Getting Ready to Stargaze: My Orion Atlas 11 Arrives Soon

[russ_watters]

I just placed an order for http://www.telescope.com/shopping/p...DUCT&iMainCat=4&iSubCat=10&iProductID=194382" Orion Atlas 11. With some luck, it may arrive by this weekend. Awesome.

 

[turbo]

Good Luck and good First Light. I wish I could share that with you.Skip

 

[waht]

Nice, it will certainly leave my 3 inch scope in dust.

Have fun.

 

[GeorgeSol]

Beautiful.

 

[neutrino]

Congrats. Hope all the clouds are on their way, too!

 

[Labguy]

I just placed an order for http://www.telescope.com/shopping/p...DUCT&iMainCat=4&iSubCat=10&iProductID=194382" Orion Atlas 11. With some luck, it may arrive by this weekend. Awesome.

Nice scope. I can tell you (hope it doesn't offend other scope owners) that of all the commercial SCT's, the C-11 seems to always beat the pants off of them.

The Meade 10" and even Meade's 12" don't hold a candle to the C-11 for sharpness, contrast and pinpoint detail. Also, Celestron's StarBright coatings seem much better than the Meade scopes. I haven't owned any of these, but have looked through at least 12-15 of each and sometimes with the same eyepiece for a fair comparison.

But, if you don't already have one, you will very soon be wanting a 2" star diagonal and can't live without it. Both Celestron and Meade offer a 2" diagonal, but the aftermarket ones seem to be much better quality than "stock". If you end up getting one, just be sure it is a mirror diagonal and not a prism.

 

[russ_watters]

But, if you don't already have one, you will very soon be wanting a 2" star diagonal and can't live without it. Both Celestron and Meade offer a 2" diagonal, but the aftermarket ones seem to be much better quality than "stock". If you end up getting one, just be sure it is a mirror diagonal and not a prism.

Ahh, yes. That is something I forgot about - thanks for reminding me. I may actually have one I bought for my old junker, but I can't remember if it is a 1.25" or not (it is a Meade prism iirc).

The Meade 10" and even Meade's 12" don't hold a candle to the C-11 for sharpness, contrast and pinpoint detail.

There is a guy in the Phillippines who uses it (with a different camera and mount) to take some of the best pictures around - amateur or pro - of Jupiter. NASA contacted him to assist them in keeping an eye on the GRS Jr. I can't wait to see what I can do (though Jupiter will have to wait - Saturn will be up soon).

Here's his site: http://jupiter.cstoneind.com/

 

[scott1]

I'm saving money for http://celestron.telescopes.com/products/celestron-c20-astrograph-dall-kirkham-telescope-with-permanent-pier-mount-32352.html"
I'll post in 30 years.

 

[carlos_dfc]

I'm saving money for http://celestron.telescopes.com/products/celestron-c20-astrograph-dall-kirkham-telescope-with-permanent-pier-mount-32352.html"
I'll post in 30 years.

I got that beat
12" f10 triplet apo by TMB
http://www.tmboptical.com/itemsRecord.asp?item_id=18&cat_id=4&

Or - from the same place - how about $36k for a 10" f9 lens cell only.

 

[vincentm]

Congratulations russ, with some given time, saved money i will be looking at investing in this. I am buying land out in E. Washington in the next year, and in about another year after that that is what i will be investing in. :)

 

[russ_watters]

Well, all in all, I had a reaaaaaally frustrating first night with my new baby. First of all, the weatherman - he's a liar. I don't care if he said it was going to be clear tonight. It wasn't. Problems went beyond that, though...

The night started with me not realizing the retractable counterweight shaft blocked the polar alignment scope and ended with a corrector plate covered with dew. In between, I dodged clouds, fixed software bugs on my camera (yes, I did shoot dark frames!), and dealt with much worse than expected tracking. The only image I took tonight worth posting is the regular camera pic of me standing next to the scope! Otherwise, I have one barely recognizable photo of M27.

The tracking was the biggest source of worry - large, noticeable error in half of my 30 second exposures. The error was mostly periodic in nature, so it could be the mount's normal periodic error, but I hope not - the magnitude of the error (accumulated over several minutes) was more than an arcminute, 2-4x more than people typically report. I've heard tracking is better with a 2 star alignment than with the 3-star, so I'll try that tomorrow night. I didn't drift align (I never have yet), but the polar alignment scope puts the alignment to within a few arcmin of the NCP, so I was hoping for better - what I got was roughly equal to what I have gotten with my ETX. Hmm - another possibility is that I aligned the polar axis before mounting the scope and counterweights. Perhaps I moved it out of alignment when I did that.

