Re: [APML]: NGC6334 for Steve Bell

[Chuck Vaughn <aa6g@aa6g.org>]

Steve Bell wrote:

> I suppose the blocked up part is the top portion of the lower left
> nebula of the 130EDT shot? If you'll note, that area in the 7" shot
> shows more detail, but at the expense of not recording as much of the
> overall nebulae.

I can't get it with my scanner and it's very hard to print too but the
detail is there on the negative. It's simply a problem of finding a way
to transfer the full dynamic range of the negative to another medium.
Nothing I suppose a drum scanner couldn't cure. :-)

On the other hand, I'm not saying I've *never* blocked up Tech Pan, just
not in this particular case. I don't count stars since I'm perfectly happy
with white stars.
 
> You know, I have a feeling an 11" RA drive is in my future.

Better pick one up from Byers before he retires soon. I heard it's the end
of this year and he's selling off his stock. I wonder why someone else
doesn't pick up the business? There's certainly a demand for it.

> But wasn't the original intent to show the difference between hypering
> methods? So, with the more fairer comparison shots, are you attributing
> the big increase in overall nebulosity recorded on the 5" shot due to
> using your new super-duper hard vac TP? Ie, if you would have used the
> hard vac TP with the 7", and done everything else exactly the same (same
> location, same exposure time, etc), do you think you would have gotten
> as much as the 5" shot?

Yes to everything! I would expect those two photos to be equal.

> And in reference to my previous question about recording a mag 8
> globular with *un* hypered TP during a 1 hr exposure, I'm real curious
> if you have any thoughts about that. I'd like to get a feel for just how
> much hypering TP really helps. I know it does, and I could do the test
> exposure myself, but if anyone out there knows how poorly un-hypered TP
> works for long time exposures from personal experience, I like to hear
> about it.

Sorry, I forgot. My experience with unhypered TP was by accident and was
very poor. Before I started testing every roll of TP I got a hold of a
couple unhypered rolls. They record very, very little. I remember a 
1 hour exposure with my old 300mm-f/4.5 lens and H-alpha filter of
Gamma Cygni on one of those rolls. It recorded about 100 stars and
no nebulosity! It looked like about a 1 minute exposure on hypered TP.

Can you photograph an 8 magnitude globular on unhypered film? With a
scope as large and fast as yours - probably, but don't expect much.

I've done a few experiments in my yard which is worse than yours - I
haven't seen any of the Milky Way in 10 years - and the best luck I
have is with the lens at f/2.8 or f/4 with an H-alpha filter and I
develop the film in HC-110 Dil. B or D76. It lets me expose longer
while holding the fog to a more reasonable level. The H-alpha interference
filter is considerably more effective than the Lumicon filter but it
sounds like your conditions are not as bad as mine.

Chuck  <aa6g@aa6g.org>