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Archive 2013 · Nightscapes using AstroTrac Tracking Mount
  
 
astro-ep
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p.17 #1 · p.17 #1 · Nightscapes using AstroTrac Tracking Mount


Getting into telescopes is really dependent on what level of perfection that you want DSLR's, especially full frame cameras have large sensors. Getting a scope that has a flat field of view over a large area can be difficult to do cheaply. But if a little coma or field curvature doesn't bother you, then there are many options.

It's very easy to suffer from paralysis by analysis. So shoot with what ya got. An Astrotrac will provide you with a lot of practical experience and very good results, if you use it within its limits (remember you can't have too much stability). You'll find that postprocessing has a much larger learning curve than learning to shoot the actual images. So put a stake in the ground and move from there. An astrotrac will easily sell a couple years from now, if you want to move to a more advanced system.

Eric



Dec 05, 2013 at 08:17 PM
cavaroc
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p.17 #2 · p.17 #2 · Nightscapes using AstroTrac Tracking Mount


Thanks, Eric!

Fortunately I have some experience with stacking images, so that's not new to me, and I've roughly learned my way around the night sky just out of interest and fascination, though I'm sure this will help me get more up to speed with where I want to be.

As for the camera, I probably wouldn't modify my 5DIII because I would still primarily use it for wildlife and nature out here. That's why I was planning on getting a used T4i and having that modified, if it wasn't already. I'm assuming for deep sky objects, or perhaps one day even planets, that little extra boost would help a lot, though I know I'm sacrificing image noise.



Dec 05, 2013 at 09:32 PM
astro-ep
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p.17 #3 · p.17 #3 · Nightscapes using AstroTrac Tracking Mount


Just in case anyone is interested in trying Astro with a modified camera (for capturing the H-alpha blocked by stock camera filters)...

http://www.fredmiranda.com/forum/topic/1260086/0#11997163




Dec 12, 2013 at 08:13 PM
Todd
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p.17 #4 · p.17 #4 · Nightscapes using AstroTrac Tracking Mount


I took more shots last night with my D800 and the Nikon 500mm f/8 reflex (mirror) lens and shot M42. I traced the sky for 6 minutes at ISO 1600 on my AstroTrac and these are single exposures... I didn't have the best night, there was some haze and the transparency wasn't the best... but for what its worth, here they are...

Todd















Feb 22, 2014 at 03:27 AM
harshaj1
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p.17 #5 · p.17 #5 · Nightscapes using AstroTrac Tracking Mount


These are excellent. Did you guide the astrotrac ?
Harsha



Feb 22, 2014 at 06:22 AM
Todd
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p.17 #6 · p.17 #6 · Nightscapes using AstroTrac Tracking Mount


Hi Harsha, I did not have an auto guider system added to the astrotrac, I just had very good polar alignment and a fairly stable tripod. I want to buy the AstroTrac wedge for extra stability. However I am quite amazed to see that the AstroTrac will guide accurately with my 500mm on it. Now take in mind that different angles and throw the astrotrac tracking off because it gets off-balance and I will get Startrail's at some point. I think that's why I need the wedge for more stability. However transparent dark skies are best for astro photos and richer colors.

Todd

harshaj1 wrote:
These are excellent. Did you guide the astrotrac ?
Harsha




Feb 22, 2014 at 02:12 PM
Dan Gillan
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p.17 #7 · p.17 #7 · Nightscapes using AstroTrac Tracking Mount


Incredible


Feb 25, 2014 at 12:42 PM
Aloicious
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p.17 #8 · p.17 #8 · Nightscapes using AstroTrac Tracking Mount


Sorry, I'm bringing this thread back up.

I recently picked up a astrotrac and wedge, I'm in the process of doing some modifications on it, but I'm going to try and get some shooting with it done during the the next few new moons. I've done some AP with larger EQ mount setups but their size, weight and bulk made them really really impractical and to take into the field for use. but I'm pretty excited about the astrotrac, it's size and weight should be really nice. and with my current gear and a few pieces I've been able to cobble together, it should be a nice solid stable setup.

