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.

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.

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.

Live stacking--and mixed results with the new Mallincam Sky Software.

The latest Mallincam software has a really valuable new addition--live stacking that auto-aligns the captured frames into a single image. This ability to stack exposures, especially short ones, allows the capture of pinpoint stars, even if the scope's tracking is less than perfect. For example, a single, 30-second integration might show some "smearing" of stars if the mount or alignment is "less-than-perfect." But 6 x 5 second stacked integrations will show virtually no tracking errors.

I tried the setup out for the first time last night with the Mallincam DS 2.3+ with 0.5x focal reducer and Orion Skyglow imaging filter. The scope was the VRC6 on the ZEQ 25 mount. The sky was less than perfect and conditions deteriorated through the evening. By 1 am, skyglow was quite intense.

The first thing I noticed is that 6 x 5 second integrations are not the same as a single, 30-second integration (the gain settings were the same and the software was set to stack DSOs). Imaging the Dumbbell, a single 30-second exposure showed significant detail, while 6 x 5 seconds stacked did not show the nebula at all.

There were also a couple of other problems I ran across. All stacked images showed linear colored noise artifacts. Here's an example from 10 x 15-second integrations of the Dumbbell. The image shows an odd vignetting feature in the top left, along with some star distortions that must be due to a non-orthagonal imaging path. This is unrelated to the stacking and might be solvable with less aggressive focal reduction. This unprocessed image shows the linear noise artifacts clearly (click for a larger image):

I also tried a long integration of the North American Nebula. The image below is 99 x 5 seconds integration (!). The processed image follows it. I'm not sure if I captured nebulosity or skyglow in this image. Note how well the software stacks-- this is an 8.25 minute exposure. Unguided, it would be a streaky mess. But here the stars are round (apart from the vignetting artifacts mentioned above) and the depth is outstanding:

Faint streaks of glow are visible in the right, central part of the image. Processing brings them out--again, I'm not sure if this is not just skyglow, which was quite intense last night:

Notice again, the linear artifacts.

I did also have a glitch where the software reported stacked images, but did not update the output image (either in the output image counter or the actual image itself). I rebooted the computer, but that did not help. In the end, disconnecting and reconnecting the camera solved the problem,

Overall, the addition of stacking to the Mallincam Sky software is a huge improvement in capability (thanks, Rock!). I'm hoping that with some expert advice and more practice, I'll be able to get it to work for me much more effectively.

The Eagle Nebula

One more f/10 image from last night--the Eagle Nebula. This image is 9 x 30 second integrations with the Universe and the 14 inch ACF. The Universe was running 3x3 binning and again, I did a quick 5 minute post processing session in Nebulosity.

A night at the Lagoon

Tonight gave us cool and transparent skies here in Indiana.  Here's a quick processed image of the Lagoon Nebula, imaged about an hour ago. This is a composite of 10x30 second integrations. The camera was a Mallincam Universe (unfiltered) running at 3x3 binning attached to the 14 inch at native f/10. Images stacked in Nebulosity with quick curve adjustments. I'm pretty happy with this, considering it is 5 minutes of data with 5 minutes of post-processing.

In the center of the "pink" region, the Hourglass Nebula is clearly visible (click image for a bigger view). This is an area where the first Herbig-Haro objects (patches of nebulosity formed by jets of gas from newborn stars colliding with clouds of gas and dust) were detected.

Mars--Seeing is Everything...

Last night's imaging session also gave me the opportunity to compare my image of Mars taken 3 weeks ago from the Isle of Palms in SC (using the 6 inch RC scope) with one taken here in Indiana with the 14 inch. The expectation, of course, is that the 14 inch would produce a much superior image. The 14 is perfectly collimated (as is the VRC 6) and, operating at about the same f/ratio with a barlow, produces a much larger image on the DS 2.3+ imaging ship.

However, my previous experience indicates that is not the case. I have never been able to get as good an image of Saturn as that I achieved in Cape Cod 3 years or so ago with my ETX 125. The 14 inch was not even close.

Why?

The answer is seeing. In Indiana, we tend to have either hazy, steady seeing, or very transparent but very unsteady seeing conditions. Transparent and steady almost never happens (although around 3:30 in the morning seems to be the best bet!).

Last night was no exception. To me, it seemed I was looking at Mars though quickly rippling water. The image was almost impossible to focus as it quivered and danced. There's a reason Percy Lowell set up his observatory in Flagstaff, AZ...

For comparison, here's the best image of Mars I could achieve last night with the 14. Syrtis Major is very visible--but that's about it:

By comparison, here's the image I took with the 6 inch scope in SC. Although the image scale was much smaller than in the 14 and I had to crop and enlarge it considerably, the much better seeing conditions in SC resulted in a more detailed image of the area of Mars presented at that time (see my Mars Through the Palms post for more details).

Conclusion: size isn't everything!