Barnard E on Tmax 400 at GSSP 2023

 Finally Scanned the Tmax

The only thing I scanned last night - had to re-learn how to scan, update Silverfast, update photoshop, and update lightroom.

Jim Cormier suggested using Tmax 400 for a few reasons: 

  • It's available in 4x5
  • At durations up to 10-15 minutes is faster than Acros
  • Beyond this duration it holds up well

I am surprised that two or three satellites still showed up on the film.  It might be due to the 400 speed catching the bright objects easily.  There's a cat whisker on the film, plus some dust and a scratch or two.  I can also see two of my fingerprints - evidence of sweaty fingers in the dark bag.  Not a big deal.  The satellites don't bother me at all because they actually help frame the dark nebula of interest.

As I say on the flickr page, my notes from the event suggest that I was shooting this at F6.  However, the coma in the corners suggest that it might be shot wide open at F5.6 (or whatever  this lens can do).  I will take a look at the lens itself to see if the aperture has been changed in the two months since the trip.

What I find interesting about this shot:  
  • As a two hour exposure - no trailing or field rotation visible, even with the full scan.  
  • The corner coma is balanced in each corner, letting me know that there is no lens sag and that the field of view is centered.  I will need to confirm focus 1/3 out from the center to minimize the coma.  
  • This is an unfiltered shot - no yellow filter to tighten the stars.  Might be useful to revisit this target at Calstar with a filter to compare results.  
  • Also, I think that I can see film grain - evident at the full size scan which resolves to 4 microns per pixel.  The full size version visible on flickr does not show the grain.  If anything, it might show the mottled background of barely resolved stars.  

Pretty happy with how it looks and this bodes well for the color shots.