Re: New Area 51 Photos

Message posted by lone wolf on January 31, 2005 at 12:43:30 PST:

The L-series glass is good, but a good telescope is sharper than a camera lens. Camera lens tend to have many elements in them to make the image very flat. Telescopes sacrifice the flat field for sharpness. Scopes with fluorite are very free from chromatic abberations. [I think the new DO lens from Canon uses fluorite.]

That said, maybe you don't need the sharpest optics if you are photographing over 26 miles of air. However, 1200mm is marginal to photograph the base from Tikaboo. You might be able to stack teleconverters, but don't think that will work with the teleconverters because they stick out a bit beyond the mount. [I have the canon 1.4x teleconverter.] I've never tried this, but perhaps you could put a macro "spacer" after the 2x teleconverter to get more magnification. This trick works somewhat with barlows (which are the same as teleconverters, but designed to fit eyepieces) on a telescope. That is, you can increase the distance from the barlow to the film plane and get more magnification. However, telescopes have a wide focus range, i.e. you can go to what would be beyond infinity on a camera, and maybe that is need for this trick.

This notion that digital cameras magnifiy the image due to smaller sensor bugs me. I read it in the magazines all the time, but if you think about it, the smaller sensor is just cropping the image. Nothing got magnified, rather, somebody stole your pixels. At 1200mm focal length, you will be cropping the top and bottom of the image even if you had the full 35mm format image. With the reduced sensor size, you will be taking more images to make the panoramic, which I don't cosider to be a problem. I have software that does the panoramic stiching automatically, but I find I can do a better job myself in photoshop.

One thing you need to do when shooting a panoramic is to keep the camera in manual exposure. Generally I sample the scene with the exposure meter in a few places,then pick the fastest shuttle speed the camera metering computes. I put the camera in manual at this speed. [I prefer to underexpose rather than overexpose because underexposure can be fixed easier in photoshop than overexposure.] If you don't force the exposure setting, the frame edges may not blend well.

You can scan film at 4000 ppi, and every pixel is sampled in RGB. This is not true with digital cameras, which use a color mask over the sensor. Film is still the gold standard.

You really can't appreciate how low the contrast will be after 26 miles of air. I just did a test shot through 6 miles of air (granted San Francisco bay air which has more moisture than the desert) and the luminosity ranges from 78 to 161 at 1 and 99 percentile points, and this is from Fuji Astia 100F pushed one stop. Thus I am using 1/3 of the dynamic range of the film. I haven't used any high end digital cameras, but if you can set the black and white levels, it will help .

For the drive to Tikaboo, you need to know when to quit. The road goes to hell rapidly.

In Reply to: Re: New Area 51 Photos posted by Kevin on January 31, 2005 at 9:34:13 PST:


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