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[Andy Resnick]

Moving the diffraction grating to the backside of the lens adapter, I was able to make the spectra appear closer to the source. It seems possible to use the camera as an imaging spectrometer for various sources- here's the sun:

[PLAIN]http://img828.imageshack.us/img828/6797/dsc6607.jpg

and streetlights:

[PLAIN]http://img202.imageshack.us/img202/5695/dsc6629r.jpg

Both of these were taken with the 15mm, and the solar image also contains the secondary spectrum. As expected, the sun provides a continuum while the Hg streetlamps have discrete spectra.

Using the 400mm, I was able to capture the spectrum of Polaris:

[PLAIN]http://img811.imageshack.us/img811/2498/dsc6632d.jpg

IIRC, this was a 1s exposure. On the original, faint spectra from other stars can be seen, but I need to work a little bit to improve things.

It's not clear if I can extract quantitative spectral information from these, but it would be interesting if I could see differences in stars, or measure atmospheric attenuation.

 

[viko]

spherical wave diffraction
:D

 

[Andy Resnick]

I wrote a bit about this in <shameless self promotion> my blog </shameless self-promotion>- by putting a diffraction grating in the light path, you can convert your camera into an imaging spectrometer. Here's a collection I finished up last night:

[PLAIN]http://img842.imageshack.us/img842/2492/spectra6.jpg

The image was downsized to comply with PF guidelines; a larger version with the measured spectra is posted on my blog. Going from top to bottom:

Sun (primary and secondary rainbow)
Incandescent lightbulb
Compact fluorescent lightbulb
Saturn
Porrima

Porrima is the star closest to Saturn right now. My 'spectrometer' has a resolution of about 0.3 nm/pixel, not enough to see a lot of detail, but enough to tell the difference between Saturn and Porrima, and (possibly) the difference between sunlight and the reflected light off of Saturn.

I'm excited about this- and looking forward to capturing Mars when it is in a more favorable position.

 

[Andy Resnick]

Here's some pics of a couple interesting items unearthed from the machine shop. The first one is a 'variac' (a variable AC transformer) that was still in the original 1963 package with a copy of the purchase order. The first image is the whole device with the top cover removed, and the second is a close-up of the windings.

[PLAIN]http://img820.imageshack.us/img820/7466/dsc7664g.jpg

[PLAIN]http://img143.imageshack.us/img143/1796/dsc7671b.jpg

I don't know what this next object is, so I'm calling it "the metatron". It's also never been used, but it didn't have any paperwork nearby. It's very intricate, and I could spend another day setting up other shots.

[PLAIN]http://img121.imageshack.us/img121/2548/dsc7540m.jpg

[PLAIN]http://img31.imageshack.us/img31/8102/dsc7546h.jpg

[PLAIN]http://img823.imageshack.us/img823/2586/dsc7544z.jpg

[PLAIN]http://img846.imageshack.us/img846/722/dsc7545.jpg