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Best simple mount for a DSLR for Astrophotography.

Leveye

By Leveye
in Getting Started With Imaging

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melsky

melsky

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Thanks guys, my camera is modded meaning it has had a filter removed from in front of the sensor that normally restricts some of the red and infra-red from reaching it,this gives good colour balance for ordinary photography but for astro we want all the light we can get.

By shooting lots of 3 minute exposures and stacking them in software your tracking only has to be good for each 3 minute exposure rather the the total 108 minutes plus it means you can eliminate the odd frame that has a cloud or aircraft trail on it.

Mel

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Gonzo

Gonzo

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I've just checked the Astrotrac website and it appears that they have an auto-guided version. Only 5 months to my birthday.... muhahahahaha

The more I read about this Astrotrac, the more I like it. I might end up selling my eq3-2.

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Leveye

Leveye

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Thanks guys, my camera is modded meaning it has had a filter removed from in front of the sensor that normally restricts some of the red and infra-red from reaching it,this gives good colour balance for ordinary photography but for astro we want all the light we can get.

By shooting lots of 3 minute exposures and stacking them in software your tracking only has to be good for each 3 minute exposure rather the the total 108 minutes plus it means you can eliminate the odd frame that has a cloud or aircraft trail on it.

Mel

Just to be clear in my understanding Mel your getting 3 minutes unguided with your setup?

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StuartJPP

StuartJPP

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AMAZING! You have my award which lens and sensor used here?

This M45 was taken with an unmodified Canon 7D with the Canon 500mm f/4 lens, it is resized and not cropped, i.e. the field of view with the 500mm lens is what you see here, it is a tight fit. With this lens I can only manage 90 second subs, mostly due to the weight of it, it is a heavy beast...3.8Kg (Lens) + 820g (7D) + 1.2Kg (Tripod Head) = Total 6Kg. I can get 2 minute subs, but trailing creeps in to most of the subs so don't bother going more than 90 seconds.

A cropped version with a 300mm lens will be about this size of image. Just to be clear, a 300mm f/4 lens can quite easily achieve 3 minutes unguided, though polar alignment has to be spot on and your rig stable. You may lose a few subs here and there. Collimating the polar scope is essential and following the same workflow each time helps to get consistent results.

Only an auto-guiding version is available from AtroTrac these days, mine was bought 2nd had and isn't the -AG version, though I doubt I would ever guide with it anyway as it only guides in RA.

I am in no way saying that the other mounts aren't capable of similar results, just that I have yet to see any real world tests with the types of focal lengths I use.

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melsky

melsky

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Yes I use the Astrotrac unguided even though I have the AG version, as Stuart say's good polar alignment is a must and I've refined my technique over several years to get it consistent. The above Andromeda shot had a little trailing but software can correct a small amount, I use Focus Magic correct motion blur.

Mel

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melsky

melsky

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What's your technique please for polar alignment?

I use a laser directly on the Astrotrac, this photo is an early prototype. I'll have to take photo's of the current setup and explain the technique in a separate post when I get the time.

Mel

post-4305-0-81772700-1359491235_thumb.jp

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StuartJPP

StuartJPP

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I use a laser directly on the Astrotrac, this photo is an early prototype. I'll have to take photo's of the current setup and explain the technique in a separate post when I get the time.

Mel

I would also like to see this setup Mel, I just use the supplied polar scope and make sure I get at least the 2nd star in...

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  • 11 months later...
iksobarg

iksobarg

Posted
Posted

I use a laser directly on the Astrotrac, this photo is an early prototype. I'll have to take photo's of the current setup and explain the technique in a separate post when I get the time.

Mel

attachicon.giflaser on Astrotrac.jpg

Hello All,

I the FNG and trying to catch up with you all and all the fun stuff there is to see, know, and read about here.

That said, I was wondering about Mel's followup?

Jawdropping images to take in here and they keep getting better!

Thanks and hope to hear back soon!!

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  • 1 year later...
whistlestop

whistlestop

Posted
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Mel....new member here, I was thinking of exactly same laser holder for my AT, mounted on RA axis....brilliant. The polar scope arm on my AT is seriously out of wack and I'm thinking that I can mount my Vixen Polaris polar scope ( love it) in the polar scope arm then I could align on the laser shot from the RA axis holder and manipulate the polar scope (shimming or with some adjustment screws in a makeshift holder) so that the laser dot is bang in the center.... Then move the mount to offset from Polaris to where the NCP is shown in the polar scope.

How did your RA axis holder work for you...the trick is the ensure that its absolutely perpendicular to the face of the unit and the laser pointer is the same.

Cheers

Lynn

Www.nightoverontario.com

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melsky

melsky

Posted
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Thanks Lynn

The laser is mounted directly to the Astrotrac as shown in the previous photo and pointed at paper target at least 10m away. Hold down the start button on the Astrotrac whilst pushing the power lead in, this puts it in a mode were you can fast forward/ reverse it. Push the button once to drive it to the start position and mark the position of the laser point with a pen, press the button again and it will start fast forwarding, keep marking the laser position until it is fully wound out. If you're lucky the laser doesn't move but more likely it will trace out a 30 degree arc, attached is a photo of one of my targets I use to align the arc between the 30 degree lines to point to where the laser needs to be centred to. You may need to do this a couple of times to increase the accuracy but you end up with a laser aligned to the Astrotrac's axis of rotation which you can then point at the celestial North Pole, I'll need to do some photo's to show how I do this or you can just aim at Polaris for short exposures.

Melb668518b8c0ab97fc10b03c10e8bd57a.jpg

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whistlestop

whistlestop

Posted
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Thanks Mel...makes great sense, 30 degrees being 2 hours of rotation. Excellent. On the holder itself what did you use for base was it all custom fabricated or DIY plumbing parts ?

As to the NCP, I'll just star hop to center on it.

Thanks for the response

Cheers

Lynn

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  • 2 years later...
TareqPhoto

TareqPhoto

Posted
Posted
20 hours ago, geordie85 said:

Skywatcher star adventurer 

+1, it is a very good one.

Or, if you can increase budget then you can get into EQ level i think, and get AVX.

If you can even increase much more then don't look anything less than EQ5 or iOptron 45 or something similar, even Orion Sirius is a very capable option, it is better to jump once, i know that SW SA is enough for your gear, but think twice and long term, SW SA won't give you more room for bigger gear onec you go for scopes, even EQ5 or AVX have limitations, but that means that SW SA is differently behind then, i started for the first time ever this year and i already got AZ-EQ6, no SW SA no EQ no AVX, and i know very strong that if i bought one of those then i will regret them and i will so soon replace them with something more.

But, with all above i wrote, i know there is only and only one big problem as always, THE BUDGET, so if your budget is very tight and you can save more or can't wait then destroy all what i wrote and enjoy with whatever you buy.

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