Sunday, March 24, 2013
Astrophotography the Old Fashioned Way
If you
entered the wonderful world of astrophotography over the last decade or so, hoo-boy
are you lucky. With your auto-guider
and your DSLR and your CCD, getting pretty pix of the deep sky is just as easy
as falling off a log, ain’t it, muchachos? No,
you say?
Imaging is
and probably always will be the most demanding and frustrating pursuit in the
broad range of pursuits we lump together under the heading “amateur astronomy.”
It’s tough no matter how good your telescope, your mount, your computer program,
and your camera. When it all gets to be too much, it might make you feel a
smidge better to ruminate on what your forebears had to go through. Yeah, in addition
to having to walk ten miles uphill (both ways) through the snow to the
observing field, we had to deal with FILM and MANUAL GUIDING.
But there’s
more to the old fashioned way than that. There’s nothing to say you can’t
employ the same techniques today. Why would you do such a thing? To save money,
mainly. I don’t consider DSLRs expensive, but a film SLR is much less expensive
than any of ‘em. Camera stores are letting their old SLRs go for a song, and I
don’t just mean K1000s. I mean all the way up to the Nikon thoroughbreds. A
perfectly functional Nikon F3, which was once the top of the top of the line,
can be had for 200 bucks or less.
The
drawbacks? Film choices are few and processing chemicals and enlarging paper are
hard(er) to get. But it’s still possible to shoot on film. Some astrophotographers
and a sizeable number of terrestrial imagers are doing just that. You
also need patience to take astro-pix the old fashioned way, but patience is the
hallmark of every successful astrophotographer. So, what is The Old Fashioned
Way like, and what the heck does Unk know about it anyhow?
I was there
almost at the beginning, in the 1960s, right before the amateur
astrophotography explosion of the 1970s. As I have often said, I am far from
being the world’s best astrophotographer. Hell, I struggle to be lousy, but I’ve been at it off and on
for a long, long time and have pretty much suffered every sling and arrow an
astro-imager can suffer.
Why did I
decide to take up deep sky astrophotography in the first place? Two reasons, I
reckon. It was mainly an outgrowth of my fascination with Moon pictures. I’d
had a high old time taking snapshots of Luna. Once I moved beyond the simplest
of the simple, afocal images with my Argus twin-lens box camera and began to
make some headway, the idea of capturing galaxies, nebulae, and star clusters
began to seem not quite far-fetched.
The other
motivator? I had wrapped my mind around the idea that no matter how large a
telescope I was able to buy or use, M33 and the other distant wonders that
fascinated me would never look like they did in photos. Even if I could get a
peep through the guiding “microscope” in the prime focus cage of the mighty
Hale 200-inch, it still wouldn’t be as good, not even close, to what was on the
“plate.” Well, then, I’d shoot deep sky wonders myself.
I did a
little experimenting with my Palomar Junior and my home-brew six inch Newtonians, but the Pal’s store-bought GEM and the
pipe mount I built to hold my sixes were not even close to being up to the
task. They were shaky and were bereft of clock drives or even slow motion
controls. The best I was able to do was some trailed images of some of the
stars of the Pleiades. I went back to the Moon; the deep sky would have to wait
till I had a sturdy mount with a drive.
It took a
few years for that to happen, but it finally did in the mid-seventies with a
Cave Model “B” on what I thought was a Rock of Gibraltar mount. After giving my
big 8-inch a sufficient visual try-out on the deep sky under the black skies of
northern Arkansas, my mind turned to astrophotography. Did I have what I
needed? I wasn’t sure exactly what I
needed, but I did have a telescope, a mount and a camera. One evening I slapped
my Base Exchange-bought Yashica FX SLR onto the scope via a prime focus adapter
and let fly.
The result?
I did get a picture of M42. Sorta. I could see a bright spot near the center of
the frame that might be the nebula. But the stars? Hell, they were just as
trailed as those in my non-driven snapshots of M45. What good was a clock
drive? I didn’t know; I didn’t know much of anything when it came to celestial
picture taking, it turned out. I’d assumed the clock drive was the key. Turn it
on, the scope tracked, and you opened the camera’s shutter and wandered back
inside to watch Three’s Company until
the exposure was done.
I took my
problems to a couple of the Jedi Masters in my club, “You did what, Padawan? You weren’t guiding? For 15-minutes? And how did you polar
align?” I shamefacedly admitted that I didn’t have much idea of what “guiding”
was, and that I’d polar aligned by nudging the mount in altitude and azimuth
till Polaris was in the eyepiece with the telescope pointed north in
declination.
Thus began
my education in astrophotography. First thing I learned was you gotta guide. Few drives then were good enough
to track unsupervised for 1-minute much less 15-minutes at 1400mm of focal
length. Hell, you’ve got to put out major bucks these days to get a mount/drive
combo that will do that.
How did we
guide back then? In the days before DC powered drives, you plugged the mount’s
AC cord into a drive corrector, one
of them electronic widgets whose pictures in Sky and Telescope had so puzzled me when I first began getting The
Magazine in 1965. You then watched a guide star in a crosshair eyepiece. The
“hand paddle” of the drive corrector would have buttons you pushed to vary the
scope’s speed in R.A. (and sometimes declination). It would adjust the
frequency of the current enough to slow down or speed up the R.A. AC motor a
bit, allowing you to keep that star centered in the eyepiece for the entire
length of the exposure. But how did you watch a guide star with the camera
mounted on the telescope’s focuser?
I next
learned what the “guide scopes” they went on about in S&T were for. You
mounted a smaller telescope, most often a long focal length refractor, to the
main scope, usually via adjustable rings. You centered your target in the main
telescope, adjusted the guide scope until a suitable (nearby) star was in the
crosshairs, and began the exposure, trying as hard as you could to keep that
pesky star centered.
So, I’d have
to have a drive corrector, a guide scope, and guide scope rings before I could
get off the ground, huh? I emptied my bank account and bought a Vogel drive
corrector, scarfed up a mount-less Jason refractor at the Little Rock flea
market one Saturday, purchased guide scope rings and a crosshair eyepiece from
one of the ads in Sky and ‘Scope, and let ‘er rip.
How were the
resulting pictures? They were much better, much better. Were they perfect? No,
the stars were still elongated, but at least they were not trails. The prints weren’t overly attractive, either; some where
too light and some were too dark, but I didn’t think that was my fault. I figgered
it was asking a lot to expect Fotomat,
those once crazy-popular little photo processing kiosks, to print astrophotos.
But it was them or the drugstore unless I wanted to go back to black and white
with Tri-X. I wanted color, so the solution would be to process color at home.
Sigh. Someday.
The next
quantum leaps in my imaging results came when I abandoned the Cave for an
Orange Tube C8 and replaced the guide scope with an off axis guider. The SCT
turned out to be better for imaging for a couple of reasons. Most
significantly, its short tube was easier to balance and was less prone to
vibration when winter winds began to blow. The moving mirror focuser of the SCT
was also a Good Thing. The camera was securely mounted since it did not have to
move to focus.
The off-axis-guider
(OAG) also helped. Y’all know I like those things about as much as a case of
the measles, but for long focal length, long exposure deep sky film
astrophotography they were a godsend. When you had to expose each frame for at
least 30 minutes, the chances of flexure—the guide scope moving independently of
the telescope due to the rings not being sturdy enough—was a fact of life.
Flexure caused trailed stars no matter how well you guided.
An OAG,
which intercepts light from the main telescope via a small prism at the field
edge, cured that. Sure, it was hard to find a decent candidate star when you
were limited to scanning the edge of the field—the prism could only extend a
little ways into the light cone or its shadow would show up in the pictures—but
it was still easier to get round stars with one.
Further
improvement in my photos was slower in coming. By the early 80s, I was finally
able to develop and print color film thanks to Beseler’s (kinda) easy to use
chemicals and “2-step” procedure. But I had to learn what a deep sky astrophoto
should look like in the first place. I didn’t get far till an old hand
explained to me that the backgrounds of my images should be dark gray, NOT
BLACK. A rule that will serve you well even today. That seemingly simple thing allowed
me to begin to understand how to print color astrophotos.
What came
next? The Halley debacle. I got a few OK images of the comet with my Super C8
Plus when it was on its way in, but when Halley arrived and the big show began
(or was supposed to have), I failed fairly miserably. The problems? There were
many. The comet was even dimmer than I feared, it was low down in the sky, the
Possum Swamp weather was its usual pitiful self, and I still didn’t like to
polar align using the drift method. I snapped away at f/10, but conditions, my
reluctance to piggyback a camera (real
men shoot through the main scope), and my poor polar alignment meant I came
out with smudges not much better than my first M42.
