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Saturday, November 21, 2009

New MoonLite focuser rig

The old Astro-Tech Crayford focuser that came with scope had issues when it came to keeping the drawtube square with the focusing assembly. Off-center position when locked down induced coma-like effects, made star alignment difficult, and fine focus was problematic. In short, it was just a cheap focuser.

Enter the new MoonLite focuser. In addition to being a solid piece of machined hardware, the primary benefit is that the drawtube is locked in position by applying pressure to the focusing shaft, not the drawtube itself.

Tried it out and focusing was a pleasure! Looking forward to using this from now on.

Saturday, October 31, 2009

Camera mod successful!

Yes!! I've done it, muwaaahaaahaahaaaaa! Below is a shot of the remnants from the offending filter...

Many thanks to Gary Honis and his great instructions from which I was able to successfully remove the IR cut filter from the Canon 450D in just under 3 hours. As I only intend to use this camera with telescopes, I decided to just remove it outright. If certain shots require some filtering, there are always premium front-mounted filters available.

Busy making new flats and master dark period is in a week or so.

Friday, October 23, 2009

Messier 35

Filling another empty slot in my Messier portfolio, here is the open cluster M35. There is actually more stars to this as it spreads across an area almost the size of a full moon. Limited by my f/9 prime focus though, I kept the view centered on the bulk of the members.

Saturday, October 17, 2009

Close Up on Alcyone, brightest of the Pleiades

Since I don't have a focal reducer for the AT6RC, the f/9 focal length
gives a bit more magnification than with the Newt. The night was so
dark and clear, thought I'd try pick one of the lights in the Pleiades
before catching up on my sleep.

Wonderful stuff.

Unguided, 1600 ISO, 250 x 15 sec. JPEG frames, noise reduction enabled, with bias/flat calibration.

NGC 7789, one of the oldest open clusters

1.6 billion years old, this cluster is one of the oldest.

Unguided, 1600 ISO, 225 x 15 sec. JPEG frames, noise reduction enabled, 250/173 bias/flat calibration.

Sunday, September 20, 2009

Messier 103

All right, back in the game! With cooler nights and cleaner workflow, its getting better. Here's a nice take of M103, the last I-am-not-a-comet object recorded by Charles Messier. Some 8,000 light years distant, Charles apparently never observed this open cluster. It was included in his work based on a report received by Pierre Mechain in 1781 of whom he became friends with in 1774.

Looks like it is time to collimate this RC scope, coma is apparent in the left and upper left bounds of the image. Gasp!

Thursday, September 17, 2009

Messier 76, Little Dumbbell Nebula

One of the faintest Messier Objects, a planetary nebula discovered in 1780 near the 4th magnitude star 51 Andromedae. 243 x 15 sec. JPEG frames at 1600 ISO, noise reduction, unguided, bias/flat calibrated.

Started taking this a little too early, as neighbor's outdoor lights came on and off a few times before going to bed. Some remnant remains. Shouldn't try starting before 9 or 10pm.

Wednesday, September 16, 2009

Messier 29, the "less impressive" cluster

As quoted by the SEDS organization on its Messier Catalog site, "Messier 29 is a rather coarse and less impressive cluster."


Kind of took that as a challenge, so I captured what I think is pleasing view of this simple open galactic cluster of blue giants, 7,200 light years distant. Charles thought enough of it in 1764 to write it down.

250 x 15 sec. JPEG frames at 1600 ISO, unguided. 250 bias, 173 flat calibration frames.

This image taken without field flattener and only flat/bias calibration. Rather than post-process dark frame calibration, the camera's built-in noise reduction (dark frame subtraction) was applied to each exposure, shortening the post-process time.

Creating a new master flat

New camera, new master flat.

After crawling numerous blog and forum postings regarding flats, I never came across anything that really explained how simple creating a master flat calibration frame can be. After some personal research coupled with trial and error, I eventually understood the purpose of and how the calculation works. In addition, it became exceedingly clear to me that a common recommendation to point the telescope at various regions of the blue sky before twilight is collectively bad advice.

I want to correct this now!

What you want is a calibration image that will scale your pixels consistently to normalize individual pixel intensity - removing the variation in detected energy due to curved optical plane, the effect referred to as vignetting. Key phrase here, "scale your pixels consistently."

