First Light With Meade 10-inch f/10 SCT 2019

[Hankmeister3]

While culling my astrophotographic library (having nothing else better to do during the present weather lockdown), I came across several single-frames to experiment upon with my new post-production techniques. These "techniques" involve a LOT of upfront tonal adjustments before tweaking contrast, luminance, saturation levels as well as applying despeckling, color and white balances in the various layers I generate within the single-frame image. Since my Canon cameras are still unmodified, I didn't capture the wonderful red rimming which occurs at the ends of both the right and left lobes. I hope to change that this Spring when I get around to having my 77D modified.

I can't remember the sky conditions back in May of 2019 but they must have been a bit above average for me to capture this relatively clean 140 second exposure of the Dumbbell Nebula at f/10 prime focus. I haven't used my Meade 10-inch SCT very often because it has this vexing problem of shifting focus as the mount slews to another sector of the sky. I've since mitigated this problem with a threaded, spring-loaded primary mirror locking rod (which Don Quixote put me on to) which still requires a very minor tweak of the GSO Crayford focuser (that I also installed) after the SCT settles for about five minutes given its new "attitude" on the mount. As everyone knows there's a lot of primary shift that goes on inside both Meade and Celestron SCTs in their unmodified state. At least that's been my experience.

I look forward to using the Meade 10-inch more this Spring and Summer now that I have some of the "bugs" ironed out.

LX90 10-inch f/10 Meade SCT
SW EQ6-R Pro (PPEC + Sidereal Rate guide only)
Canon EOS 80D DSLR unmodified
140 seconds, ISO1600, no filters
full-frame

[Bigzmey]

Nice shot! But how did you get diffraction spikes with SCT?

[Hankmeister3]

Ahhhh, someone finally noticed the SCT "diffraction spikes"!

Simple answer: A few weeks before capturing this image I bought a 20 foot roll of 1/16 inch black automotive pinstriping at one of our local auto parts store and applied four strips to the corrector plate of my SCT! And yes, trying to lay down four very flexible strips of pinstriping perfectly straight and exactly 90 degrees to one another without trashing the coating or the corrector itself was quite a nerve-wracking chore. It took about an hour!

I'm a real old school sucker for the diffraction spikes one gets using Newtonian or RC telescopes which use a secondary spider arrangement. So I "customized" one of my SCTs (I also have a Celestron 800 CPC as well as a 1990s Celestron 8, the latter I'm dedicating to solar photography in the near future), that being this Meade 10-inch. I bought it used in mint condition for under $600 so it wasn't like I was doing irreversible surgery on a $2500 'scope.

About three months ago I posted a DSO image I captured with this same 'scope which had even more noticeable "secondary spider" diffraction spikes and no one caught this apparent anomaly!

Congrats!

[Bigzmey]

That's the first, but what ever makes you happy.

[Kanadalainen]

Lovely shot -> thank you!

[Hankmeister3]

Thanks, Ian, for your kind appreciation.

For anyone else interested in pinstriping their SCT to simulate a Newtonian/RC capture, here's a photo I took several weeks later of M42's Triangulum region. This is a full-frame image captured with an unmodified Canon EOS 80D DSLR, 70 second exposure at ISO 1600. Captured on 10/8/2019, this was an experimental frame taken with the previously mentioned SCT primary mirror stabilizing shaft installed. I also reprocessed this image using my latest single-frame post-production techniques so it has a little more pop and detail to it despite the bit of noise it still exhibits. Triangulum is clearly defined in this single-frame despite the seeing conditions being around a Pickering 4. This was a pretty challenging image to capture given the new hardware and my general unfamiliarity with the 10-inch Meade SCT. I had purchased LX90 10-inch from a Wisconsin APer several months before but never got around to using it until late September because I was then having too much fun with my Orion 6-inch f/4 fast Newtonian.

If you look closely this particular capture exhibits more of the (pinstripe) "diffraction spikes" that bigz noted in the capture of M27 above.

[MariusD69]

Great shot! Well done!

[Don Quixote]

Congrats Henry !

[helicon]

Congrats on winning today's APOD! Cool story about the diffraction spikes, too.

[Hankmeister3]

Thanks, Mark. I can't wait until this weather breaks in a couple of weeks when the Moon is in a more favorable position for AP. Maybe then we can start putting together some mutual sky safaris though it may run into middle to late March before temperatures become more comfortable. Night time temperatures of 38 to 40 degrees is my lower limit any more.

[Juno16]

Congratulations on image!

[Hankmeister3]

Thanks, Michael. The pinstripe-on-the-corrector plate ploy was something I first read about in a late 1970s Sky & Telescope magazine. At the time I only had a home-built fork-mounted Newtonian with a Meade manufactured 10-inch f/5.5 highly parabolized primary mirror guaranteed to 1/8th wave at some green wavelength. But I always dreamed of getting a Celestron 8 or whatever the equivalent was back in the late 1970s, and install a set of pinstripes on the front corrector plate but I never had the money to do that once I got married and had children by the 1980s. Personally, I think diffraction spikes are pretty cool especially when there are several bright stars in the frame. I haven't photographed any DSO yet with a significantly bright star nearby the very few times I was imaging with my Meade 10-inch SCT except for a test image of Capella which created a magnificent set of diffraction spikes. Even so, for whatever reason, diffraction spikes tend to be rather minimal when installing pinstripes on glass. Maybe it's the back coating on the corrector plate which minimizes the spikes.

[Hankmeister3]

Thanks, Jim. It was an unexpected honor to receive another POTD especially for what I thought was a very "humble" image.

Your compliments and advice as well as those of other members have been so encouraging over the months.

[STEVE333]

Congrats on the APOD award. You are definitely the "king of single frames"

Cheers,
Steve

[Hankmeister3]

Thanks, Steve. The irony is, if I wasn't so lazy I'd be doing a lot more stacking! Heh!

I mean, acquiring 10, 20 or even 30 hours of data to generate an astro-image sounds like a lot of "work" to me … even though I know it's a labor of love with an eye on excellence.

BTW, when I scan your (and other members') library of images, I'm always gobsmacked.

Clear skies to you, sir.