When Halley
had fled back into the darkness, I was well and truly disgusted with celestial
picture taking and gave up astrophotography for nearly five years. But the bite
of the imaging bug is a lifetime infection they say, and by 1993 I was missing
the smell of hypo and those odd Bessler soups, and was outside taking more Moon
pictures. In 1995 I began accumulating the gear I’d need get back to the deep
sky, including a modern SCT, a Celestron Ultima 8,
and was soon ready for Comets Hyakutake and Hale Bopp. What helped me take some
nice pix of the two comets, and especially the Boppster? Not just the more
modern U8, but a book, and me (finally) embracing piggybacking.
Heretofore,
the knowledge I’d gained of astrophotography had come from two sources: buddies
and my own experience. Neither of which is a bad way to learn, but I lacked systematic knowledge. That was provided
by Michael Covington’s Astrophotography
for the Amateur. It had everything from tables that told you how long to
expose the Moon during afocal imaging, to plans and a schematic diagram for a
drive corrector. It was (and is) the best introductory book ever written for
film astrophotography.
One of the
most important things Mike Covington’s book did was convince me to piggyback,
to mount my Pentax K1000 SLR on the tube of the C8 and shoot the sky in wide
angle fashion through the camera’s lens. Piggybacking made sense for a comet. A
comet was BIG. You needed the comparatively wide field of a telephoto lens to
get the whole thing in. The biggest plus was that at 80 - 100mm of focal length
or thereabout guiding and polar alignment were non-issues.
When my
first Hale-Bopp pictures came out of the print tank I was some kinda happy. They were not perfect—I
had not captured the delicate blue ion tail due to the short exposures
necessary in the light polluted Swamp. But they looked damned good if I did say
so myself. Astrophotography bumbler Rod didn’t get his pictures published in Sky and Telescope’s “Gallery,” but they
did appear in The Possum Swamp Register.
In addition
to piggybacking, one other thing improved my pix: better film. I had always
used Kodak and nothing but Kodak. But then I heard there was More Better Gooder
in the form of an emulsion from Fuji called “Super G 800.” It was fast and it worked well for
astrophotography. The owner of the local pro camera store told me he thought it
was the best color print film he had ever used—for its speed—and, while he
didn’t know pea turkey about taking pictures of the sky, it was so good he
betted it would do a bang up job on that, too.
It did. I
still like the piggyback shots I did with Super G. Its reciprocity
characteristics—its sensitivity decline over the course of a long exposure—were
excellent, it was easy to color balance, and if there was grain in this ISO 800
film, I had a hard time seeing it. It worked so well that for a while I was
flat out piggyback crazy. But in the back of my mind a little voice still
whispered, “Unk, you will not be a REAL astrophotographer till you master
through-the-scope picture taking.”
I resolved
to get back on the prime focus wagon, but this time I would make things easier
on myself. Y’all know I don’t like to spend money, but I ponied up 150 bucks to
the folks behind the table at the (late, lamented) Pocono Mountain Optics booth
at the 1997 Texas Star Party. For a Celestron f/6.3 reducer/corrector.
Celestron
had introduced this widget some years before. What the thing did was speed up your telescope. At f/6.3,
exposures could be 2-½ times shorter than at f/10. The field would be wider,
too. But that was not all. Optics guru Jim Riffle, who designed the reducer/corrector
for Celestron, added in the “corrector” part. The “r/c” would flatten the
scope’s naturally curved field, making stars look better at the edge of the
35mm frame. Sounded too good to be true, but folks I trusted told me it worked
like a champ.
It worked
just great, both for imaging and visual use. Hell, I got some acceptable
pictures of Omega Centauri that very night at the TSP despite haze, clouds, and
high winds. The reducer wasn’t magic, of course. Making the SCT faster resulted
in more “sky fog” from light pollution. I’d just have to do my picture taking
from darker sites once I got back home.
So, when a
new club member stood up at a meeting and said he’d arranged for us to use an astrophotography quality site only an hour from The Swamp, I was
a happy little camper. Why don’t y’all join me in reliving that expedition? Not
only will you see how it went, you will see how an astrophotography run worked in
those days near the end of the film era.
