Tuesday, December 25, 2007

Spicy Hot Pot

When the weather turns colder nothing warms you from the inside like a big bubbling pot of fiery broth loaded up with meat, veggies, and whatever else you want. This is not a dish for the 100-degree summers of Georgia - it is best enjoyed on a cold winter's evening. The broth is made up of a store-bought hot pot soup base and either water or chicken stock for flavor. In this case we chose a Taiwanese soup base in a jar. Some beef tendon was pre-cooked in the hot pot base using a pressure cooker to soften the tough connective tissue. When cooked for a long time, beef tendon takes on a wonderful gelatinous texture and absorbs the rich flavor of the broth.
The hot pot ingredients can be quite varied and up to your own particular tastes. Usually there's thinly-sliced meat and/or seafood, vegetables, tofu, and tofu skin at a minimum. The great thing about hot pot is you can have whatever you like. On the side there's usually a sauce into which you can dip the cooked bits of stuff. My favorite is sa-cha sauce mixed with a raw egg yolk and a little soy sauce. The other sauce we like is a simple mixture of sliced scallions and vinegar. The vinegar sauce compliments pork very well, but I prefer the sa-cha sauce on everything else. I think I am a sa-cha junkie - I love it with stir-fried beef and I always use it to make a sauce for pan-fried dumplings.
For our hot-pot meats, we took the easy route of buying pre-sliced pork belly and ribeye steak at the local Super H-Mart. The pork takes a little extra attention to make sure it's cooked properly, but the beef only needs 30 seconds or so to preserve it's tender texture. We try to load up heavy on the vegetables and this time we used sliced king oyster mushrooms, enoki mushrooms, brown & white beech mushrooms, and bok choy. We also added tofu that had been previously frozen. The freezing process changes the texture and creates some holes which allow the tofu to soak up the broth. Tofu skin, purchased as dry sheets, is another tasty item which softens up in the broth and soaks up lots of spiciness. Frozen fish cakes and imitation crab meat were added for some seafood flavor, although scallops would have been good too (but so expensive!). At the end of the meal we put in some tang-oh (Garland chrysanthemum - Chrysanthemum coronarium) which soaks up a lot of the spicy oil floating on top of the broth.
This is not a meal for everyone - you have to really love spicy food. This one burns coming and going! But you can always opt for a regular soup base and enjoy it just as well. After two days in a row of this spicy stuff, we are taking a break tonight with some Peking duck (more on that later).

Sunday, December 23, 2007

Pictures from the past

The weather here has been awful for astronomy or pretty much anything else you could do outdoors. To ward off cabin fever I have been digging through some older pictures and picking the ones I felt could be improved with a little processing.
Here's one from the not-too-distant past. It was taken in October of 2006 at Brasstown Bald, Georgia. This is the highest point in Georgia at 4,784 feet. At the time I had just started using my Rebel XT with the Canon 50mm f/1.8 II lens. These are berries on a mountain ash tree:

Sunday, December 9, 2007

Outdoors with the WhiBal Card

Today I went outside and took some shots of what few plants still seem alive right now. OK, I didn't quite make it to the "great outdoors" but I did manage to walk out the back door, stand on the deck for a few minutes, and walk back in. What a shame being so lazy when it's 76° in December! It'll probably be cold and raining next weekend. Oh well...
We have some hen & chicks (or is it hens & chicks?) growing on the deck in little "mini rock garden" containers. Everything else has pretty much died off, but these little plants are doing just fine with almost no water.
First photo, cropped just a bit:

Next one, a full-frame photo:

Last one, another full frame:

These were all taken with my Canon Rebel XT and Canon 50mm f/1.8 II lens. I really love that little lens - very cheap and very sharp! I set the WhiBal card over one of the plants for the last image I took, then used that to set the white balance for every other image. The WhiBal makes my workflow extremely easy and efficient. I won't be leaving home without it!