What does that mean? It means record a neutral image of your optical curvature. What does neutral mean in this context? It means without preference to any color channel (i.e., grayscale, folks). If you still don't get it, find a new hobby or just follow the instructions below and don't worry about it.

So, here's a simple recipe for creating flat calibration frames for DSLR prime focus astrophotography:

1) On a bright, sunny afternoon bring out your telescope and attach the camera exactly as you would for shooting
2) Ensure the camera is "focused", this will require some thinking on your part (suggestion: lock the focuser down from a prior night's shooting when the camera was focused on a star)
3) Tape a white sheet of paper without wrinkles across the opening of the telescope (see picture above)
4) Set the camera to aperture-priority mode and ISO 100 (best dynamic range/low noise), this will record our "white" light in the median range of the combined color channels - forming our grayscale image. Afterwards, look at the histogram readings from the images and you'll see what I mean.
5) Take as many shots as you can, I strongly recommend over 100 to get good saturation and signal coverage. This shoot I'm taking 250 as I tend to go for 200+ image frames on any good outing.
6) Once you've collected them, use your favorite stacking program to apply a standard distribution.

You'll also want to adjust the RGB channel offsets, so they are right on top of each other (this is a one-click operation in Nebulosity called Adjust Color Background). This will account for the slight fluctuations of the channels we recorded and then you'll have your wonderfully neutral master flat!

Good luck!

Thursday, September 10, 2009

Canon T1i mod gone bad...

Well, attempted to mod the T1i by removing the IR cut filter. Got into the point of removing the sensor plate, only to discover some special torque screws (for which I have nothing to get them out). Put it back together, apparently a little too quickly, only to discover that it will no longer take a picture - "temperature too high." Great. Something is shorted...could be one of a hundred contacts that were involved in various ribbon cables or even the aluminum shield plate.

When I have more time, and patience, I'll look into trying to bring it back. For now, I've decided to continue the DSLR path and when convenient, pay someone to do the mod. A new Rebel XSi has arrived, a couple hundred cheaper than the T1i, lighter and less noise (see previous post).


Tuesday, September 1, 2009

Noise and more noise

After a few months of taking additional photos with the new Rebel T1i (500D) DSLR camera at various high speed settings, there really has not been any improvement in eliminating high end noise as compared to the early generation Canon Rebel XT. In fact, after some comparative study of detailed reviews carried out by professional camera webzines, the T1i fares slightly worse than the model its intended to replace, the Rebel XS (450D). And my test photos support this, too.

The good news is that noise reduction modes at ISO 1600 perform comparably with the 450D.

It is not a complete loss. Where the Rebel XT was an 8 mega-pixel camera, the T1i is 15!! Longer battery life, and more importantly no battery amp glow!! There is still much I would like to accomplish with DSLR astrophotography. In the near term, I am looking forward to eventually replacing the IR cut filter with a wider band version designed for deeper reds and extended UV.

Sunday, August 16, 2009

Messier 30

Back at it...a couple great dark nights are upon us! Here we have another in the Messier marathon series, M30, a globular cluster in the constellation Capricornus. This will be the last photo taken at 12,800 ISO setting for a while. Even though much has been removed from the shot, the noise is a bit excessive. Taking this last super high gain shot also allowed me to test my flat I created.

Worked great. Vignetting go bye-bye.

This unguided photo taken with the Canon T1i as 104 x 15 second JPEG frames, long exposure and high ISO noise reduction enabled, and calibrated with 200 bias, 100 dark, and 200 flat subs.

Below is my exciting new flat used in the calibrating the photo above. Created it by placing the telescope under the patio in this bright Arizona afternoon sun and taping a white sheet of paper across the telescope opening. Made sure the sunlight was indirect and bright across the entire surface of the paper. Set the Canon into AV exposure mode and ISO 100, proceeded to collect 200 frames!

After calibrating with bias, the frames were stacked together creating this master flat. The histogram in the camera showed it nailed dead center and the red, green, and blue curves aligned right on top of each other. Don't think I could get it any closer to grey than that!

Tuesday, July 28, 2009

IC 4665

A break in the weather and finally able to test out my workflow changes. Turns out the camera built-in noise reduction really needs to be enabled for this kind of photography. In this case, both long exposure (dark frame subtraction) and a new enhanced high ISO speed noise reduction is enabled. Successfully eliminated the mysterious banding I was seeing in post-processing.

