Saturday, 2 August 2008

Milky Way photograph, and a tale of lens covers...

Yesterday was one of those occasions... The evening was beautifully clear here. The passes of KH's USA 129 and 186 were too much in twilight (I did see USA 186 visually though, but got no points) and I tried to photograph a pass of IGS 1B half an hour later, using my new Tamron Di II AF 17-50/2.8 lens.

The Tamron lens needs to be focussed using the "live view" function of my camera (Canon EOS 450D), as it has no "hard stop" at infinity, like most modern lenses.

I ran into trouble though. Pointed it to Arcturus but no star to be seen on the screen whatever I tried. Dito with Vega, Deneb. Frustration! Then worry. Was my camera malfunctioning?!?

I looked up. And saw a bright IGS 1B majestically sail accross the sky. Grrr!

I took the camera again. And then the quarter finally fel....

Yep: forgotten to take off the lens cover....

* bangs head against desk repeatedly *

Later that evening I made a series of images with the 450D camera + Tamron lens piggyback on my ETX-70 telescope. 69 frames of 10 second exposure each at 800 ISO and 17mm/F2.8 were stacked into this image of the Milky Way in Cygnus, mimicking a 11.5 minute exposure:

(click image to enlarge)

Difficult to believe for me too that this was obtained right from a town center, but nevertheless it is true! Stacking large numbers of short exposure images makes this possible.

1 comment:

Tom said...

First of all: Thanks for this interesting blog. It keeps reminding me to look up more!

What magnitude was IGS 1B last night? I don't think it is in the database.

What is your approx cut-off magnitude for visual viewing of satelites? (In Leiden city)?