Another 6" achro Joop....!

[Kokatha man]

Got up to water the lemon tree around 3.30am and noticed the stars were quite steady.....being the loon I am I decided to have a go at Joop - should've dropped back to 4X or 4.5X in hindsight for a bit more sharpness/clarity of resolution, instead of going with the 5X.....but caught the GRS and later on a shadow transit (haven't checked which moon yet!)

Somewhat "brownish" with my colour-twiddling of the old 6" achro but might play a bit more with the best avi after going through them later (this is the first avi "off the stack") Might even try imaging the sunspot group later on as I had to leave the scope uncovered due to the considerable dew this morning!

Sharpened up a bit by reducing to 85% or original size.....:D

[neil phillips]

Thats a really nice shot for such a early attempt at jupiter, some nice sharp detail there, I think this year with jupiter being somewhat higher than when i tried last year, it promises to be a bit better for us. looking foward to trying as soon as, myself.

I had a 6 achro myself once, there nice and contrasty, but colour is always very green heavy, theres a lot of pure whites on jupiter, so its easy to see this false colour cast. might be worth trying to drop the green channel a little in PS, i can see detail in the GRS excellent result.

Neil phillips lunar and planetary images

[Psychobilly]

Very nice "acchro" Joop from the Southern Hemisphere KM .... Too low down for me to image from the obs up here in the "North"

Peter...

[Kokatha man]

Thanks Neil, Peter.....the rest of the avi's didn't live up to their promise.....the first few with the moonshadow just after ingress were quite good (and my colour-renderings were slightly better also imho:D)

BUT the dreaded "onion-rings" disease struck.....my research on this phenomenum has people suggesting under-exposure as one source of said occurence and I know I was using less gain than I usually employ just to get a handle on the factors influencing imaging quality: there's a teensy bit on the first image I posted but it got worse as I progressed where I was tryin to reduce gain and balance it with gamma increase, with histograms that were only stretching just over the midpoint.....usually I don't skimp on the gain and my histos stretch much further (and onion-rings don't usually rear their ugly heads!!!)

I've yet to uncover any really comprehensive info on using the DBK21 on the internet and I just fumble along using these setbacks to (hopefully:rolleyes:) help advance my understanding of settings etc.....using 4X would've meant a disk 60% smaller, meaning at the scale I did image there's roughly 50% less light spread over the disk - so perhaps I could've done better that way as per my original post.....but I still await a night of "crackerjack" seeing to try and extract the maximum out of the old achro before it gets supplanted by the 12" newt!

Here's an example just after shadow ingress.....:cool::evil6:

[Kokatha man]

.....EDIT: "60% the size"....!

[neil phillips]

Hi again problem solved, its gamma causing the onion skin, i tried the same last year and got bad onion skin, as soon as gamma was set to 0 ( this might depend on the camera scale ) as my DFK and DMK are different ? point is no extra gamma, I assume default gamma should be fine.

Especially as you say you increased gamma and it got worse. ill bet its gamma.

Its hard getting the colour right with a achro refractor as you drop the green channel blue becomes too heavy, drop the blue then red becomes heavy, and you just keep dropping untill little colour is left. might be worth taking the dropped green shot ( now blue heavy ) and experimenting with hue on PS it might not work but its worth a try. im no colour expert others might be able to offer better processing advice here. would be nice if you could get a more neutral colour though, as these refractors contrast and detail wise are clearly actually pretty good, might be worth trying a fringe killer filter but i have no experiance using them. just a suggestion you might want to look into. Hope this helps, just out of interest where was the this shot taken i assumed in the uk is that correct ?

[Kokatha man]

Hi again problem solved, its gamma causing the onion skin, i tried the same last year and got bad onion skin, as soon as gamma was set to 0 ( this might depend on the camera scale ) as my DFK and DMK are different ? point is no extra gamma, I assume default gamma should be fine.

Especially as you say you increased gamma and it got worse. ill bet its gamma.

Its hard getting the colour right with a achro refractor as you drop the green channel blue becomes too heavy, drop the blue then red becomes heavy, and you just keep dropping untill little colour is left. might be worth taking the dropped green shot ( now blue heavy ) and experimenting with hue on PS it might not work but its worth a try. im no colour expert others might be able to offer better processing advice here. would be nice if you could get a more neutral colour though, as these refractors contrast and detail wise are clearly actually pretty good, might be worth trying a fringe killer filter but i have no experiance using them. just a suggestion you might want to look into. Hope this helps, just out of interest where was the this shot taken i assumed in the uk is that correct ?

No Neil, I'm in South OZ in the Sthn. Hemi. where Jupiter is still pretty near around the zenith at max elevation (well, perhaps 75+ degrees as opposed to almost 90 last year!)

I was leaning to the gamma as culprit too.....especially as that was how I was attempting to "shift" the histo across in the absence of my usual amount of gain.....

The reason I altered my usual regimen was to see if dropping the gain created any benefits - from my brief trials the other night I'd say not.....gain = increased noise but when stacking around 900 frames I guess that becomes a bit more academic with its' smoothing out of said noise as opposed to the benefits of the gain.....

I use a Baader "semi-apo" filter which is a uV/iR cut and "fringe-killer" that works almost perfectly for visual and makes quite a remarkable difference photographically (you should see an image taken without it!)

I've been "fiddling" with the Hue/Saturation and Colour balance creating layers in CS3 and think that this method gives some possibilities, also modifying layer transparency before flattening layers to give me a bit more option.....intend to explore my Canon Utilities software with the tiffs from the avi's as I know the RAWS from the dslr can have the colours manipulated quite a lot therein when opening in CS3:icon_scratch:.....but as you say it is hard to colour-correct these achromats despite there contrast clarity etc, imaging being so demanding therein.

As for the comments re a "default" position most of the sliders stay at whatever setting they were employed at the last time used.....I'm not sure about gamma at zero but next imaging session I'll do some more experimenting and see what transpires - thanks, I appreciate the comments and input in grappling with these issues.