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ISS over Texas

KE5BPR – March 3, 2007 – 03:03

Tonight the ISS made about a 43 degree visible pass over San Antonio, TX. I quickly grabbed my telephoto lens and my Canon Digital Rebel XT camera and snapped a few photos. I really didn't expect any to come out since I was holding the camera (no tripod) and since the station moves pretty rappidly, I figured it would blur. But I had one photo of the 20 I took that seems to resemble the station. I'm not sure if it's pure coincidence or if it really is the station. I would like some of you (that have more knowledge about the station) to look at it and let me know what you think. Thanks a lot!

Here is the image I took:

Thanks again and 73's to all,
-Rob

Observing ISS
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Yes, that's the station

AH6RH – March 3, 2007 – 08:42

Looks pretty good for a handheld. Keep in mind that the exposure value would be pretty much the same as sunlight, so it's F/16 at ISO speed.

Then, there's the 1/focal length rule for the shutter speed. What was the focal length of the lens? 300? Then your "min" speed should be 1/300, or closer to 1/250. And, you were probably panning the shot too.

If your settings was consistent with the above, I'd say you got a good shot.

Ron H, AH6RH

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I'm still learning about

KE5BPR – March 4, 2007 – 01:57

I'm still learning about photography and it's really going to show in this post.... A friend of mine let me barrow the lens I shot that picture with. I don't know a whole lot about it, except on the end of the lens it says: "f=500mm" is that the focal length? and then is says: "1:8". I'm not too sure what that means either. I did set the camera up to take RAW images and I adjusted the shutter speed to a rapid setting. I honestly don't recall what it was exactly I set it to. And then I just took some shots. I didn't think any of the shots would come out due to the fast shutter speed, being in the dark, and therefore not much light was able to enter the lens. But I knew if I left the shutter open any length of time then the ISS would blur. So I just did it this way as an experiment.
But anyways, I'm glad to hear that appears to actually be the ISS.

-Rob - KE5BPR

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That's the true ham spirit!

AH6RH – March 5, 2007 – 09:03

Hi Rob,

That's the true ham spirit. Experiment. You'll never know and never learn unless you tried. Looks like you got your hands on a 500m f8 mirror (reflex) lens. That's good for what you tried to do. It's light, and relatively fast f8. That also means you're aperture is fixed, so the only adjustment you got for exposure is the shutter speed.

Given that, with f8, you should 4x your shutter speed. For example, if you were hand holding your digital camera at ISO 400, you should use a shutter speed of 1/1600, instead of the 1/400 suggested by the f/16 rule.

The 1/1600 shutter speed would be way faster than the 1/500 shutter speed indicated by the 500mm lens. So, you minimize your blur.

Since you're shooting Canon, and I'm assuming your camera has a 35mm sensor, you did pretty well with your setup. It's given me inspiration to true the same -- except I like film.

Here's a write-up using a Nikkor 500mm f8 lens.

http://ronhashiro.htohananet.com/photography/nikkor-500mm.html

Ron Hashiro, AH6RH
Honolulu, HI

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