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Showing posts from February, 2010

Learnings (Part 3): Using Predictive Autofocus

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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.

Music of Manolo Camp

I've been looking at Creative Commons licensed music for use with my videos.  There are a number of licenses, but typically they allow sharing and use in non-commercial products.

There is a lot of web sites dedicated to free music, and I've found some music by Manolo Camp that I really like.  Here's two web sites with his music for download:
Opsound.orgccMixter.orgFor example try Morning Coffee or Ships in the fog.  I'm already picturing some video that I can shoot for that second track.  Anyway, hope you like it.

Update 11/12/10: I've published my first video using Manolo Camp's music "Medieval". I think the music really adds polish to the video.

Learnings (Part 2): Time-lapse battery, shutter and aperture life

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 @ TimeScapesPhilip BloomRoss ChingI'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 eliminates the mirror flapping since the v…

Learnings Index

Remember when you were young and you used to know everything.  Yeah, me too!

Now, even when I'm an expert on a subject, I'm constantly learning new things.  I guess it seems more profound or gratifying when you do have an in-depth subject knowledge, and then discover a new dimension.

This is a collection of things that I've learnt, and hopefully they're things you'll find interesting too.

I'll add to this post when/if I learn anything else.

The index:
Part 1: Fractional ISOPart 2: Time-lapse battery, shutter and aperture lifePart 3: Using Predictive Autofocus

That's it for now.  Check back later.

Learnings (Part 1): Fractional ISO

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, this actually a result of over ex…