Telescope Reviews: What are the advantages of film astrophotography?

Interesting thread. Just a few random things to add...

1.) Film works by sensitizing the emulsion with heavy concentrations of photons per unit area. This means that f-focal is a key component per given aperture. HOWEVER, f-ratio doesn't have the same effect when the aperture changes. While the light cone remains the same steepness, f/10 on a 14" scope is hammering the film with MANY more photons than at f/10 on an 3" scope. So, film photography at f/10 is perfectly feasible if you have enough aperture. Sometimes I think we forget all the great shots taken of smaller objects taken by guys like Philip Perkins over the years with "slow" SCTs.

2.) Film photography isn't always without a larger startup cost. Yes, an old SLR can be cheap, but inevitably you start sinking more money into it when you figure out that you can't focus such a camera with the cruddy focus screen...which leads to knife-edge, ronchi, and even expensive camera prisms. I ended up putting more money into my Nikon F2 setup than even a new Digital Rebel once you add up the accessories.

3.) Film can yield great results, even today. While DSLRs are really popular right now, its not necessarily true that they can produce better images. I've seen some really good film stuff out there over the years...and while there is some good stuff being taken with DSLRs (especially modified ones), I've yet to see anything that total blows away film images.

4.) I don't think anybody has mentioned the importance of really dark skies with film. That's the advantage of digital cameras...you can shoot them in lesser skies, if needed. Even so, nothing beats dark skies, regardless of the media.

5.) Astrophotography is difficult...period. It was hard when shooting film, it is hard shooting digital. Better equipment and shorter focal lengths does yield a higher rate of success, but there is a certain amount of expertese to all types of imaging. Heck, just because you have $60k worth of high-tech equipment doesn't mean it works by itself. Just like any computer system, it must first be programmed...and that requires somebody who really knows what they are doing, able to speak the "language" of the system and able to troubleshoot all the problems that come up.

6.) I've always said that FOV is highly overrated. Unless all you care about is wide fields, then small CCD chips will work very well...looking at Mark Sibole's images with the DSI, that fact becomes quite obvious. Now, that might sound weird coming from a guy with 6.3 and 11 megapixel astro CCDs,

but for the most part such real-estate is quite often wasted, especially once you begin to specialize on specific types of objects. In such cases, resolution can be more necessary than FOV. So, while film and DSLRs do have really nice FOVs, I think we tend to overvalue that quite a bit.

7.) The cost of film, including processing and digitizing, isn't all that cheap. I'd agree that film is cheaper to start with when compared to a CCD, but at some point you WILL start to spend more than the CCD you could have had to begin with. Again, remember that you don't need the same FOV CCD chip to make the comparision, but rather the one you'd need to accomplish your goals. For example, after two years of E200 or 400F photography with a Nikon F2 (with "C" screen and DW-2 6x finder), you've spent quite a bit of money, especially if you image a lot. By that time, you might have spent so much that you could have purchased an SBIG ST-2000, in either single shot color or monochrome CCD...a camera that can shoot a lot more objects than film or DSLRs. Or, considering the success that can be had with a DSI-type camera, I don't think you should get into film images solely because of the cost savings.

8.) With reference to the last point, you can take as many images as you want with a CCD, throwing away what you don't like. Likewise, it costs you no extra money when you do want to shoot lots of shots with a CCD. The value of that is in FEEDBACK, which I believe is the most important aspect to improving in the hobby. You just don't get that with film.

9.) With film, print size is determined by the emulsion size...at some point, you will see too much graininess. But in the digital world where you can resample an image before printing, you don't need larger chips...merely good, well sampled data. I've got _portions_ of my CCD images that I could crop and blow up as large as I want and it'd still look great. I've seen 24" x 48" blow-ups from 2 to 3 megapixel cameras that would blow your mind...the better the quality of the image, the better it will enlarge for print.

10.) Autoguiding is hard to do. Great autoguiding seems almost impossible sometimes. Either way, it's a big accomplishment, not without lots of effort and know-how.

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jay
www.allaboutastro.com