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Would I get bad results imaging at around 4 arc seconds per pixel?


Chris

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Hi, 

 I've bought a WO66 ED refractor purposefully to piggyback on my C8 for imaging, and I've been looking at either a small mono camera like the Atik16ic  which will both help with the Moon/LP, and allow me to start this guiding lark with my C8 / 350D combo. Or I could use my modded 350D on the WO66 with an reducer flattener.

There is a slight worry though when I input the figures this into 12Dstring:

Atik16ic with WO66 = 3.93 arcsec/pixel

350D with WO66 = 3.41 arcsec/pixel

350D with WO66 + 0.8 RF (which is what I'd want to use if imaging with a low sensitivity DLSR) = 4.3 arcsec/pixel !!

I remember reading that 2 arcsec/pixel was probably about right with British skies, I'm not sure how good or bad 4 would be? Would I be under sampling significantly at 4 arcsec/pixel? or do folks think this is doable and worth it?

Very interested in peoples thoughts on what resolution is thought to be usable or not?

I might also help me decide if my next purchase should be a little mono camera/guider, or 0.8 reducer/flattener for the 350D?

Cheers any thoughts welcome :)

Chris

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chris buy earls 314+L it will  be awesome in the c8 on PN'S and galaxy's!!!!!!!!!!!!!!

:D I looked at that Dan, 750 is a little bit much for me at the moment though.

I'm trying to strike a good balance between visual and imaging so free'd up some dosh by selling the PST and a couple of EP's. I've only got about 350 left after buying the WO66 so I need to be careful what I buy  :icon_scratch:

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I think I might have waffled a bit too much in the question (I do that), so I will try and keep the question short :)

Does anyone image at 4 arcsec/pixel? 

If so do you feel that your results are sharp and full of detail? or soft and lacking in detail? 

If you are unsure how to check what arcsec/pixel your imaging kit gives, you can input your scope and camera here:

http://www.12dstring.me.uk/fov.htm

It would also be interesting to see what kind of consensus there is with this??

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Rather than thinking about the pixel scale as a negative, think about the FOV as a positive. The 350D on the reduced 66 would get the whole of the NAN or Veil on a single frame, or the Flame, Horsehead and M42 in a mosaic of 2 with a big overlap. You'd need to mod the camera for best effect on those targets though. The reasonably fast f/4.5 would also help though not sure how flat your field would be so might be worth searching astrobin for some examples.

Wide fields shot with a lens have insane pixel scale but still look good. You could also try drizzing (especially in PixInsight). I am shooting at about 2.5app with my setup and provided you dither and get plenty of subs ( 20 or more) you can double your pixel scale with no noticeable increase in noise.

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All the images that Tom and I post from the Tandem Tak are at 3.5 arcsecs per pixel. Eg http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-J6hBf6k/0/X3/VDB14%2015%20TO%20SOUL%20Web-X3.jpg

The great master of just the rig you're discussing was John Punnett. These were taken at my place with 66 and 16ic. http://www.jpastronomy.co.uk/lesgranges%202008.html

Unable to get any sense out of my Meade fork mount for long FL imaging I started imaging by using a 16HR in a flattened ZS66 piggybacked while guiding through the Meade. This is similar to what you propose and it worked.

NORTHAMLCE%20copy-L.jpg

I like to think I've learned a bit since then! 

Olly

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I frequently image at 4.68"/pixel which is using a 400mm FL scope (Esprit 80ED Pro and now also an ST80 for narrow band) and Atik 460EX binned 2x2.  I find the skies here rarely allow as good as 2"/px TBH.  If I can do that I consider it a very good night.  IMO you should get good results at 4"/px - go for it :)

My attitude is always "try it" for almost anything :)  But I think you probably know that :D  I have been amazed at how many things to which the general opinion would be "nah - waste of time" have actually worked :)

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Rather than thinking about the pixel scale as a negative, think about the FOV as a positive. The 350D on the reduced 66 would get the whole of the NAN or Veil on a single frame, or the Flame, Horsehead and M42 in a mosaic of 2 with a big overlap. You'd need to mod the camera for best effect on those targets though. The reasonably fast f/4.5 would also help though not sure how flat your field would be so might be worth searching astrobin for some examples.

Wide fields shot with a lens have insane pixel scale but still look good. You could also try drizzing (especially in PixInsight). I am shooting at about 2.5app with my setup and provided you dither and get plenty of subs ( 20 or more) you can double your pixel scale with no noticeable increase in noise.

Thanks Ian, good point about the field of view, yes I guess you wouldn't really notice chunky resolution if you're effectively zoomed out over a very big FOV.

I have both full spectrum modded and a standard 350D's so I'm well sorted in that respect :)

I was thinking small mono chip with ST4 port might be quite a practical thing to have though for guiding my C8 when the dew isn't too bad. plus the Moon does have a big habit of blazing away on almost rare clear nights so I was thinking it would be handy for narrow band. When   

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I suspect there is no exact answer. I have read values that range over so much that 4 arc sec per pixel could be considered in the middle.

Best answer is the simple one, give it a go and see what comes out.

Very good point, part of the joy of imaging is of course the experimentation :) 

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All the images that Tom and I post from the Tandem Tak are at 3.5 arcsecs per pixel. Eg http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-J6hBf6k/0/X3/VDB14%2015%20TO%20SOUL%20Web-X3.jpg

The great master of just the rig you're discussing was John Punnett. These were taken at my place with 66 and 16ic. http://www.jpastronomy.co.uk/lesgranges%202008.html

Unable to get any sense out of my Meade fork mount for long FL imaging I started imaging by using a 16HR in a flattened ZS66 piggybacked while guiding through the Meade. This is similar to what you propose and it worked.

