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RE: [APML] Poor Blue in 400F?
Hi Alen,
I just remember I had to stretch the contrast hard to bring up the blue for my 60-minute shot. I also did a shot of M42 which turned out fine using 400F, so I just figured Pleiades is a tough shot for the Provia. Since I took that shot, I've kind of gotten the impression from various sources that you ought to use E200 for blue nebulae. I've been wanting to go back and shoot Pleiades for a while now. Maybe I'll use this as an excuse to go back and do it, and shoot it under same conditions with both 400F and E200.
I've still got my image floating around if you want to compare. I thought it was a 45-minute shot but the caption says 60-minutes. Fortunately the written word is much better than my memory. <g> You can probably calculate what the equivalent exposure at f/5 would be (mine was taken at f/6.3). The skies were approx mag 5.5.
http://www1.iwvisp.com/opticman/astroimages/Pleiades.html
Uh, ignore the horrible framing and background gradient :)
Cheers,
Jason
-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Alen Koebel
Sent: Monday, August 22, 2005 12:54 PM
To: Discussion of Film Astrophotography
Subject: RE: [APML] Poor Blue in 400F?
Well, like I said, the last roll of 400F showed much
more blue response. I shot the Pleiades on that roll
too. Granted, I wasn't shooting with the same
equipment that time - I was using a 300-mm telephoto
at f/5.6. Not accounting for the effects of
reciprocity failure (which works in this comparison's
favor, actually) that should be equivalent to a
36-minute exposure at f/5, assuming my math is right.
My 30-minute exposure thus is a bit weak (and
certainly very weak compared to the usual exposures
people do for this object, I know - at least one hour
sounds about right to me). But not weak enough to
account for no nebulosity AT ALL (not even a hint!),
given the amount I'm seeing on the 45-minutes f/5.6
shots.
Maybe atmospheric conditions explain it.The
transparency wasn't great that night (although the
seeing was superb).
> Hi Alen,
>
> That sounds about right for 400F. At f/5, shooting
> at Pleiades with 400F, 30 minutes is too short for
> the reflection nebula to show up well. I've shot it
> at f/6 for 45 minutes and haven't gotten much. What
> I did get required a lot of histogram stretching to
> be even half-decent. I'd say don't bother with
> anything less than an hour exposure shooting
> Pleiades with 400F.
>
> Unless they are actively trying to, developers at
> the automated photo labs can't screw up slide
> processing, and really can't screw up the negatives
> either. What you see is what you got. Heck I take
> mine to Wal-Mart to get developed and they turn out
> just fine. Scan it and tinker, that gets you the
> good results. :)
>
> Hope this helps,
> Jason
>
>
>
> -----Original Message-----
> From: astro-photo-bounces@seds.org
> [mailto:astro-photo-bounces@seds.org]On Behalf Of
> Alen Koebel
> Sent: Friday, August 19, 2005 6:08 AM
> To: APML
> Subject: [APML] Poor Blue in 400F?
>
>
> I just got some recent 400F slides developed and I
> am
> very disappointed with the blue response. For
> instance, a 30 minute f/5 shot of the Pleiades
> yielded
> NO reflection nebula at all. What the..? I got
> decent
> blue response from the last roll of 400F and
> certainly
> more than this even from E200. Could the lab have
> screwed up the processing? Tired chemicals? I tried
> this supposedly very good lab for the first time on
> the recommendation of a fellow APer, so I have to
> wonder. The film itself was fresh (Dec 2006 expiry),
> was kept refrigerated until the day I started using
> it, didn't experience high heat and I had it
> developed
> a couple weeks after I took the pictures.
>
> You know, even if this isn't a lab problem, I've had
> myt fair share of them (which is why I tried a new
> one
> this time). I'm tired of them compromising, and in
> some cases ruining, my efforts. I think it's finally
> time to take them out of the equation. I hate to say
> it but next year it's goodbye to film for me and
> hello
> DSLR.
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