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Old February 16th 19, 03:17 PM posted to sci.astro.amateur
corvastro
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Posts: 19
Default Let's Photograph Comet 46P Wirtanen

On Sunday, December 23, 2018 at 4:30:39 PM UTC-8, hleopold wrote:
On Dec 22, 2018, Davoud wrote
(in article ):

hleopold:
...Always a joy to see your photos, David, I look forward to more in the future.
I mostly read here, hardly ever comment. Not to mention I am jealous of your
set-up, though not of your location, as bad as our seeing is here you have
it worse.


Your words are kinder than I deserve! I have complained here about
Maryland sky conditions from time to time, but not too bitterly, I
hope. I try to take it with equanimity; I get what I get and I try to
make the best I can of it.


As, for the vast majority of us, we all must.

Same for my vision. I am 74 years old and I have macular degeneration.
My corrected vision in my left eye is 20/25, i.e., very good. But over
the past few months I have noted a deterioration in my right eye to the
point where I cannot read with my left eye covered. My ophthalmologist
referred me to an optometrist who specializes in low vision. My right
eye can't be "fixed," but a new pair of glasses, coming in about two
weeks, will help.


Age eventually gets us all, I am only 67, in 3 weeks to be 68, and my eyes
just ain’t what they used to be. Of course in my case I have to go back to
when I was 12 when my eyes went from practically perfect to very near-sighted
and very strong astigmatism in both eyes. Correctable but slowly getting
harder to focus as I age.

Good that I'm not a visual observer; I can still
focus on a laptop display, but faint fuzzies don't work for me in an
eyepiece. I use a Bahtinov mask on my Tak 106
https://www.flickr.com/photos/primeval/30364292358.


Way back in the late 70s early 80s I did, for a while, try photography with
my scopes, but otherwise I have been strictly a visual observer. I can’t
believe the great stuff that we have these days. I am not really a fan of
digital photography in many ways, I loved shooting film, and that was how I
did astro photos back then. Used a home-brew camera and cut my 35mm film to
single frame. My camera was much like one that was described in Sky and
Telescope back about that time, starting with a short extension tube and
built up the body out of flat sheets of black opaque plastic glued together
to hold the film in place plus a dark slide to take the shot. If was fun, but
fairly frustrating at the same time. At that time I did most of my
photography using B&W film, so I was able to do my own processing. Not really
an easy thing to do on a Navy ship. About once a week I would take over the
head for our dept. berthing area to do processing. Even at night the light
leaks were ridiculous, I used a lot of black tape every time. And hoping like
everything that no one needed to use it for the few minutes while
transferring the exposed film to the tank. Yeah, I did used a changing bag
but you probably know how that works.

These days, though, I just mostly like to look at things through the scope.

--
Harry F. Leopold

The Prints of Darkness (remove gene to email)


You could have used one of the various methods that I used in my youth which allowed me to use a standard 35mm camera - so I didn't have to cut up individual frames of film.

1) Afocal - focus telescope for visual use, mount camera focused at infinity, then do fine focus with telescope eyepiece.

2) Projection - I experimented a bit with positive projection. That involves just mounting the camera without a lens, then focusing the telescope eyepiece further out to move the primary image to the camera focal plane.

3) Direct Objective - what I finally chose, but it took a lot of work as my telescope was a reflector. I think it would have been even more difficult with a refractor. I had to move the primary mirror forward a bit to make the image plane accessible, use a larger secondary to capture the whole light cone and a larger diameter eyepiece holder(2") to keep the lens tube from blocking some of the cone. This produced by far the brightest and sharpest images. The primary disadvantage was that I needed to use a short extension tube for my eyepieces when doing visual work. But since I had installed a 2" lens holder, I needed an adapter anyway so my 1 1/4" eyepieces would fit..
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