35mm Astrophotography Basics

Hi, my name is Jenny and I've been an astronomer for the past 6 months. Three months ago I spent $1500 on a Celestron C8S-GT 8” go-to Schmidt-Cassegrain telescope and now I want to try some Astrophotography. I have a budget of $600 to do this. What should I buy and how do I do it?

Recommendation

Based on the telescope you purchased and your budget, I am recommending that you pursue astrophotography via a 35mm SLR film camera. The primary reason for this is it allows you to photograph almost anything the sky has to offer without the need for a computer or complicated image processing techniques. Why not a digital camera? Good question, there are many digital photography options (web cams, specialized CCD cameras, digital cameras, etc) available to you but these methods are either cost prohibitive or require a PC/Laptop as well as a certain amount of computer savvy. For example, an entry-level CCD camera designed specifically for astrophotography will run you about $1000 plus. Web cams and your basic consumer digital cameras are mostly limited to the moon and a few planets unless you are very computer savvy.

Your shopping list

Your are going to be buying equipment that will allow you to participate in two methods of 35mm astrophotography. Prime Focus and AFocal (otherwise known as eyepiece projection).

• Olympus OM-1: Discontinued model. Can be purchased used at your local camera store or on eBay for about $150.
• Celestron T-Ring (Part # 93414): Couples your camera body to a T-Adapter. $14.00 at handsonoptics.com
• Celestron T-Adapter (Part # 93633-A): A T-Adapter allows you to attach your camera to the prime focus of your telescope. $27.00 at handsonoptics.com
• Meade flip-mirror (Part # 647): Helps you center and focus your target. $249.95 at www.astronomics.com
• ScopeTronix Digadapt (Part # STDADPT): Allows you to photograph through your eyepieces. $69.95 at www.scopetronix.com
• Spiral Bound Notebook: This is for your record keeping. $1.00

Preparations

• Ensure that your telescope is properly polar aligned. You should already be familiar with this process.
• Be familiar with the camera. Know where each button, knob and switch are located
• Be familiar with how to load film (especially in the dark).
• Read the manuals that came with each piece of new equipment that you purchased.
• Practice assembling and disassembling your new equipment.

Method 1 – Prime Focus

In this method you attach your camera body to your telescope by using the t-ring, t-adapter and flip-mirror. This essentially uses the telescope as the camera’s primary lens. The term "prime focus" is derived because the image is being projected directly onto the film at the point of focus.

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Method 2 – AFocal (eyepiece projection)

In this method you utilize your eyepieces by inserting an eyepiece into the ScopeTronix Digadapt and attaching your camera body. Being able to use your eyepieces means being able to photograph at a greater magnification. Through the use of the flip-mirror you can easily center and focus your target.

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Camera Setting Tips

• Set focus to infinity
• The brighter the object the faster the shutter speed. For example, the moon shoots good at 1/250 or 1/500.
• Lock the focusing mirror (this will help eliminate vibrations caused by the mirror)
• Film with ISO speeds of 200 to 400 works good

First Night Out

I am not going to give you a blow-by-blow here because I think it stifles creativity. If you have read the manuals the came with your new equipment you are more than ready to put your new equipment to the test.

• Experiment with different shutter speeds.
• Experiment with different film speeds.
• Experiment with different eyepieces.
• Experiment with different objects.

As you are experimenting make sure that you are documenting what you are doing. An entry in your log may look something like this (do what works best for you): 1- 4/14/03 10:30pm – My Backyard – Crescent Moon – iso 400 – 1/250. This would read 1st picture of roll on 4/14/03 at 10:30pm. Taken in my backyard. Subject was crescent moon. Film Speed 400. Shutter speed 1/250.

Practice! Practice! Practice! Just as with any type of photography the more pictures you take the better you will get. And the more you experiment the quicker you will learn what works with your equipment and location and what does not.

Additional Help

An excellent book on 35mm film astrophotography is Astrophotography for the Amateur, by Michael A. Covington, Cambridge University Press. It provides a wealth of information on basic techniques and it focuses on 35mm film photography.

Clear Skies