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FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial
Thread started 19 Dec 2017 (Tuesday) 17:06
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Advice wanted regarding astro tracker / camera setup

 
01Ryan10
Senior Member
Joined Aug 2012
OC, California
Dec 19, 2017 17:06 |  #1

I've used my iOptron several times with my Canon 6D and Rokinon 24mm F/1.4. It is a bit heavy and thus, I can't really track for longer than 60ish seconds. I'd have to buy the counterweight to balance it out. The CW is $80.

So...I got to thinking, why not just buy a quality point and shoot like the Sony A5000 and use that instead. It would be much lighter, and I'd assume I can track for 3-5 mins not problem. What I don't know is how the coma and quality will look on a Sony A5000 if I stop down to F/4 or F/5.6. I have a feeling it will look great, but I just don't know. At F/5.6, I'd probably have to shoot for 4-5 mins to achieve roughly the same exposure that I'm doing on my Rokinon at F/2 for 60 seconds.

Any thoughts?


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IG: @01ryanluna10 (external link)

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Roy ­ A. ­ Rust
Senior Member
Joined Dec 2015
Dallas, Texas
Post has been edited 1 month ago by Roy A. Rust with reason 'add comment'.
Dec 19, 2017 17:45 |  #2

01Ryan10 wrote in post #18522066 (external link)
I've used my iOptron several times with my Canon 6D and Rokinon 24mm F/1.4. It is a bit heavy and thus, I can't really track for longer than 60ish seconds. I'd have to buy the counterweight to balance it out. The CW is $80.

So...I got to thinking, why not just buy a quality point and shoot like the Sony A5000 and use that instead. It would be much lighter, and I'd assume I can track for 3-5 mins not problem. What I don't know is how the coma and quality will look on a Sony A5000 if I stop down to F/4 or F/5.6. I have a feeling it will look great, but I just don't know. At F/5.6, I'd probably have to shoot for 4-5 mins to achieve roughly the same exposure that I'm doing on my Rokinon at F/2 for 60 seconds.

Any thoughts?

Which iOptron are you using? I've been using the iOptron SkyTracker for years with heavier loads than your camera/lens combination with no problem tracking for 20 minutes or more. From my favorite 'Dark Site', I commonly expose for 10 minutes or more with no star trails at all. I haven't used the new iOptron tracker, but it's supposed to be able to handle a bit more weight than the one I have.

The only times I've had any problem at all with it not tracking was when the internal batteries were too low to power the tracking motor, but would light the red LED just fine, and I thought the batteries were okay. (I now use an external 12v battery to power it.)

Are you sure you are getting a good polar alignment? There's gotta be something wrong besides the load.

EDIT: BTW... after commenting here, I checked your gallery. You've posted some BEAUTIFUL pictures!!! I look forward to seeing your astrophotos when you get the tracker working properly.




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01Ryan10
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Senior Member
Joined Aug 2012
OC, California
Dec 19, 2017 18:09 |  #3

I"m using the Skytracker Pro, (newest base model).

Well...If i remember correctly iOptron recommends max load without counter weight at 3.6 pounds. My 6D and 24mm are right there at that threshold. I've quadruple checked how tight I've screwed everything down. I've ensured polar alignment with Polaris, even to the point where I place the star in the exact scope location referenced by the iOptron alignment app based on my latitude.

I feel that when my camera is sitting more horizontal, the weight just pulls the motor a tiny bit faster. If my camera is sitting at a more vertical location, (12 O'clock), then it's not "pulling" on the motor much at all.


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IG: @01ryanluna10 (external link)

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01Ryan10
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Senior Member
Joined Aug 2012
OC, California
Dec 19, 2017 18:13 |  #4

I should do some more testing in my backyard against some of the brightest stars at F/5.6 and ISO 400 or something so I can test exposures of 5+ minutes in heavily light polluted Orange County. Perhaps I'm missing something.


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Roy ­ A. ­ Rust
Senior Member
Joined Dec 2015
Dallas, Texas
Post has been edited 1 month ago by Roy A. Rust with reason 'typo'.
Dec 19, 2017 19:00 |  #5

01Ryan10 wrote in post #18522133 (external link)
I"m using the Skytracker Pro, (newest base model).

Well...If i remember correctly iOptron recommends max load without counter weight at 3.6 pounds. My 6D and 24mm are right there at that threshold. I've quadruple checked how tight I've screwed everything down. I've ensured polar alignment with Polaris, even to the point where I place the star in the exact scope location referenced by the iOptron alignment app based on my latitude.

I feel that when my camera is sitting more horizontal, the weight just pulls the motor a tiny bit faster. If my camera is sitting at a more vertical location, (12 O'clock), then it's not "pulling" on the motor much at all.

I just checked the specs for the SkyTracker Pro, and the maximum payload is given as 6.6 pounds, so your camera/lens setup is only about half of the max. I don't use the app to polar align it, so I don't know how it's presented in that app... I use Stellarium to see where Polaris is located, then invert its position in the alignment scope. The scope inverts the image, so Polaris has to be positioned 180 degrees from it's position in Stellarium, but still on the 40' circle.

The first time I used my iOptron, I didn't adjust it for being inverted, and got LOTS of star trails, and thought something was wrong with the tracker - until I realized it was inverted, and it's worked just fine ever since.

The only suggestions I have are to be sure the batteries are fresh, be sure to align Polaris on the middle of the 3 inner circles in the reticle (40'), check to see if you need to invert the position of Polaris in the scope compared to the image in the app, check all the switches to be sure you have it set to the northern hemisphere, and be sure the speed is set to sidereal. Other than that, I don't know what the problem might be.




