unless you view just at sunset an then it is still not optimal with lots of atmosphere between us and it.

Venus isn't much to look at except for viewing the phases. To me it never looks much better than a blurry disc and that's how it should be. There's no actual detail visible.

As for testing your collimation the most apparent thing is that stars start to look like comets with a little tail.

A star test will also show it. Center a bright star at high magnification and defocus it slightly. Look closely and you should see the diffraction rings. They should be concentric circles. If they bulge out to one size you need to collimate.

 

[mercurial]

You won't believe how badly mis-alligned my scope was I managed to get it collimated, after an initial struggle

 

[Crusader]

Mercurial, you've got a 12" right? Apparently the larger the dob the more often it needs to be collimated. Luckily after the first major one it tends to be only minor tweaks of the primary.

How do those of you with the EQ mounts find them? I'd think that polar alignment will be quite difficult without any bright stars close to the SCpole.

 

[mercurial]

Yip, 12". It's massive and I'm probably gonna need to collimate it very often. I'd love to have an EQ mount for it but I'm to scared to imagine how much that would cost.

 

[Kalvaer]

How do those of you with the EQ mounts find them?

You get used to it after awhile. Its generally also alot easier if you do it in your back yard each time so you know what to look for.

I spent a number of nights doing drift star alignments along with some star trail film photographs to work out exactly where the SP is. I then marked the location of the legs in my backyard and try to set the scope up in the exact same position each time.

Of course if I go to a new location then I have to do it all again if the SP is not clearly visable

 

[Crusader]

That's the reason I love my dob. No alignment needed, but then I'm strictly into visual viewing. For photography a EQ mount is essential.

 

[mercurial]

That's the reason I love my dob. No alignment needed, but then I'm strictly into visual viewing. For photography a EQ mount is essential.

Not necessarily. I've seen many good pics taken with DLSRS (hand-guided). It's certainly much easier to use an EQ though.

 

[Crusader]

I was thinking of long exposure DSO photography. And then newts struggle to get to focus if you want to use a camera at prime focus - at least from what I read.

 

[mercurial]

For long exposure, it's a must need yeah. With DSLRs, people usually take exposures around 3 mins each and take multiple exposures. For that, it's ok, but like you said, for long exposures, you do need an EQ

 

[Crusader]

My package arrived in George this morning. I hope that Berco isn't like the other couriers that only deliver here on Tuesdays and Thursdays. If I'm lucky I might get the new scope by this afternoon, but I shouldn't get my hopes up...

 

[Kalvaer]

If you do.. I guess it will be raining all weekend

 

[nimthor]

Crusader,

I usually find my EQ mount in the spareroom if it is cloudy or windy outside, otherwise I use my red headlight to find it in the dark ;-)

I love my LXD75 mount. It has a built-in polar scope, and even here in Durbanville I can see sigma Octans through it, well actually four of the "brighter" Octans stars. The polar scope has a little picture of the 4 stars which you use to align it up with. I find it just too hard on the neck so never use it. I use my handcontroller to do a rough polar alignment, use 3 star alignment and it calculates how far you are off from SCP. For AP I drift align, usually takes me about 30min. I also have marked spots in the backyard whee the tripod feet goes, but I am in the process of seting up a portable pier, but it would be left in place permantly. I am not allowed to dig up the congrete for a permanent pier :-(

I started out AP with a barndoor tracker that I motorised with a stepper motor from an old floppy drive, for shorter focal length shots I could go to 60sec exposures without trailing.

Clear skies!
Charles

 

[Crusader]

If you do.. I guess it will be raining all weekend

The curse was a bit premature. As soon as I got notification of the package shipping it clouded up and the following day it rained. Hopefully that's it, but I haven't looked at the forecast for the weekend.

Crusader,

I usually find my EQ mount in the spareroom if it is cloudy or windy outside, otherwise I use my red headlight to find it in the dark ;-)

I love my LXD75 mount. It has a built-in polar scope, and even here in Durbanville I can see sigma Octans through it, well actually four of the "brighter" Octans stars.

LOL! Obviously you'll find it with a red headlight...

Sounds easy enough to polar align. I just have one problem at my location... Octans is hidden behind the mountains. Guess I'll just stick to Alt-Az mounts for the time being.

 

[Kalvaer]

I just have one problem at my location... Octans is hidden behind the mountains. Guess I'll just stick to Alt-Az mounts for the time being.

Octans is a pain in the butt to find even if you do know where it is and can see it. Drift alignment might be a bit over kill, but you learn quickly how to do it. Once you get the general region right, you learn to start doing it while viewing to correct the drift if its not 100%.

Remember you wont need it perfect anyway unless your doing AP.

 

[Crusader]

Wohoo!!!! My scope got deliver about 3 hours ago.

I've spend the better part of an hour assembling it. Since the manual wasn't explicit in the instructions it took some time to get things right, but I hope I've done everything correctly.

From what I can tell the build quality seems good. The AZ3 mount seems very solid, although I'm having difficulty with coarse adjustments in altitude. Seems like you just take hold of the scope and force it upwards/downwards - the manual states that altitude movement is controlled by a friction bolt but I can't find any easy way to adjust it.

The azimuth movement is very easy. You just need to loosen the azimuth locking knob and then use it to point the scope in the desired direction. The slow motion controls are something totally new to me. Their movement seems easy enough, but I'm sure they'll take some getting used to.

I'll have to wait till tomorrow to actually test the scope out. I've got to get to bed since I've got to work tomorrow