lucky imaging with Alt/Az and EQ mounts?

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barnstorm
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lucky imaging with Alt/Az and EQ mounts?

Post by barnstorm »

So...

During the last cycle I was learning to do solar imaging and science outreach with a PST on an iOptron Cube Pro.

I plan on using this with my SMII60.

I am in the process of purchasing a 90mm, (20+lbs payload) and need a new mount.

I read in some posts online as well as the Philp Pugh book that EQ mounts were better for solar imaging. So I bought an EQ GoToMount.

Now I am having buyers remorse as I sit here on a rainy day thinking about polar alignment during the day and at public events. (iOptron Alt/Az has simple GREAT daytime alignment to the sun)

I since we are only doing short captures/stacks using the lucky imaging technique just how much does an EQ mount help?

My night planetary lucky imaging on Alt/Az does not seem any better than the same equipment-mounted EQ.

What am I missing?


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Re: lucky imaging with Alt/Az and EQ mounts?

Post by Montana »

I use an alt az mount for my PSTs with the Sun and never had a problem at all. You are only capturing a minute of avi at most so the difference does not affect the stack at all. The only problem you will have is if you plan to do lengthy timelapse animations. Then the resulting video will be a queasy watch. I have done this and it is not great. It doesn't matter at all, the animation is still great, you just can't watch it cycling for more than minute without getting queasy :lol:

Alexandra


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Re: lucky imaging with Alt/Az and EQ mounts?

Post by barnstorm »

Thanks Alexandra!

Good to know. I use a planetary pre-processor software for my planetary imaging that aligns the video for me as long as it stays in the FOV. I wonder if that would eliminate the issue with time-lapse videos you describe?


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Re: lucky imaging with Alt/Az and EQ mounts?

Post by EGRAY_OBSERVATORY »

This question has come-up before about AZ & EQ differences for Solar viewing/imaging and setting-up to the north.

Due to the brightness of both the Sun and Moon, imaging-times are very short in any of the available lines of light and single-frames for instance - a very few milli-seconds. I can recommend SharpCap as the free program to download which will confirm that. Alternatively FireCapture (also free) but more complex to learn how to use.

As far as pointing a portable set-up mount of either Az, Eq or AZ-EQ such as the SkyWatcher AZ-EQ-6 etc., simply know approximately where Polaris is from the location you intend to observe/image from ? Use a distant object/building/tree/mountain or whatever and use that to align the mount. Accuracy outside of a very-few degrees is not too important - at this stage.

If horizontal accuracy is possible, then using GOTO facility to the Sun and then afterwards, centralise the Sun in say a 10mm E.P.
If not centralised, then simply adjust the mount's Azimuth bearing to align above or below the Solar-disk.

If the Sun is too-high or low, check carefully that the mount is horizontal and then double-check that the Latitude-setting is correct for your location on the Earth's surface...

If then the Sun is staying somewhat centred in the E.P., for a few minutes at least and assuming the mount has applied "Solar Tracking" rate, then it is quite likely that the position on the ground (being used again for another session) and whilst turning the scope exactly 360-degress/North and 90-degs/Horizon is pointing at the place to use for setting-up in future, BUT ALWAYS FROM EXACTLY THE SAME PLACE.

Marking the ground by placing-markers for the tripod will assist. Better option - could be to - horizontally-lay small concrete pads for each of the tripod-legs.

EQ mounts are preferable for longer-time imaging as the apparent-rotation of the Sun is appropriately catered-for over numerous-minutes/hours (compared to Az mounts) and which really applies to long imaging sessions with EQ operations...

I hope this assists your requirements

Terry


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Re: lucky imaging with Alt/Az and EQ mounts?

Post by DeepSolar64 »

I use alt-az mounts for both visual and occasional imaging. I use my Losmandy AZ-8 for imaging with my SMII90 even though is lacks tracking of any sort. You just have to remember to keep your AVI files really short. I rarely go more than 300 frames. It seems that if the files are too big that the software, I use AVIstack, cannot line them up correctly. It presents no trouble at all for single frame captures. I also have a Sky-Watcher AZGTi which does have motorized tracking but it too in my current setup is an altazimuth.

James


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Re: lucky imaging with Alt/Az and EQ mounts?

Post by Dennis »

Im using a alt az mount too and dont have any problems imaging solar system objects. Planets are being derotated with software afterward. And for the sun i dont image longer then 1 minute, now im moving to 30 seconds for more closeup pictures. I often wonder what is the ideal maximum time to image the sun, but until now no problems.

im too lazy for the oldschool eq mount type and setup routines that come with it. Im placing the alt az mount to the same spot on the balcony, switching it on and it still remembers the auto alignement from the last time. A quick sync of the sun and basically instant observe / imaging.


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Re: lucky imaging with Alt/Az and EQ mounts?

Post by cybermayberry »

Montana wrote: Sun Nov 14, 2021 6:08 pm I use an alt az mount for my PSTs with the Sun and never had a problem at all. You are only capturing a minute of avi at most so the difference does not affect the stack at all. The only problem you will have is if you plan to do lengthy timelapse animations. Then the resulting video will be a queasy watch. I have done this and it is not great. It doesn't matter at all, the animation is still great, you just can't watch it cycling for more than minute without getting queasy :lol:

Alexandra

One can just use post stabilization to address the "queasy" effects as well.
davinci resolve would handle it easily and it's a free and very powerful option.


Rich

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