16 Inch Meade DS-16A advertisement, mid 1980's.
Me and astronomy go back. Way back! The Apollo missions were the catalyst for me and at the tender age of 12, I managed to buy everything I needed from the Calgary Centennial Planetarium to grind and polish a 6 inch f8 telescope mirror. I finished it in 1973 at the age of 13 and was hooked! It wasn't until 1985 that the astrophotogrphy bug bit me. And it bit HARD! With Halley's comet coming up I decided to shut down a couple of other hobbies and to put all my efforts into astrophotography.
Back in the day, the magazine ad that caught my attention was the full page ads from Meade for a 16" f4.5 Newtonian telescope that was apparently optimized for taking pictures. So, without the benefit of Google, Amazon feedback or even a chat group, I ordered one. It arrived late 1985.
The first thing one notices with this kind of scope is that it is much bigger than it looks in the magazine ads! And it has weight too, lots of it. Mine weighed in at 240 pounds or about 110KG and it filled the back of my 1973 Chevy truck. But I was still in my 20's at this time and wasn't going to let the sheer size of this beast beat me! I learned how to polar align the scope using the drift method, loaded up my Olympus OM-1 35mm SLR camera with film and off we went!
And the pictures were terrible. None had round stars! In reviewing the ad I didn't think I was doing anything wrong. It said "Exposure times so short you don't really need a drive corrector or guide telescope..." so I polar aligned, slapped the camera on, focussed and hoped for the best but the best never came. I then began to understand why people used a "guide scope". This was another telescope bolted to the main scope that allowed you to see what was going on when the shutter was open. So, I went down that path. I picked up a 4.5" SCT telescope, a pair of rings and mounted it to the main scope. Well... that didn't work! The DS-16 had a cardboard tube which as you can imagine isn't terribly stable. The guidescope mass would cause the cardboard tube to flex and introduced all sorts of errors. Sometimes the pictures turned out worse than if I had done nothing at all!
By this time I had picked up a "reticule eyepice" which is a fancy name for a high power eyepiece with crosshairs in the field of view which were lit by a red LED. This allowed you to see if your reference star is being tracked properly. The idea is that if you guide the reference star well enough, the stars in your picture will be nice and round. Great. Except that didn't work either! I quickly discovered that I had two problems to fix. There was a slow drift of the star due to the weight of the guidescope against the cardboard tube. The other was that the accuracy of the drive gear system was total rubbish. To fix the guidescope problem I scrapped the idea completely! I sold that scope and got something called an "off-axis guider". In a nutshell, this device sits between the telescope focuser and the camera. It puts a small prism in the light path and deflects a sample of the light entering the camera to my guiding eyepice. Essentially, the same optical system is used for taking the picture and guiding.
So there it was - a custom drive corrector that not only could handle the massive drive gear errors I had but it could also power up a small B&W TV in the field as well! I made the joystick pinout compatible with Commodore 64 joysticks, thinking that I would never run out of them. Finally, I was on my way to getting good astrophotos... but only on some nights! Still many issues to wrestle with. First, the scope itself was working against me! This is a big scope, I knew that. But I didn't fully grasp the fact the Calgary skies, often riddled with Chinook winds, can cause problems with bigger scopes. Something we call "seeing". The best nights are when the stars do not twinkle and the atmosphere is stable. Well, that just doesn't happen in southern Alberta! Due to our proximity to mountains we often get many thermal gradients which cause stars to be twinkly, fat and blobby. The bigger the scope, the more of an issue this is. OK, blobby stars then. In addition, the scope presented a huge surface area to the wind so any breeze moved the scope causing streaked stars. No amount of clutch tightening or tweaking of the Meade mount would fix this and I did eventually downsize the scope to an 8" Newtonian. On the same mount, many of these problems went away but that is another story!
So, now that I had the scope working fairly well on many nights, I thought the hard part was behind me. Not so fast!! I had simply moved down to the next layer in the astrophoto onion. FIlm itself was becoming a big problem! Not all films worked well and how well they worked changed with the seasons. I will be putting up more pages on how I dealt with just the film problem. What I found was that in late spring 1986, when still cold, I could get a pretty good shot in about 15 minutes. But come summer, I could not duplicate the results at all. This was due to something called "reciprocity failure". The rule of doubling exposure time to get a picture twice as dense only applied to a short range of exposure times. Typically a few seconds to 1/2000th second or so. I was exposing for many minutes on faint objects and time/density relationship completely failed. And, it turns out that the warmer it is, the more pronounced the failure! Late summer of 1986 is when Simon Hum of Quasar Optics introduced me to hypered film. The idea is that oxygen and water moisture is baked out of film and replaced with an inert hydrogen/nitrogen mix. This reduces reciprocity failure! I took his advise and used a hypered fine-grained B&W film called Kodak Tech Pan 2415. It responded to hypering well, had fine grain and responded well to the deep red of nebula. I quickly learned to develop 2415 at home which ultimately led to a full blown darkroom at one point! By this time I had also figured out, with the help of the few other people I knew taking astrophotos, that there were a few brands of film that worked well without hypering. (Those people include Geoff Kennedy, Russ Chandler, Carl Savage and Jim HImer)
So wow, what a journey 1986 was! From terrible beginnings I managed to work the problems systematically and managed to get some OK pictures from my setup. Some of those pictures are below. In addition, I had identified where I needed to focus my attention in order to improve both my technique and the capabilities of my equipment. Namely a smaller scope on the same mount, better darkroom technique and down the road, a better drive gear was obviously needed. But for now I was happy! I ended New Year's Eve 1986 taking pictures on hypered tech pan through my 16" scope. What a contrast from pictures taken 9 months earlier!
| Home - New - Comets - Solarsystem - Nebula - Galaxies - Clusters - Messiers - 110 - Odds - Equipment - History |