I like to think I've learned a bit since then! 

Olly

Thanks Olly, well that nicely illustrates it to me :)

The resolution of your widefield shot at 3.5 arcsec/pixel looks great to me, and John Punnett's shots with the WO66 plus Atik16ic look good but are certainly a bit softer probably because they are effectively zoomed in.

Still I'd be fairly please with them, I have no ambition to make the glossy mags with any of my images :D

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I frequently image at 4.68"/pixel which is using a 400mm FL scope (Esprit 80ED Pro and now also an ST80 for narrow band) and Atik 460EX binned 2x2.  I find the skies here rarely allow as good as 2"/px TBH.  If I can do that I consider it a very good night.  IMO you should get good results at 4"/px - go for it :)

My attitude is always "try it" for almost anything :)  But I think you probably know that :D  I have been amazed at how many things to which the general opinion would be "nah - waste of time" have actually worked :)

I hadn't realised you where imaging at 4.7 arcsec/pixel Gina so that's very encouraging indeed :)

Good point about the skies hear, all too often are they a bit soupy so maybe imaging at 4 arcsec/pixel is actually quite a practical thing to being doing in the UK? :D I guess it would increase sensitivity and reduce tracking errors over higher resolution also.

Very good point about trying things for your self to see what works and what doesn't, your ST80 thread certainly shows this! :)

In the interest of experimentation I did come across the Orion G3 which has a larger chip than the ic16 or Titan and only costs 319 pounds on Amazon. I've not found that much on this camera bar one or two reviews which said its good but has week cooling (only 10 below ambient). If I don't find a second hand Atik16ic or Titan etc I might give it a go beings its about the same money new. It might be good to put some images out there on a camera that doesn't have much of a following perhaps.

I think folk where skeptical about the super cheap 130pds being upto imaging a couple of years ago when I bought one, now look at it go in the right hands! :D

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 I did once have a similar camera so I've tracked down some images to remind me what the deal is with this size chip. These were at longer focal lengths of 600-750mm and 2.5 to 2.9 arcsec/pixel, so I would be in for more field of view but less resolution.  

http://www.insideastronomy.com/index.php?/topic/713-first-attempts-with-the-brightstar-mammut-m51/ 

http://www.insideastronomy.com/index.php?/topic/784-bubble-nebula-rgbl-with-the-mammut/

Looks like I was hung up on 2.9 arcsec/pixel at the time, and here's me thinking this is the first time its bothered me  :rolleyes:

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Thanks Olly, well that nicely illustrates it to me :)

The resolution of your widefield shot at 3.5 arcsec/pixel looks great to me, and John Punnett's shots with the WO66 plus Atik16ic look good but are certainly a bit softer probably because they are effectively zoomed in.

Still I'd be fairly please with them, I have no ambition to make the glossy mags with any of my images :D

ZS66 versus Takahashi FSQ106 is hardly a fair fight!

:grin: lly

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Most of my imaging  was done using a Megrez 72 with FFIII and Canon 1000D piggy backed on a Celestron CPC800 ... So working  around 3.41 arcsec/pixel....

Peter...

I think imaging this broadly is more common place than I first thought :)

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I've been offered an Atik 16 (not the ic, just 16?), I don't know much about this camera so I'll do some digging :)

msg-6611-0-36540700-1417017763_thumb.jpg

That could be a 16HR. There was an Atik in the same body which had a smaller chip so beware. But if it really is a 16HR then it is not significantly different from the current 314L. The later model has 1) set point cooling which really doesn't matter much on the Sony chip which is so low in noise anyway and 2) a faster download time. This makes framing easier but is, at best, a fairly trivial luxury. Would you tell any difference between picures in a 16HR and a 314L? I very much doubt it. (A more robust answer would just be 'No!' and 'No' is what I really thnk.)

Olly

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I thought the same thing Olly so I asked the chap if he was sure it wasn't the HR model, he said I wish! :D

Its like the HR but has a more entry level ICX429ALL chip which I think might be a slight step up from the Atik16ic? 

A found an Atik pdf about the Atik16 and Atik16HR, I've never heard about it before now?:

http://www.zen81542.zen.co.uk/download/Manual%20Atik%2016-16HR.pdf

I've also been offered a 314e but he wants me to make an offer on it? I haven't a clue about second hand prices on these? don't hear much about the 314e now days. I wouldn't mind a 420L with future hyperstar in mind, jeez! at this rate I will be buying Earls 314L+ :D

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:D I looked at that Dan, 750 is a little bit much for me at the moment though.

I'm trying to strike a good balance between visual and imaging so free'd up some dosh by selling the PST and a couple of EP's. I've only got about 350 left after buying the WO66 so I need to be careful what I buy  :icon_scratch:

Hi,

Where did you get the WO66 from, I can't find one anywhere as they don't make them anymore.

Been after one for a couple of years now

:)

SS

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Hi,

Where did you get the WO66 from, I can't find one anywhere as they don't make them anymore.

Been after one for a couple of years now

:)

SS

I know they are like gold dust arn't they! I was really lucky basically! I advertised a few times on Astrobuy for a small ED refractor, and on the last advert a chap got back to me with the goods. Did I mention I was really lucky?

I had one of these a few years ago and really regretted letting it go so I will be hanging onto this little sapphire beauty :)

Just keep on placing wanted ads for one here and on UK astrobuyandsell, hopefully one will become available for you, fingers crossed :)

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Well it looks like I'm buying the Atik 16 ! Definately worth a shot for 140 pounds!

Its been in storage for a while so its untested, but he's very kindly offered to let me try before I buy to make sure it works ok :)

With my WO66 it will give me a field of view of:  57.3' x 44.4' and a chunky 4.57"/pixel 

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