[APML]: New Photos & Comparison

[Chuck Vaughn <aa6g@aa6g.org>]

Hi All,

I've got some new photos taken in the last week.

After all this discussion of film hypering I have an interesting comparison
between Lumicon Tech Pan and my high vacuum hypered TP.

I have an older photo of NGC6334 taken with a 7"-f/9 StarFire. It's a 90
minute exposure on Lumicon TP from Chews Rdige.

http://www.aa6g.org/Astronomy/Old/ngc6334.jpg

I have a new photo of NGC6334 taken with the 130EDT. It is a 75 minute 
exposure with my high vaccum hypered TP from Chews Ridge.

ftp://shell3.ba.best.com/web2/aa6g/ngc6334a.jpg

This is not a perfect comparison as I don't know to what level the Lumicon
film was hypered but I doubt it was more than 0.4 and 0.3 is more likely.
My film was 0.6. A 75 minute exposure is equal to a 95 minute expsoure at f/9
so think that is close. The change in reciprocity failure with TP over that
small time is almost non-existent so I don't think that's a factor. You'll
see a significant difference between the photos. One test certainly isn't
definitive but it's all I have right now.

Other new photos with the 130EDT:

Dark nebula B92 and B93 is a 60 minute exposure from Digger Pine Ranch, our
not as dark site.

ftp://shell3.ba.best.com/web2/aa6g/b93b93.jpg

Cederbald 214 is a 130 minute exposure from Chews Ridge. This turned out to
be a very nice nebula. Much of the surrounding nebula is very faint. It is
located at 00h04m RA and +67deg Dec.

ftp://shell3.ba.best.com/web2/aa6g/ced214.jpg

Sharpless 2-157 is a 150 minute exposure from Chews Ridge. I think I met my
match for white light photography. :-)  This nebula is rather faint to get
much detail and the field is awash in moderately bright stars which detract
from the photo. SH2-157 is located near NGC7635 - the Bubble Neblua.

ftp://shell3.ba.best.com/web2/aa6g/sh2_157.jpg

I learned some new adjustment techniques when scanning SH2-157 with my SprintScan 35. I 
had never used the Gamma control much and usually left it
at 1.00. This negative was so dense that I couldn't get the blacks to be black.
The Exposure control was all the way to -2.00 and the contrast stretch was at
maximum. I found that setting the Gamma to around 0.5 darkened the image and
allowed the Exposure to be moved into a usable range again. The Brightness
and Conrast also had reasonable adjustments. I combined a small Tonescale
adjustment with these other 3 adjustments for the final scan.

Apparently I've been missing out on some of the dynamic range of my scanner
by not using the Gamma adjustment because I didn't understand how to apply
it. I may have to go back and rescan some other negatives. :-)

Hopefully all the URLs are correct this time.

Chuck  <aa6g@aa6g.org>