Took this a few weeks ago but never processed it. Now that its wet and cloudy what the heck. I think it's a bit out of focus. I have received my robofocus and installed it but havnt been able to use it yet. I will be interested to see what a similar shot with robofocus can produce.
Details
TV85, SBIG 2000 XCM, EQ6, self guided @ -15 C
4 by 60 second lights, flats plus darks.
TV 0.8 reducer uv/ir filter, slightly cropped
The cluster resolves nicely Paul. Well done. You may wish to raise the black point in the blue and green channels to neutralise the background more, but this is a minor thing. Perhaps a little noise reduction if you're keen.
The Robofocus will improve your image quality if you believe soft focus is the cause. When you perform an autofocus run, make sure its on a star between 4-8 magnitude. Don't pick a bright one as this will cause fluctuations in the FWHM/HFD calculations. Make sure you get some good v-curve runs complete in FocusMax to get consistent focusing within the CFZ.
Whats with the "from Glebe" thang. Either its "Im inner city trendy", or "Glebe skies are crap, so its hard", id understand the later, in that case well done .
Reprocessed version is much improved!
A very nice jewel box there!
cheers Gary
Thanks Gary. The more you post the more you learn. I never thought of adjusting just the green and blue channels, thanks Jase.
Quote:
Originally Posted by Bassnut
Whats with the "from Glebe" thang. Either its "Im inner city trendy", or "Glebe skies are crap, so its hard", id understand the later, in that case well done .
Hmm, definately not an inner city trendy, unless freezing your balls off in the park at 3am is trendy
I just say that rather than image taken under crap skies; and believe me they are crap. Where I am there are park lights, oncoming headlights and I can see the people having dinner in the centerpoint tower (if i pointed my scope in that direction). Still it's possible to image so I keep on banging away and emptying my wallet.....
I have only been out under dark skies twice, and only for a 5 minute shot with the SBIG. I would love to get out again but cant seem to find the time.
Quote:
Originally Posted by jase
Looking good Paul. Glebe...crap for RGB...narrowband imaging could be your forte.
Thanks Jase. You can get reasonable RGB in Glebe, I am very happy with my attached Eta. Still, I am thinking of going narrowband with a 6nm astronomic Ha filter. And then getting the RGB later on. I should read more; but if i go narrowband and take say an hour of Ha luminance. How much RGB should I take with the OSC to colour it up? Also, would I be limited to nebulas, as galaxies and planetaries are not rich in Ha?
No disrespect, but I don't think I have ever seen an amateur or professional image of any colourfull cluster that does them justice.
The view through the eyepiece wins hands down for me.
Ron
I should read more; but if i go narrowband and take say an hour of Ha luminance. How much RGB should I take with the OSC to colour it up? Also, would I be limited to nebulas, as galaxies and planetaries are not rich in Ha?
Ha data is rich and "contrasty". It doesn't lend itself well to RGB leading to colour balance woes. This can be overcome, but is frustrating when you try it for the first few times. Get as much RGB data as you can. The better the data, the harder you can stretch it to match the Ha data intensity. You can acquire Ha data on nebulae, various planetaries but are limited with galaxies. A few imagers are doing Ha galaxy imaging to bring out the HII regions. It appears to work well, though it would not apply to all galaxies.
Depending on your arcsec/pixel combination you can always bin (2x2) the RGB data to boost the camera sensitivity. Then take the Ha data unbinned (1x1) for the best resolution. Just upscale the RGB to match the Lum/Ha when processing and layer it over the top of the Lum/Ha. You don't need super high resolution RGB data as Fred points out (crappy will do, though I don't necessarily agree with his analogy). All the exquisite detail will be coming from the Lum/Ha anyway. In binned mode, you can get away with shorter exposures, but I recommend keeping them long considering a CCDs response in linear. I can't give an exact figure on the quantity of data required to match Ha, but I try to work on a 40-60% ratio to the total Lum/Ha data acquired. There are many variables. Put another way, you can never have enough data. The more data, the smoother the final output. Don't be afraid to shoot the same object night after night to get the data - sounds hard/painful if you've got to set up your gear every time. The dedication will be rewarding... and yes, you'll experience glitches/human error such as acquiring binned luminance data or dodgy calibration files that black clip your data. Persistence and patience comes to mind.
