Re: [APML] some ideas

[Stephen Pitt <lthuedk@pe.net>]

Hi Tony.  Have you had the opportunity to try the Provias yet?  They 
appear to be less contrasty than other chromes, and the p100f seems to 
give good density without star blowout.  

Stephen : http://www.light-to-dark.com/

Tony Hallas wrote:

> Hello,
>  
>     Since I am now mired down in a confirmed El Nino winter (storms go 
> from Japan all the way to CA) and the only good prospect is awesome 
> skiing, here's a few thoughts that might or might not work for chrome 
> users...
>  
>     First off, chrome is more contrasty than negative film... it's 
> possible to get the bright parts of anything to show up and have the 
> rest of the image fade into black. Pushing chrome films by developing 
> them longer in the first developer does two things... it opens up the 
> shadow areas and it converts any blue caste in the shadows to a more 
> neutral gray. Not all films have the "blue shadow" problem but if they 
> do, this cleans them up. If you leave the film in for more than 2 
> stops the Dmax begins to disappear, this is actually a good thing for 
> astro stuff because when you scan a chrome, pure black = no data. You 
> never want to use chrome film that has a pure black... you can always 
> set the end points AFTER the scan... but if you have to scan pure 
> black, you ain't got nuttin', honey.
>  
>      The other major problem with chrome films is the bright stars... 
> if exposing to sky fog or pushing to sky fog, the bright stars go 
> ballistic. What to do? I have not tried this yet but I think it will 
> work...
>  
>      1.   Shoot a series of shorter exposures that have the stars as 
> smaller points and have color.
>  
>     2.   Here's the laborious part.... put a circular selection around 
> the short exposure star that looks the best from the "short exposure 
> series" and cut and paste it on top of the blown out star. This will 
> now be a layer sitting on top of the blown out star. Go to your layer 
> control box and see how much you need to reduce the opacity of the top 
> layer until the dark ring surrounding the star blends into the blown 
> out part of the star below it. This will give you some idea for the 
> next step... go back to 100% and take the eraser tool at 10% and start 
> to whittle away at the dark ring... you will hit a point where the 
> remnant of the "dark ring" blends in perfectly with the surrounding 
> areas below it.. If there are any color issues, you can adjust the top 
> layer to match the bottom layer. Theoretically, you can replace your 
> worst stars with nice ones using this technique. It is not complicated 
> but it is a bit laborious... just the thing for those days of being 
> house bound as winter blizzards howl outside and the snow piles up 
> over the observatory...
>  
>       Tony




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