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01Ryan10
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Senior Member
Joined Aug 2012
OC, California
Dec 19, 2017 19:28 |  #6

Yeah...i'm going to run some tests this evening. I will say that what I've read and heard on Youtube is that with 24mm, you should be able to just point the scope in the "vicinity" of Polaris and you should be able to track for 2-3 mins without trailing.


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Roy ­ A. ­ Rust
Senior Member
Joined Dec 2015
Dallas, Texas
Dec 19, 2017 20:24 |  #7

01Ryan10 wrote in post #18522189 (external link)
Yeah...i'm going to run some tests this evening. I will say that what I've read and heard on Youtube is that with 24mm, you should be able to just point the scope in the "vicinity" of Polaris and you should be able to track for 2-3 mins without trailing.

I think that's about right.

Just after I got my tracker, I did a blind alignment test, just by pointing it North by the compass on top of mine, and then cranking the declination adjustment up to about 32 degrees (Dallas, Texas). I managed to get a VERY close alignment by doing it that way - at least once! I took a series of pictures, longer and longer, to see where the stars would start to elongate. I quit when I got over a 16 minute exposure without any appreciable star elongations. And that was with a 55mm lens. So, sometimes, close enough is good enough. I didn't think anyone would believe it (I almost didn't!), so I superimposed the EXIF data on the image. I couldn't see Polaris from where I set it up, so don't know how close to a proper alignment it was - must have pretty much nailed it, though... just with the compass and declination markings on the tracker.

I'd go out and do some more tests to see how long an exposure I could take with a 28mm lens without trailing, but it's been raining non-stop all day, and doesn't look like it's going to clear up around here for a while. (Just heard some thunder!)

How much experience have you had with your tracker - or any tracker?

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MalVeauX
"Looks rough and well used"
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Joined Feb 2013
Florida
Dec 26, 2017 08:44 |  #8

I'm willing to bet your issue with tracking is not weight and is actually your polar alignment accuracy.

I routinely tracked 35mm F2 IS on a T4i APS-C for 240 seconds without trails on an iOptron Skytracker (non-Pro) in the Northern Hemisphere. And I was able to get 90 seconds with an 180mm F3.5 on the same setup, which exceeded the weight recommendations too.

Just tighten up your sequence for polar alignment and you'll be good.

Very best,


My Flickr (external link) :: My Astrobin (external link)

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Marcy
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1,752 posts
Joined Aug 2007
on the road in an RV
Post has been edited 24 days ago by Marcy.
Dec 26, 2017 14:17 |  #9

I used my iOptron to track the Eclipse this past summer had canon EOS 5d III and 70-200 + 1.4 extender shot for the entire length of the eclipse had no trouble just got my angle and used my compass to get north got great shots and I have the older version smaller




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AdamT
Member
Joined Jan 2013
Dec 27, 2017 08:31 |  #10

Please keep us posted on if you find your issue. Considering a similar setup and would love to know about any issues in advance of purchases.


Canon EOS 6D | Canon EF 24-105mm f/4L IS USM, EF 100mm f/2.8L Macro IS USM, EF 50mm f/1.8 II |

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01Ryan10
THREAD ­ STARTER
Senior Member
Joined Aug 2012
OC, California
Dec 28, 2017 22:05 |  #11

Ok...I was able to do a very unscientific experiment tonight.

I took several shots, and I'm posting what amounts to the same results.


First...

Here is my setup. I am shooting the silver flashlights. I want to know if my ballhead is in any way "creeping" with the slightest movement due to the downward torque of my camera when sitting on more of side position.


This picture is from my cell phone and is only used to show how i have my setup. The setup is nearly identical when I mount the iOptron to my tripod, only the tripod is positioned more normal. I had to position my tripod in the picture below, so I can try to simulate how my ball head would be sitting on the iOptron; hence, the funky looking setup.

IMAGE: https://farm5.staticflickr.com/4641/39332946742_c5a8ed30d6_o.jpg
[IMAGE'S LINK: https://flic.kr/p/22VH​CJb] (external link)20171228_192913 (external link) by Ryan (external link), on Flickr


Without the iOptron, here is the result....
70mm, ISO 100, F/14, 4 mins
As you can see, a 100% crop shows the image tack sharp with no motion blur from ball head movement.

IMAGE: https://farm5.staticflickr.com/4731/38654783824_94fac88207_o.jpg
[IMAGE'S LINK: https://flic.kr/p/21TM​Sw5] (external link)_MG_0944 (external link) by Ryan (external link), on Flickr

Here is the typical results I got with the ball head mounted to the iOptron and camera sitting on the side in nearly the same position. YES, THE iOptron WAS OFF.
70mm ISO 100, F/14, 2 mins only
As you can see, there is a noticeable blur. You cannot see the "duracell" logo, because I slightly moved the flashlight and accidentally turned it away from the camera.

IMAGE: https://farm5.staticflickr.com/4692/38654783714_f21b7494ed_o.jpg
[IMAGE'S LINK: https://flic.kr/p/21TM​Sub] (external link)_MG_0941 (external link) by Ryan (external link), on Flickr

So...here is my conclusion. If the camera is sitting on more of a side position, the weight is too much on the iOptron drive and will "pull" the motor causing the blur; thus, the need for the counterweight. I have not used the iOptron in real world situations enough to know if I need to position my camera like that. When I have my camera at more of straight on top position, i can get 6+ min exposures with no blur because the weight is not pulling the motor.

http://RyanLunaPhotogr​aphy.com (external link)
IG: @01ryanluna10 (external link)

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Advice wanted regarding astro tracker / camera setup
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