Once upon a
time the paper companies were the lifeblood of Possum Swamp. All the big ones, including
Scott and International Paper, had huge plants here. They were stinky, yeah, but
that was, we said, the smell of money.
The paper plants with their jobs were our saviors when Brookley Air Force Base
shut down for good in 1969. Even after the plants began to leave for Asia a
decade later, their lingering memory remained in tracts of company-owned pine
forest. When the newbie said he had connections that would allow us to observe
from one of those forests, I was excited.
I figured the
spot just might be good enough for serious astrophotography. Looking at the
map, the area in question was almost equidistant between the Possum Swamp and
Pensacola light domes. I didn’t expect “perfect,” just “good enough” for
half-hour exposures of a Messier or three.
So it was
that one Saturday night me, my buddy Pat, and several other Possum Swamp Astronomical
Society members convoyed across the bay to a gas station where we met Joe Newmember
who would lead us to the site. We drove. And we drove. And we drove. One thing
was sure: we would need the dude to lead us out when we were done; there were countless
twists and turns over miles of rutted dirt roads before we got to the spot. My
reaction when we did? “Oh for god’s sake!”
I suppose
what I had envisaged when Bubba told us there was a tree-free area on the land was
a spot that had been clear cut. Uh-uh. The open area he’d found was tree-free because
it was a clay pit. It hadn’t rained in
a while, so at least our vehicles didn’t get stuck in the red dirt, but, almost
as bad, the arrival of the cars stirred up a thick cloud of fine red dust that
lingered.
I had my
doubts, but we’d come all that way, me toting my full astrophotography kit, so
why not give the place a chance? Also, I also gotta admit “full astrophotography
kit” wasn’t anything like a CCD setup today. No computer. No cables. No five or
six batteries. Just the telescope and tripod, the dew shield, the camera bag,
the Star atlas, and the small battery for the Kendrick dew heater. I was set up
in two-shakes. Shoulda brought a tarp to put the scope on and prevent me from
having to kneel in the clay dust, but otherwise all was well.
Until I went
to polar align. The fine latitude adjuster for the wedge tilt plate consisted
of a threaded rod, a bracket, and four nuts, two threaded onto the rod on
either side of the bracket. Somehow two of those nuts had come loose, were way
down the shaft. And the bracket had worked itself loose from the wedge tilt
plate. Basically, the whole cotton picking thing fell apart in my hands. With
the coming of darkness pressuring me, I got fumble fingered and had a hard time
figuring out how to put it back together. I said bunches of bad words, which
were echoed from the other side of the field by Pat, who’d dropped something or
other onto his 24-inch primary mirror.
By the time
I had got the latitude adjuster back together, it was full dark. I could
finally polar align, but I wasn’t in the mood to do a drift alignment. I’d just
use the Ultima’s “polar” finder. The 7x50 had a reticle that, with the aid of a
little round paper slide-rule like calculator, allowed you to do a decent polar
alignment. You set the date and time on the slide rule, and placed Polaris on
the spot on the reticle it indicated.
Worked
pretty well, but only if the finder and the scope’s polar axis were parallel.
You ensured they were by rotating the tube in right ascension, adjusting the
finder, and re-centering Polaris till it stayed dead in the center when you moved
in R.A. I was too antsy to get going to do that, and just put Polaris on the
reticle where the slide rule said to put it.
I liked to
start out on an easy one, and M42 was still visible on this early spring night.
Screwed the f/6.3 r/c onto the rear cell, mounted the Meade (yes) off axis
guider onto that, and attached the Ricoh KR-5 Super II (like an improved Pentax
K1000) to the guider by means of a T-ring. That was the easy part. The hard
part was finding a guide star.
I put a
reticle eyepiece, a 12mm Meade, into the OAG’s focuser. Focused the camera on a
bright star, and focused the same star in the OAG’s guiding eyepiece. Which was
not easy. Even the brightest stars were dim in an SLR viewfinder. They were
derned near as faint in the OAG eyepiece.
Focus
achieved, it was on to M42. Centered it in the camera viewfinder and went back
to the guiding eyepiece. I was lucky a useable star was in view. Often I had to
loosen the ring attaching the guider to the scope and rotate the OAG around the
back, “scanning” for a guide star on the field periphery. If I couldn’t locate a decent
star, I’d have to move the scope till I could find one, which would result in
the imaging target being off-center. It was a constant battle to keep the deep
sky object in the camera frame while seeking a guide star.
