[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: [APML] Rho & M8M20

Steve, on the Rho picture you say 45 min at f4.5. From my site 45 min on 
400 film at f4.5 is the sky fog limit so I think your exposure choice is 
correct. I have not been to the RTMC but would assume it is relatively 
dark as is my location. Pushing two stops would explain a lot of the 
graininess you mentioned but that would seem excessive given the exposure.

On the M8M20 shot, you give the same data but exposure 15 minutes. 
Pushing that two stops would be about the same as 45 min unpushed AND 
explain the grain. Assuming same roll of film, I'm guessing the 45 min 
exposure was pretty wild looking prior to processing in PS.

Also, I don't think the experts recommend backing off exposure duration 
to solve vignetting, you remove what you have as you did using an AV mask.

Great shots in any case - I'm warming up my 180mm ED lens in anticipation!

Stuart

Steve Lindsey wrote:

>Here's a couple I got last weekend at RTMC.  There was a lot of thin clouds
>Fri night when I took these and it was my first try with my friend's 300mm
>f4.5.  I think the Rho shot was overexposed at 45 min f4.5 and it vignetted
>quite a bit wide open.  It did give me a great opportunity to learn one of
>Jerry's AV techniques however.  Interesting that the M8M20 shot showed no or
>very faint noticable vignetting at 15 min though.  Do I need to shot at f5.6
>for the faint stuff or just back off on exposure time?
>
>http://home.earthlink.net/%7estevelindsey/Rho.html
>http://home.earthlink.net/%7estevelindsey/M8M20.html
>
>There was also some arced star trailing at the bottom of the Rho shot but
>the worst was cropped out.  Let me know any ideas on what you folks think
>caused this.
>
>Comment always appreciated.
>
>Steve
>
>
>_______________________________________________
>Astro-Photo mailing list
>Astro-Photo@seds.org
>http://seds.org/mailman/listinfo/astro-photo
>
>  
>


_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo