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astrophotography stacking?


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Hello I am completely new to astronomy and am researching scopes and dslr camera connection to scope, I am currently looking seriously at the Skywatcher Explorer 150P EQ3-2 (after a bit of advice from the forum cheers).

My question is would I need the scope to track to be able to photograph deepish objects?

My other question is I have heard the phrase "photo stacking" come up a lot but I am not really sure what it is and can this be done on say the moon without tracking motors?

Sorry if this is a bit jumbled but I don't really know what I am doing I have spent the last few days trying to research as much as I can on the net and with a book.

any useful links, explanations, advice greatly appreciated

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To get good Deep Sky Objects tracking is required but you may get off in the begining with objects like the M13 and M42 if you take several shorter exposures and stack them. For the moon you will not need to track as the brightness of the moon is such that very short exposures are required.

To stack Deep Sky Objects download (free) Deep sky stacker.

For the moon download (again free) Reistax.

You can also stitch together images of the moon using Microsoft Ice (download free)

Good luck

Neil

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Have look at my blog on the lets do astrophotography sections that might clear up a few thing for you I use a skywatcher 200p and an eq5 mount with a single ra axis drive started off with a 150 sky watcher first but upgraded very quickly.

Sent from my GT-S5670 using Tapatalk

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Quatermass has a great blog on getting your astrophotos set up. I would recommend getting some books on the subject as well, it will save you from making an expensive mistake (buying the wrong equipment) and a lot of headaches (DSLR settings and stacking). Making Every Photon Count by Steve Richards is your best bet (he posts on this site as well) Good luck:)

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For DSOs is it recommended to stack a large amount of short duration exposure?

Is there any rule any rule of thumb or general guide line as to exposure time vs number of photos.... Or is this all preference?

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Yes it is recommended, especially short duration exposures.

The idea is to gather as much data as possible and stack them. You could get away with 20 minutes of data, but you will see images with literally hours and hours of data to pull out those small details and eliminate noise.

So lets say you are imaging something big like Orion, m42. Its so bright that long exposures may not be necessary because you could wash out the image. If you take 30 images at 3 minutes of exposure time and stack them, you will have 90 minutes worth of data. Not to mention that a single 90 minute exposure is really out of the question.

Another example would be a very dim DSO, lets say the Pinwheel M101. You would need long exposure images to pull out detail, but if you go too long guiding errors will occur and if using a DSLR noise will litter your image. So, you take 20 images at 5 minutes and stack them, you have 100 minutes worth of data in one image.

These are just examples, but I have learned that each DSO is different and I make adjustments depending on what it is. I would recommend doing more research and getting Steve Richards book, Making Ever Photon Count. It is extremely helpful, I have only been imaging for a couple years and the book saves many headaches. Good luck:)

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Also, does stacking images give an advantage in light pollution?

Looking at some DSOs under light pollution do give the fuzzy look and often makes it difficult to make out the object clearly.

Can stacking multiple exposures clear this in the final product?

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If your interest is in deep sky photography you may find that the EQ3-2 isnt up to the job as its not really stable enough. Normally an EQ5 is reccomended as a minimum. The EQ3-2 is fine for planets and the moon though. In my own opinion (and thats all it is) id buy the a scope and spend a few months learning to use it and reading up on AP etc before jumping into it

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Stacking your images if they are taken in heavy light pollution will also stack the light pollution so use a filter or go to a dark site. The better your images the better the final stack in other words bad pictures produce bad stacked images ;-)

Sent from my GT-S5670 using Tapatalk

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Thanks

To get good Deep Sky Objects tracking is required but you may get off in the begining with objects like the M13 and M42 if you take several shorter exposures and stack them. For the moon you will not need to track as the brightness of the moon is such that very short exposures are required.

To stack Deep Sky Objects download (free) Deep sky stacker.

For the moon download (again free) Reistax.

You can also stitch together images of the moon using Microsoft Ice (download free)

Good luck

Neil

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i agree with 99.9% of above but IMHO now is the best time as you have Orioin coming into play the best object to learn astophotgraphy on as it can be an easy target for short exposures ad a challenging one for longer exposures you can learn most techniques needed whils using this one target. my first year i spent most of the NOv to Mar imaging it and got from one to the other of these images the one is oct 2005 the second oct 2006

post-13529-133877684589_thumb.jpg

post-13529-133877684591_thumb.jpg

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That's a really good improvement from the two images, I really like the second image.

I know that Orion is out nice and early now with plenty of time to play with it but I've had a difficult time getting out lately either being too busy or stuck with a series of cloudy nights.

And as for light pollution, would you recommend any specific light pollution filter?

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Id be tempted to just image it first and see how bad your light pollution is. I did my shots of orion nebula last december without a filter and that was when i was living in the centre of a town with street lights all around me. Dont own any filters except a moon filter so cant advise on that sorry

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Have look at my blog on the lets do astrophotography sections that might clear up a few thing for you I use a skywatcher 200p and an eq5 mount with a single ra axis drive started off with a 150 sky watcher first but upgraded very quickly.

Sent from my GT-S5670 using Tapatalk

Why did you upgrade so quickly?

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And as for light pollution, would you recommend any specific light pollution filter?

thank you for your kind comments

i am luck whilst there is LP here i don't suffer so much as others. a good quality one I used was the Orion skyglow

and i have used the IDAS LPS-P2 31.7mm MBT and IGAD Photographic light pollution filter.

there were none used on these images though.

IGAD (Ion-Gun Assist Deposition)

MBT (Multi Band-pass Technology)

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I upgraded because my little 130 skywatcher was just not giving me the detail in the things I wanted to see the 8inch mirror in the skywatcher 200p is perfect for me and with the eq5 your able to do astrophotography as well so long as you have a single axis drive. Its the entry level set up for astrophotography sort of but it does serve me well and I have a lot of fun with it. Later on I will upgrade again but for now I am very happy with it.

yes it was aperture fever it will get you as well so watch out lol

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I may be wrong but essentially for imaging DSO with an unguided/non-tracking scope, the trick is to take MANY SHORT exposures and then stack them. The more exposures you take the better. Take hundreds/thousands of short exposures and stack them. The result is quite amazing.

How long these exposures should be boils down to the level of light pollution where you are. DSLR are very sensitive to the stuff and you will be shocked just how bad it appears in images because to the naked eye while observing it really doesnt show up as badly.

I live in a semi rural kind of area (about 20 miles south of Dublin city) and i consider my skies to be pretty dark. Yet when i point my cam skywards (on a tripod, no scope) i find that my exposures are limited to about 5 seconds each before the dreaded orange glow starts to show.

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While imaging with multiple short duration exposures and the sky not moving so much, does guiding become less necessary?

For certain DSOs, yes, guiding becomes less necessary. Sadly, most DSOs are not Andromeda or Orion. When you image most DSOs, which are very dim, the long exposures become a necessity and require guiding. And depending on the scope you use, the earth rotates quite quickly. With my small 6" newtonian, Jupiter moves very fast without tracking. It all depends on what you are doing.

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I may be wrong but essentially for imaging DSO with an unguided/non-tracking scope, the trick is to take MANY SHORT exposures and then stack them.

Without tracking there is a general rule of tumb to get the max exposure time for a given focal length, before trails are noticeable. It's 600/FL = time in seconds

So with a 16mm lens 37s are possible. With a scope however you'll have to expose for under a second and, even with thousands of subs, I don't think you'll manage to get any detail.

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Something that no one else has mentioned yet, but I think should be touched upon, is illustrated in the two pictures of M42 above. Although the subject is the same, the treatment of it in the two pictures is radically different! That is one of the fascinations of astro-photography! You can take the SAME DATA, and by manipulating it in a program such as PhotoShop, end up with entirely different results! You will never get tired of the hobby, once you really get into it !

JMHO Jim S.

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I would put the HEQ5 as the minimum mount becuase it has the finely controllable motors needed to move up to autoguiding later, somethng which is necessary for serious imaging whatever mount you have. Imaging is about mount first, camera second and scope third.

I agree with Pvaz that, unguided, all you can do is find out the longest exposure time possible by trial and error. You will end up discarding perhaps a third of your short subs but keeping the good ones and stacking them. You can't have too many but diminishing returns syndrome sets in at about 50 subs.

Although bright, M42 is a tricky object because of the high dynamic range. I found I needed to combine subs of 10 secs, 50 secs and 5 minutes in a Photoshop technique. But walk before you run!

It is so rewarding though, is imaging the night sky.

I second the recommendation of Steve's book Making Every Photon Count and would urge you to ignore entirely anything appearing on manufacturers' blurbs. While they don't actually lie, they gravely mislead in many cases. Trust Steve's book and what experienced imagers tell you on SGL. Also keep an eye on the DS imaging board and see what people are acutually using (and, indeed, what they are not using...)

Olly

http://ollypenrice.smugmug.com/

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For certain DSOs, yes, guiding becomes less necessary. Sadly, most DSOs are not Andromeda or Orion. When you image most DSOs, which are very dim, the long exposures become a necessity and require guiding. And depending on the scope you use, the earth rotates quite quickly. With my small 6" newtonian, Jupiter moves very fast without tracking. It all depends on what you are doing.

Currently I'm using a CGEM but if all equipment is different I'll need more information on guiding, since I haven't really tried it yet and don't know a whole lot about it.

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