Saturday, December 8, 2007

Photography with a modified DSLR camera

A modified DSLR camera is a powerful tool in the hands of any astrophotographer. Depending on the model, it’s a fairly low-cost method to obtain results close to that of the big, expensive CCD cameras that are made just for astronomy. You can save even more by doing the modification yourself. My first modification, as described in this post, was completed one year ago and I have done several more since then. My goal at that time was to have two cameras – one unmodified camera for normal photography and one modified camera for astrophotography. That goal didn’t last long once I realized the value of a nearly-new modified DSLR and needed some money to buy other astro equipment. Before long my unmodified camera was modified and quickly sold. After modding a couple more cameras and selling them, I was left with one modified Rebel XT. I installed a Baader UV/IR cutoff filter to replace the stock Canon filter in front of the sensor. This filter passes much more of the red spectrum, including the all-important 656nm H-alpha wavelength. This gives all images a red cast.
At first, normal photography was not a problem as long as I was using my X-Nite CC1 filter from MaxMax.com. This filter closely mimics the spectral response of the stock Canon internal filter and does a wonderful job of bringing the colors back to normal. Without it, my white balance is always wrong. But, as I have acquired more lenses and become much more interested in photography, the CC1 filter becomes more of an issue for a couple of reasons. First, my lenses have different filter sizes and it is inconvenient to change the filter with step rings if I need a quick lens change. Second, the CC1 filter increases my exposure time and makes hand-held photography in low lighting impossible without a tripod. It’s marginally acceptable with my Canon 50mm f/1.8 II lens – the only fast lens I own (because it’s cheap). My zoom lenses are f/3.5-4 at the widest, and I don’t want to spend a lot of money on fast zoom lenses.
I tried shooting without the CC1 filter and correcting the white balance when opening the RAW file in Photoshop. This works sometimes, but other times I just can’t seem to get the while balance right. Here’s an example of getting it right (or at least pretty close):

The left image uses the “As Shot” white balance setting in Photoshop RAW. A custom white balance was set from the inner lip of the white dish. It worked well in this case, as seen in the right image. Unfortunately I am not always going to get this lucky and find a nice neutral color in every situation. I could spend an hour trying to adjust levels and all sorts of other things to get the balance right, but I don’t want to do that on every photo I take!
I searched around on Google and read through dozens of websites discussing white balance. This seems to be a big topic of discussion for photographers based on what I found. There are so many products out there to help correct white balance, but which one to choose? After reading several reviews I finally decided on the WhiBal card from RawWorkflow.com. This little card is made of a neutral material that they check with a GretagMacbeth SpectroEye Spectrophotometer just to make sure it’s really neutral. It has a black & white label on one side that serves dual purposes – setting black & white points in Photoshop, and also telling you if you are getting glare by looking at the black portion (it’s reflective, so if it’s not black, you got glare). The WhiBal card arrived quickly and I immediately began taking some test shots. The WhiBal card is very compact and made of a sturdy foam-like material. It comes with a similarly-sized piece of black foam with a slot cut in it to serve as a stand. Also included is a lanyard with a quick-release clip and a carrying case made of very light material (feels like tent fabric).
The card takes a bit of getting used to at first. Finding the right angle to eliminate glare was tough at first, partly due to the so-so viewfinder of my Rebel XT, and partly due to shooting in a room with multiple light sources (overhead incandescent light and two windows). Below is a comparison of the “As Shot” white balance vs. the Custom white balance set from the WhiBal card:

The top image has the usual reddish cast that one gets from a modified camera. The bottom image appears natural and normal. Below is a comparison of the histograms from the Photoshop RAW editor. The left image shows the As Shot white balance with the red channel clearly exposed more than the blue and green channels. The right image shows the Custom white balance obtained by using the white balance eyedropper tool and clicking on the WhiBal card in the image. You’ll see that the individual color peaks are not aligned, but the image appears exactly as it looked to my eyes. The red channel is brought down and more in balance with the other two channels. As an experiment, I aligned the three channel peaks manually in Photoshop, but the resulting color did not look right at all. Therefore, I feel the WhiBal card performed perfectly.

