Additional Tak Epsilon 180ED images

Since the night sky is absolutely miserable and the rain seemingly relentless (not all bad, as New Mexico is the only interior Western state not suffering the ravages of forest fire), my only recent images have been of the new imaging instrument.

The first image shows the beefy Tak focuser. I have the 10.8:1 Tak microfocuser on order (not pictured here). The rack and pinion knob is at the bottom and the focus lock at the top. The "frame locks," which allow the imager to rotate the camera, are the shafts protruding from the aluminum ring around the focuser.

The second image shows the 180mm mirror and the offset secondary, designed to offer the maximum image circle.

The final image shows the hyperbolic ED corrector (designed as all correctors are to optimize the flat field).

Max

Who says that reasonably priced mounts won't deliver?

This beautiful image of M-31 is compliments of my friend, Eric Jacob. Click on the image for a full frame version. Eric purchased my CG-5 just a short while back. The image is a stack of 32 unguided 2 minute subs using the CG-5, an unmodded Canon Xti attached to a Celestron 102 widefield (500 mm focal length), processed using Nebulosity with final touches in PhotoShop.

Eric opines this is his best M-31 to date. He's promised to put together a 3-panel image of his previous M-31's: one from the film era, one from the Canon 10D and EQ mount era, and the most recent.

You can find out how to get started in relatively low cost astro-imaging by visiting Eric's website. Click here.

And Eric is always available for free consultation with folks just gettin' started. Heck, he even talks to me. :)

Cheers.
Max

The July Tale of Photon Starvation

The July report can be brief so far as photons go: none, zero, nada. Not only was New Mexico slammed with relentless cloudy skies, but much of the nation was (as noted on various Cloudy Nights threads). However, my old photon collecting pal Eric Jacob did well this month. You can see his work on his CheapSkate Astrophotography webpage.

My report consists primarily of an equipment update. The main events (skipping over ancillary purchases) are:
(1) the CG5 has found a welcome home in Eric’s hands. He’s running up to two minute unguided exposures with about a 50 percent usable rate.
(2) I replaced the CG5 with a second CGE (used). That’s a long story that I won’t go into.
And (3) I purchased a new Takahashi astrograph. That’s a long story that I will go into.

Making the transition from visual astronomy to astroimaging means – at least for me – a continual shaking out and revaluation of the equipment. Astroimaging equipment reminds me of the time when I first became passionate about fire arms, particularly shotguns and center-fire rifles. I must have owned and sold at least twenty different guns before I finally wound up with the keepers.

I started the month with a long standing order for a TMB 130SS APO f/7 at about 900mm focal length. No doubt this is a fine telescope. It’s received nothing but rave reviews. But after repeated queries to the vendor yielded nothing more than "we’re trying to fill orders as fast as possible," I began to rethink the entire issue. "Why duplicate the SV115APO?" became the question of the month. "After all, Max, you’d only gain about a half inch of aperture. Why not try something else?" The something else, as it turns out, is a Takahashi Epsilon 180ED – 500mm focal length at f/2.8. More on that instrument below.

Dean Rowe, a fine and very experienced astrophotographer, and owner of a Tak 180, helped me think the decision through. His advice was reassuring. One of the great things about the astroimaging community is the willingness of almost all its members to share their insights generously. Thanks to Dean. You can view his outstanding work on his website.

The Tak weighs in at 22 pounds, just about the same as the TMB130 would have. The Takahashi Company has a fine reputation, and from what I can see without actually using the new instrument, it’s well deserved. "Built like a Mercedes" is the phrase that comes to mind. Flawless paint and fit everywhere. Five year guarantee. And state of the art technology. Or so this old man is led to believe.

So what are the innovations? To simplify, Tak took the basic premise behind a Schmidt Camera – combining a convex mirror with a concave surface yields a flat field – and improved upon the design. According to Wikipedia, "The Schmidt camera was invented by Bernhard Schmidt in 1930. Its optical components are an easy to make spherical primary mirror, and an aspherical correcting lens, known as a corrector plate, located at the center of curvature of the primary mirror. The film or other detector is placed inside the camera, at the prime focus. The design is noted for allowing very fast focal ratios, while controlling coma and astigmatism." (Source)

Takahashi designers, aided by computers and contemporary glass, created a hyperbolic ED (extra-low dispersion) glass corrector (the concave surface) combined with a precisely ground mirror (the convex surface) to yield a 44mm image circle. The user’s manual notes: "Since the stars in the field of the E-180ED are only 10 microns [in diameter], very precise focus is needed to keep the stars pinpoint on the image." Yah, I bet so. The manual notes that the instrument was specifically designed for the new generation of large frame CCD cameras. Gee whiz, I might just have to get one.

