The Canon 450D is a consumer model DSLR camera, which offers great value for astrophotography without breaking the bank!
Canon 450D
Also known as the Canon XSi, the 450D is perfect for use with a Time Machine because it has a great APS-C sensor, it has relatively large pixels, and it pairs well with the kind of lenses that you're likely to use with it. Meaning, it won't excel at taking great pictures of planets, and it won't excel at taking wide-field pictures of large structures like the Andromeda Galaxy, but it will take great pictures of just about everything in between. Especially the Moon and the Sun (when done safely). It's also dirt cheap used, has modern USB connectivity, and will still work with every EF and EF-S lens that Canon has ever made. So you can use it for weddings, wildlife, and astrophotography!
Technical Specifications
The Canon 450D was released in March of 2008 and despite being almost 17 years old (as I write this) it still works like a champ. Especially for astrophotography where the specs are less important than the quality of the sensor. Here's some of the specs that matter most to Astropotamuses:
- 12.2-megapixel CMOS sensor (4272 x 2848)
- DIGIC III image processor
- 14-bit analog-to-digital signal conversion
- Live View mode
- ISO 100–1600
- Canon EF/EF-S lenses
- SD and SDHC memory card file storage 32 GB max
- File Formats include: JPEG and Canon RAW
- USB 2.0 computer interface
- Approximate weight 475 g (16.8 oz)
What That All Means
So 12MP might not be a lot by today's standards for a camera, but for use with a Time Machine, it's all you need. Even some of the most popular dedicated astro-cameras are less than 10 megapixels in resolution. Why? Because it's not about the number of pixels, it's about their size and sensitivity. The DIGIC III processor is also old by today's standards, but we don't need auto-focus, scene selection, eye-tracking, and all those other things that most people want in a camera. We just want a great sensor.
And that's what's in the 450D. With 5.1um pixels this is a good size for most astro-imaging purposes and with a good telescope and a good mount you can do some amazing Astrophotography with this combination. In fact, you don't need a telescope, you can just stick a normal camera lens on the end of it, get a good photographic tripod and take widefield images of the night sky that will dazzle everyone who sees them. The sensor will let you choose a good range of ISOs and the 10x zoom on the live-view mode will help you get crisp focus.
Expectations
Let's say you have a reasonably affordable 400mm/f5.6 camera lens to put on your Canon 450D. According to our favorite tool for computing Astrophotography Fields of View we can expect the Moon to look something like what you see to the right. That's pretty good! It fills just under 5% of the field of view of the sensor, which means that it's filling up about 0.5 mega-pixels. All thing considered, that's a fair amount of data to work work and if you have more advanced optics, you can get even closer!
This doesn't mean it's the perfect camera for everything, though. When I first started, I used my 450D for lots of things and that also meant a Celestron C8. While I was still learning how things worked and it wasn't my best work, I will say that it was a troublesome combination because that telescope is actually too big for this camera. It leads to something called "over-sampling" and means that you have to have a really good mount. I did not have a really good mount at the time, so my pictures were always a little soft. Luckily, there are things you can do to compensate for that (I finally got a really good mount) and using a Focal Reducer will help with that a lot, too.
Conclusions
I still have my Canon 450D and I still use it. I have a Rokinon 500mm/f8 catadioptric lens that I have hard mounted with a Rigel Systems auto-focuser that is my go-to combination for Moon photography now. You can see what that looks like on the right. This is about 0.8 megapixels, or about 60% more pixel coverage than with the 400mm/f5.6 lens mentioned earlier. Plus, with the auto-focuser, the computer can handle all the details, the mount can track, and the whole thing takes great Moon pictures (and Sun pictures, too, since the Sun and the Moon are the same angular size as seen from Earth).
If you can find a Canon 450D on an auction site, a thrift store, or online vendor for less than $100, you will be hard pressed to find a dedicated astro-camera that will do more for you at three times the price!