Saturday, September 29, 2007

20070929 Sun (AR971)

The sun has been silent for quite some time. The sky has been cloudy too.

Finally, the sun is in a good position from inside my home, so that I can use my C5. While waiting for the sun to go to a really good position, I did an experiment with my C5 with my Cheapy-ERF, and the Herschel Wedge. A Herschel Wedge can usually only be used with a refractor, but with a ERF in the front, it can also be used with my C5.

The first shot is conducted with half aperture still blocked, Cheapy-ERF + Herschel Wedge + ND3 at AR970, C5 at f/10:-

Seeing was no good at around 1-2/10, transparency was like 4/10 at first but dropped to 2/10 for the last few shots. Peltier cooling was used except for the first few shots, but I only powered the Peltier/fan using power from USB, so the cooling is just about to put the setup back to a few degrees below ambient, also due to the direct sun light.

** Internal reflection is the prime killer of this setup, if the Cheaper ERF can be tilted further, I believe the contrast will increase tremendously ** The last few shots were fine tuned by tilting the Cheapy ERF a little bit more to reduce internal reflection.

1508 (GMT+8):-

1519 (GMT+8):-

1530 (GMT+8):-

1532 (GMT+8):-

All kinds of issue come out like internal reflection or ghosting, dust, newton's ring, etc.

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