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Stacking images vs. Longer exposure time

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18 years 4 months ago #24596 by dave_lillis
Replied by dave_lillis on topic Re: Stacking images vs. Longer exposure time
Eirik,
One trick I found doing 2-3 minute exposures with the etx, is to wait until the object is near or almost crossing the meridian, that way the declination drive is almost stopped, so one less drive to worry about.

I agree with Dave McD, the etx70 is a good deepsky starter scope due to its nice widefiled of view, I would not rank it as a good planetary scope, the skylux does a better job of them.

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor

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18 years 4 months ago #24639 by Eirikg
If you use a dslr camera, 35mm and etx 70 is only 350mm = 10x maginification. Is that good enough for deep space? Can you use barlow?

Say if i buy another mount, how much would i have to spend? And woulnt it be better to spend less on mount and then use guidescope ect?

dmcdona: the mount you got dont need guiding, but woulnt it be alot cheaper to use guiding with a cheaper mount?

Dave Lillis: So you dont use a wedge? How much better would that be?

Im thinking abit about a dslr camera as it could be used to other things to. But as with the etx mount i got it would thouch the body, so a mount (that maybe even could be used for later heavyer scope) sounds good. As long as we are not talking in the pricerange as dmcdona's mount! :O

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18 years 4 months ago #24700 by dmcdona
Replied by dmcdona on topic Re: Stacking images vs. Longer exposure time
Hi Eirik - I'm sure there are plenty of mounts out there cheaper than mine :D And of course, you shouldn;t have to spend that money. But again, do beware, even an autoguider will not compensate for a dodgy mount.

Additionally, if you go down the seperate guidescope and guiding imager, you are adding extra strain on the mount...

I'm sure if you are prepared to spend a thousand or two on a mount (possibly less if you get a secondhand bargain) then you should be OK.

For deep sky, magnification is not that important. In fact, for some objects, the less magnification the better - extended objects like nebulae; detaile milky way shots; large galaxies (e.g. Andromeda). Of course, small galaxies and paletaries usually need a good bit of magnification but usually less than solar system planets...

To get the extra magnification, yes, you can use a Barlow. A 2.5 x powermate would give you x25 in your example.

The thing about deep sky is the (usual) low brightness of the objects you are imaging requiring long exposures. You can expose planets in less than a second. But a lot of the M oejcts eg require 10 seconds plus. Sometimes into minutes worth....

As ever, hope this helps

Dave

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18 years 4 months ago #24704 by Eirikg
euros?

Then i think 1000 would be max what i could spend.

Up to 30x with 3x barlow sounds good, thats about same as 12mm eyepice. Now i havent watching any other nebulas other then m42, so i dont know the size of other m object. Beside others ive seen in pictures in the orion constalation.

Could you give some suggestion to mount?

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18 years 4 months ago #24719 by dmcdona
Replied by dmcdona on topic Re: Stacking images vs. Longer exposure time
If you had 1000 euro for a mount, I'd say you'll get a good second-hand one or possible a heavily discounted new one.

As for which mount, that's a tricky one and I don't really have any concrete advice for you. Try Cloudy Nights reviews - they have honest reviews of astro equipment - I'm sure they have mounts in there.

Or some of the folks here could comment...

Cheers

Dave

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18 years 4 months ago #24956 by Eirikg
just so i got this right

Togheter with a t ring ect (prime focus) you can use barlow?

Have anyone tried a Nikon D50? How is it for astrophotography? I read it gives more noise?

As i also want to get in to photography in general im thinking of getting the camera first. And then maybe try a bit with the mount and all that i got.

As for mount i only found one that maybe is in my price range, CG6 ?

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