Max

re: low resolution images

re: M101, more on the SV115 + SBIG

This is far, far from the best Pinwheel Galaxy image that you can find online. The image here is a stack of seven x 120 seconds subs, and thus a total exposure of fourteen minutes. I would estimate that at least an hour's worth of exposures are required to really bring out the finer details and beautiful structure of M101.
All the image processing details are as with the previous image. Here's some of the technical data on the scope and camera from June 19.
The camera was thermoeletrically cooled to 20d Celsius below ambient (which was about 60% of the total cooling capacity available). I used the CCDOPS (SBIG camera control software) autodark feature. Apparently the initial dark frame is subsequently used for calibration of the light frames. That's a huge time saving feature.
The image scale using the StellarVue115 with the .8 TeleVue focal reducer is 2.37 arcseconds/pixel with a 47x63 arcminutes field of view. (I've cropped the M101 image.)
I also tried the CCDOPS track and accumulate feature on two different objects. Unfortunately this feature did not produce usable images, as the "accumulated" stack lacked precise alignment. Over an hour worth of imaging time was wasted on this dead end. After consulting the manual (on the following day), I discovered that track and accumulate is recommended only for relatively short exposures.
Max

re: the Trifid Nebula

So here's the first decent image made with the SV115 + the SBIG ST2000-XCM + the CGE + CCDOPS (SBIGs proprietary camera control software) + ImagesPlus + PhotoShop CS2 + lots of trial and error. :)

Let me make a long story very short. New equipment means plenty of trial and error testing. After setting up, calibrating, polar aligning, recalibrating, and enrolling in the school of hard knocks, I finally had some usable subs. Of course, the first thing I discovered is that I did not have enough back focus for the SV115 at f/7. The TeleVue .8 focal reducer saved the night. The image that you see is the famous and fabulous M20, the so-called Trifid Nebula, located in that most wonderful of all constellations, Sagittarius!

The composite image is a stack of 15 two minute subs, converted, aligned, and combined and digitally developed in Mike Unsold's ImagesPlus. FYI, for my money, this is absolutely the best investment any imager can make in software. Can't afford PhotoShop? Fine. In fact, why bother with PS? IP will give you everything you need and more in a powerful image processing and camera control program that is, frankly, awesome. Here's a link to the IP page. Mike also participates on a frequent basis in the Yahoo ImagesPlus group.

I'll fill in all the wonky processing data at a later time. But I'm pleased with the results. I've seen better Trifids, of course. But hey, I'm just foolin' around, havin' some fun!
Max

re: new cameras!

The first day of Summer and shortest night of the year has arrived! How I hate nights that have clouds! And I hate nights where it's still light at 9:30 ! Tonight is a double whammy! :) So it goes.

My part of New Mexico has had a long and incredibly cloudy spell...nearly two months. By all indications the monsoon season came very early this year. So I've had lots of time to anguish. And spend money on new gear. A simple fact: at my age, I'm not inclined to wait years before I try to peek at what's over the next mountain. Thus my desire to test modified DSLRs and dedicated CCD imagers.

The upgrades are two. A Hap Griffin modified Canon 350D. More on that camera later, after I have a chance to acquire some photons. And an SBIG ST-2000XCM single shot color camera. A full run down on the SBIG ST-2000XCM can be viewed here.

Believe it or not, I finally caught a night to test the camera! Results will follow in subsequent posts. My initial impressions are: the single shot XCM is one fabulous camera. The self-guide feature alone makes the camera worth the $! (One disappointment: the camera came to me with a big finger print smack in the middle of the optical window. SBIG has not seen fit to offer so much as an apology.)

Two facts convinced me to buy this particular camera. Fact one: I'm not ready to shell out $8K or 9K for the high end, 35mm frame SBIG camera.

Fact two: the image at the top of the page indicates that the single shot XCM performs at a qualitative level across the RGB spectrum to satisfy all but the fussiest of imagers. Maybe a monochrome multi-filter camera awaits me in the future. But for now I'm a "one shot kinda guy!"

Max