Sunday, August 28, 2016

Three full-frame Dumbbells

The scope/imager combo is critical to capturing the objects you want to image. There has been a great deal written about pixel sizes, focal length, optimal sampling, etc. I'm not going into that here, but I thought it would be interesting to show two uncropped images captured with the same scope (f/4 Newtonian) and two different imagers. The first image is a full-frame capture from my Mallincam Universe. You can see some vignetting as the Universe has a large, 6 MP imager. 



The second pic was taken with my DS 2.3+, which is has a 2.3 MP imaging chip. Notice the smaller FOV, but also notice how much more detail in the nebula the DS captures due to the larger image scale. Zooming the Universe (built for stunning wide-field views) does not produce as much detail.

I think this demonstrates well why no one imager/scope combo will "do it all." Needless to say, neither of these combos would do a great job with planetary imaging. So, as with anything else, you have to choose the right tool for the job.  Just for interest, here's another pic of the Dumbbell taken with the 6 inch RC scope and the DS 2.3+ with a .5x focal reducer for an f/4.5 ratio . Yet again, the scale is a little different.




Sunday, August 14, 2016

Stacked Dumbbell

I took this image on the August 7. This is cropped image from a stack of 5 x 15-second integrations using the DS 2,3+ and the f/4 Newt. I turned the gain down to around 3 and the stacked image is a huge improvement over my earlier image (a couple of posts ago) where high gain resulted in prominent stacking artifacts.


The stacking produced some slightly misshapen stars, but overall, it's a much better pic.


Sunday, August 7, 2016

The Sun 8/6/2016

Solar activity is diminishing after a disappointing solar max. While white light images show just a couple of small sunspot groups (ARs 2571 and 2572), H-Alpha shows much more detail, including prominences, granularity, filaments and, in this case, minor flaring from AR 2571.  I've also added an inverted image from May, 2013, as a comparison.