Shooting the Stars

Hale Bopp Comet

I have to admit profound guilt at having let another cold winter intimidate me from observing the things I love to view. Actually, this winter wasn’t terrible as winters go, but as I’ve gotten older, I notice that braving the cold is getting more and more difficult. But I’m getting ready to re-enter the fray as winter wanes, and this year I intend to get back to some star photography, after years of visual work. If I’m lucky, I’ll even get another chance at a comet, like I did years ago with Hale Bopp. The image above is a piggyback obtained picture I took back in 1997.

As I re-new the challenge of star photography, I’ll start lightly by doing some simple piggyback photography using either (or both) of my old, basic SLR cameras. Those would be my trusty EXA 1A and my Zenit 122K. The cameras are described in detail at my Choosing a Camera web page. With the type of limitations panned by experienced photographers, these classic cameras have precisely the attributes I find useful for star photography. Of what need do I have for light meters, high shutter speeds, and built-in timers when I’m just going to lock the shutter open for a minute or two?

I also hope to take some photos directly through my 6 Inch f/5 Newtonian for some more detailed images. I want to start with the Messier catalog. I have one problem with that, however. The camera setup I normally use to shoot through a telescope uses a telescope adapter fastened to the front of the telescope, as shown below.

Camera with Telescope Adapter

You can see that the lens has been replaced with a telescope adapter, which is just a snout that fits into a standard 1.25 inch focuser. It works great when trying to focus when using Barlow lens projection, but not so great on my 6 inch at prime focus. The problem is I can’t rack the focuser in far enough to focus on the film plane. So, I plan to use the following setup:

Eyepiece Projection Setup

What is shown is my planned eyepiece projection setup. It consists of a .965 inch eyepiece of long focus, which will fit snuggly into a telescope adapter, which will attach to the camera with a T-adapter. The eyepiece can get close enough to focus, and a low power 20mm eyepiece projects an image onto the film plane with about 2/3 the field of view of a prime focus setup. Barlow lens projection can’t give me the field of view that I need.

Eyepiece In Adapter

This is a closeup of the smaller diameter eyepiece fitting into the 1.25 inch telescope adapter, making a nice, compact projection system. I’ve checked the system out by looking at a few targets with my ETX 90, first through a 25mm eyepiece then through the camera apparatus.  It seems to work well, but I did discover that I won’t be able to use anything but the EXA with that configuration. The reason is that I can’t focus through the telescope with a penta prism viewfinder. However, the EXA has a waist-level ground-glass viewfinder option, which does let me focus through the telescope.

Once the camera with projection setup is in place, I won’t be able to guide the telescope, so I’m hoping that tracking will be good enough for exposures up to at least a minute or so. It will be hit or miss, but I think a few good shots can be had. One option I have is to perhaps locate a longer focus projection eyepiece so that the field of view will be bigger, and thus require a bit less accurate tracking.

Copernicus Crater with ETX 90

But as photography is tedious, I’ll also gear up to simply view one of my old favorites — the moon. I love looking at the ever changing views of the craters, like the details illustrated in the above photo from my ETX 90 photos page. The lighting variations of the countless craters bring up fantastic details each time I look. As the ETX link illustrates, I do enjoy some lunar and planetary photography on occasion, and with another summer Mars encounter coming along, I’ll try to be ready for that also.

 

Leave a Reply

Your email address will not be published. Required fields are marked *