I'm still combing through the posts, but has anyone used the TH3010 head with it? any thoughts or info on it? being able to balance the scope/lens with independent planes of movement would be really nice, similar to a GEM, much better than a ball head, or even a gimbal. I thought about building my own version of it to save some money, but the fabrication time and cost wouldn't end up being too different so I may just end up grabbing a real th3010 in the end if it comes to that.

The only issue I worry about is it's weight limit, the TH3010 spec'd for "about 20lbs" weight limit. I'm wondering if that is fairly conservative or not...If I did get a H3010, it would be the weakest point (at least according to weight limit specs) in my setup by quite a long ways (astrotrac is spec'd for 35lbs, wedge is also 35 lbs, my leveling head is spec'd for 100+ lbs, legs are 88lb)...I do have some fairly heavy setups I would like to use with the astrotrac, the heaviest of which is a small 6" RC reflector scope with a D800E mounted to it prime focus (scope is ~12lbs, camera body is roughly 2lbs, a few accessories, cabling, plates, etc, and I'm already at 15+ lbs payload) I typically like to keep the weight limit of my support equipment at least 2x the weight of my heaviest setup, so the only part that doesn't fit in that would be the TH3010...hmm...I have more research to do, but any thoughts are appreciated.



Mar 24, 2014 at 06:19 PM
astro-ep
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p.17 #9 · p.17 #9 · Nightscapes using AstroTrac Tracking Mount


Sounds like you have a good grip on the reality of astro imaging. Stability is a lot more critical for astro than for regular photography. So you're derating of the capacity is a good idea.

I'd think the TH head would be more stable than a ball head, but if you use a sliding rail system (Arca or similar), you can balance the scope/camera combo by sliding the scope/camera along the rail. This is how I do it on my regular CCD-astro set-up. Using a large ball head may work better like this, than with a large weight offset. But trying to align this on a target might be pretty tricky, and worse with the longer focal lengths. Again, the TH head might help here. Never used it, nor an astrotrac, so I'm just speaking from my regular astro experience.

Eric



Mar 24, 2014 at 07:30 PM
Aloicious
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p.17 #10 · p.17 #10 · Nightscapes using AstroTrac Tracking Mount


Thanks! yeah I was thinking of just using my sidemount gimbal and a rail to balance the dec head axis (tilt), though the RA axis (pan) wouldn't be able to be fully stabilized without a counterweight bar.

I do have a good ball head (BH-55) though I'm not much of a ballhead fan normally, let alone with large payloads like a scope, they're just a little too imprecise for me, especially if I wanted to do some kind of stitched matrix image at longer focal lengths. as it sits I'm thinking the TH3010 might be the best option...I'm still researching though.

all my stuff is arca standardized (camera L plates, flash brackets, lens feet, even all my heads use a arca dovetail on the tripod mount for easy switching/setup), so fabricating something using arca bars wouldn't be hard. its really the scope that I'm mainly concerned about, regular lenses I could even put a nodal slide on my L plate to balance on the gimbal (or on the TH3010 if I end up getting it).

I'm kindof just thinking out loud here, I haven't really quite settled on anything yet.

This is my old setup:


I still have everything except the main scope (that's an 8" orion RC, I downsized to a 6" TPO Ritchey-Chretien, which is just a smaller version of the one in that pic) I mainly just used it for observing, but it was a severe PITA to take anywhere, especially if I wanted to hike out to an observing spot that isn't vehicle accessible, but its all a game of sacrifices...



Mar 24, 2014 at 08:07 PM
 

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astro-ep
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p.17 #11 · p.17 #11 · Nightscapes using AstroTrac Tracking Mount


A nodal slide was exactly what I was envisioning, for the declination balance. I think using an astrotrac, for the ease of set-up and portability, you sacrifice some of the other features that make it easy to align and use for long focal length imaging. If I were to use one for imaging, I'd probably stick with focal lengths under 200mm. That would ease the requirements a bit and wouldn't require guiding. Many use them at much longer focal lengths. But for the complexity & stability of balancing a long lens, using guiding and a separate guide scope, I'd rather just use my EQ mount.

