Saturday, May 28, 2011

Imaging in the weeds

As planned - I spent last night at the "secret location" intending on doing some long exposure astrophotography. All was well - the sky was clear, the equipment worked well, but the wind was an issue. Gusts up to 25 miles per hour ruined about 1.2 hours worth of exposures out of the 6.5 attempted.

My first target was Omega Centauri (NGC 5139) - a BIG beautiful globular Cluster. A challenge from my latitude as it never gets higher than 10 degrees off the horizon. I managed to get 2.1 hours of data on the bugger though.

Lastly, M20 and M8 - both in the field of the Takahshi E160 and the 5DII camera body but also never very high off the horizon. I was not happy with the results from my "one-shot" color system. The IR blocking filter and the bayer mask made the H2 regions look very blue and washed out. Sigh, I guess its time to consider something with a little more efficiency and red sensitivity.

Below are images of the observing site and my equipment as well as the final products for the evenings effort. Click on the images for a larger view.

Wednesday, May 25, 2011

Star testing the Canon 14mm and 17mm TSE

Well - my visit with the two Canon L series lenses from CPS is going to end tomorrow - have to send them home. But - before I do I have to give them the ultimate test for any optical system capable of focus at infinity - the star test. The most severe test one can perform on a telescope or lens is to see how it handle point sources across their field of view - especially in the extreme corners of the field.

So - I took them with me up to mount Lemmon Observatory last night. I had to help the CSS astronomers Steve Larson and Ed Beshore work on their new 1 meter telescope and decided to take a few portraits of the new scope with the 14mm . . .

When it finally got dark I setup the camera and lenses on a tripod and made a couple of short exposures at high ISO and the lowest f ratio for each lens - doing critical focusing on a star near the middle of the field using the live view mode of the 5D mark II body I employed for these final images. I then examined the stars at the corners of the field of view (highlighted in the full frame image.) Note that coma is apparent in both lenses - not unexpected and not as bad as other lenses I have. All in all the 17mm performed best and it is most likely my next lens purchase.

The 14mm . . .

The 17mm TSE . . .

Saturday, May 21, 2011

UMC Architecture

More from the front lines with the Canon 17mm TS-E lens - this evening - University Medical Center.

One problem with the 17mm - lens flare. Bright light sources as much as 40 degrees outside the field of view can produce lens flare in the large protruding front element. In the image below - the light source that produced the flare was 90 degrees to camera right!

Tilting and Shifting

As a member of Canon Professional Services (CPS) I have the opportunity to get "evaluation" use of some of their lenses and cameras. Last night I was fortunate enough to get to use two high-end wide angle architectural lenses - the 14mm F/2.8L rectilinear and the 17mm F/4L TS-E - the later being a "Tilt-Shift" lens that is designed specifically for architectural photography.

What a TS-E lens allows you to do is to keep the vertical lines of a building from "converging". For example - take the image below taken with the 14mm tilted up to frame the Madonna sculpture at the San Xavier Mission . . .

Note that the vertical lines converge toward the top of the photograph. Now - the same subject from the same position taken with the 17mm TS-E shifted to correct for the perspective distortion . . .

My student and I spent the afternoon and evening downtown playing with the new lenses and evaluating their capabilities. I have access to them for the next few days and will be testing them thoroughly - including some astronomical work with them. So far - amazing!

Thursday, May 19, 2011


Earlier this year I entered the Epson International Pano Awards. According to Epson:

"The Epson International Pano Awards showcases the work of panoramic photographers worldwide and is the largest and most important competition for panoramic photography."

Well - the results are in. No I didn't win - but I got a couple of "Silver" Awards which entitles me to have my images displayed in exhibition in Sydney, Australia later this year. Of the 3,586 entries they received I placed 7th and 19th. Yea.