A Bi-Colour poet

[gregbradley]

Nice image Mike. Not my favourite of yours though. The colour is a bit weak (I'm talking about depth not how saturated or otherwise) compared to your normal. Pushed a bit hard?

Greg.

[strongmanmike (Michael)]

Originally Posted by gregbradley

Nice image Mike. Not my favourite of yours though. The colour is a bit weak (I'm talking about depth not how saturated or otherwise) compared to your normal. Pushed a bit hard?

Greg.

Well...given I am not the best imager on this forum what did you expect? ... ok sorry only my humour there, I think Martin was just tired, I know you get me

Colour too strong, then colour too week...arrrg you drivin me crazy man no probs about being iffy about the colour, I only had two to play with essentially...maybe I'll get the third...and take darks..and flats

Mike

[rat156]

Originally Posted by strongmanmike

Well, yes, I guess under extreme scrutiny almost any system will reveal something imperfect, in fact and even though it is not displayed at full res and to me it doesn't matter, the stars are not uniformly round in your shot either nor in Rolfs if you look closely...it's the nature of our beasts but it doesn't detract from the overall visual experience in my opinion, we can become way too fixated on optical perfection rather than imaging sometimes Newtonians are indeed very hard to get absolutely perfect in all situations, especially fast ones, but never the less produce arguably superior sharper looking images to many RC's and certainly to SCT's, of significantly longer FL

Yeah, I have a tilt problem to sort out, the upper 1/4 of my images are hard to keep in focus, everything else is in focus, except the upper 1/4, shows up in the corners. You don't need full resolution to see it either. A problem to be sorted at another time, may require shimming something. I need to discover if it's in the camera/corrector or the focuser. Wanna lend me your scope??

Originally Posted by strongmanmike

Hey, perhaps you are right... but in the end it is a processing choice and the level of sharpening is usually an aesthetic choice in most cases rather than actually revealing real extra details without looking noisy. I did try sharpening more during processing of the main bi colour image (I worked out how to use the decon better in Astroart ) but yes, as you say with your version (sorry) it looked slightly "over" sharpened and didn't actually show any more real "features". I decided I liked it looking ever so slightly soft rather than super hard edged...all the same features are still there - again just a choice .

What can I say, I like 'em sharp, although most of the time I'm sharpening for differential contrast, trying to make the black bits blacker. I'm OK with what it does to the noise. I'm constantly on the lookout for a method to treat the noise differently, it'll come in time and experimentation.

Originally Posted by strongmanmike

The seeing was pretty good for my Halpha

Thanks again for taking the time to make a worthwhile response

Yeah, the seeing was good for my place, but that's still not good by any reasonable measure. Looking at my data I might just do a Sidonio on it boost the contrast a bit and sharpen less. Always willing to learn. It's also cloudy and rainy here.

Always happy to critique your work Mike, it's the only way we get better. You can look at an image for days and not see a simple error that someone else picks up in seconds.

Cheers
Stu

[strongmanmike (Michael)]

Originally Posted by rat156

Yeah, I have a tilt problem to sort out, the upper 1/4 of my images are hard to keep in focus, everything else is in focus, except the upper 1/4, shows up in the corners. You don't need full resolution to see it either. A problem to be sorted at another time, may require shimming something. I need to discover if it's in the camera/corrector or the focuser.

Oh I forgot too.. most of the slight irregularity you see in my star shapes in that 100% Ha crop is because (shock horror and don't tell anyone) I partially layered in a star minimised version, acting just on the stars, to shrink them a tad further than the 12nm Ha filter supplies, so under very close scrutiny, the faint stars especially, do have that slight skew-iff shape characteristic of the minimum filter...hopefully most casual eyes will miss it

Wanna lend me your scope??

Why? they have the same optical sets made by the same manufacturer (unless you went with Lomo?) but mine is Ultra Grade ...only the corrector is different..oh and your secondary spider is double, err? and my focuser base has extra inner and outer tube bracing and I have three cooling fans ...but yours is black and Red

Mike

[David Fitz-Henr]

A nice image Mike, and I hasten to add that the colour works well for me The overall level of sharpening appears quite pleasing to my eye as well. I guess the perfect amount of sharpening would be that which compensates for the noise in the total system (incl. atmospherics / optical / read / shot / etc); no more, no less

I'm not sure about flats introducing noise though; assuming that a reasonable number of flats are combined I would think that noise may be reduced, due to the slight variations in sensitivity between pixels. In other words, the noise introduced by the flat would be overwhelmed by the variation in pixel sensitivity (given also that there is high SNR for flat frames). I'd be interested in others opinions here
Edit: Actually, upon looking at some flat subs my initial impressions appear incorrect, the variation in pixel value does not appear to be consistent even for high signal so is probably attributable to noise rather than pixel sensitivity after all ...

[strongmanmike (Michael)]

Originally Posted by David Fitz-Henr

A nice image Mike, and I hasten to add that the colour works well for me The overall level of sharpening appears quite pleasing to my eye as well. I guess the perfect amount of sharpening would be that which compensates for the noise in the total system (incl. atmospherics / optical / read / shot / etc); no more, no less

I'm not sure about flats introducing noise though; assuming that a reasonable number of flats are combined I would think that noise may be reduced, due to the slight variations in sensitivity between pixels. In other words, the noise introduced by the flat would be overwhelmed by the variation in pixel sensitivity (given also that there is high SNR for flat frames). I'd be interested in others opinions here
Edit: Actually, upon looking at some flat subs my initial impressions appear incorrect, the variation in pixel value does not appear to be consistent even for high signal so is probably attributable to noise rather than pixel sensitivity after all ...

Hey cheers Dave glad you weren't driven insane by the bi-clour palette

Re flats, Terry Platt (owner of Starlightxpress) convinced me some time ago that with these Sony chips doing darks was very likely to only add noise and that dithering should be all that's practically necessary and my experience seems to confirm this. The avoidance of flats is more a personal desire and the smaller H694 chip and my large well illuminated field has largely let me get away without them and the associated noise introducing flat darks. However, this avoidance was definitely not the case with the ProLine 16803 of course and here I need darks, flats and flat darks for the usual reasons

Mike

[Harel_Boren]

Wonderful, wonderful work !

Cheers,
Harel

[strongmanmike (Michael)]

Originally Posted by Harel_Boren

Wonderful, wonderful work !

Cheers,
Harel

Hey, thanks Harel, I'm not the only one with a crazy retina

Mike