Observing Mars With Webcams Options

[MichaelT]

I would like to open this new topic with some Mars images that I obtained using a Philips ToUCam Pro 740k and a telescope. It's really amazing what you can do today with these webcams, a moderately sized telescope and some image processing.

You simply have to unscrew the webcam's lense and fit an appropriate adaptor to attach the cam to the telescope. In this case I used a refractor with 20 cm aparture and a focal length of 3 m. It's the main telescope of Hanover's astronomy club (German homepage) that I am a member of. Additionally I used a 6x barlow lens yielding an equivalent focal length of 18 m.
After finding Mars and focusing, I usually record AVIs which are later split into seperate images (frame rate of 5 Hz).
Then I take 600 frames (2 minutes) and average them with a program called "Giotto 2.0". That program also allows to use various filtering routines to enhance details in the images.
The first image (from left to right) is a raw image, the second the average of 600 frames. To that second image, I apply butterworth and other filters. The resulting images are processed (layers, color adjustments etc) in Photoshop to obtain image 3. A bit of unsharp masking finally yields image 4.


This image is from 22 September (4 UT) The south polar cap is visible to the upper right, Syrtis Major is the large dark area to the lower right. The bright area below the south pole is the Hellas basin. The north pole is veiled by clouds. All the dark areas are not topographic features, but merely differently colored soil. Such detailed images are only possible if the seeing is exceptionally good.

I took images over a period of more than an hour and generated a GIF-animation from them (29 frames, 2:58 UT - 4:03 UT):

Full resolution (900 kB)
From the rotation you can see that the visible structures are real and not artifacts from processing.

One pixel is equivalent to 0.08 arc seconds (~ 33 km). However, the smallest structures visible are certainly larger than that.

Michael

[mhoward]

Love the animation - that is lovely.

[dot.dk]

That is some amazing stuff!

Very well done!

[odave]

[Old Fart]
Why, back in my day you spent thousands of dollars on a CCD and processed your way in a blizzard on ice, uphill (both ways) for a bunch of fuzzy images. Nowadays some punk with an $80 webcam comes along and blows you out of the water!
[/Old Fart]



Seriously, the state of amateur digital imaging has progressed incredibly over the last 5-6 years.

Very nice images, MichaelT!

[mike]

Wow, that is quite impressive, especially the smooth animation. I wouldn't have guessed it was possible to get imagery that good with (I'm guessing) relatively inexpensive equipment. Nice work.

[dot.dk]

I wouldn't rate a 20 cm refractor as inexpensive...

[mike]

I was guessing. I've never even looked into buying any telescope equipment. I'll take your word and forget the 'relatively inexpensive' part - it's still an impressive animation.

[Guest_Myran_*]

Thank you for sharing MichaelT, it was interesting to see the difference from raw to finished image, and yes I liked the animation too, quite amazed in fact.

[Decepticon]

WOW!

[MichaelT]

[Old Fart]
Why, back in my day you spent thousands of dollars on a CCD and processed your way in a blizzard on ice, uphill (both ways) for a bunch of fuzzy images.  Nowadays some punk with an $80 webcam comes along and blows you out of the water!
[/Old Fart]

I saw some *really* incredible images in German astronomy forums that were obtained with 14-18" mirror telescopes by some "amateurs".
What amazes me the most is that all the information visible in the final image is already there in the second I wonder what will be possible in 10 years time...
And you don't need a 20 cm refractor. I saw some very nice images from people with every-day 20 cm Schmidt-Cassegrains which are not that expensive.

Michael

[dvandorn]

The amount of detail you got is truly astounding. Great work!

My only constructive criticism is that the dark areas ought to be greenish-grayish, instead of purplish...

-the other Doug

[MichaelT]

My only constructive criticism is that the dark areas ought to be greenish-grayish, instead of purplish...

You are right. I set the tonal correction of the webcam to "auto" and thought I could change the colors appropriately later. I was wrong. No matter what I tried, something always looked strange, either the dark or the light areas.

Michael

[tty]

You might be interested to know that essentially the same technique (attaching a simple digital camera to a relatively cheap spotting scope) has revolutionized bird photography in the last few years. This is known as "digi-scoping", perhaps a useful term in astronomy too?

tty

[sranderson]

 

I saw some *really* incredible images in German astronomy forums that were obtained with 14-18" mirror telescopes by some "amateurs".
What amazes me the most is that all the information visible in the final image is already there in the second I wonder what will be possible in 10 years time...
And you don't need a 20 cm refractor. I saw some very nice images from people with every-day 20 cm Schmidt-Cassegrains which are not that expensive.

Michael

What is interesting to me is that you, an amateur using today's fairly common equipment, have made an image that astronomers of the past would have given their lives for. If your images would have been available in 1877 when Schiaparelli made his map, or in 1910 when Lowell was talking about irrigation systems on Mars, you could have proven that there were no canals.

I wonder what year it was that we did actually prove that there were no canals. The Mariners put the nail in the coffin, but were there ground images that pretty much proved it before?

Scott

[Bob Shaw]

What is interesting to me is that you, an amateur using today's fairly common equipment, have made an image that astronomers of the past would have given their lives for.  If your images would have been available in 1877 when Schiaparelli made his map, or in 1910 when Lowell was talking about irrigation systems on Mars, you could have proven that there were no canals.

I wonder what year it was that we did actually prove that there were no canals.  The Mariners put the nail in the coffin, but were there ground images that pretty much proved it before?

Scott

Scott:

Although visual observers did (quietly) report seeing craters and the like on Mars under *very* special circumstances, no emulsion-based photography ever seemed to show much more than a blur. Think of all the hundreds of frames which are tweaked to get one good image with a webcam, and then do the reverse, fuzzying them to death, and that's what we used to see.

Have a look at Sky and Telescope November 2005 p64 for an intriguing story about the visual observations made by John Mellish 90 years ago. He's not the only person who saw surface detail, either!

Bob Shaw