Here’s another comparison taken in my wife’s sewing room. At the time this was shot, there was a mix of incandescent, halogen, and natural lighting coming from all sorts of different directions. Not the most ideal situation for the WhiBal card, or so I thought. I simply held the card right over the middle of the pens (where my camera autofocused the first time) and snapped a photo. I used this image to save a custom white balance setting in Photoshop RAW, and then applied that setting to my first image. Below is the comparison:

The left image is of course the As Shot white balance. The right image is the Custom white balance setting derived from the WhiBal card. So far I am pretty impressed. Next I'll need to get outside and see how the WhiBal performs in the great outdoors. I'll be sure to post my results here when completed.

Wednesday, December 5, 2007

Some other stuff....

As the change in my blog title reads, I am going to be expanding my blog from astronomy-only to pretty much everything in general. Astronomy will still be the main topic here, but I'd like to share some of my other interests like food, (non-astro) photography, and more food.
A few weeks ago we drove over to the parks around Lake Lanier, the reservoir that supplies drinking water to us and most of north metro Atlanta. The lake is just a mile from my house and many parks are close by. Due to the drought we have been experiencing since 2006, Lake Lanier has now reached the lowest level since it was originally filled with the water of the Chattahoochee River back in the 1950's. As of today it was around 1051-1/2 feet in elevation, a long way from the 1070 foot full pool level. Many interesting things are being exposed by the receding water, from old tires & fishing equipment to old house foundations and even a small racetrack. Unfortunately the racetrack is a long drive away (it's a big, big lake) but I'll get up there pretty soon. Back to our visit a few weeks ago - I took a lot of photos but I just wasn't happy with most of them. I am still learning a lot about photography and figuring out the right exposure, focal length, and composition. Here is one of the few (two actually) that I felt were interesting enough to spend some time processing in Photoshop:

I liked this one because a small tree is growing from the base of an old tree stump that should usually be several feet underwater. This was shot with my ultra-cheap Sigma 18-50mm lens that actually does a pretty good job. The raw image didn't look great, but after some processing I am pretty happy with the result. Keep in mind this is the first time I have ever tried to process a non-astro image in Photoshop.
The other image I felt was worthy of a little more processing was yet another tree stump. For some reason I find old tree stumps really interesting:

I think I might have over processed this image. But that's the good thing about saving things in Photoshop format - all my adjustment layers are intact and I can go back any time and tweak it. So far I am only doing a few simple adjustments like curves and levels on selected areas of each image. I try to work on each area separately and use masks to isolate whatever part is to be affected. Thankfully there is so much information out there and great photographers to learn from. Being out with the camera was a lot of fun and I can't wait to get out again. Hmmmm...I think I just got hooked on another expensive hobby!

Monday, December 3, 2007

"Starfinder" from DK Publishing

I was recently offered a copy of the book "Starfinder" from DK Publishing to review. I have quite a few Astronomy related books sitting around already, many of which are collecting a bit of dust right now. But it's always interesting to read something new, so I quickly accepted the generous offer. The book arrived and I was immediately surprised by the size. The "book" is actually a multi-functional case for it's contents. It is different & interesting with it's rounded shape, interior compartments, and a planisphere built right into the cover. While the size makes it stand out among other books, it is also slightly inconvenient since I don't have any shelves to accommodate it's 12+" by 12+" dimensions. I prefer the typical 8-1/2x11 size book, although making "Starfinder" any smaller would probably make the planisphere very difficult to read.
The cover opens up to reveal some how-to information for using the planisphere, as well as a guide to using the included constellation charts, found in little compartments on the interior of the book. Also inside the book is a small red LED flashlight. I must admit I laughed when first seeing this diminutive device, but it actually performs pretty well under total darkness. Most of us already involved in this hobby will have a good red LED flashlight, but for beginners this one will do just fine.
There are 44 double-sided constellation charts included made of sturdy high-quality card stock measuring 5-1/2"x3-3/4" each. They are divided up into 22 northern hemisphere cards and 22 southern hemisphere cards. Each card has a chart of the constellation showing the brighter-magnitude stars and Messier/NGC objects. There's a brief description of interesting objects which indicate if the object is visible by naked eye, binoculars, or telescope.
Tucked inside the back is a similarly-shaped reference book which is 72 pages long. This book is divided into three sections: Finding Your Way, The Solar System, and a Monthly Sky Guide. Finding your way has a lot of good information for the beginner explaining the vast distances involved in the universe, how our view of the sky changes with the seasons, basics of constellations, the mechanics of the solar system, objects of our Milky Way and beyond, basic info for getting started viewing, and an overview of "star-hopping." The Solar System section takes you on a tour from the Sun all the way out to Neptune, and even beyond that with comets, asteroids, and dwarf planets.
The final section is a Monthly Sky Guide which takes the reader month-by-month through the sky, describing interesting events & planetary positions over the next five years. A handy chart shows where the planets can be found among the constellations, and if they are in retrograde motion. The Monthly Sky Guide section includes information for both northern and southern hemisphere observers.
Besides the physical size issue I mentioned, my only other minor complaint would be the planisphere. While it is a very nice planisphere, it is built into the front cover and cannot be removed. I would love to be able to take just the planisphere outside without having to hold up the entire bulk of this book. Overall I found the content to be appropriate for the beginner while still being a handy guide for the seasoned observer. This book will give anyone a good start into astronomy without a lot of technical talk. The price is not bad either, just $18.40 from Amazon.com.