Hokay, almost
ready to roll. Next step was to attach the remote (cable) release to the camera
and double check that the camera’s exposure was set to “B,” which would hold
the shutter open when I depressed and locked the cable release. I am guessing I
am not the only film astrophotographer who ever shot an entire roll of “long
exposure” images with the shutter speed at 1/100-second.
Then the real
work began. Using the hand-paddle, I centered the guide star on the reticle and opened the shutter. The work was keeping that rascal centered. If it
drifted the slightest amount, I had to press the hand paddle button that would
move it back where it belonged. Immediately. The slightest deviation would
result in an off-round star. I had to be sure I pushed the correct button, too;
the image would be ruined if fuzzy-headed me mashed the wrong direction button
at 3 a.m.
The biggest challenge
was doing that for the duration of a long exposure. No 2-minute “subs” in them
days, younglings. For the brighter objects, you wanted 30-minutes at f/6.3.
Dimmer stuff? You’d be sweating over that guide star for an hour. I was lucky
in that my scope had PEC, “Periodic error correction,” the ancestor of today’s
PERMANENT PEC. The difference was that I had to redo PEC every night—once the
drive was turned off, the recording disappeared. I’d guide for one full
rotation of the worm to record my corrections and then playback the PEC file for
the rest of the night.
It was well
worth it to spend a few minutes doing PEC “training,” since it meant that
momentary distractions would not usually result in a ruined picture. I still
had to guide, but I could take my eye from the guiding eyepiece for a few
moments—to swat a mosquito, to scratch my nose, to see what Bubba next to me
was hollering about—and still get a good shot.
I kept going
until the kitchen timer that was one of my most important astrophotography
accessories dinged at the end of 30-minutes. What then? Rested for a few
minutes, had a swaller of coffee—no Monster Energy drinks in the Dark Ages—and
did another shot of M42. I still like to take “insurance” shots of my subjects,
but it was especially vital in The Day. Now, I can usually tell whether I’ve
got an object “in the can” by looking at the finished CCD or DSLR exposure on
my monitor. It will look rough, but I will be able to tell. In the film age,
you wouldn’t have any idea whether you’d got a good one or not till the
negatives came out of the soup the next day.
And so it
went. I essayed three subjects that night before the combination of blowing red
dust and weariness got to me. I did a little visual after that, had some looks
through Pat’s big-dob, and then our new pal decided it was about time to call
it a night. I can’t say I was sorry. If there is a worse observing location
than a clay pit, I don’t know what it is. Best thing? Back then gear tear-down
was quick and easy. In about an hour and a half I was once more within the
comforting halls of Chaos Manor South. “Never again,” said I, and we never did
go back to that fracking pit. Our friend moved away in a few months anyhow. His
heart had been in the right place, but, gee
whiz, A CLAY PIT?
My results
when I developed and printed The Clay Pit Astrophotos a while later? As usual,
then and now, “OK, pretty good. Some problems.” My impatient refusal to do a
good polar alignment resulted in some trailing due to field rotation, and there
were spurious reflections generated by the reducer/corrector I should have
fixed in the darkroom. I could bear to look at the pix, though, and can still
bear to look at ‘em.
Does film astrophotography
sound like torture? It really wasn’t, muchachos. It sounds at least a little
worse than it actually was, and once you got into the groove it could even
be—dare I say it?—fun. It’s
certainly possible to still practice the art today, with a few dodges and
workarounds regarding film, paper, and chemicals, and I might have a little
more to say on that some Sunday if’n y’all don’t mind.
Next Time: My Favorite Star Parties: TSP '97...
Comments:
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A very interesting installment about shooting film, Uncle Rod. But I am not certain about the opening statement, that photography is the most demanding pursuit within amateur astronomy. To most amateurs, the challenge of photography is primarily technological (getting the equipment to work); the challenge of visual observing is primarily personal (trying to see). Neither is inherently more difficult. Seeing a detailed galaxy as a featureless blob is not demanding; imaging the detailed galaxy as a featureless blob is not demanding either. Astrophotographers are just not as content with fuzzy blobs as visual observers tend to be. One reason is that it is the nature of man to be demanding of a machine.
The challenge in imaging is _getting everything to work right_ and it can be very tough. Yes, visual observing requires skill, but at least you don't have to worry about them dadgummed egg-shaped stars. ;-)
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