You sound like me. I fabricate a lot of what I use for Photography and Astro imaging (and other hobbies). I don't do much off-site imaging, doing mostly narrowband imaging from my backyard. But I was tired of my old imaging tripod. It was heavy, The set-up was not repeatable and took too long to set-up and take down. Worst of all it was poorly designed for ease of leveling. So I designed and built my own. It works spectacularly well and holds a huge load. Here's a shot of my setup (less the electronics package & laptop), on my new tripod. I call it the Ericpod MkII (second design).



I kept the Mk1 tripod, as I think it would make a really nice platform for an astrotrac or similar portable imaging set-up. I'd be interested (and I'm sure others as well) would be interested in following your progress with this set-up...

Eric




Mar 25, 2014 at 01:18 AM
Aloicious
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p.17 #12 · p.17 #12 · Nightscapes using AstroTrac Tracking Mount


that's a nice Tak, and your tripod looks great, I do a bit of automotive fabrication stuff, so most metalwork isn't a big issue for me, and I've already got the tools for it like a plasma cutter, TIG, etc...though most of my mods to the astrotrac aren't really that extensive, just mainly getting it setup for compatibility with all my arca swiss stuff (like mounting the wedge to the tripod with an arca dovetail, then having the astrotrac itself accept heads with arca dovetails on them, etc...

I'm lucky to live very close to some of the darkest skies in the nation, so I usually drive a couple hours to the middle of nowhere to get the darkest skies I can. under 200mm won't be much of a problem with the astrotrac, and I've got plenty of excellent lenses in that range (70-200VRII, zeiss 135 APO, etc) but since I've already got the astro equipment and it's weight should hold up on everything fairly well, I'd also like to try and make use of some of it too.

my 6" RC scope is ~1300mm f9, I might get a focal reducer to speed it up a little too if needed, and I've got a 500mm f4 I wouldn't mind trying, I don't see it being too much of an issue with proper balance and stability, guiding will probably be needed, but I can do that, I'm working on something for that as well.



Mar 25, 2014 at 03:31 AM
Aloicious
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p.17 #13 · p.17 #13 · Nightscapes using AstroTrac Tracking Mount


well, it was inevitable, get my astrotrac setup ready to use and the clouds and storms come...right at the new moon....ah well... next month perhaps, it'll let me iron out any slight nuances in the setup.







Mar 30, 2014 at 05:45 AM
dgdg
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p.17 #14 · p.17 #14 · Nightscapes using AstroTrac Tracking Mount


I'll risk a cross post here as my most recent milky way image is quite a bit different from my initial landscape thread that needed further processing. Post processing the milky way or nebula takes (me) a great deal of time compared to capturing the image.

Anyway this was out at Arches National Park. The sky was at Fiery Furnace during the only clear night I had. The foreground did not work out as I intended, so a couple days later in a similar direction I captured another twilight foreground that I think works well. The glow in the lower right is from a bit of thin cloud layer and the town of Moab, I'd crop this out if printed. Out of 20 images, only two were clear of clouds, then stacked in DSS with darks and bias frames before going to Photoshop. ISO 800, 3 minutes, 35mm, f/2.8.









Apr 23, 2014 at 12:35 PM
voltaire
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p.17 #15 · p.17 #15 · Nightscapes using AstroTrac Tracking Mount


Amazing image, dgdg! Thanks for sharing.


