M16 Eagle neb

[Tamtarn]

Taken last weekend.

Details

Celestron C9.25
Canon 40D unmodded

Total exposure 2hrs
15 Lights 15darks .. 8min exp .. ISO800
Temperature 16degrees

Larger image http://barb.david.1.googlepages.com/






Any helpful hints on improvement always appreciated

[AlexN]

looks nice guys.. it has a cool 3D depth look about it from the bottom left through to the pillars of creation... It looks a little soft maybe, though that could just be me? did you run a noise reduction filter over it? that may be the culprit, as the data looks to be focused well, it just has a softened look to it..

Very nice shot of a lovely target that I for one am very happy to see back in the sky (not that I've seen the sky for several weeks.. )

[Tamtarn]

Originally Posted by AlexN

looks nice guys.. it has a cool 3D depth look about it from the bottom left through to the pillars of creation... It looks a little soft maybe, though that could just be me? did you run a noise reduction filter over it? that may be the culprit, as the data looks to be focused well, it just has a softened look to it..

Very nice shot of a lovely target that I for one am very happy to see back in the sky (not that I've seen the sky for several weeks.. )

Only did NR on background and outer limits of the neb Alex I've boosted the saturation a bit maybe that helped take away the softness.

Know how you feel not having clear skies for a few weeks we've been through it here many times

[multiweb (Marc)]

Wow. I like it a lot. Do you guys use any kind of field flattener on the C9.25? I'm asking coz your stars look pretty round.

[Tamtarn]

Originally Posted by multiweb

Wow. I like it a lot. Do you guys use any kind of field flattener on the C9.25? I'm asking coz your stars look pretty round.

We use the Meade 6.3 Reducer/Flattener Marc and now the mount is on our pier that's helped as well

[Quark (Trevor)]

Hi Barb & David,
Well done, very nice image of a stunning object.

Cheers
Trevor

[allan gould]

Nice photo et again,avid and Barbera. LUCKY TO GET SOME GOOD WEATHER FOR IMAGING. Always like your photos and processing.

[Craig_L]

Very, very nice David and Barb. Has a lovely delicacy to detail and colour which gives it that 3D look.

[dugnsuz (Doug)]

Really like the Repro - thought the brighter stars had a bit of elongation in the larger original (on your website), might be my old eyes playing tricks.
Nice processing Barb!
You're doing lovely stuff with the 9.25" scope David.

Noticed you're doing separate darks - do you find you get better results?
How do you temp match??
Doug

[Tamtarn]

Might still be getting a little flexure sometimes with the standard Celestron dovetail bar Doug.
Have a Losmandy Dovetail Plate coming and then will get a new Losmandy Head and puck setup, so that should take out any flexing that we may get.

The main reason for doing separate darks is to obtain larger amounts of data on the night.

We have a temp sensor in the obs with the thermometer inside the house and we monitor the temp of our lights every 15 - 20 minutes.

As long as the darks are within 3 degrees of the lights they work okay.
Next step is to start doing flats.

David

[dugnsuz (Doug)]

[spearo (Frank)]

Looks good!
the colors are very nice especially inthe second version
I've always found that my images with my DSLR require the slightest hint of unsharp mask as a final staep to sharpen up the image
might be worth a try and if you dont want it to affect the nebula you can put 1 in the Threshold value box, about 1.6 in the radius and about 35 to 65 in the percentage

looks great
you gotta love the C9.25 excellent scope!
frank

[Garyh]

Looks very nice Barb and Dave! Well captured!
Good to see some more of your work posted!
cheers Gary

[CoolhandJo (Paul)]

Very nice!

[Tamtarn]

Thanks for the encouraging comments Trevor Allan Craig Doug Frank Gary and Paul much appreciated

Originally Posted by spearo

Looks good!
the colors are very nice especially inthe second version
I've always found that my images with my DSLR require the slightest hint of unsharp mask as a final staep to sharpen up the image
might be worth a try and if you dont want it to affect the nebula you can put 1 in the Threshold value box, about 1.6 in the radius and about 35 to 65 in the percentage

looks great
you gotta love the C9.25 excellent scope!
frank

We're finding the 9.25 has lived up to our expectations yep we love it!

I have used unsharp mask but I'll try your setting next time thanks for the hint Fank

Barb

[jase (Jason)]

Nice image Barb and David. Not sure if the seeing was on your side however. Not the usual sharpness. It may help to review your subs closely to determine if there are one to two offending frames. If so, remove them from the stack. Its always nice to combine as much data as possible for noise reduction, but when the data is mediocre, it will not yield a better result. (less can be better!)