Thursday, October 25, 2007

M31 - the Andromeda Galaxy (in progress)

Now that the full moon is blazing brightly in the night sky (made even brighter by being in perigee) I am taking some time to go back over the images of M31 collected two weeks ago under the dark skies of the new moon. I spent two nights in a row collecting 5 minute, 3 minute, and one minute exposures at ISO 800. In hindsight I should have just taken a lot of 5 minute exposures and a few short ones, but I was curious if I could get close to the same result with a lot of 3-minute exposures. There was no contest - the 5-minute subs resulted in a much better image than lots more shorter subs. Eventually I will work up a comparison. I got to a stopping point last week with the stack of 5-minute subs, and decided to take a break for a while and come back later with a fresh start. Here's the result of that previous work:

It's a pretty good image, I think, but maybe it could be better? Maybe I've been looking at it too much and noticing all the flaws. I'll keep reading "Photoshop Astronomy" and going through the tutorials provided with ImagesPlus to get some ideas. I still have lots to learn about image processing. The above image was mostly the result of a few Levels and Curves adjustments in Photoshop, along with a high-pass filter mask.
Looking back at where I was a year ago while just starting out, I believe I have improved quite a bit. Here is last years M31 - my first:

Wednesday, October 17, 2007

The crescent moon passes near Jupiter

Last Sunday evening I just happened to glance outside and see a thin crescent moon low on the horizon with Jupiter beginning to shine brightly above it. The color of the sky was interesting and I quickly grabbed the Rebel XT and the tripod for a few quick images.

The next evening the moon was even closer to Jupiter. Clouds were rolling in and I managed to find a break to capture this view. The bright star Arcturus is visible to the right of the moon.

Wednesday, October 10, 2007

The Moon, Saturn, & Venus Get Together

Finally fall is here and the muggy skies of summer are clearing out to reveal deep black skies with stars seemingly shining brighter than ever. The clear, drier air really makes the stars pop - a welcome scene after months of heat, haze, & humidity. On the morning of Sunday 10/07, the Moon teamed up with Saturn and Venus to make a nice grouping in the eastern pre-dawn sky. I was excited the night before with the thought of viewing this event and capturing it with my camera. I was a little less excited when the alarm went off at 5:30AM, but I crawled out of bed and got set up outside, still partially asleep. This was a good opportunity to try out my new Sigma 55-200mm zoom lens. At about 147mm everything framed up nicely and I snapped several images at various exposure times. I combined four images ranging from 0.4s to 2.5s to make the above image. After just watching this beautiful alignment for a little while, and catching a few bright meteors whizzing by, I headed back to bed for more sleep. I'm so happy "imaging season" has returned to Georgia.

Sunday, August 12, 2007

Another night in about a minute

Saturday night I set up the camera again, this time pointing more towards the northern part of the sky. Exposures were set to 16 seconds with a bit higher gain than before. You'll notice the top of the chimney flashing in the lower left corner. That's my neighbor's motion-detecting light coming on every time a car passes by on the road in front. One of the lights on his front corner points straight back into my backyard - very annoying!
Anyway, I think I caught one meteor - pretty disappointing.

