Seeing and Transparency

OK. In the astro photography newsgroup, people frequently list both
seeing and transparency at the time of their photos on a 1-10 scale
with 10 being good. I realize that this is somewhat subjective and I
can understand 1 (cloudy for transparency and looking at the horizon
in the sahara at noon in the middle of summer for seeing) and 10
(crystal clear and no distortion at all), but what do the intermediate
numbers mean? Is it all subjective or are there some guidelines?

Hi Edward,

I use three different scales, one for seeingm one for transparency and
one for sky darkness. I use the Thompson scales. I've got them from a
fellow astronomer, but he doesn't know the origin. Of course there are
other scales you can use. For seeing there is the pickering scale and
for sky darkness the bortle scale. Follow this link to my website:

http://www.backyard-astro.com/Logs/logsreport.html

Read the text on top of the page. There you will find links to the
Pickering and Bortle scales. If you scroll down the page you will find
the three scales I use, numbered from 1 to 10, with all the
descriptions. For me, these scales work fine. I think that it doesn't
matter what scale you use. Important is that you use the same scale for
all your observations. That's my personal opinion.

If you have any more questions about the scales I use, please feel free
to ask.

Best regards,

Math
http://www.backyard-astro.com

Here is a link to the Pickering seeing scale definitions:
http://schmidling.netfirms.com/seeing.htm

Best regards,

Dennis Persyk
Igloo Observatory Home Page http://dpersyk.home.att.net
Hampshire, IL

Comet T7 images
http://home.att.net/~dpersyk/new.htm

Edward Smith wrote in message . ..
OK. In the astro photography newsgroup, people frequently list both
seeing and transparency at the time of their photos on a 1-10 scale
with 10 being good. I realize that this is somewhat subjective and I
can understand 1 (cloudy for transparency and looking at the horizon
in the sahara at noon in the middle of summer for seeing) and 10
(crystal clear and no distortion at all), but what do the intermediate
numbers mean? Is it all subjective or are there some guidelines?