First three

[KenGee]

I have been making a all sky image using my 300mm lens and a Sbig 11000. Still got a lot of data to get but I've assembled three pannels to see how it's going. See how many ngc objects you can see. It has lost some detail, going from a 180 meg Tif file to a 195k image for upload.

[dugnsuz]

That's a beautiful start to this mosaic.
Is it difficult to match black points on each panel? Or is it simply a numeric match-up?
Is it more useful for picture assembly to try and arrange that the 'joins' are in areas of little nebular detail, just stars and background!!??
Very impressive Kenny! The 185Mb original must be something.
Which 300mm lens did You use?
Doug

[Alchemy]

given the intensity , i take it youve gone Ha only at the moment ?

[AlexN]

STUNNING! :) Loving it so far.. should be an amazing product once you complete the project.

Alex.

[KenGee]

I'm using a Tamron f2.8 I picked up 2nd hand. Clive I'm taking in Ha, O and S Narrow band. Each pannel will be 3x10 with the O and S binned 2x to increase the SN. I'm still not sure if this is enough? 6x10 might be better but will take a hell of a lot longer. Here is a preview, haven't got the colour balance correct. For some reason the it is harder to much the colours and contrast up when using the colour data.
BTW it new Moon and it's cloudy and raining, Fancy that.

[AlexN]

Man thats going to be special!

Is that the Tamron 300mm F/2.8? I used to have one of those, I sold it because I couldn't thing of a way to mount it, then 3 days after I sold I devised a cunning plan of how to mount it up and was utterly devastated. I've been regretting selling that ever since..

[Alchemy]

ummm youre gunna have to ask Jase the technical blending stuff, ive got no idea, im still OSC , it should be a corker finished and at a resolution we can get intoo the nitty gritty and see all the detail.

as for the weather, pretty ordinary here, and ive got that new flt132 to play with :rain:

[dpastern]

Wow - I like it. It's a lot of work, but it'll look grand when it's all done :-)

Dave

[KenGee]

Alex I know what you mean I've had the lens for a while, I have had the nikon to sbig adaptor for some time to, but I only recently found a adaptall2 to nikon mount so I could get the two to work together. The lens is a lttle soft at f2.8 but seems fine if you stop it done to f4. I think I like the multi pointed stars. I'm using a robofocus for focusing burrowed form my refractor.

Clive isn't it always the way.

[dugnsuz]

The narrowband composite looks amazing Ken.
Doug

[jase]

Good God Ken! You plan on doing an all sky mosaic in narrowband with a 300mm lens. Certainly a first. I've seen a few 50mm lens all sky mosaics in both lum and Ha. They look great, but at such a scale lack detail which is a little disappointing in my opinion. 300mm would look spectacular. You could always give a hybrid composite a go i.e. use a 50mm for the wide sweeping FOV, the add data from the 300mm on specific targets to give depth. Maybe when you're feeling comfortable with such a concept, give it a try.

As you've found (and can be seen), you've matched the Ha panels exceptionally well. In general, matching the luminance data is quite easy providing its gradient free. Just keep an eye on the stellar profile sizes. If you're stretching the data too hard to match another frame, stars will bloat and not match surrounding frames. You may find that lightly pre-stretching the data using DDP or similar prior to stitching will assist. The trick here is to keep the background and midtone difference value equal between the panels. You'll do less work in PS in making them match, but the use of curves is unavoidable (and in some cases the brightness/contrast tool). Registar has a features to match the brightness of mosaic frames, but I've found it erroneous. Really, PS is the tool of choice. Dennis posted (http://www.iceinspace.com.au/forum/showthread.php?t=45061) a link to download some online photography mags that contains excellent information. The first few editions are gold. Having completed numerous intermediate and advanced PS courses, I've not come across this information as articulated in these mags - simple and to the point. The curves info explains the fundamental of the histogram, along with the basic curves process, followed by advanced multi-anchor, then finishing off with the traditional s-curve. The second edition has info on removing colour casts. I don't necessarily agree with one of the approaches used, but the others are good - they'll all work. Anyway, I digress, point is PS curves is the solution.

Colour does add an extra dimension (or should I say challenge). Unfortunately, its all about compromising colour fidelity. There will be some frames that will match relatively well and only require colour balance tweaks in shadows for example, and then there will be others that no matter how hard you try in PS, they wont match up. For these, you're best to performing a colour combine again on the SII, Ha and OIII data again but with different weightings. The replace colour tool can also be handy if you need to tweak hue, lightness and saturation for specific areas.

The approach I would suggest is to stitch your luminance frames first i.e. the Ha data. Match the brightness and contrast, then use layer masks for a smooth transition between the frames. Once complete, build the SII, Ha, OIII combine frames with your usual weights. 4:1:3 ratio is a good start for a SHO palette. I don't really like tools such as MaximDL neutralising the background automatically. I've contributed to a post on narrowband processing using a pixel math method which gives much greater control. It can be found here (http://www.iceinspace.com.au/forum/showthread.php?t=43530). Narrowband ratios are not a strict as traditional RGB so experiment to you get a blend that is appealing to you. Register the colour combined narrowband frames to align the stitched luminance. Leave the stitched luminance frames as normal blend mode and add the colour combined narrowband frames as colour blend mode. You can also drop the opacity of the luminance to regain colour saturation or use other methods such as colour dodging (http://www.iceinspace.com.au/forum/showpost.php?p=439546&postcount=26). Similar to the luminance frames, use layer masks to ease the transition between the frames. Using the luminance frame as the base, you'll address the contrast problem you describe, leaving you to juggle with the colours.

There's no substitute for experience when it comes to mosaics, so keep at it. Keen to see how you progress. Should be quite a spectacular result.

Cheers

[Alchemy]

yep he knows his stuff..... im still confused:shrug:,

lets see the finished version with all the bells and whistles, now that you understand it all perfectly

[glenc]

Very well done Ken, I look forward to seeing more, especially along the Milky Way.

[KenGee]

Jase your a champ, thanks for the advise mate.

[multiweb]

NIce. That's gonna look awesome. Cant' wait to see the progress. Keep'em coming. :thumbsup: