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300 secs (5min) unguided on HEQ5

peroni

By peroni
in Getting Started With Imaging

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peroni

peroni

Posted
Posted

Well I wasn't expecting that. :Envy:

I've been playing around with polar alignment over the weekend. Lucky to have a couple of clear nights.

I don't want to complicate things more than they already are, so I've not gone down the route of computer attached or guiding.

Image below is a single shot taken last night. 600 secs exposure at ISO800.

I'll try stacking them later. I took 18 shots, some need to be thrown as they show movement (probably inaccuracy in gears). But I'd say about 14 shots are usable.

post-15911-0-25225800-1364901968_thumb.j

It felt like there is more to be had. I stopped at 600secs as I wanted to get some data last night and even test shots start to take a while at that exposure time.

How far have others managed to push their unguided exposures on an HEQ5?

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peroni

peroni

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600 seconds, that's impressive. I know guiding has a reputation as being a bit well, temperamental, but it can work "straight out of the box". If you were to try it you may be pleasantly surprised ;)

Any more hardware purchases are out of the question for now. I know I'll guide at some point but until I get a more permanent observation platform, I'll stick with the basics :grin:

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RikM

RikM

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Fantastic result. It pays to get your polar alignment as close as possible. The short focal length is a big factor in this as well.

With a 300mm lens and DSLR on an EQ3-2, I managed 5 min unguided.

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peroni

peroni

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600s unguided. :o Awesome shot. I have an EQ5, and for that length of time, i always have to guide, and even then, some nights it doesn't work out too well

It does seem a bit trial and error, this polar aligning.

On Sat night I aligned no trouble and got 150 secs easy. Last night for some reason (user error :huh: ), I aligned on a star that wasn't Polaris. Needless to say my guiding was out until I spotted the obvious mistake.

Note to self: Always check the mount is level and altitude is set at roughly 51 degs. That'll make Polaris easier to find :grin:

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ollypenrice

ollypenrice

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Looks great!

If you do a sucessful 3-star polar alignment, does it still matter how good or bad the setup was (tripod leveld, correct pos for polaris in RA etc)?

From a tracking accuracy point of view your 3 star alignment is totally irrelevant. It only controls where the mount thinks the stars are, not how well it tracks them. Nor does it matter that your mount be level, though if using the polar scope reticle to polar align it does matter. Ultimately all that matters is polar alignment of the mount.

I suspect you've set the record for unguided subs on an HEQ5. That 10 minute shot is incredibly impressive and far better, I think, than your average HEQ5. I have two HEQ sixes which wouldn't get near that. You have a seriously good one! Guiding doesn't complicate imaging, it simplifies it, but when you're spent up you're spent up, I know!!

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2277139556&k=FGgG233

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peroni

peroni

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If only my multiplication was correct :huh:. What's 5 mins converted into seconds? er 300 secs I think! Not 600 light my head incorrectly worked out.

I could use April 1st as an excuse but even then I'm a day late. :rolleyes:

Apologies for getting everyone excited about what appears to be a more average unguided 5 mins.

The question still stands though...

What do other users achieve as a max unguided time on HEQ5?

I'll try and edit the post and title now.

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Jessun

Jessun

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5 minutes is still a tribute to your polar alignment and accuracy of the mount. I don't know what the PE cycle is on the HEQ5 but it may come more into play for longer subs.

Very good work!

/Jesper

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Black Knight

Black Knight

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Any more hardware purchases are out of the question for now. I know I'll guide at some point but until I get a more permanent observation platform, I'll stick with the basics :grin:

Fair enough. In the meantime, 300 seconds unguided is perfectly acceptable :D

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chrisshillito

chrisshillito

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300s unguided is certainly very good going and you must have nailed a pretty good polar alignment! You are doing relatively low resolution imaging up in ursa major, and this also acts in your favour. The closer you get to the pole the less pixel movement an object makes for any given angular movement of the mount, so the observable effect of PE is reduced and the easier unguided imaging becomes.

Chris.

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peroni

peroni

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300s unguided is certainly very good going and you must have nailed a pretty good polar alignment! You are doing relatively low resolution imaging up in ursa major, and this also acts in your favour. The closer you get to the pole the less pixel movement an object makes for any given angular movement of the mount, so the observable effect of PE is reduced and the easier unguided imaging becomes.

That's a good point. Here is the finished image of 10 shots stacked in DSS. No darks unfortunately but I had flat and bias frames.

M51 10x5mins

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Welrod50

Welrod50

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I don't know how you managed that! The key thing will be if your mount will consistently give you that level of tracking accuracy. I know my EQ3 Pro unguided will do 60 second subs without trailing all night long (if the wind doesn't come into play) most nights. I've been out every night this week so far ( :) ) and every night with the exception of last night was pretty good. I've obtained 90 seconds unguided with DSLR mounted directly onto the mount with 300mm lens, but lost almost half the subs to wind movement. Last night was almost a complete waste, had to re-align with two star alignment about nine times (for some reason) and had trailing above 45 seconds. Yet the polar alignment was bang on, as it has been every night this week. Weird! And well done. Good luck for next time!!! ;)

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  • 3 weeks later...
dph1nm

dph1nm

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Remember the effect of PE, which is what ultimately limits your exposures, depends on focal length, pixel size in microns of the camera and the distance from the pole. My HEQ5 will only do 30s on the equator with 1 arcsec pixels. This is about right for my measured +/- 15" PE, given the 10 min worm period. If you have significantly better PE than this from an HEQ5 then I reckon you are very lucky - whatever you do, don't sell it!

NigelM

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