This image was taken with 180 x 15 sec. JPEG frames at 3200 ISO, field flattener, strong noise reduction, and of course, unguided.

Saturday, July 25, 2009

So much for the TI-89

Apparently, the data I/O output signal has been changed in the TI-89. Frequently, an extra "pulse" is detected by the camera. This utterly screws up the whole mirror lock up routine. Without putting a scope on it, I suspect the TTL level changes are not as long as in the older TI-83 model. Guess I'll keep the TI-83 and give up the shiny new TI-89.

Sunday, June 28, 2009

Monsoon Season is upon us...

Well, so much for stargazing...can at least enjoy the evening light show when the storms roll through. In the meantime, I will be preparing for the next outing. A new TI-89 programmable calculator is on order, and this one includes a real-time clock for more accurate shutter control timing. This will consume a little extra time to revise my ASTROTMR TI-BASIC program with improved settings.

A short focuser extension tube and a Lumicon broadband filter are also on order. The short extension tube should permit me to put the diagonal back in, now that I'm committed to using the field flattener in my astrophotography. The broadband filter will help reduce the additional sky glow, especially when imaging more toward that part of the sky with the Tucson "light dome."

Since I've made progress using the field flattener and corrected my process to create darks and bias frames, thinking about going all the way and experimenting again with 12,800 ASA! I've already taken 100 bias frames set at that speed. Will plan on taking 100 darks at this extreme when the next clear night arrives and maybe shoot for the Lagoon Nebula, again. Pretty exciting stuff!

Monday, June 22, 2009

47 Messier objects and counting...

...only 62 to go.

Messier 21

Yep, I think I've definitely hit the sweet spot with this new camera and RCT configuration. The field flattener delivers. The open cluster M21 here, 180 x 15 sec. JPEG frames, 3200 ASA, Astro-Tech Field Flattener, calibrated with 100 bias and 100 darks.

Messier 19

The globular cluster M19 here, 180 x 15 sec. JPEG frames, 3200 ASA, Astro-Tech Field Flattener, calibrated with 100 bias and 100 darks. Note, additional noise reduction not enabled, standard DSLR picture settings.

Vignetting resolved!

Introducing the new 2" field flattener from Astronomy Technologies. Designed originally for use with refractors, it appears to work extremely well with a Ritchey-Chretien telescope, too. Last night I used it in taking both M19 and M21, and I am very pleased with the results! The impact on the uneven distribution of light (vignetting) across the image has been dramatically reduced, to the point any negligible artifacts are easily stretched away.

Unfortunately, I lose my forever focus as it requires I remove the diagonal and add a 2" extension. I'll see about ordering a 1" extension and putting the diagonal back - the diagonal makes for a more comfortable viewing position of the camera LCD image display.

Thursday, June 18, 2009

M11 and M18

Seized upon a great dark night and grabbed these two shots of Messier objects 11 and 18, both open clusters. Messier 11 is known as the Wild Duck Cluster. I understand the bright stars appear to form a triangle like a flight of geese, don't see it.

Worked on my image processing some, and in these shots all additional noise reduction on the Rebel T1i was turned off. Camera brightness, contrast, sharpness, and saturation levels were all in standard settings. As such, I took 100 darks and 100 bias frames to perform image calibration during post-processing. This time I did bias correctly by setting camera to the shortest shutter speed, 1/4000. No flats this time, that's for another blog entry.

The following picture of M11 comprises 180 x 15 sec. JPEG frames at 3200 ASA, calibrated with 100 bias frames. Stacked and stretched.

This lovely shot of M18 is 1800 x 15 sec. JPEG frames at 3200 ASA, calibrated with 100 bias and 100 dark frames.

Wednesday, June 3, 2009

M22 and M57

Here are the last two shots taken in May, the lovely M22 (one of the largest globular clusters in our galaxy) and a retake of M57. The last time, M57 was taken I used a 2x Barlow lens and, of course, it magnified all my fine errors. Interesting that this time using an f/9 telescope, the 15 megapixel DSLR can capture M57 at the same equivalent magnification and resolution as was with the Barlow on the 6" f/5 Newt. Well, I guess that makes sense, f/5 x 2 = f/10. Both these images were unguided, 180 x 15 sec JPEG frames, 3200 ASA, with noise reduction enabled.

See ya' in a couple more weeks.

Monday, June 1, 2009

Wrapping up...

