Timelapse shutter speed rule of thumb explained

The widely accepted rule of thumb for shooting timelapses is that your shutter speed should be 1/2 your interval. What this means is if you are shooting one shot every 3 seconds, then your ideal exposure is 1.5 seconds.


The point of shooting timelapses is to end up with video at some point, right? Film cameras have dealt with this issue for some time now. In a film camera, a piece of film rapidly advances one frame, stops, is exposed to light, then the exposure stops, the film advances and the whole process begins anew. This process can occur 12, 24, 30 or more times per second. The camera needs some time to move the film into position, so it spends some time with the shutter closed (moving film) and then it spends some time with the shutter open (exposing film) The standard for a long time now has been to spend half of the time exposing, and half of the time moving film (not exposing.) On film cameras the shutter is often on a shaft and rotates through the film plane. Thus a 180 degree shutter literally is a half circle that blocks the film from getting light half of the time.

180 degree shutter


Well, that’s still a good question. Digital cameras can go from practically 0 degrees up to literally 360 degrees. The big difference is in what it looks like. Motion blur is what this is really all about. Regardless of your exposure or frame rate, a shorter exposure will have less motion blur on it. On the flip side of the coin, a longer exposure will have less action occur when the lens is ‘closed’ and it will look less strobe-like. The balance between those two things is how people decided on a 180 degree shutter, and that brings us back to shooting stills.

When shooting a timelapse, if your shutter speed is smaller than half of your interval then your video will start to look strobey. What I mean by that is that there is a continuity gap from one frame to the other. If the video is of a car driving, then the distance that the car moves between frames will increase and the resulting video will look jumpy.

If your shutter speed is larger than half of your interval you will end up with more motion blur. Trails will occur behind moving objects. This is generally less of a concern because our minds are much less confused by trails than by strobing. Strobing can be dissociative, while motion blur is more like an artistic statement.

In conclusion: Like all rules, this rule of thumb is meant to be broken but it can never be ignored.

Addendum: When you are shooting video in movie mode, this should also guide your shutter choices. If you shoot 720p 60, then you should have a shutter speed of 1/125, and if your are shooting 24fps, then it should be 1/50. Feel free to deviate but know what will happen if you do.

Canon 7D firmware 2.0 and 2.0.3 released

Canon released firmware v2.0.3 for the 7D recently. Go here to find it. It fixes some things broken by the 2.0 update.
The 2.0 firmware enables a bunch of new features. Here is the canon site explaining everything. My favorite options are the higher burst rate, higher max iso, and the manual audio levels.

Oh, and while you’re at it – check out Magic lantern on the 7D. It’s finally making some progress!!

Magic Lantern on 7D! with Video!

I was about to put up a post about the new 7D firmware v2.0.3 from canon being released, but it was eclipsed by some amazong news. Over on the Magic Lantern site it seems that User g3gg0 has figured out the weird dual-digic configuration and has been able to run a hello world test on a 7d! It is not a fully developed release (not at all) but it is GREAT news, and an awesome step in the right direction.

UPDATE – Magic lantern just tweeted this video. It mainly shows the overlay window, but it also shows focus trapping. Even a tiny step is great, but this is a HUGE STEP!

I’ll DEFINITELY keep you updated as this develops. I donated to Magic lantern a few weeks ago, but I’m about to re-up! Here’s that link again, just in case a little $$ will get this first release out the door faster!

CHDK Compatible Powershot G series cameras

G series
The G series is really the jewel in the powershot line. All of the cameras from the G7 on up have metal bodies, full manual modes, and are built with dials and buttons in order to allow you to use the manual mode without going through any menus. Most of the cameras have a threaded ring around the lens that allow you to mount (a few) accessories like a wide angle lens. These cameras also all have hot-shoes for mounting flashes just like a dslr. Even broken, these cameras will sell for a few hundred dollars. If you can get your hands on one of these affordably, then jump at the chance. The listed price is the lowest (usually used) price on Amazon.

G7 CHDK 10 6 y 2.5 2005 dpreview.com


G9 CHDK 12.1 6 y 3 2007 dpreview.com


G10 CHDK 14.7 5 y 3 2008 dpreview.com


G11 CHDK 10 5 y 2.8 2009 dpreview.com


G12 CHDK 10 5 y 2.8 2010 dpreview.com


G1x CHDK 14.3 4 y 3 2012 dpreview.com


As with every camera purchase, you’ll need to make sure that you end up with an appropriate memory card (or two), a battery, and charger. If you buy new this is less of a concern, but a lot of these cameras are only really available on the used market so keep an eye out for what accessories are bundled with the camera.

Go Back to the CHDK compatible overview page

CHDK compatible Powershot A series cameras
CHDK compatible Powershot ELPH series cameras
CHDK compatible Powershot S series cameras
CHDK compatible Powershot SD series cameras
CHDK compatible Powershot SX series cameras
CHDK compatible Powershot G series cameras

How to use SDMInst to install CHDK

Let’s assume that you have already used ACID to find your camera’s firmware and then download the appropriate CHDK build. Now we are going to use SDMInst to format your sd card and then move the CHDK build onto it.

If you are running Mountain Lion (10.8) then go here in order to figure out how to start up the app. Other versions can simply double click it.

First, select your memory card from the “Select card drive:” dialog. You will know which one it is by its size in comparison to the others, and the name in the “SDM Volume:” field. You may not even have any choices. I happened to have a lot of mounted disk images that showed up as options. Next click on the browse button, or drag the directory containing your CHDK build into the “Copy all files from” box.

Finally click on “Prepare Card” and watch it do its magic. Eject the card, lock it, and then put it in your camera to test!

