Larry, I’ve got Tom’s diffraction grating and software. It works quite well. I used it last year during the ALCON affair in Bryce. It works as advertised. Some video cams and CCDs require a small spacer between the diffraction grating and the camera barrel you are screwing it into to observe the entire width of the spectrum. However, you can rotate the spectrum within Tom’s software and put it into the viewing area diagonally to make up for any part of the spectrum that leaks out of the visual frame. Up to a point. Unless you have calculated the length of spectrum you would obtain with your particular setup (I think Tom’s site has an algorithm for this if I remember, correctly) it would be wise to purchase the spacer. It’s not very expensive. Just in case. Tom did a great job with the software. Fire it up before you go out and work through the tutorials. It seemed very intuitive to me and my skill with telescope accessories is almost zilch. I really need help with the CCD learning curve. Everything I do looks like crap. I may go back to the spectrum-chasing business just to feel I have had a productive night with some toys. Dave