You will notice a quality improvement of your RGB data if you can acquire it under dark skies. Hopefully you wont have to deal with gradients too - always a bonus. Perhaps collect your Ha while at home and RGB on the road. You can also do synthetic colour imaging using narrowband filters, but I'd start with the basics first.
Your Eta image is looking good. Take time to understand the characteristics of the histogram. Its a powerful tool in validating image quality and squeezing the maximum from your data. Watch out for white clipping (below) even if its minor. You may have set your initial levels (non-linear stretch too low to being with) which may have caused this. Keep at it.
No disrespect, but I don't think I have ever seen an amateur or professional image of any colourfull cluster that does them justice.
The view through the eyepiece wins hands down for me.
Ron
It's all good mate . I used to think a C11, a few naglers and I would be in heaven. I used to look at SBIGS and FLI's on OPT and think ha ha, what idiot would buy one of those.
Well, oops.
Anyway, you may be right. I remember looking at the Jewel box and Albireo many years ago through my 6 inch newt and I was blown away.
Still, I have got the photo bug and until i recover its watch out wallet
No disrespect, but I don't think I have ever seen an amateur or professional image of any colourfull cluster that does them justice.
The view through the eyepiece wins hands down for me.
Ron
I can associate with that Ron. Fair comment, certainly for clusters. Not sure where would we be without imaging for nebulae though... Perhaps IC2118 (Witchhead Neb) would still be uncharted, considering its such a difficult visual target amid many others. Food for thought.
Your Eta image is looking good. Take time to understand the characteristics of the histogram. Its a powerful tool in validating image quality and squeezing the maximum from your data. Watch out for white clipping (below) even if its minor. You may have set your initial levels (non-linear stretch too low to being with) which may have caused this. Keep at it.
Thanks Jase.
Plenty of food for thought.
When I process i initially do all my callibration and stacking in Maxim then do a linear stretch to Max Pixel and save as tiff; after which I bang away in PS2. Are you saying this is wrong or that i have clipped the white during the processing. I may have been a bit over eager with the curves
When I process i initially do all my callibration and stacking in Maxim then do a linear stretch to Max Pixel and save as tiff; after which I bang away in PS2. Are you saying this is wrong or that i have clipped the white during the processing. I may have been a bit over eager with the curves
Paul
I have not used the MaximDL linear stretch to max pixel function. In most cases you want to do a non-linear stretch to bring up the dim regions. Do you mean under the process | stretch menu (as shown in the first image below)? I'd need to do some tests to validate the results - blinking various images.
There are many ways to stretch your data to maximise its potential. While advanced features such as logarithmic, DDP, spline curves can work their magic. I typically revert back to the basic levels and curves in Photoshop for key functions as they provide the greatest level of flexibility - imo anyway. Regardless of what you use, you need to keep an eye on pixel values (again check the histogram).
While I've used many of MaximDL's capabilities, I have not used them all. Everyone's processing routine is different. MaximDL DDP is good for stretching data. Now and then I use it for RGB data, boost saturation as far as the data will permit without inheriting too much noise then integrating into PS with the lum/ha. Keep in mind that MaximDL's DDP by default sharpens the image as well. This is something I don't like happening during the DDP task - prefer greater control over when the image is to be sharpen and by what process or tool I use. To disable sharpening, just create a user defined filter like show below (second image).
Do you mean under the process | stretch menu (as shown in the first image below)? I'd need to do some tests to validate the results - blinking various images.
Yes Jase. I think you have answered my question. I do the above simply to calibrate my data with darks, flats, OSC RGB convert and then move on to ps2 to process it using levels and curves. So any white point clipping hopefully is not a result of my calibration in maxim but of my processing in ps2.
For my eta image after calibration, stacking, stretch to max pixel and save as tiff in Maxim, i load the image in ps2 and get the first histogram. The stuff to the left is noise as over an hour exposure the field moves a bit. So initially I crop the edges slightly to get the second histogram as my starting point, a very dim image; and then use levels and curves from there on in. For my Eta image i guess i used curves/levels iteration too much and clipped the white point as you point out.
So I am hoping that my initial processing calibration, stack, stretch and save as tiff in Maxim is not wrong. As for my processing skills in ps2, well , more data helps enormously!
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