Saturday, August 11, 2007

One night in about a minute

I've been thinking about building an all-sky camera for a while now. It's not something I really need but it seems like a fun project. I recently received a small optical dome from Surplus Shed. I don't know what camera I will end up using for the final version. Last night I set my DMK21AF04.AS camera up on a tripod with a Fujinon 2.8mm lens attached. I taped a Baader UV/IR filter on front of the lens and pointed the camera straight up. The exposures were set to about 20 seconds each with the gain set fairly low to reduce noise. I let it run from 10PM to 6AM and used the Y800 mode for recording the video in IC Capture. The video starts with Vega shining brightly just above left of center, and ends with the Pegasus moving off to the right as the Pleiades and Mars approach on the left before dawn. I was hoping to catch a few Perseids but I think I only caught air traffic going by. Here's the result, converted to 15 frames per second:

I will eventually get a wider angle lens since the 2.8mm Fujinon only has about a 90-degree field of view. There's a more expensive varifocal lens that covers nearly 180 degrees. A little more saving will be required before I get that lens. But then my birthday is coming soon!

Monday, August 6, 2007

My first Jupiter in LRGB with the DMK21AF04.AS

My new Astronomik LRGB filters came in last Friday and I was just itchin' to try them out. Saturday night seemed like my best opportunity in a long time - the skies were about as clear as it's gonna get in summer. In other words, hazy and humid. The seeing was just OK but that wasn't going to stop me.
I had a couple of other new "toys" - the Atik manual filter wheel and a Televue 2X barlow. I also picked up a C-mount to T-thread adapter to mount my DMK21AF04.AS camera to the male T-threads of the filter wheel. The other side of the filter wheel uses a T-thread to 1.25" nosepiece adapter.
I started out by slewing to a medium brightness star and checking focus using Metaguide. I've used Metaguide a lot for autoguiding, but one feature I really like is the FWHM measurement. That gives me a quick way of dialing in the right focus without messing around with a mask or any other focusing aids.
Once centered on Jupiter I fired up IC Capture and adjusted for the right exposure. I should have taken some screen shots here, but what I did was open up the histogram and adjust the exposure & gain settings to get the maximum spread of the histogram with each filter. The luminance filter required a shorter exposure and less gain while the color filters needed longer exposures. The blue filter took the longest exposure and as expected, due to atmospheric turbulence, it produced the worst quality image. The atmosphere affect the longer wavelengths more than the red (shorter) wavelengths. I only took no more than one minute of each color and luminance at 15 fps. Jupiter rotates very fast, so you must move quick. I was pleasantly surprised to find Io transiting across Jupiter's disk when I got started. The moon Io is similar in size to our own moon. I took a couple of quick LRGB sequences and worked on the results in Registax. The resulting images were saved in TIFF format, then some minor adjustments were made in Photoshop. I then used ImagesPlus to align the images and combine as a LRGB image. Here's the result which also shows the separate channels:

I am very happy with the result, especially since I really don't know what I am doing with Registax, and have only been at this for less than one year. I still have a lot to learn but I am enjoying it and taking things slowly.
After taking some AVI's with the DMK camera, I decided to pop in the SPC900NC webcam before Io was gone to make a quick comparison. I took a few one-minute videos and tried my best to squeeze out some detail in Registax. This is the best I could get, and it's definitely not even close to the quality of the DMK:

Now I need to find a good home for the SPC900NC. It doesn't look like it will see much use anymore.

