The Ghostly Tower - AG12

[strongmanmike (Michael)]

Originally Posted by Leonardo70

Very interesting object .... and a very good image Mike ...

All the best,
Leo

Thanks Leo, getting there...

Originally Posted by philiphart

I'm with Marcus and Greg.. you'd have to be very bloody happy with those stars now. Geez f3.8.. Sweet as..

Phil

Yeh happy enough Phil but some improvements still to come though I think?

[QUOTE=Peter Ward;721389][QUOTE=marc4darkskies;721263]Start with flattened layer. Duplicate it twice. Make the top layer invisible for the moment.............. /QUOTE]

While I have no problem with instrument artifacts ( in a sense they give a hallmark to an image) I do have a problem with localised image manipulation.

Are you taking pictures of deep space or painting them?

Sure you can paint any picture you like, but is this reality???

As I have mentioned many times before....Cindy Crawford has a mole... yeah
right....photoshop can fix anything....except it wouldn't be Cindy.

I know what you are saying Peter and artifacts from optical configurations bother me very little, in ths case though the ajustment is pretty minor so I think it is acceptable ...Marcus's method isn't as easy as it looks either (for me anyway ) to get a natural look, he has clearly had experience with this technique...my quick go last night didn't look as good as his effort

Mike

[marc4darkskies (Marcus)]

Originally Posted by Peter Ward

While I have no problem with instrument artifacts ( in a sense they give a hallmark to an image) I do have a problem with localised image manipulation.

Are you taking pictures of deep space or painting them?

Sure you can paint any picture you like, but is this reality???

As I have mentioned many times before....Cindy Crawford has a mole... yeah
right....photoshop can fix anything....except it wouldn't be Cindy.

What?! You don't use layer masks when processing? If you do, that is in fact "localised processing".

I'll bet if Cindy had a black eye you might want to help her.

Originally Posted by Peter Ward

....Marcus's method isn't as easy as it looks either (for me anyway ) to get a natural look, he has clearly had experience with this technique...my quick go last night didn't look as good as his effort

Mike

No mate, I don't get reflection artefacts this severe so it's not something I need to do. My green filter tends to cause some noticeable reflection from time to time but the others don't. If I find that objectionable, I'll colour balance and level it out. Other than when the artefact overwhelms the space around the star, you wouldn't use median filtering like this - it's very destructive.

[strongmanmike (Michael)]

Originally Posted by marc4darkskies

No mate, I don't get reflection artefacts this severe so it's not something I need to do. My green filter tends to cause some noticeable reflection from time to time but the others don't. If I find that objectionable, I'll colour balance and level it out. Other than when the artefact overwhelms the space around the star, you wouldn't use median filtering like this - it's very destructive.

Well, I tried it last night and my result wasn't as good as yours ..I had trouble following your instructions actually, perhaps a mouse click or two missing there somewhere (or assumtipons made about my PS efficiency )...anyway I was pretty tired last night after some all nighters over the weekend so I'll try again when I am fresher with fresher more patient eyes

Cheers

Mike

[Moon (James)]

From all the many images I have seen, those reflections are normal for the Keller/Wynne corrector. There was a discussion on the astrooptik web site about it - the info has been removed recently but you can still read it using the internet wayback machine: LINK

There is also a brief discussion here: LINK

I have one of these on order, hopefully it will be here soon. When it gets here I'm fully expecting some halos, but I won't be processing them out - but that's just me.

The only alternative I know of that comes close was the Paracorr STL (now out of production). It works well, but it's only 2 inch and hence causes too much vignetting. Hence it's a non starter. On the positive side, it's doesn't have halos. Example images here.

As always it's a compromise.

James

[strongmanmike (Michael)]

Congrates on the impending scope James, what is on its way exactly? What's the ETA?

There are none of the reflections detailed in that Keller corrector link visible with the Orion Optics Wynn corrector in the AG12, so that's good, just the bright ring halos around the brighter stars.

Mike

[Moon (James)]

what is on its way exactly? What's the ETA?

A 3" Wynne corrector. It should be here any day now. Hopefully they are reading this! I'm planning to put it in my GSO 12" f/4.

I know it's a different product, but to my eye all the images here have a very similar halo. I always assumed it's some type of reflection, but perhaps not. It would be interesting to do a test like the one done by Brian Lula.

James

[Paul Haese]

Nice image Mike. Halos or not I like the plethora of stars and the star shapes are a lot better. Looking forward to more.

[strongmanmike (Michael)]

A 3" Wynne corrector. It should be here any day now. Hopefully they are reading this! I'm planning to put it in my GSO 12" f/4.

Ah yes this is teh GSO 12" F4 in the equipment thread, ooooh fun times ahead there

I know it's a different product, but to my eye all the images here have a very similar halo. I always assumed it's some type of reflection, but perhaps not. It would be interesting to do a test like the one done by Brian Lula.

A lot of those shots are a few years old of course..?

Mike

[strongmanmike (Michael)]

Originally Posted by Paul Haese

Nice image Mike. Halos or not I like the plethora of stars and the star shapes are a lot better. Looking forward to more.

Yes you and me both ..