This dark period is almost over, and the night is wonderfully clear. Here are a couple photos of the new gear in action! Alignment was spot on tonight, tracking extremely well. I have to admit, using the calculated transit for Polaris really makes unguided work painless. Was really waiting for the Moon to go down so I could get one last shot in, M22. So, while we were waiting I went ahead and took 180 frames of M57, the Ring Nebula. Should be interesting to see if the baffling makes any difference in the moonlight.

Sunday, May 31, 2009

I'll never have to focus again...

In trying out my new quartz dielectric diagonal this weekend with my AT6RC, not only did I have to remove both 2" extensions, but with the focuser dialed all the way in and locked camera was in perfect focus! It seems to me that if the diagonal is simply a reflection plane at 90 degrees, then this must be all about the AT Ritchey-Chretien telescope design. Amazing. I've sent an email off to Astronomics to see if they or the manufacturer know if this was intentional.

I've attached a picture below if you're not sure what I'm talking about.

Messier 12 and 25

Okay, so 12,800 ASA was a bit over the top. I've settled down now, 3200 ASA with this new camera will work just fine and reduce some of the time it takes to collect the images. It appears that 180 frames would be a good goal for a DSO, giving me more exposure time in less time than the Rebel XT at 1600 ASA.

Here we have a fine globular cluster M12 and a bright open cluster M25. M12 would have had more frames, but I bumped into the mount (wandering around in the dark) and caused the subsequent images to shift over 30 arcminutes. Pooh.

Saturday, May 30, 2009

Messier 9 and 10

Both globular clusters shots, unguided 30 x 15 sec. JPEG frames at 12,800 ASA, noise reduction enabled. Roughly 7.5 minutes of exposure time.

With just a few more Messier shots, I will have the first 20 Messier objects captured! ...just another 60 or so to go.

New Camera and Messier 8, the Lagoon Nebula

The Canon Rebel T1i DSLR camera just arrived and I've been checking it out. The camera is capable of 12,800 ASA and even boasts double the pixel density from my Rebel XT! It now takes only 20 minutes to collect the same amount of unguided exposure it would normally take me 3 hours to collect, still using 15 second frames. Clearly, noise processing is different but my initial results seem very pleasing.

So, here is the Lagoon Nebula taken with the new Ritchey-Chretien telescope and camera.

Oh yeah, no amp glow either!! That's a relief.

Tuesday, May 26, 2009

Messier 6

Well, its getting better. This shot of M6 was taken with 243 x 15 second JPEG exposures, 1600 ASA, approximately 60 minutes of exposure. I've created a new border template for the images, too. Getting easier to align the scope, and tracking was good. Now, I need to start learning about vignetting, something I didn't have to deal with on the Newt.

Monday, May 25, 2009

Messier 14

Unguided 193 x 15 second frames, 1600 ASA. This globular cluster includes numerous variable stars, there was even a Nova here in 1938.

Had trouble with clouds during this shot, not as bright as would like, but it is 2 orders of magnitude less bright than M2.

Messier 2

Unguided 72 x 15 second frames, 1600 ASA, noise reduction enabled, stacked and stretched. This a photo of the globular cluster M2, one of the largest. This object is 37,500 light years away and comprises approximately 150,000 stars!

Always make sure the batteries are charged

Forgot to charge my second battery. Arrg. After waiting for it to recharge, my second shoot of the night (early morning) of M2 captured only 72 exposures before daylight crept in.

Sunday, May 24, 2009

Photo shoot commencing...

Cloud cover finally cleared my target area, calculator kicked off for 250 takes. Again, I hope the clouds stay away.

Second night out

Alright. Everything is tightened down, now. No rotating. No tension on any of the wired connections. No motion sickness tonight.

3-star alignment went well. Zeroed in precisely on Antares right afterward, centered in the crosshairs. Focusing proceeded quickly, 2 minutes this time. I also took the time to align the new 60mm piggybacked refractor. What an excellent short scope, the view was crystal clear with excellent contrast. I viewed M57 with both a 25mm high quality Plossl and one of my wide-view 5mm eyepieces. Fantastic.

I'm pursuing M14 tonight. Waiting for a few clouds to dissipate. Hope they stay away.

Setting up...

Well, attempted shooting Messier 3 last night with limited success. Dark night, mostly clear. It's been six months since my last outing...a little out of practice, I guess. Focusing took quite some time, as I soon learned to take shorter bright star exposures to focus on the diffraction lines. The visual acuity of this RC scope is impressive. It turns out that only a few 3-second 1600 ASA exposures is all that is needed to perform LCD-review focusing. Now I know.

