Mark's Blog about Tech and Cool Stuff

Any modern DSLR camera supports (or should support) predictive autofocus tracking. While they might have this capability, there is an art to using it effectively, and therefore getting in-focus shots of moving subjects. This is actually something I only learnt on the 19th of August, 2009.  Yes, I remember the date, it's an important date.  This is after having a DSLR many years, and never being able to effectively shoot moving subjects.  I would resort to doing things like: Stopping down , therefore increasing the depth of field, such that the moving subject might still be in focus. Increasing the shutter speed ('cause clearly I didn't understand the difference between motion blur and just plain out-of-focus). Pre-focusing in front of a moving subject. These can give acceptable results, but why not get the camera do what it's supposed to do.

Time-lapse movies are cool.  Especially when they are really professional looking.  Some of my favourite time-lapse movies are made by these people: Tom @ TimeScapes Philip Bloom Ross Ching I've made a couple of time-lapse movies which you can find in high-definition on YouTube .  Perhaps not in the same league as those guys, but it's still fun and rewarding anyway. I hope to do a lot more, and have recently learnt some new techniques to maximise battery life and minimise wear on the camera. On a SLR camera, every photo causes the mirror to flip up, the shutter opens and closes, then the mirror flips back down.  Being moving components, the mirror and shutter have a finite lifetime.  During a time-lapse you may be taking thousands of photos, therefore reducing the life expectancy of your camera. These techniques can be used with the Canon 7D and 5D mk II cameras (and possibly others) to reduce mirror and shutter activations. Live View mode eliminate...

The ISO setting on a digital camera controls the gain applied to a digital sensor (making it appear more sensitive to light) - in the same way that ASA film speed specified the film sensitivity. Having previously owned a Canon 20D, I was familiar with traditional ISO values (associated with powers of two), for example: ISO 100, 200, 400, 800, 1600. Due to my computer background I had assumed that boosting the ISO was achieved through bit-shifting - or digital amplification/gain.  It turns out that this is wrong.  ISO gain is achieved by analog means prior to analog/digital conversion.  That said, ISO expansion modes such as ISO 12800 on the Canon 7D and ISO 3200 on the Canon 20D are achieved by digital gain (bit shifting). My Canon 7D supports fractional ISO values such as 125, 160, 250, 320 etc.  There has been discussions circulating on the Internet saying that the 2/3 of a stop values result in less noise.  While there is an apparent loss of noise, t...

TVersity has built-in support for photographic raw files, using dcraw to perform transcoding/conversion on the fly. Unfortunately the dcraw (version 8.88) included in TVersity version 1.7.4, does not support the Canon 7D camera. Pukkita's Digital Darkroom Corner has more recent builds of dcraw.  There are actually two versions, and type which works on my system (the file dcrawMS.exe ) still does not contain Canon 7D support. Instead, I've got a version from LibRaw .  This is not exactly the same.  The file dcraw_emu.exe is mostly compatible - but does not support the -c option (which TVersity uses).  This option is used to force output to stdout.  I've modified dcraw.bat to handle this incompatibility: @echo off echo TVersity is converting a raw digital camera image ... dcraw_emu.exe -w -h %1 move %1.ppm %2 Of course, once TVersity is updated, then this will no longer be necessary.