[gregbradley]

Originally Posted by strongmanmike

Well, I tried it last night and my result wasn't as good as yours ..I had trouble following your instructions actually, perhaps a mouse click or two missing there somewhere (or assumtipons made about my PS efficiency )...anyway I was pretty tired last night after some all nighters over the weekend so I'll try again when I am fresher with fresher more patient eyes

Cheers

Mike

They are fairly easy to fix really.

Duplicate layer.
Circular marquee tool Hold down the shift key and drag the lasso to the right circular size. Drag the circle over the offending star.

Feather it say 5-10 pixels. Control H to hide it (its distracting) control H again brings it back.

Use the selective colour tool. click on neutrals. Now use the sliders to reduce the offending colours. Then tweak it more by selecting the colour that in the halo - say blues and cyans. Work on it more.

Then you can also use - sponge tool set to desaturate, you can also use the healing tool set to colour or luminosity (not normal).

You can also use curves to make the star less bright.

Then deselect or drag the circle over to the next star to repeat. You could record it as an action on one star then drag the circle on to the next one and use the action to save time.

I did this on my recent Dark Tower image and it worked well.
It may not be as well known that the healing tool can be set to colour or luminosity rather than normal where it affects everything around it.

Greg.

[SkyViking (Rolf)]

That's a spectacular image Mike. And those orange hues are pretty interesting and really add an extra dimension to it.
Seems like you have calibrated the new scope to perfection now. Only those prominent halos detract a little (very little), but as others have suggested it should be possible to process them out - which I think is perfectly fine to do.

[Peter Ward]

I have 3 UK schmidt glass plates...now framed and backlighted.

The brighter stars have halos.

This is what tells me they came from the schmidt and makes them so sublime.

I suspect these, now quite rare, works of science are becoming art/collectables.

[mill (Martin)]

Originally Posted by Ross G

Wow...have never noticed the mole!

Yeh right you only notice two other cold water moles

Ps Mike your pic looks just like Cindy, beautiful

[strongmanmike (Michael)]

Ah sigh...to halo or not to halo that is the question...?

I am with you on this one Peter, know exactly where you are coming from, I have a similar feeling toward sattelite trails in images for the same reason.

Mike

[strongmanmike (Michael)]

Originally Posted by mill

Yeh right you only notice two other cold water moles

Ps Mike your pic looks just like Cindy, beautiful

Yeh the two blue stars close together at the bottom of the image look like......her other two distracting assests

[Phil Hart]

i noticed marco had halos that look almost identical in his widefield shots with the Pentax lens.. a very different optical system. he is using the same camera though. perhaps it is a reflection between the sensor glass and the filters? i wonder if marco and you have the same filters in your FLIs?

[strongmanmike (Michael)]

Interesting Phil, I'll look into it

Thanks for the interest

Mike

[multiweb (Marc)]

Originally Posted by philiphart

perhaps it is a reflection between the sensor glass and the filters? i wonder if marco and you have the same filters in your FLIs?

Correct. I too believe it's something very close to the sensor. My guess would be light that bounces back and forth on to the large glass corrector inside the drawtube reflecting back to a piece of glass that is closer to the CCD. It'd be good if Mike could post a cross section of his imaging train at the focuser level and post it. I'm sure somebody will analyse the light path and pinpoint the problem. JasonD's (Catseye whiz) is pretty good at raytracing.

[gregbradley]

Its unlikely its between the filters and the CCD chamber window (which is antireflection coated fused quartz on a FLI Proline). It would show in other images on the AP scope which it hasn't.

It is more likely to be between the filters and the corrector.

When 16803 cameras first hit the streets from Apogee U16M and FLI Proline 16803 (the first 2) there was a lot of internet posting about reflections visible in flats.

It boiled down to reflections between the filters and the correctors/flatteners.

The chip is so large that basically every scope needs a corrector/flattener for it to work. This then showed up the high level of reflectance off of the then various filters.

What happened is you had most of the filter manufacturers come out with new antireflection coatings on their filters. Apogee added an aperture mask to their camera as well. Most blacken the edge of their filters with matt black paint to further reduce reflections. Square filters can have uneven edges that cause reflections.

As Mike has not had trouble with his antireflection coated Astronomiks Mark 11 filters I suggest his O111 or S11 or even Ha are not antireflection coated and hence the reflections.

If you used O111 S11 and Ha filters that are coated this most likely would go away.

It is almost certainly reflections off the narrowband filters (which look like mirrors) back and forth off the rearmost corrector lens.

By the way is the corrector AR coated and if so is the rear facing element AR coated?

Not really that big of a deal really. If it were in your LRGB images then it would be.

Greg.

[strongmanmike (Michael)]

It's not as easy as that Greg, using the PL16803 with the AP (which had a big flattener about the same distance from the CCD/CCD window 86mm v 78mm) the L and Ha filter showed almost no halo but the RGB all did, with the AG12 and PL16803 it appears the RGB and L give very little halo but the Ha shows the small solid halos. I got similar small halos with the Ha filter and PL11002 with the Starfire, so it is not as easy as it looks to tell who the real culprit is...?

The Orion corrector is ED glass, fully coated and the elements have blankened edges.

In the end, as Peter Ward says, optical diffraction effects are sometimes just trade offs for other capabilities I guess..? Having said that there may still be the ability to mitigate the effect...soooo you know anyone with a set of Astrodon genII 50 X 50 filters I could borrow for a little while to test the theory...:prey :

Mike