Thursday, December 26, 2013
Sadly my 300mm lens and 8 megapixel sensor isn't going to produce an image any bigger than this. I do wonder how much better this would be if I used a film camera and one of the 1,000mm mirror lenses that abounded in film days. In our conversion to digital we have lost so much variety in lenses. We have concentrated solely on the shorter lengths with the maximum commonly available being 400mm. That, of course is far too short for a lot of the fun stuff.
We have also lost our handy-dandy exposure tables. Had I been doing this in the days of film I would have had access to an exposure table that would have told me that the lunar surface had an EV of f11 and 1ISO. It would have then told me adjustments that should be made for various phases of the moon. There were whole guidebooks of exposure values for various scenes. They're almost impossible to find now though. Thus, it's back to experimentation.
The lunar image above is 595 x 482 pixels. That, off a sensor of 3456 x 2304 pixels. That's 1/27th of the image area. A longer lens would have increased the moon's size on the image area. Certainly we could use a sensor with more pixels but that's not really the point. The point is that a 300mm lens is too short for good moon photos. 400mm is not really any better.
What we need ideally is a telescope and a T2 adaptor to put our camera onto the telescope. Sadly, few of us have telescopes and fewer the ability to set the telescope to track the moon. The moon really travels quite fast and it gets faster the longer the telescope you use to view it. The lunar motion is very different from stellar motion so most astronomical tracking mounts won't work.
This is a fun project for somebody out in the wilderness with loads of time, some tools and the enthusiasm to put lots of effort into taking really good lunar photos.
at 11:03 PM
Errant Brit roaming the United States armed with a Webley MKIV, a camera and a bevy of gorgeous women sharing his Aston Martin.... Oh phooey - what a load of codswallop. I'm out with my camera when I have time and blogging when I'm home.