4964 replies to this topic

[jlandy]

So it's been a while, but I've got all my new parts and finally pictures! Will post the updates to the telescope tomorrow, too excited about the results to not post a few pictures!

First tonight's half moon, then... Saturn!

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[jlandy]

Saturn! It's not much... still trying to figure out the stacking software

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[jlandy]

I brought the telescope to rhode island's frosty drew observatory last night, and with some help found three new objects! The great Hercules cluster, the Ring nebula, and Alberio!

I would encourage all beginners like me to do the same, having an experienced stargazer point out where to point double the number of things to look at now in under 15 minutes.

Back to modifications on this little reflector- would it be entirely inappropriate to add a counterweight to an altazimuth? I bought an Orion st80 to help with imaging, but now the assembly is too heavy... Thoughts?

[SteveG]

Absolutely ok to add a counterweight. You might try the magnetic ones sold by Scopestuff.

[jlandy]

I took you up on your suggestion Steve to make an internal sleeve for the truss. Yours is a lot more robust, but I had the materials lying around, which cost me ~$2 originally - no real loss if I have to remake it.

It's crafting foam sheet from Michaels, I spliced two sheets together with hot glue, glued on a few tabs, and glued the whole thing to the inner rim and the factory shield. Fits like a glove, required no disassembly. New England weather has been abysmal the past week, will report in with more updates hopefully this weekend.

Thanks for the suggestion!

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[kfiscus]

That looks very acceptable in the photo. Good job. You timed it right moon phase-wise. Get the bad weather over now.

[SteveG]

That looks excellent!

I'll be using mine on an upcoming trip to central Oregon in two weeks (new moon). Can't wait!

[jlandy]

M13! this is one of several photos... again too psyched that i actually captured a photo to wait to stack everything. I took a movie of saturn too, just need to figure out how to post process the results.

120 second, iso 1600, 30x mag...

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[jlandy]

So I promised I would continue to update the status of the little newtonian, document some of the troubles I ran into and the solutions, so here we go:

Taking pictures - it seems like a lot of newtonian owners have the problem of not being able to focus. Everyone's solution is "add a 2x barlow", which I did without any luck. I believe the reason for the problems is the focal point after the secondary mirror is too close to the centerline of the telescope, the DSLR can't physically get close enough to focus. A barlow pulls the focus point outboard to a spot that you can focus on. Or so they say...

The first picture is the setup that everyone recommends, that (at least for my telescope) did not solve the focusing problem)

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[jlandy]

My "ah ha!" moment was when I attached the camera adapter to the 32mm eyepiece T-thread, and inserted it into the Barlow. Finally, at the very end of travel, I was able to focus on a distant object across the road with my camera.

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[jlandy]

The smaller eyepieces seemed to give the best focus range, which led me to purchasing the Celestron 24mm-8mm zoom eyepiece, which I now use almost exclusively. Finding an object and focusing is incredibly easy with it, and it has T-threads!

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[jlandy]

Here is the final product. Adding the Barlow allows additional zoom (but I think there might be a detrimental result... more on that later) while keeping the camera's sensor in a focus-able spot. This setup has the added benefit of being able to "fine-tune" the zoom on the camera without having to worry too much about the helical focuser. The moon shots turned out great! but more modifications were on the horizon to get my pinnacle goal of saturn

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[jlandy]

Preface - I really like the red dot finder that comes with the telescope. It is insanely easy to simply "point and shoot" without having to wonder if you are going to be pointing at the right general area of the sky.

That being said, the red dot alone is not adequate for finding saturn in the camera. I spent an hour trying to find the planet in the camera, caught a fleeting glimpse, and lost her. Doing some reading it seemed like everyone taking pictures is using the Orion 80mm ShortTube refractor as a guidescope. The deal was right, I bought some 160mm tube rings, and upgraded the telescope.

[jlandy]

Word of advice to people who plan to get the ST80 - you *will* need either a 2" extension or a diagonal to get any image whatsoever. Ironically, the focusing problems I had with the reflector were back with the refractor, however this time I couldn't get enough out focus. So now I have a superb reflector, with a great refractor attached, and I run into my next hurdle - weight

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[jlandy]

The problem now is the combined weight of both telescopes was waaay too much for the simple alt-azimuth mount I had bought back when I first started these posts. Not too much of a problem, I was using the refractor to check out the moon at parties attached to the alt-az, and mounted the reflector back onto the dobsonian mount it came with. At a clear Friday night at the Frosty Drew Observatory in Rhode Island however I was inspired by an equatorial mount with tracking.