Sunday, August 5, 2007

First light with the DSI Pro

Saturday night I headed out for a quick test of my new Meade DSI Pro. The weather finally cooperated on a weekend - first time in 3 months. Even after 10PM it was still pretty hot outside, and I had to wear long pants and a long-sleeved flannel shirt to keep the mosquito bites to a minimum. I was sweating, uncomfortable, and busy swatting the skeeters away from my face & ears, but I managed to capture a quick set of images. After taking a few test shots to tweak the focus, I set the long exposure mode to 60 seconds and let the software take it from there. Looking at the individual frames was not that impressive, but there was something there. Here's a single 60-second image of M27 - the Dumbbell Nebula:

I chose the option to save all raw images to FITS format. Since the DSI Pro has non-square pixels, the raw format file actually comes out "squished" horizontally to 508 pixels wide instead of the full format of 648 pixels wide. When using Envisage to do all the combining it automatically corrects the image scale. I am comfortable with ImagesPlus, so I just transformed the horizontal dimension in IP after alignment and stacking. I also took a few dark frames - here's one 60-second dark frame at around 80 degrees:

Having only 20 exposures I wasn't expecting much, especially after seeing the noisy single frames. But I was pleasantly surprised after a median combine and a quick DDP adjustment in ImagesPlus. The outer faint details in M27 were clearly evident in the resulting image. Next time I will try with my new LRGB filters. Overall I am very impressed with the DSI Pro and looking forward to much more imaging, weather permitting. Here's my result of 20 exposures at 60 seconds each:

Tuesday, July 31, 2007

The DSI Pro arrives!

Today my new DSI Pro arrived from the fine folks at Astronomics. I bet they were pretty busy shipping out loads of these cameras. There's going to be hundreds and hundreds of happy new DSI & DSI Pro owners all across the country. I opted for the DSI Pro to get more sensitivity. I had previously ordered an Atik filter wheel and a set of Astronomik LRGB filters for planetary imaging, so getting a monochrome CCD camera was a "no brainer."
The first order of business was to install the Meade Autostar Suite software. Installation went without a hitch on my Dell laptop running Windows XP. As many people have recommended, I rebooted after the installation and then installed the Autostar Suite Update 4 from the Meade website. Once the software was all squared away, it was time to get my hands on the camera. I must say I am pretty impressed with the overall build quality of the camera. It feels solid and heavy in my hands, not unlike the feel of my DMK21AF04.AS firewire camera. For some reason, the heavier something is, the more robust and well-constructed it seems. It's a world of difference from the cheap feel of my Philips SPC900NC camera with it's plastic housing and next-to-nothing weight. Getting back to the DSI Pro, I had already ordered a low-profile adapter from Scopestuff. This replaces the filter holder nosepiece, which is of no use to me. Here's an image of the DSI Pro next to the Scopestuff adapter:

The nosepiece is easily removed by loosening the four small screws at the four corners. The Scopestuff adapter comes with new screws that are much shorter. The adapter simply mounts to the same four holes and that's it. Now you have a female T-thread connection for whatever you need:

The DSI Pro now fits nice and snug to my Atik filter wheel:

Here's another view:

The new setup is almost ready to go. I'm just waiting on the Astronomik LRGB filters to arrive. They should be here on Friday, and if the weather cooperates I just might get some imaging in this weekend. I'm not too optimistic after two months of hazy skies, but I will keep my fingers crossed.

Friday, July 20, 2007

New stuff on the way!

Boy, I sure do love getting new stuff. I sold a few things I had sitting around which were all not getting used much. I think astro equipment needs to be used, so I just can't see letting it collect dust (so to speak of course - I keep my stuff covered or stored in cases). One of my two modified Canon Rebel XT's also needed to go. There was no point in keeping them both any longer when I was just itching to get some new gear. I don't have an unlimited budget so I usually have to sell something to buy something else. Anyway, here's a list of what will be coming soon:

  • Televue 2X barlow

  • Atik manual filter wheel

  • Astronomik LRGB filter set

  • Losmandy mounting rings (getting rid of the fixed mounting rings)

And, one more thing I wasn't planning on: a Meade DSI Pro monochrome camera. Meade marked these down to $129 and I could not pass up that price. It should go well with the filter wheel and filters. I also ordered the DSI low-profile adapter plate from ScopeStuff (gotta love ScopeStuff!). This should keep me very busy as the (hopefully) clearer skies of fall and winter approach in a couple of months.

Tuesday, July 10, 2007

I am not enjoying summer!