Tried to get 250 frames, but could only use 147. Something else I learned is to make sure the heavy duty Crayford focuser is securely tightened. The focuser unit on this RC scope can be rotated 360 degrees at your pleasure, unless its not fully tightened then it rotates on its own. I also found that I had not made sure the camera 2" extension was tightened. It was loose, too. Sooooo, the meandering image began with exposure number 148, and continued to do with the rest of the exposures - watch the bouncing ball.

Below is the not so impressive image of M3 taken with only 147 exposures.

Saturday, May 23, 2009

First trial photo...

Here is a 30-second shot at 1600 ASA of Arcturus, this time no noise reduction enabled, and parameter settings cleared. In getting into focus, it struck me how crisp the diffraction lines were - like sabers. This is likely not perfect focus as the visual acuity of this new scope clearly exceeds the limits of my 8 MP camera. When they say the AT6RC is an astrograph, they're not kidding. Be forewarned, the AT6RC is not intended for visual observing. Both of the 2" extensions were necessary to achieve prime focus with the DSLR. Evaluating image with eyepiece required a barlow and extension...looked like a damn microscope mounted on the back of the telescope. Very glad I added the 60mm short, great for viewing and with a 2" compression adapter I'll play with the camera use on it, too.

After this I took several 30-second shots of M4 before clouds set in, so I could get some feel as to overall improvement on a short collection of exposures. Found that stars were consistently spherical. Still picked up perceptible tracking error at 30 seconds (expected), and I did notice coma in the lower left and part of lower center in the overall image. This suggests I need to check collimation. The coma is certainly no where near as bad as on the Newt. I'm really just being nit picky. The image is excellent.

Unfortunately, my attention was diverted by the increased amp glow captured in so little frames. Yikes. I mentioned in prior posts the increasing strength of the glow. It would seem reasonable to deduce that over time taking the length of exposures required for astrophotography are pushing the limits of this camera design. The battery unit and power supply are just too close and the sensor is not well isolated from the energy produced - the amp glow is "burning in" to the sensor.

For the record, this is the 10,152nd exposure taken with the Rebel XT. Guess, it is time for a new camera. Supposedly, the new Rebel designs have improved noise reduction and have eliminated amp glow. Therefore, I should get considerably much more life out of a new camera. The XT will work just fine consigned to normal day photography, and I have a lovely lens kit for it.

A little pricey, but I've decided to purchase the new Rebel T1i (body-only of, course). It jumps two generations in DIGIC processor technology, almost doubles the image density to 15.1 megapixels, doubles my gain to 3200 ASA, and includes HD movie capture. Curiously, the movie capture mode suggests I could take planetary images like the current webcam craze...with way better resolution.

Ok. I done spending money, now.

Thursday, May 21, 2009

The New Telescope is Ready!!

Excellent! Here are some pics of the new rig. We shall have a wake in honor of my venerable $380 6" Newt, for it served me well. I'll try to keep it in safe storage, as I expect my young daughter will be very interested to use it.

Check out the extensions I had to add for prime focus.

Sunday, May 17, 2009

New telescope on the way...and it is not the Vixen

Sorry, Vixen. Astronomy Technologies new line of Ritchey-Chretien astrographs has you beat! I placed my order tonight for the AT6RC from Astronomy Technologies along with a 66mm short tube refractor (sporting a 2" Crayford focuser) as another photographic platform.

The AT6RC is 6" f/9 true RC hyperbolic mirror design, with 1/12th wave BK-7 mirrors, and enhanced aluminum coatings for 96% transmissivity. Like the Vixen VC200L, the AT6RC mirrors are fixed, and focusing is external. Unlike the VC200L, this new RC scope is a true reflector, no optical lenses. For another $600 I could have gone for the larger 8" RC with dialectric coatings for 99%, but just couldn't bring myself to do it.

Should have some great experiences with this!

Saturday, May 16, 2009

I'm back...

Alrighty. After several months away dealing with life, I'm ready to kick off some nightly astronomical activities.

The telescope mount has been realigned, camera batteries charged and cooled, and I've upgraded to Nebulosity 2.

The dark sky is upon us, and I'm just waiting for the clouds to clear...