I had the night before finally caught Saturn in the camera, but was frustrated with only being able to take a single 0.5 second exposure before having to carefully re-center the image using the alt-az so as to not lose it forever (the fuzzy picture of saturn posted earlier was the only shot that came out somewhat). What got me to decide to make the investment in the equatorial mount however wasn't the astrophotography aspect, it was sharing views with a lot of people.

The guy with the EQ could point at an object, sit back and talk while sharing the image with the people at the observatory. I, on the other hand, would show my friends saturn, step back for 30 seconds, then have to refocus for the next person. It was a really rewarding experience, but it would have been nice to not give people the boot every time to center on the image. That led me to my latest purchase - the Celestron CG-4 equatorial

[jlandy]

OK, final post for the night, here is the current setup - seems to do everything I need. CG-4 mount, AWB reflector with 160mm tube rings to mount the Orion ST80. It's HEAVY! but very stable, at least compared to my alt-az. I don't regret buying the alt-az, it's great for throwing into the car and traveling, but this is starting to look like a legit setup.

That being said, here is where i need the experts help-

My friend who pointed out M13 to me originally noted that I got some coma action going on with the image I posted earlier. Not knowing what that meant, I did some reading...

So the coma is due to the lens not being aligned with the reflected image. It is inherent in newts, but I'm thinking that the torque of the camera from the zoom eyepiece/barlow moment arm is torquing the focuser, and increasing the coma effect... thoughts? will something as simple as a bungie coord fix this? or should I think about reinforcing the focuser? Any commentary is welcome!

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[jlandy]

oh I forgot to add - the motor for this mount seems to do the job perfectly. I found saturn with the ST80 as planned, moved her centered on the camera and started a video. The image seemed to stay put for at least 10 minutes without correction. Here is the stacked image from the video - big improvement from the single shot!

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[kfiscus]

Whoa, back up! Coma isn't caused by misaligned optics. It's caused by the collected starlight being refracted at extreme angles. Coma correctors and premium eyepieces can be used to deal with/correct coma. I grew up with extreme coma in the 1980's with the very fast Astroscan (f/4). Many people aren't bothered by coma, some can't stand it...

BTW, I think your paired rig is cool.

[jlandy]

I'm basing that entirely on the wiki article I read, I'm by no means an expert. My thought was I was skewing the incoming light off the secondary through the eyepiece from the weight of the camera... just a theory!

I haven't noticed any coma effect when just observing, is there anything about the photography end of the thing that could be causing it? If it's unavoidable (without huge expense) that's fine, I just want to make sure it's not due to something I'm doing inadvertently

[jlandy]

M5! Then improved M13! I found M81 and M82 last night, if the weekend pans out I'm going to try to find a dark sight to take a picture of the galaxies.

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[jlandy]

M13

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[jlandy]

I "accidentally" caught this picture Sunday night... M57!

I was experimenting with a bahtinov mask and a polar finder with pictures of M13, my mount was going to crash into itself so I thought I'd point at the ring nebula and quickly take a shot before I packed up. The nebulae are (In my opinion) a bit boring in the eyepiece, but holy cow color! I'll definitely be trying my hand at other nebulae in the future.

Still have to resolve the coma issues (if possible) without sacking my bank account... I'll continue to post less than adequate/novice photos here for critique in the meantime. As always, suggestions for improvement are encouraged

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[jlandy]

M13, no guiding, 210 seconds (7x 30secs) @ ISO800. Finally started to figure out stacking, excited for guided stacks in the future!

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[jlandy]

Wasn't out to catch this... but no complaints! Only got two shots before she fell behind the trees - M51

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[BFaucett]

jlandy,

Are you deliberately trying to drive me crazy and make me go insane???

I have been the owner of an AWB OneSky scope since the first week of July (2014). But, of course, the summer views of the night sky (and the weather) have SUCKED down here in southeast Texas since I acquired my new scope.

I think it must be the curse of new equipment!!!

Thanks for sharing your experiences with the scope and the photos!

Cheers!
-Bob F.