Posts Made By: Gianluca Valentini

Hello guys,

out of sheer desperation for lack of solar phenomena to document, I returned to old captures and reprocess them.

This is an image taken on Aug. 26th with my new h-alpha set up. I've posted a similar image from an avi taken one minute before this, but it was in false colors and it was processed with less alignment points.

The set up was:
TEC 180mm APO,
Solar Spectrum 0.3A,
180mm Baader ERF
4x telecentric (which bring the system to 5000mm focal length @ F28)
Lumenera Infinity 2-1M.
The seeing was OK but not great: I used only 45 out of 300 frames captured.

Sorry for bugging you with reruns, but boredom can make you do things you never thought you would :S

Ciao

Luca

Hello guys,

I know it must be a matter of simple mathematics, and so this is ultimately a dumb question, but I can't get it

How do I translate my image scale in area covered on the target?

I mean this: if I image an object at distance d at 1 arcsec/pixel, how many square meters on the object's surface does a pixel cover? Is there a simple formula that ties these quantities (image scale; distance; target surface)?

The area covered must be directly proportional to the distance d, but that's about as far as I can get. I also thought it could be approximated to calculating the base of an isosceles triangle with height equal to the target distance d and vertex angle equal to, in our example, 1 arcsec (the other 2 being then 1/2*(180°- known angle)). Unfortunately, I don't know how to calculate the length of a triangle's sides knowing its angles. If I could find the length of the long side, I could Pythagoras to calculate the short side and with it the area covered by one pixel and by my whole sensor.

I often wonder how much solar or lunar surface is pictured in my images and, with such a formula handy I would know at once

Sorry about the long post guys and thanks for any help you can give!

Luca

Hello guys
a question for the most experienced:

I have a large number of 600sec st11K images. I cannot process them all at once (my pc, although powerful, cannot cope): what would be the best way to go about it?
If I process smaller groups, stack them (via averaging) and then process the resulting averages as if they were single images stacking them also via averaging, would this work as if I were processing the whole batch and average-stack them?

I have an ongoing project that I cannot complete unless I find out how to solve this problem

thanks for any advice guys

Luca

Hello guys,

this is the first coarse processing of a part of my project: I've always liked the complex of the dust clouds at the center of the Rosette and I would like to image it in emission line. This is the first part of my idea.
This is 4hrs 20min of h-alpha in 10min subs.
Scope: TEC180APOFL @ F7 with field flattener
Mount: AP1200GTO
Camera:STL 11000XM
Average of 26 10min subs guided
Processing in CCDStack and a fast tweak in Photoshop CS3.
Image reduced to 75% and decreased to 80% quality to fit the size limit.

I'm still working on the whole image, which doesn't include the whole nebula, but is a little larger than this crop.

I'm waiting now for OIII and SII data to complete my project

Please comment and suggest: I'm a newbie at DSO.

Luca

Hello guys,

this the full image and first stage of my project.
Again this is 4hrs 20min worth of h-alpha data. It is reduced to 50% size and 75% quality.

info on the equipment are on my previous post (Rosette a work in progress)

As usual I'd love to hear what you guys think as these are still my first steps in DSO imaging and, most importantly, processing

Ciao all

Luca

Hello everyone,

should I sum or average the single subexposures of the individual channels in order to obtain the single images to combine in the RGB?

Thanks for any assistance.

Luca

Hello everyone,

after my failure at producing a decent color image, I'm back to greyscale practicing

Here is an M42 taken while waiting for the moon to be in a good position to shoot some avis. So these are 5 10min subs plus 5 1min subs average combined and then merged in PS using the color range tool: good practice, OK result (to my eyes, naturally). Frankly I paid much more attention to the core correction than to the rest of the image. I will get to that as soon as I collect more data

Needless to say, your input is always well appreciated

Luca

Hello everyone

eventually I believe I have managed to come up with a decent LRGB image

I have to thank Floyd and Dan for their support and advice, and special thanks go to Tyler, who worked a lot to receive and to process my data to come up with an image that told me that, somewhere, I had a good image and I only had to learn how to make it appear from the messy data I gathered.
I also have to thank Russ Croman for his incredible Gradient Xterminator, an invaluable tool when it comes to get rid of this great enemy of ours

So here it comes: I'm still working on it, since I managed to get some flats done only yesterday and the first image with flat applied already looks better than the one before. Also my color balance isn't that good (the h-alpha data give a pinkish hue to the image, but I know that there is way to dispense with it: I just have to get to it )

Needless to say I'd love your feedback and further advice.

Ciao
Luca

Hello guys

has anyone an idea of why my color channels are so weak?

These are the average combine of 12 10min subs taken with my TEC180 at F7 with the SBIG STL11000XM unbinned. I know I should have probably binned the exposures, but I wanted to keep the star size as small as possible to match what I considered a good h-alpha luminance.
However, I thought that 2 hours of color would have given me a pretty good result, but I was evidently very wrong :C

Any help/suggestion would be greatly appreciated: I'm loosing sleep over it, while I should loose it imaging

Ciao
Luca

Hello guys,

I'd like to ask you if anyone can provide a short list of possible targets for narrowband imaging. Alas, my project for the Rosette nebula will have to wait next season, since now it sinks into the murky horizon too soon to collect enough data.

Thanks for any info you can provide guys

Luca