29 replies to this topic

[WebFoot]

I'm a very experienced night-time imager, with purpose-built CCD cameras, etc.  But I have very little experience with planetary imaging, and none with the sun.

 

I have a very nice solar scope (listed in my signature).  It gives me great views, and I've used it enough now that I'm starting to get a good handle on how to get the best out of it (with the three ways there are to tune it).

 

So, when we had a sunny day yesterday, I went out with my Canon 5D3, and snapped away.

 

I'm fully capable of making the camera so there's no vibration (mirror lock and self timer, so there's no vibration).  And I can make the exposure as fast as possible, with the high-ISO capabilities of the camera.  And I'm pretty good with Lightroom and Photoshop.

 

But my results weren't very good.  I'm suspecting that I could get better, but I'm also suspecting that a DSLR isn't the best way to go with this activity.

 

And I don't think my SBIG ST-8XE is likely to be the right way to go, either, with it's 0.11 second minimum shutter speed, and fairly long download time.

 

So I'm considering a webcam, since apparently they're not expensive.  But I have no idea which one to get (to match up well with this scope), and I have no idea how to control such a camera, nor how to process the thousands of files that a webcam will produce.

 

Any hints would be welcome.  I've downloaded and looked at the manual in the forum index page, but it looks a bit dated.

 

Thanks for your help!

 

Mark

[BYoesle]

Not many using webcams anymore.  Industrial video cameras are what most people use today.

 

I favor cameras from Point Grey Research with Sony ExHad CCD chips; these are smaller than your DSLR chip but much more sensitive, and the bigger ones are expensive -- the bigger you can afford the better.  Get only a mono camera, as the Bayer filter layer removes 3/4 of the pixels and losses half the resolution.

 

You'll need to see what interface you have available for your (laptop) computer -- USB 2 or 3, GigE, etc., then find the appropriate camera model.

 

I and many others use FireCapture for image acquisition, and it seems to work well with PGR and most other common industrial based astronomy cameras.  Then use a stacking and alignment program such as RegiStax, Autostakkert, etc. for using frame selection to pick of the best frames, and a sharpening software such as the RegiStax wavelets.  Then do final processing in your favorite photo editing software.

 

Here's a typical DSLR image in H alpha (with a double stacking image ghost):

 

 

Here's a typical video camera image with the same telescope and filter system  (mosaic of six frames):

 

Edited by BYoesle, 01 February 2015 - 01:00 PM.

[BYoesle]

Here's my PGR Chameleon, real small and inexpensive, with an excellent Sony ICX445 CCD sensor:

 

 

These cameras can get warm (especially in the daytime in summer), so I went the extra mile to add a TEC cooler -- most people don't:

 

 

You'll also need to make a screen or cover to better see the laptop screen in daylight:

 

Edited by BYoesle, 01 February 2015 - 12:32 PM.

[BYoesle]

In FireCapture you'll get an image with a screen allowing you to pick your capture parameters:  Gain, gamma, exposure time, length of time of capture, etc.

 

 

As with most subjects, it's important not to overexpose in order to later extract the most detail.  I use the historgam to keep the highest white values at 255 or just slightly below. 

Edited by BYoesle, 01 February 2015 - 12:43 PM.

[BYoesle]

Once you capture your solar "movie" you open it up in your stacking and alignment program; here I use RgiStax6.  Then you will select the number of alignment points, frames to be stacked based on quality, etc.

 

Edited by BYoesle, 01 February 2015 - 12:25 PM.

[BYoesle]

Here I use as many alignment points as I can without spilling over outside of the disk, and I also try to align on brighter prominences if they are present:

 

Edited by BYoesle, 01 February 2015 - 12:33 PM.

[BYoesle]

The alignment screen indicates the amount of alignment required for each point:

 

 

[BYoesle]

Stacking the selected number of frames can take a few to many (many) seconds:

 

Edited by BYoesle, 01 February 2015 - 12:45 PM.

[BYoesle]

Once all the selected frames are aligned and stacked, I use wavelet sharpening -- a magical tool to eek out detail.  This is a matter of trial and error to see what settings work best for your particular set up, seeing, etc:

 

Edited by BYoesle, 01 February 2015 - 12:35 PM.

[BYoesle]

Wavelets applied to the entire image, which can now be saved in whatever file format you prefer:

 

[BYoesle]

Here's before and after wavelets:

 

 

[BYoesle]

Next use photo editing the image to adjust brightness, contrast, etc. to enhance and bring out fainter details:

 

 

 

 

 

 

[BYoesle]

You can also create a mosaic for getting a full disk image; I use iMerge with six panels:

 

 

Edited by BYoesle, 01 February 2015 - 12:27 PM.

[BYoesle]

Mosaic completed:

 

[BYoesle]

Adjust in photo editing software again for brightness, contrast, etc:

 

[BYoesle]

The final result:

 

 

 

A bit of work, but the results are worth it.

 

Hope this will get you started.  Good luck and have fun!

[WebFoot]

Wow, thanks so much!

 

I have my work cut out for me, but I at least have a bit of a roadmap now.

 

Mark

[Scott Beith]

Bob that is one heck of a nice tutorial!  

Thanks for posting this.  

[nickatnight]

Very interesting tutorial, and I'm still miles away from solar imaging. But your tutorial got me closer. 

[WebFoot]

Ok, so now I'm getting serious, in anticipation of summer coming to Seattle someday.

 

I'm thinking of upgrading my scope to a larger blocking filter, and a good focuser (the scope's great, but the focuser is too sloppy for critical focusing, and the 15mm blocking filter is something of a bottleneck).

 

And I'm looking at cameras.

 

PGR has a dizzying array of cameras.  I want to get one with a CCD chip, not a CMOS chip.  And I would like to get as large a chip as I'm ultimately willing to pay for.  

 

Is any CCD monochrome PGR camera suitable for solar/planetary imaging, so I just sort through the various models (and options within models), or am I missing something?

 

Also, as a closely-related question, doing mosaics in "regular" astrophotography is a lot of work, and adds days/weeks to the imaging time (and hours and hours to the processing time); is doing a mosaic of the sun (thereby getting by with a much smaller chip) a lot more time-consuming than having a much larger chip?

 

Thanks.

 

Mark

Edited by WebFoot, 26 February 2015 - 07:06 AM.

[WOBentley]

This should be considered for the "best of" section. Just fantastic! 

[NeilMac]

Great Tutorial :thumbs:

[woodscavenger]

MAKE A TUTORIAL STICKY!!!

[ASTROTRUCK]

larger chips are more expensive - anyways i use an imaging source dmk 41 mono camera with a somewhat smaller chip than the pgr's but also not as good an image as the raw pgr. - in an earlier post comparing the dmk to pgr approx same chips the image of pgr raw was already as good as the dmk image processed.

 

for mosaics in solar there is a very good program called IMERGE -

i must take 2 images one upper area & one lower area of the sun as my system does not quite get the full disk.

 

i use registax for both images for bringing out more detail then use imerge to bring the 2 images together using the setting "256, 25 & 0"

- obvious when you look at the program - only one type of settings for merging the images - idea is to show no seam where the merge takes place - this setting was recommended by another poster on this site & works very well.

 

once merged use photoshop to play with the image -

your ha images will look fascinating when you reverse the image positive to negative - the prominances realy stand out 3d like.

imerge works quite easy & quick.

[nitegeezer]

It does not get it's own sticky, but I hope this does the job.