Solar Pt Grey vs. Imaging Source

[El Paso Eric (Eric)]

Howdy Folks,

First post here in IIS. Thanks for having me.

I've been pouring through some of the stunning solar images on this site. I mainly do deep sky imaging, but Summers in this area are plagued with evening clouds and thunderstorms. This continues from about June through late September.

So...I'm considering the purchase of an Ha solar scope for next Summer. I've been going a lot of research on cameras. The PGR Flea3 look to be very popular and have higher bit depth. But it seems that a lot of solar imagers are using the DMK 41.

I was wondering if anyone was using the Flea3 for solar. It seems like most are using the Flea3 for planetary.

Any feedback would be great.

Thanks,

Eric

[iceman (Mike)]

hi Eric, to IIS!

What scope will you be using?

I think most people use the DMK41 simply because of the bigger chip, and the ability to capture the whole disc in one frame, or at least, use less frames when putting together a mosaic.

If you're using the Flea3, it will require more frames to get a full disc mosaic.

If you're using a big enough aperture solar scope, then the Flea3 might be better because you can do longer focal length shots (close ups of sun spots etc), and the higher frame rate (60fps) will be better than the DMK41 which can only do 15fps.

[Paul Haese]

I have found over the years that using a 640x480 sensor for imaging the Sun is not worth the trouble. You can still image at very hi resolutions with the DMK41. Or conversely you can use the lumenera skynyx 2-2. Each have large sensors which are perfect for this job. Frame rate speeds are slower but it is less important to have a high frame rate for capturing the Sun. Added to this you can do mosaics of the solar surface very quickly.

I have a Flea3 for planetary work where I need the speed. It is the usual story for astronomy, not one camera will do all the things you need it to do.

[El Paso Eric (Eric)]

Thanks for the reply... I probably should have specified that I was looking at either the 1384x1032 or 1624x1224 versions of the Flea3. Since I was planning to dedicate it for solar, I wasn't as worried about the small-is pixels. Both these cameras do about 15 FPS. I certainly understand the benefits of a large chip. I use my FLI 11K camera for deep sky imaging, and love it.

I was looking at the Lunt LS80THa scope. I will definitely be looking for a larger chip, but also like having the added benefit of the 12bit depth. I guess my real question is this... In solar imaging, does the benefit of the 12bit depth have significant value over the 8 bit cameras? I was thinking that higher bit depth might allow the imaging of prom's along with the granularity of the surface.

But if there's not a huge benefit, there's no need spending 1.5-2X the cost of the DMK41.

Thanks again for the feedback...

Eric

BTW Paul, your 1 August 2011 image is spectacular! Did you image proms separately? Use a mask to blend them in? Superb!

[Merlin66 (Ken)]

I use both the DMK21 and DMK41 firewire cameras for solar Ha imaging.
I use a double stacked SM60 (on an ED80) and a 88mm modded PST.
I find I always need different exposures for the surface and the proms.
The surface is usually around 1/120s and the proms as slow as 1/11s.
You obviously combine the images.
HTH

[Paul Haese]

Hi Eric, I should have asked what size sensor you were look at. I reckon either would be good. Funnily enough I have never thought I could use 12 bit for the solar work. However, it could technically be better with more data per pixel, but probably not necessary.

That image I did not bother capturing the prominences separately. I am planning on doing separate prominence runs from now on. In that instance I will be using a layer mask to blend in the prominence over the top of the existing data.

[Peter Ward]

Big sensors help enormously. I use the SkyNyx 2-2 and while it doesn't give a blistering frame rate, 12fps, at 1600x1200 pixels there is a lot of data coming down the pipe. You can run it in 12 bit, but apart from the larger file sizes I have seen zippo quality difference in the data.

[El Paso Eric (Eric)]

All very useful info, Thanks. With the 12bit data I was just thinking that there would be a better chance to catch deep proms with the surface data, all within the same exposure. Going from 8 to 12 bit is a pretty significant jump in dynamic range (256 vs. 4096 shades of grey).

I was wondering also about processing 12bit vs 8. I know when I work on deep sky images. 8 bit images (JPG) tend to fall apart pretty quickly. But doing filtering and other routines on the 16 bit images from my FLI CCD, the image data holds together very well.

I'm probably over-analyzing all this, but since I have to save for a long time to purchase my equipment, a camera mistake would set-me back quite a while...

In my Engineering group, at one of my previous corporate jobs, we called this "paralysis by analysis".

BTW, El Paso is known as "The Sun City" - What better place is there to do solar imaging