As Frank mentions, some unsharpening can do wonders, but be careful you don't take it too far. The use of the high pass filter (HPF) may give you finer control in extracting details. In all instances of sharpening, mask the stars as the consequences are usually nasty if not done. The only exception to this is clusters where you're trying to make the stars pop - but even then application of sharpening should be very low if you're trying to keep the scene natural. I do like the colours you've portrayed in this image. Overall well done. Looking forward to when you bite the bullet and try imaging at 2350mm and chase some distant galaxies.

[Tamtarn]

Thanks for the feedback Jase

I did use the HPF with an overlay hide all mask using the brush tool on finer details but I think the seeing wasn't the best as the DSE had been burning the day before and and we could see a bit of a haze lower on the horizon before dark so I guess we were imaging through it. As you advised we will check our date individually anyway.

Regarding imaging at 2350mm

We have to wait for our new Losmandy dovetail mounting system to arrive before we try 2350 should improve things now we're on the pier.

We're still using the Celestron orange dovetail at the moment which doesn't help with flexure

[jase (Jason)]

Originally Posted by Tamtarn

I did use the HPF with an overlay hide all mask using the brush tool on finer details

Good stuff. Have you tried this same process, but with a larger radius for HPF? Give it a try to see what you think on some of your images. Try between 40 to 60 pixels. A larger radius brings out the large structures of nebulosity and big features. Gives it a little more punch and definition. You can apply this via a mask as you've done previously or over the entire image. There are not many functions you'd apply across an entire image, but this can be one of them as its very time consuming to paint the large structures with a hide all mask. If you do decide to apply across the entire image, after the application of HPF, you'll notice the stars have gone "wacky" and don't look natural as the process has heavily pushed their saturation. Use the colour range tool to select the stars, expand and feather the selection. Then delete them (Delete key or Edit | Clear menu item) from the HPF layer. This will allow the more natural looking stars to come back through the layer below (typically the background layer). If this HPF layer is too abrupt, just drop the layer's opacity to taste.

I usually work on a two step process with this technique. Work on the large structure, then the finer details. I first perform what I've highlighted above, flatten, then do the same thing, but with a smaller radius say 6 pixels to really pick out the finer details using a mask. The brush flow and opacity are always set at 100% along with the hardness. Make sure you blur the hide all mask to provide a smooth transition. Then dial back the layer's opacity to your liking. There probably a few other ways to do this, but this is what I've found most effective. I've also been experimenting with the shadow/highlights tool on monochome luminance layers, but we'll leave that for another day.

Yes, flexure could be an issue for 2350mm. Also with the guide scope, unless you plan to use a pick off prism (OAG) along the optical path for guiding. Look forward to seeing more.

Cheers

[Tamtarn]

Thanks for the tutorial Jase it will be a great help

Whilst on the subject of guidescopes we use a 70x500 at the moment now we need more focal length to help with guidestars.

We have read that ideally a guidescope should have a closer fl to the imaging scope. Is that correct? Wer'e contemplating a 1000fl GS do you think that would help with guiding more accurately? We use PHD by the way

Thanks again

Barb

[jase (Jason)]

There were some general guidelines I recall posting a year ago that a guide scope FL should be 1/3rd the imaging scope. However this did not consider many factors such as differences between image scales of the imaging chip and guider etc. I also believe advances is guiding algorithms has lead to greater accuracy. Most algorithms calculate on the guide star centroid with sub arc/sec accuracy. I'm aware of a 3300mm (14.5" RC) being successfully guided by a Tak Sky90 operating at ~400mm, so don't believe the tolerances are so high as once believed. I've tested the image scale theory myself with my own basic rig - imaged at 3.5 arcsec/pixel and guided at 5.7 arcsec/pixel with no problems at all. Not hugely different image scales, but different. The common issue here is flexure. Regardless of the guide scope, if flexure exists, its going to be difficult to guide accurately. On axis guiding has its benefits, but also short falls - finding guide stars in a small FOV is one of them.

This link maybe of use in your quest - http://www.wilmslowastro.com/tips/autoguiding.htm

I'd recommend speaking with Fred (Bassnut) as he's done some work in this area before with his own long focal length rig. He'll probably chime in. A few others are pushing the 2000mm FL barrier too.