Old 29-04-2019, 12:22 PM
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sharkbite is offline
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Deep sky on an alt-az...


I had some time to bolt my camera lens to my lx90 to use it as a tracking platform. Lens is a Canon 70-200 f4L. I have also attached a ZWO 224 to the back of that.

the results are the photos attached - all except eta carinae are at the 200mm end. Eta is at 70mm.

all are a stack of around 15-20 minutes worth of 10-15 second exposures,
with about 20 darks stacked in DSS. final adjustments done with curves in GIMP.

Do any kind folk have some constructive criticism as to how i can improve my results without spending money on more kit?
Attached Thumbnails
Click for full-size image (20190425 southern pinwheela.jpg)
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Click for full-size image (20190425carinae.jpg)
197.1 KB49 views
Click for full-size image (20190427centaurus a.jpg)
100.2 KB41 views
Click for full-size image (20190427tarantula.jpg)
126.3 KB37 views
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Old 29-04-2019, 03:31 PM
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RyanJones is offline
Join Date: Jun 2018
Location: Melbourne,Australia
Posts: 664
Hi Sharkbite,

Great efforts there. Well done.

I've been there too on an alt-az mount. First question I'll ask is is your LX mounted on a wedge so you can polar align it ? If not that would be a suggestion. Genuine wedges though are astronomically priced ( pun intended ). The only solution without spending money would be to get creative and make your own ( this is said without knowing how handy you are with tools ). This is going to give you the ability to take longer subs without star trailing and prevent feild rotation.

If you can't/don't want to go down that avenue and just want to work with exactly what you have already. My best suggestion to you would be to take at least 10 times as many subs. Aim for the 2-300 mark. This will increase the signal to noise ratio and you'll find you'll be able to stretch the image further to extract more faint detail before horribly introducing noise.

Certainly a great start there. Well done
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Old 29-04-2019, 06:52 PM
Starbloke (Roy)
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Starbloke is offline
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Location: Out west
Posts: 11
You have a fast lens which is great, how did you focus your images? Try to find the limit at which you can do a single image before you get star tails. Having an alt az mount isn’t bad for such a small focal length, I think find the limit to your subs then go from there, more the better for faint DSO.

Clear skies
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Old 29-04-2019, 10:50 PM
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Ukastronomer (Jeremy)
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Location: Llandysul, WALES, UK
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Who says you can't image on AltAz
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Old 30-04-2019, 05:26 PM
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xelasnave is offline
Join Date: Mar 2005
Location: Tabulam
Posts: 12,194
I am thinking that with something like pole master or sharp cap to get polar align you end up with a good polar axisis ( I think someone could comment) and a great dec...better than an equationial mount would could think.
I recon you could build a wedge with motorised alt and asmth ... now that could be a game changer in prefered mounts..imagine the computer tells the motors and perfect PA which is monitered and corrected as the mount moves maybe due to temprature what ever...mmm got me thinking☺.
Anyways great photo you must be very happy and so you should.

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Old 01-05-2019, 09:35 AM
Look up!

sharkbite is offline
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Thanks all...

these are about 80 lights, so i'll crank it to 200 and see how it goes.

I did try 30 second subs, but ended up with 'triangular' shaped stars,
so think 15 seconds is the limit for this mount.

I like the idea of a motorised wedge - and have the bits and pieces, just no time to to it right....
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