[vsnet-chat 4910] RE:Telephoto + CCD survey cameras

[drtakao@bronze.ocn.ne.jp (Akira Takao)]

Dear Mr. Brian Skiff

Thank you very much for your interest in my CCD+telephoto combination and yo
ur suggestion.I think this set-up is easy to operate and time-saving for the
amateurs who cannot spend enough time for taking images.

I had not experimented taking images in the twilight to know the limitting m
ag. I tried it this morning.
The set-up was ST-8 and 200mm F4 telephotolens.The center of the images was
12h36m-04d, at the elongation of about 34 degrees.
Today the sun rise was at 6:40 AM (JST)  here. Mag was compared to some GSC
stars.

At 5:42 AM(JST) , slightly bright --- exp.30sec, limiting mag13.4, NGC4546(m
ag 11.45) : detected clearly
At 5:54 AM(JST)  --- exp.20sec, limiting mag 12.4, NGC4546 : detected
At 5:58 AM(JST), bright ! --- exp.10sec, limiting mag 10.8, NGC4546 : not de
tected

I could not take iamges under this elongation due to the fense of my house,
but I think the result
would be almost same at the elongation of 20-30 degrees.

There have been a standard V filter on my desk for a long time.Maybe I will
be trying it soon.

Regards,

Akira Takao
Kitakyushu, Japan

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