Apr 29, 2014 at 11:13 AM
Todd
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p.17 #16 · p.17 #16 · Nightscapes using AstroTrac Tracking Mount


I sent this PM to Fred and I wanted ask all of you as well... For those of you with the AstroTrac and a Nikon or Canon DSLR with the capability of multiple exposures in menu setup. My Nikon D800/E has a maximum of 10 multiple exposure frames, I've tried using this option while the camera was on the AstroTrac. Single long exposures give me good results, but the multiple exposures (I don't remember the frame count), did not give the same results. I got elongated stars equivalent to the length of a grain of rice, the images didn't line up during the multiple exposures and I don't know why. I did use an electronic cable release and made sure I didn't move or shake the camera. I did recently upgrade to a better tripod and got the AstroTrac wedge, I got rid of the jr gear head which had some flexure but that still doesn't explain why each image did not line up while the camera was beating tracked. So to sum up: long single exposures do not have star trails but stacked multiple exposed ones do....can any of you share your experience with this if you have done it? I would greatly appreciate it.

Now that I have my wedge, I'll have to try it again soon and experiment with different frame counts and exposure times and different ISO speeds.

Todd



May 08, 2014 at 02:15 AM
dgdg
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p.17 #17 · p.17 #17 · Nightscapes using AstroTrac Tracking Mount


Sounds like your gear, tracking, and polar alignment are fine if individual long exposures are ok.
If you are taking multiple sky images and stacking them in your camera, I would suspect it just does not do as good a job as traditional computer software. Stacking software actually looks at your star patterns in each image to perfectly align them, doubt your camera can do this acceptably.
Deep Sky Stacker is one good and free example. Try that. I never even thought of doing this in my 5DIII - maybe I should have.... I doubt the wedge will improve your issue, but it is a great piece of kit and makes aligning much easier.


David



May 08, 2014 at 01:19 PM
astro-ep
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p.17 #18 · p.17 #18 · Nightscapes using AstroTrac Tracking Mount


Hi Todd,

It sounds like your polar alignment might not be perfect. It sounds like might be happening is that the alignment is OK for a single exposure (movement might be less than a few pixels). But when you multiply this time over 5 or 10 shots, the error becomes more evident. If you have individual frames, you could click through them and see that the stars are moving, indicating an error in your polar alignment. By stacking in the camera, you're essentially challenging the mount to an exposure that's the same length as the number of minutes per exposure x the number of exposures. Most mounts can do good short exposures, but need autoguiding for longer ones.

The in-camera stacking is not doing any star alignment, it's only stacking the frames on top of each other. So any movement of the stars will show as streaks, when stacked. This is the same as taking individual images and stacking the in software, with no alignment to the stars. If you use external software, like David suggested, you can align the images on a star (or stars) and then the frames will stack, with the stars aligned.

Just so you're aware, this is fairly typical behavior for unguided mounts.

Hope this helps,

Eric



May 08, 2014 at 02:32 PM
Fred Miranda
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p.17 #19 · p.17 #19 · Nightscapes using AstroTrac Tracking Mount


Todd,
Depending on the focal length and exposure time, it won't be possible to take multiple exposures without guiding. There is a very cheap solution for this and the guiding is done by software. You can download it here:
http://www.stark-labs.com/phdguiding.html

Auto guiding basically allows you to stay on your target. The auto guiding camera is connected to your computer and autoguiding software. It also connects to the Astrotrac mount using a special cable. It works quite well even though Astrotrac only corrects in RA.

It seems complicated but in about 3 minutes, you are ready to start your shooting sequence. I used BackyardEOS to connect to the camera.
http://www.backyardeos.com

Also make sure you are aligning polaris with the updated chart I created and posted below. Also check the images of a cheap guiding solution. Eric (astro-ep) helped me put it together!

Fred




Current polaris alignment for Astrotrac



















May 08, 2014 at 04:09 PM
Fred Miranda
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p.17 #20 · p.17 #20 · Nightscapes using AstroTrac Tracking Mount


BTW: Using the above set-up, I was able to capture the image below. Shot with EOS 6D, Canon 500mm f/4 II @f/4.
It's a very long focal length but I was able to lock on the stars for a few hours exposure.




Astrotrac with auto-guiding, EOS 6D, Canon 500mm f/4L II @f/4




May 08, 2014 at 04:14 PM
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