Equatorial Mount Testing

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Jan 22, 2019
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Jupiter, FL
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Andy
I decided to invest a little money and, more importantly, some time this winter to learn how to use an equatorial mount in hopes of getting some better wide field photos of the Milky Way core this year. Today, I tried for the first time an iOptron Skytracker Pro. It is actually quite easy to use once it is set up. I do believe a few more outings will be enough to gain proficiency in using it, but I was up and running within about fifteen minutes even on this first attempt. I don't think I got the Polar alignment exactly right, but the equatorial mount can be quite effective even in inexperienced hands.

Here are two heavily cropped images of identical exposures of the same section of sky. Both were 30-second exposures with a 52mm focal length, so they were well beyond the limits of the 500-rule guidelines. Orion's Belt is in the top half of the frame on the left and the Orion Nebula is in the lower right corner.

1. With SkyTracker Pro
SkyTrackerPro_Denver_21C_8573.jpg
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2. Stationary Exposure
SkyTrackerPro_Denver_21C_8576.jpg
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By coincidence, I did all this the same night that Keith posted his own Orion Nebula image in this forum, something that has been top of my list to try since purchasing the equatorial mount.

I had planned to test the weight bearing capability of my Skytracker Pro with a telephoto to see if it could track accurately enough to preserve the details of a nebula. The iOptron Skytracker Pro is rated to 3kg. My scale confirms that the combo of my ball head, Z6 with L-bracket, FTZ and 70-200 weighs just about exactly that amount. So, not exactly the rig for deep sky photography. I'll call this a "shallow sky image," obviously another significant crop.
3. Orion Nebula
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Here's an example of what happens to the foreground for a 90-second exposure. The house becomes blurry since the mount rotates to keep the stars sharp.
4. Waiting for moonset
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By coincidence, I did all this the same night that Keith posted his own Orion Nebula image in this forum, something that has been top of my list to try since purchasing the equatorial mount.

I had planned to test the weight bearing capability of my Skytracker Pro with a telephoto to see if it could track accurately enough to preserve the details of a nebula. While the moon was supposed to set at 2:00 a.m. The iOptron Skytracker Pro is rated to 3kg. My scale confirms that the combo of my ball head, Z6 with L-bracket, FTZ and 70-200 weighs just about exactly that amount. So, not exactly the rig for deep sky photography. I'll call this a "shallow sky image," obviously another significant crop.
3. Orion Nebula
View attachment 1677625
Very nice image Andy.
 
Joined
Jan 22, 2019
Messages
2,221
Location
Jupiter, FL
Real Name
Andy
Since I got away with the 70-200 on the equatorial mount, I hoped that the 500 PF would work. In an effort to get the weight centered better and to reduce torque on the equatorial mount motor's axis, I used a Z-clamp to reposition the rig, but it introduced too much leverage (I think), and messed up the tracking. Stars visibly moved within the frame even in live view; not as much as they moved without tracking, but the frame definitely was not locked onto a section of sky. Based on this, either too much instability was introduced by the Z-clamp or the incrementally small weight increase was enough to overburden the motor in the equatorial mount. I'll have to go back out another night to try changing one variable at a time.
 

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