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Cygnus Widefield


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Getting a bit more "serious" now. (Excuses! lol) :p

Canon 100D + 24mm Pancake, f/2.8, ASA 1600. 
10x30s  (no darks) + random FLAT gymnastics!

But beginning to find this FUN! I left the reddish
hue 'cos I was surprised to even SEE nebulae! :D

Aside: Recalling the hours I spent, as a kid, gazing in wonder at the "Harvard Plate" star maps
in D.H.Menzel's "Field Guide to the Stars and Planet"s. No claims for this, but there is a certain
IRONY that I can come some way towards that with casual efforts + MODERN technology? :)
(Not to mention my RED sensitivity, compared to their plates - Even with a standard DSLR)

Best effort.jpg

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No special skills, I assure ya's... As a slight "discovery": I wan't getting very far with
merely twiddling the "levels" within GIMP. For whatever reason, subtracting a FLAT
(produced entirely separately) allowed me to feel I was "getting somewhere".;)

It's all about finding *something* that gives us (me!) incentive?
I mentioned that on another thread in totally different context :D

There are clearly a whole host of things I can now DO? Improve
the focus, reduce the aperture, more "lights", use "darks" etc. ;)

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1 hour ago, Bonnylad said:

What tracking and processing software did you use?

Oh... that's just the standard setup I use for "everything" around here!
The mount is an HEQ5 and all driven by Carte du Ciel / EQMod etc.
At least the mount is not unduly strained by just a DSLR on the top! :p

Still much on the learning curve re. DSLRs, but have sussed (read up on)
some things now! Still working with .jpg's - I do now save .cr2 files but yet
to get around to processing them! For want of effort, still use Registax 5
to stack the jpg's. Created "flat" by pointing the 100D at computer screen.
There is a fair fall off towards edge of frame, so I crop images square? :D

Flat.JPG
 

I use GIMP for all my current processing. Used "levels" on the image
and layer "subtract" mode with the flat (weighted via transparency).

P.S. Have JUST discovered the top-bottom asymmetry was in part
due to not holding the cam perpendicular to the screen? (Doh!). ;)

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Computer screens can be very sensitive to the viewing angle. This is easy to check by tilting the screen while you look at it. They may therefore not be suitable for flats. For a DSLR, you can always try making flats by pointing the camera at an evenly lit wall that does not have any structure.

As for correection method, the optical system is multiplicative, so you should apply flats by using division as correction method, and apply it to raw images. I have sometimes used RawTherapee (free software) for image correction. It allows you to correct using a dark fram, a flat frame and also has hot pixel removal.

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For flats you could try throwing a white shirt/cloth over the lens/hood and then putting it up right against the screen. Works for me pretty well. Don't scratch your lens though!
Maybe try deepskystacker? Just for kicks

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(Belated) thanks ALL for interesting replies (generous flattery)! :)

@wimvb: I sense the region is genuinely "a bit more red" than
imagined. I may indeed try not suppress this quite so much...
Recalled FLATS are divisive (Not quite sure why I subtracted)! :p

@Jazza: Thinking about FLAT/DARK production. Not disturbing 
the setup during the process! Working on FOCUS too... Re-think
the TYPE of lens. Recalling the relative ease when camera lenses
still had "infinity" stops! :evil4:(Noted Registax versus DSS etc.) ;)

Experimenting with a (DIY) electric focusser! Maybe this even:
http://www.teleskop-express.de/shop/product_info.php/language/en/info/p3286_Microfocuser-and-focus-lock-fuer-camera-lenses-up-to-D-135mm.html
(For the longer lenses, clearly) Onwards and upwards etc. etc.

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Onwards and Upwards (maybe!) :D

Thinking a bit more about FLATs... To be pedantic, they aren't simply "divided" are they?
Or at least there is some overall normalisation factor! Persisting with GIMP... clearly true
that "subtraction" ain't the way to go - Despite it (superficially) working modestly OK. ;)

I did re-do the previous flat, using an 8'x4' white painted hardboard sheet (seriously!)
There was a bit of asymmetry. but rather better than before! I suspect if I photograph
it directly in front of my WHITE vertical blinds, we might get closer to Nirvana! Anyway:

For GIMP users mostly: For now sticking with this (artificial) flat. Sort-of "normalising"
(cutting on "levels") then using the inverted image in (layer) OVERLAY mode. I sense
this at least is somehow "multiplicative / divisive". And it seems to work "quite well"! :)

Throwing caution to the wind re. RED colouration and cutting DEEPLY into "Levels",
this the full-frame Cygnus (10x30s) f/2.8 ASA 1600 with the 24mm Pancake (50 deg
diag on APS-C chip). Still arbitrarily mixing 16 and 8-bit processing, using jpeg's etc. :evil4:

Without (artifical) flat:

NoFlatSmall.jpg

With (artificial) FLAT: 

Best Effort.jpg

Still a bit TOO "lively" in the Upper Right quadrant (Captain?). But quite FUN! :D
(8-bit Video Astronomy and H-Alpha gradient fixing pale into insignificance. lol)

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56 minutes ago, Davey-T said:

Iris eh, bit of a masochist are you :grin:

Sssssh... "Remove Gradient (polynomial fit)" is the only thing I know! 
Dialog boxes suspiciously like GradientXterminator... but who knows? ;)

Clegg.jpg

All images have gradients. An image is not an image wi' out a graaaadient... :D

 

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