I was able to get a glimpse of M27, M57, and M13 through the eyepiece, but with bright skies and clouds, they were just dim, gray spots on the eyepiece. Even M13, which I had to give up on completely due to clouds. Go-to's were pretty good: all 3 objects were in the eyepiece (when the clouds moved out of the way) when ordered.

Actual setup of the scope wasn't too bad. Actually, the worst of it was that I pulled a muscle in my back yesterday at the gym - first time I've ever had to quit in the middle of a workout in my life. Now how the heck am I supposed to set up a 120lb telescope with a bad back?? Really, except for not being able to see Polaris real well through the counterweight shaft (and I tried for half an hour), I had no problems at all setting it up.

 

[Labguy]

another possibility is that I aligned the polar axis before mounting the scope and counterweights. Perhaps I moved it out of alignment when I did that.

I can guarantee you that was, and would always be, your biggest alignment problem. Another point: did you loosen both the RA and DEC axis (one at a time) and move the scope & counterweight for a near-perfect balance?

 

[turbo]

Hmm - another possibility is that I aligned the polar axis before mounting the scope and counterweights. Perhaps I moved it out of alignment when I did that.

Really, except for not being able to see Polaris real well through the counterweight shaft (and I tried for half an hour), I had no problems at all setting it up.

Russ, check your instruction manual for the mount. You should be able to install the counterweight shaft in such a way that the polar alignment scope is not obstructed (perhaps not insert it so fully). If not, it will be difficult for you ever to get a decent polar alignment. Once you load that mount and tripod with ~100# of OTA and counterweights, they will flex. The mount has to be loaded and balanced before you align. As for balance, it can be a help to have the scope and counterweights slightly out of balance, so the weight of the scope loads the RA main gear slightly and the RA gear let's the scope drop gently (or vice versa). If your counterweights balance the scope perfectly, you can experience image shift due to a slight amount of play in the drive gearing.

Good luck!

 

[tony873004]

I think the 2 and 3 star alignments are just to help the GoTo feature. It tells the telescope your setup errors. For tracking you only need to be certain you are pointed dead north, and that your mount is properly adjusted for your latitude, and that your tripod is perfectly level. Then it should track fine with or without a star alignment.

I'm only going on what I've read, as I've never had an equatorial mount before.

I'm not sure if this is what you meant by drift align, but errors in those 3 areas (north, latitude, level) will each have their own signature in a star's drift. (Is that known as drift align?)

Also, make sure you're set to sideral tracking. I don't know why the default would be set to anything else, but double check anyway.

And wooden decks are quite good at transfering the vibrations from your footsteps to the telescope, and causing your telescope to jump out of alignment if a tripod leg slips into a groove between boards (this is from experience :) ) Is that a 2nd story deck, or is there ground beneath the wood?

Thanks for sharing your experiences with us. Good luck with the weather.

 

[russ_watters]

Another point: did you loosen both the RA and DEC axis (one at a time) and move the scope & counterweight for a near-perfect balance?

Yes, I balanced both axes.

Russ, check your instruction manual for the mount. You should be able to install the counterweight shaft in such a way that the polar alignment scope is not obstructed (perhaps not insert it so fully).

The shaft is permanently installed and retractable. If I had mounted the telescope and counterweights before aligning like I should have, I wouldn't have had that problem.

The mount has to be loaded and balanced before you align. As for balance, it can be a help to have the scope and counterweights slightly out of balance, so the weight of the scope loads the RA main gear slightly and the RA gear let's the scope drop gently (or vice versa). If your counterweights balance the scope perfectly, you can experience image shift due to a slight amount of play in the drive gearing.

Yeah, there certainly could be some play - the motion I saw was fast enough that it could have been slop rather than actual PE. Some people also experience problems with the grease getting viscous at cold temps (it wasn't that cold for me last night), so I may break it down and "tune it up" anyway.

I'm not sure if this is what you meant by drift align, but errors in those 3 areas (north, latitude, level) will each have their own signature in a star's drift. (Is that known as drift align?)

Yeah, observing and adjusting for it is drift aligning.

And wooden decks are quite good at transfering the vibrations from your footsteps to the telescope, and causing your telescope to jump out of alignment if a tripod leg slips into a groove between boards (this is from experience :) ) Is that a 2nd story deck, or is there ground beneath the wood?

Second story deck, but a 15' usb cable takes care of the wobbling (and keeps me warm ) by letting me image from my couch. At some point I may install a pier, though.

 

[russ_watters]

Well, I'm up and running again. Fighting with the weatherman again, but not as bad as last night.

I have the same tracking error as last nigh and here is in the first photo. This is about 10 minutes of 15 second frames, not aligned with each other. The peak-to-peak is about 38 pixels of a 648 pixel photo spanning about 19 arcmin. So that's 1.1 armin of error. It still could be something fixable (I was really hoping for 20' peak to peak), but I may need to regrease and/or tighten up the drivetrain. I didn't try loading the ra axis yet - even with the error, I'm getting decent images and I don't want to mess with that right now. Images to follow in the astrophotography thread...

 

[tony873004]

neat pic, despite the tracking error. Actually, I had a couple beers after work today, so it looks fine to me :)

Does your hand controller know you're in equatorial mode? You are tracking wrong on 2 axes, which implies that its tracking in alt az, or vibrations / tripod shifting position during exposure may be the problem.

 

[Labguy]

I'm not sure if this is what you meant by drift align, but errors in those 3 areas (north, latitude, level) will each have their own signature in a star's drift. (Is that known as drift align?)

Yeah, observing and adjusting for it is drift aligning.

Drift alignment is usually reserved for scopes on a permanent mounting. It takes a long time to get it right. I once did it on a 16", f/ Newtonian on a 2000 pound mount. With one helper, it took two nights but then stayed dead-on for two years.

Seeing drift in the eyepiece has nothing to do with "drift alignment" unless you are doing that process at the time. A decent description of drift alignment can be seen at:
http://www.petesastrophotography.co....html&tutormain=/tutorial/polaralignment.html

 

[Chronos]

Russ, you should be able to manually dial in your local settings using
GPS. The three star method is reliable. Read between the lines on this:

http://www.optcorp.com/product.aspx?pid=6390&kw=Free%20shipping%20on%20this%20CPC&st=1

 

[russ_watters]

Quick update - after some help from another forum, I checked the leveling of my tripod with a bubble-level prior to putting on the mount head and using its permanently installed bubble level. To my great surprise, I had to adjust one of the legs by about two inches to level the tripod. After I put the mount head on, I found the bubble for the level almost all the way to one side of the level. So it isn't properly attached to the mount head.

After aligning the polar scope to the telescope and checking for cone error, I did a 3 star alignment and the resulting go-to performance was nothing short of phenomenal. It took some imagination to see that the objects I looked at were not quite centered in a 26mm eyepiece (110x magnification).

Tracking, however, shows the same high periodic error I had before. Later in the evening, I tried an "iterative alignment" procedure to improve the RA alignment and it all-but eliminated the DEC drift. Using periodic error correction, I was able to get the PE down again, and tracking was decent, but it still - even with PEC - wasn't as good as the out-of-the-box performance some people are getting.

I'm going to spend another night troubleshooting and talk to Orion before deciding if I should send it back.

 

[turbo]

Even some great mounts can exhibit periodic error if the counterweights and OTA are too perfectly balanced - basically, you see any tiny bit of slop in the RA drive. When I want to photograph with my 6' f:8 Astro-Physics, I keep the RA gear loaded against the worm by unbalancing slightly. If the object is East of the zenith, I move the counterweights toward the mount so that the drive is slightly loaded by the weight of the scope, and has only to control its descent. When photographing something West of the zenith, I move the counterweights away from the mount to slightly unbalance in the other direction so the drive has only to control the descent of the counterweights. Try this to see if it reduces periodic error. You can also try moving the counterweights in the other direction so that the RA drive always has to lift some weight instead of resisting its fall. Not all drives are the same, and yours may respond better to one mode or the other.

Good luck.

 

[russ_watters]

That makes me a little nervous, but I'll probably give it a try.

 

[turbo]

That makes me a little nervous, but I'll probably give it a try.

Don't make it way overbalanced, Russ. Just enough so that when you unclutch the RA drive, the scope wants to rotate about the RA axis in the direction that it will be driven. Even very well-built mounts can benefit from this little trick. I am very lucky in that my counterweights are threaded onto the counterweight shaft. I can set up the two of them that the mount is slightly tube-heavy for objects in the East, then rotate the bottom weight downward to make the mount counterweight-heavy for objects in the West. From the picture in the catalog, it looks like you have three counterweights held in position with set-screws. I suggest that you set the three of them touching one another far enough down the shaft to make the mount counterweight-heavy for objects in the West, then when you want to image objects in the East, raise only the top counterweight (it probably won't be much - maybe an inch or so) to make the mount OTA-heavy. This way, if the top weight slips, it's only going to get as far as the other two below it - no harm. I'll bet this will help you.

Good luck.

 

[tony873004]

Turbo, since the scope would want to rotate in a different direction after it crosses the meridian, does this mean that you'd have to shift the weights a little depending on if you're aiming east or west of the meridian?

 

[turbo]

Turbo, since the scope would want to rotate in a different direction after it crosses the meridian, does this mean that you'd have to shift the weights a little depending on if you're aiming east or west of the meridian?

Yes. You would want to see if you could reduce tracking errors by doing this, and if gravitationally pre-loading the RA drive helps, you may wish to try to address the imaging of objects crossing the zenith within an imaging session or perhaps avoid imaging such objects in the first place.