zds – random thoughts

rhyme and reason :: light + fashion

Leds woven into a knit garment. Results are just gorgeous!

I have for some time been stretching the limits of what can be imaged with a compact camera, so when I managed to break my trusty Powershot A620, I decided it was time to upgrade. I ended up buying a Canon EOS 450d. I has faster burst speed than its cheaper sibling, 1000d, and it bests or equals the other sub-1000€ SLRs in terms of high-ISO-value image quality and overall sharpness of the image. Because I often operate in challenging lighting conditions and print the results in A3+ size, these features are very useful to me.

Naturally SLRs kick compact cameras in large variety of areas, but my first impressions are these:

Damn it’s fast. Taking the 3-image set with -2, 0 and +2 EV takes no time whatsoever. Saving only RAW (not RAW+JPEG) the 450d can shoot around 6 shots with no delay whatsoever between the shots.

4EV range is not that much and getting more range is painful. I got used to the power of CHDK, with which I could shoot as many as 10 shots with up to 3EV between the shots (tho in case of compact camera I ended up using 1EV, more than that and I started losing details). And in images like this, even the 9EV range was not enough:

With 450d I have to shoot manually those series of three images, which with my lousy tripod means the images are not longer perfectly aligned. Which then adds lots of CPU cycles spent and some more manual work.

The extra resolution is very nice to have. The 450d has 14.4 megapixels and the actual resolution is almost as much. Which means I can get to my target resolution of 20MP with 4-6 times less (HDR) frames than with A620. Panoramic imaging requires some 50% overlap to each direction and compact camera could not capture actual resolution even up to the 7.1MP it had on sensor, so to get effective resolution of 20MP I often had to create a source image of 22..28MP and then scale down.

With 450d I can cover the 20MP of real resolution with 2-3 images, compared to 6 to 17 needed with A620. That makes my life a lot easier, and also makes it less likely the scene will change too much during the shooting. Having to shoot like 60 to 150 source images with camera that took couple of seconds per raw shot to save was a bit impractical.

A reduction by factor of 4-6 in frames to be shot is nothing to sneeze at.

Why 20MP is my target? It’s a compromise between print resolution and swap-factor. 20MP is just enough to cover A3+ sheet with 300dpi and anything more and processing speed will grind to halt. Apparently some internal indexes of Photoshop stop fitting to cache of my CPU between 22 and 25MP, or similar, because after that all operations take 10 times more time or more, even when there’s now swapping going on. So 20MP is it.

This image I edited at 28-29MP size and I can guarantee you it was painful:

But.. the results then are sweet. In the print I can see every single detail in almost every leave in the foreground. Lovely!