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DeepThought

Realistic exposure times on unguided EQ5

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Hi

I just wondered if the community had any opinions on what sort of exposure times I should be getting using an unguided EQ5 that is well polar aligned?  Currently i'm getting up to about 90 seconds towards the poles before some evidence of trailing and I wondered if I should be aiming for better?

Guiding is obviously my ultimate goal but I can't throw any more money at this currently and I'd like to get the best out of what I already have first.

The scope I'm using is a 127mm maksutov with 1500mm focal length so magnification is relatively high, perhaps not ideal for AP but it's what I've got.

Cheers

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That´s actually incredibly impressive, that you are able to get 90 sec unguided at 1500mm focal length on a regular EQ5 to be honest.

You should be very pleased with yourself for pulling that off.

The regular EQ5 doesn´t exactly have as good tracking motors as the HEQ5 Pro and People are happy if they can get 2 minutes unguided subs at short focal length on those Mounts.

So I am really suprised you manage to pull it off on the EQ5. You must be one of the Lucky few that has a good batch of tracking motors on that Mount.

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I think the key point there is pointing at the poles, however getting 90 seconds is great and well beyond what I can do with my EQ3-2 mount with only 650mm.

Experimentation is the way to go with lots of frustrations and throwing images away.

Well done for getting such lengthy exposure times.

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I can get 120 seconds with my 200P/EQ5 on a good night, but normally 60 seconds is the best I can do.  So 90 seconds with a 1500mm f/l scope is very impressive.

Don't be put off by having the "wrong" kit.  I have seen people do all sorts of things with equipment that you wouldn't normally choose for the job.  I met a guy who had imaged the whole Messier cataloge with a 127 Mak on an alt-az goto mount.

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I would be very surprised if you could do 90sec on the equator at 1500mm (with a Canon 1100D). That would imply a periodic error better than many 5K mounts! I'd certainly never sell that mount if it could do it (and wrap it in cotton wool when not being used).

NigelM

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Thanks for the responses, and there was me feeling hard done by with my exposure times.

I suppose the next logical question is what sort of objects can I hope to image with this setup?  The orion nebula is of course very rewarding for a beginner and relatively straightforward thanks to the high surface brightness, but what else is within reach of my "modest" kit?

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With those sub lengths you will need to stick to brighter targets - maybe clusters and the brighter galaxies.

I must admit I never had any sucess over 1 min with my old EQ5 / 200P set-up, and that only has a f/l of 1000mm, so you are doing well.  The only tip I can give you is to take a lot of subs (100+) and be ruthless in discarding any that are not up to scratch - with my set-up I would reckon on throwing 25-30% in the bin.

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guiding's actually one bit that needn't be expensive, I do mine with a Meade LPI and a T70 travelscope, that I got for about £50 each off ebay, works a treat

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I've got an eq5 too coupled with a 150pds which is 750mm FL. I can just about squeeze 2 mins out. Beyond that the stars are no longer round and trails start to appear.

90 seconds at 1500mm.. that's real impressive! If I could get that, i'd NEVER move the scope from it's position!  :Envy:

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Wow - 90s unguided with a Mak. I'm well impressed - I should dig out my Mak and have another go at imaging the Messier catalogue... But it's just so much easier with a Newt. (and that's hard already...)

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We'll like I said, that's near the poles, and a bit of a fluke I think, was only managing to get a minute last night.

Believe me I'd love a proper imaging setup but you've got to 'love the one you're with' so to speak.

Tonight's target is M101, we'll see what happens there.

Sent from my iPad using Tapatalk

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As people have said very impressive i can manage 2mins with the eq3-2 but thats with 330mm FL.

Alan

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I'm pleased to read this thread - I was disappointed with my EQ5 at 60 seconds, but it turns out that it's quite normal!

Having started imaging just a few short months ago, I'm staggered with what can be achieved with just a 10 second exposure (if you stack enough of them)

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On my eq5 pro and with my 127mak at f10.3,

I do drift aligning low horizon east or west and then again on the merridean and then get up to 180sec on Orion without guiding and up to 300 on m82 near polar star.

Popper polar align and then drift for at least 5 min per axis is critical.

With guiding theses go up to 360 and 500.

I have never pushed higher than 500 as not seen the need for it yet.

I do throw away about 10% of subs though.

Kit in sig.

Edited by Christopher Davenport

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That is very impressive at that FL.  I can just about do 90secs at FL2350mm on my HEQ5 Pro.  Well done.

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 I can just about do 90secs at FL2350mm on my HEQ5 Pro

Wow - that is also amazing.  If that is on the equator with a typical DSLR, then we are talking no more that 0.5" movement in 90secs, or a periodic error of less that 3" peak to peak.  My HEQ5 struggles to do 30sec at 1200mm (~1" pixels), which is about right for 30" peak-to-peak, which I thought was typical for these mounts.

NigelM

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On my eq5 pro and with my 127mak at f10.3,

I do drift aligning low horizon east or west and then again on the merridean and then get up to 180sec on Orion without guiding and up to 300 on m82 near polar star.

Popper polar align and then drift for at least 5 min per axis is critical.

With guiding theses go up to 360 and 500.

I have never pushed higher than 500 as not seen the need for it yet.

I do throw away about 10% of subs though.

Kit in sig.

Sorry guys I got my numbers wrong on here,  :eek: - apologies if this has caused anxiety to anybody! 

I have not been doing exposures without guiding for a while.

Just check my subs in my archive and the correct numbers are

These are max numbers and have to throw away subs.

Depending on if my target is near horizon and meridian vs M82 near polar

1350 Mak, Unguided: between 90 to 120 sec, Guided between 300 to 420

600 ED, Unguided:  between 120 to 180 sec, Guided between 360 to 500 

 I can just about do 90secs at FL2350mm on my HEQ5 Pro

This is pretty impressive as it is almost double my Mak FL, so 90sec is pretty impressive.

Edited by Christopher Davenport

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