For astrophotography, that is. It was September last year when I bought my mount, scopes, & camera, so I had just missed the soupy skies of summer. The fall and winter skies really spoiled me with many nights of crisp, clean, steady air. Now, even when you think it is clear, it's not really clear. I'll peek my head out and there will be a light halo around Jupiter, or maybe a thin layer of high clouds covering the sky. That's been the story pretty much every night this summer. Too much water vapor in the air, which just seems to make the light pollution even worse. I can't wait for fall to come!

Wednesday, June 6, 2007

More videos

Now let's take a look at a couple of Saturn videos. The first was taken with the DMK21AF04 in my Celestron C8 using a 2X barlow.

And here's a video taken right after the above but using my Philips SPC900NC color webcam. I'm not sure what's causing the poor signal quality.

Monday, June 4, 2007

A couple of videos

I thought it would be interesting for anyone who hasn't yet tried lunar/planetary imaging to see what the raw video looks like coming out of a DMK21AF04 camera. You can get an idea of how much things move and shimmer around. The first video is the area of the moon around Tycho and Clavius. This video was taken in my Celestron C8 at the native focal length of 2032mm @ f/10. Things look pretty steady at this focal length:

Now let's crank up the magnification by adding a 2X barlow with a 2" extension between the barlow and the camera to increase the overall magnification to about 3X. At around 6000mm focal length, things start moving around much more and the tiniest little bump of the tripod or scope shakes the image pretty badly for 2-3 seconds. Also, the image becomes darker, requiring longer exposures and some extra gain:

Saturday, June 2, 2007

Another Saturn

This is from last week and it's a slightly better image of Saturn than my first attempt. I was using the DMK21AF04 along with my 2X Siebert barlow in the C8. Saturn was getting a little low in the sky at the time, but the great transparency helped me get a little more detail:

Then I swapped out the DMK for my Philips SPC900NC webcam and tried to get a color image. The images I get from the SPC900NC always seem to have some banding that I haven't quite figured out yet. I removed most of it in Photoshop using Noel Carboni's Astronomy Tools plugin "Vertical Banding Noise Reduction."

Then I tried to manually add the DMK image above as a luminance layer to the color image. This was difficult since the two images did not line up and I could not get ImagesPlus to align them using the auto planet align function. A slight improvement, maybe??

That's probably it for Saturn attempts this year. Next on the list will be Jupiter, then maybe Mars.

Sunday, May 27, 2007

More lunar imaging with the DMK camera

Last Friday night, under good transparent skies, I tried my hand once again at lunar imaging with the DMK21AF04. This little camera continues to impress me. It makes it so easy to get great results. Of course a properly collimated telescope and good focus helps too. I think I got the collimation spot-on but focus is always tricky.
I started the night with the slightly-more-than-half-full moon directly overhead, which is a prime spot for getting good images. The Tycho & Clavius area was my first target. Below is my first image, recorded at the Celestron C8's native focal length of 2032mm at f/10:

To get closer in, you need to increase focal length. A barlow is the most common method of doing this and they come in various power ratings and quality levels. My barlow is a 2" Siebert telecentric model with a 2X power rating. This doubles my focal length and allows some really close-up viewing of the moon. The power can be further increased by adding an extension between the back of the barlow and the camera. Here's a close up of Clavius using this method with a 2" extension:

As you increase focal length, the image becomes darker and movement from atmospheric distortion gets magnified even more. It gets really difficult to capture a good image at this focal length. Below is another extreme close up, this is Tycho:

Without the extension the same area looks like this:

The same effect can be seen here on the crater Plato. Here's an image with the 2X barlow and 2" extension:

Removing the extension increases the field of view as seen below:

Next, I recorded several AVI's around the crater Copernicus and created a mosaic in Photoshop:

Here's some other highlights from the evening:
Craters Walter & Lexell:

Craters Stöfler & Faraday:

Craters Saussure, Orontius, Huggins, Nasiredden, & Miller:

Rupus Recta:

Craters Purbach & Thebit:

Craters Ptolemaeus & Herschel:

Craters Pitatus, Guaricus, Wurzelbauer, & Hesiodus:

Craters Fra Mauro, Bonpland, & Parry:

Craters Arzachel, Alpetragius, & Thebit: