Wednesday October 1, 2003
Holy Coyote, Batman!

Nine in the evening and out on the dew drenched porch enjoying the stars. One nice thing about winter is the early night time sky. Faith is off at statistics class (what are the odds?!) while Zeke and Tink dream of her coming home and feeding them wet food.

A car drives by, things quiet down a bit, and then a sound starts. Testing, or a tuning at first, and then full volume. For a second I figure it's the next door neighbor kids doing a fine job of impersonating wild coyotes. A really fine job. The thing is that they are way too good at it and stretching the bounds of human lung capacity. In addition to the normal, hackneyed movie sound effect call we all know and love, there's the obnoxious and annoying yip of pups completely out of rhythm and tune. So it sounds like a movie coyotes AND a room full of dogs getting their tails stepped on.

A few seconds of this, at these volumes, might be pulled off by dedicated pranksters, but when it goes for over a minute without any real letup then I'm pretty sure it's the real thing. The true test though was calling Zeke out to go to the woods (to the "bathroom" is the correct term). He comes out as instructed, heads into the woods, and is back in a jiffy, ready to go back inside.

"Hey, this is too weird for me. Lemme in, man!" says courageous the dawg.

I let fearless back in the house and enjoy the rest of the concert. At one point the neighbor kids might have tried to join in, but they just didn't have the sustain or temerity to pull it off.



Calibration
40mm frames

I hooked the Canon A70 to the laptop while it was mounted on the telescope in order to get an idea of the best ways to use it for astronomy photos. The lens is a 40mm and the telescope is focused on a branch about thirty feet high and a hundred feet or so away.

This photos series shows six zoom steps of the camera lens, starting with no zoom to maximum zoom. The only other change I made was to try and obtain a good focus for each zoom. In photoshop I shrunk the photos down and put them together, but otherwise no color balancing or sharpening.

As I've mentioned before, Canon includes remote control software for the camera. The software allows complete control over the camera settings (including zoom) and a little "live" preview window. Well, it's not totally live or totally accurate. In order to send the image over slow USB 1.0 (why don't cameras use firewire??!!) they compress the heck out of it and only allow for a small thumbprint preview window. I'm not sure which is harder to focus with, the on-camera screen or the remote window.

Taking photos this way is kind of slow. Instead of storing them on the camera the Canon software takes the snapshot and then downloads it over USB. It's kind of funny to see the estimate of free space as room enough for 6,000 hi-rez pictures. Still, it's workable and a fair sight better than the alternative (no control, no view). I wonder if an iSight could be repurposed as a telescope camera? (of course...)

The first thing I noticed was that without zoom there's this dark elliptical area on the right side of the image. Gently twisting the camera/lens/telescope assembly will make it worse or almost get rid of it entirely so I bet it's an alignment issue with the dozen or so lenses that the light is winding it's way through. I haven't found an adjustment combination that clears it up without assistance.

Once you start zooming in the darkening fades a bit and moves more to the right.

Zooming in on the images in photoshop I can see that it's not quite focused or something else is slightly off. Maybe it's Chromatic Aberration? (redder colors bend less than blue colors so you see rainbow of colors around the image) Or maybe I just didn't get the telescope focused. Hard to say. I probably ought to re-check the telescope's collimation. Collimation is the alignment of the front lens assembly in order to maintain a straight light path through the telescope and into the eye piece.



Tedhieron • 2003-10-02 06:03pm

I *knew* there was a justification I could use to buy an iSight! ;-)