How to find the firmware version of your Canon Camera

In order to install CHDK on your memory card you need to know what version of the firmware your camera is running internally. This happens to be blissfully easy due to an app called ACID.

ACID stands for Automatic Camera Identifier and Downloader. It was written by Dave Mitchell and is one of three great CHDK-related apps that he hosts. Not only does this app find your camera firmware but it also will download the correct CHDK version for you! Note – you have to move the app onto your computer for this to work. It can’t download anything if you run it from the .dmg.

The next step is to use SDMInst in order to format your card and upload the freshly downloaded CHDK build to it!

Installing CHDK on a SD card in osx Mountain lion 10.8

I just tried to properly format an sd card and put CHDK on it for the first time since I upgraded to Mountain Lion. I ran into a bunch of trouble. Ill put the steps I used to fix it here so that I can save you the trouble!

At first I used macboot but I ran into an error that I could not fix. If you want to use macboot, then jump to the bottom for the resolution.

Next I used ACID in order to look at a jpg from the camera and determine the firmware version in use. It wasn’t causing the error, but I wanted to make sure that I was using the correct version of CHDK for the Powershot A490 that I was using. ACID is pretty slick, and it worked exactly as described.

SDMinst is an app from the makers of ACID that will format your sd card and then copy over the appropriate CHDK files.

Now generally I don’t read very much documentation for apps that have GUIs. These three apps all have clearly marked buttons and that was enough for me. The one thing that would have saved me an hour was that macboot and SDMinst both have trouble doing what they need to do in 10.8 due to permissions. i.e. they both need to be run as root. I’m sure there are people who would be concerned about giving root to an ‘untrusted’ app, but I wasn’t in this case. Dave Mitchell is the writer of all three apps, and he has also written small terminal scripts in order to open them as root. Here is the script for SDMInst. Here is the script for Macboot.

If this is your first time, then here is a tutorial for finding your firmware version, and here is one for installing CHDK using SDMInst

How to buy a CHDK compatible camera on amazon

I LOVE CHDK. It lets you do so much cool stuff on canon powershot cameras, from shooting timelapses, to enabling RAW file options, to shooting video on cameras that never had video before. For the uninitiated, CHDK is an alternate firmware that your camera loads from the memory card. That keeps it relatively safe and allows you to reset your camera simply by switching the memory card! I’ve been using CHDK on and off since 2009, and I recently decided that I wanted a new camera to play around with. One of the toughest things about finding a good camera to run chdk on is that most, but not all canon cameras are supported. It is really hard to find a canon powershot and KNOW that it is compatible with chdk without doing a lot of work. Earlier today I had a tab open with the CHDK FAQ and a page open on amazon. I kept switching back and forth to find a good resolution, well featured chdk supported camera at a good price. That meant I had to keep a lot of info in my head. I quickly gave up on that and made this whole slew of amazon product links. It’s not the absolute best (that would be a database of megapixels, features, and price) but it definitely helps to hone in on your ideal price point.

Just in case you came here looking for a suggestion: go for the G series if you can swing it. They are amazing cameras in a small package. On the other hand – if you are dropping that much coin you might want to consider going for a dslr and running Magic Lantern on it. Magic lantern is like chdk, but coded explicitly for Canon’s dslr line.

On the other end of the line if you are just beginning and you don’t know how useful this will really be, don’t feel bad about buying an older camera. I would even recommend buying it used, but make sure that you get the charger and battery with it. Even if you get a mid level camera you will still end up with a better camera than the phone in your pocket!

Note: I’ve done my best in order to keep this clear and correct. I strongly urge you to cross reference any camera that you find with the CHDK FAQ before you click buy. So without further ado, here are the links. I plan on keeping it updated, so if it is useful – spread the word!

It seems as if Amazon doesn’t love the idea of having a solid page of ads, so they may have blocked them. I will break it up into separate pages by camera family in order to see how they feel about that.

CHDK compatible A series cameras
CHDK compatible ELPH series cameras
CHDK compatible S series cameras
CHDK compatible SD series cameras
CHDK compatible SX series cameras
CHDK compatible G series cameras

How to easily test in-camera sd card speed

This is a cross-post from my other blog you down with fcp because it seemed just as applicable here. Go there for final cut pro related tidbits!

I picked up a canon t2i the other day to save some timelapse-related wear and tear from my 7D. Unlike the 7D, the t2i uses sd cards. I was really happy to find out that sd cards in general are far cheaper than CF cards, but I quickly realized that some cards are better than others, even when they have the same specs. I was inspired by this post over on peta pixel to run a quick test. This isn’t a very broad test, but I tested all the cards I could scrounge up.

In order to do this, I just popped in an sd card and fired off 15 shots. I recorded audio of the camera firing and then compared the waveforms in final cut.. The quick cards bogged down significantly less than the slow cards. You can see the in-camera buffer get filled up after 7 shots, and then the real test begins. The gap between shots is now due to the write speed of the card. The end of the green bars represents the total amount of time that the card spent writing buffered data. Since I didn’t line them all up starting at time=zero the numbers to the right of the green bar represent the total time to shoot 15 shots.


Sandisk extreme class 10 45mb/sec 32 Gig – 9 Seconds

PNY professional 20mb/s 32 Gig – 15 Seconds

Sandisk Ultra II 2 Gig – 17.75 Seconds

Sandisk 1 Gig – 26.20 Seconds


What does this mean? Well, it shows the comparative speed of different cards I have available to me. You may get drastically different numbers based on your cards and cameras, but you will probably still show the same trend. I wouldn’t even think of using the slower smaller cards for video, but this certainly puts some data behind that feeling. For stills the speed really doesn’t effect me very much, but it is crucial for video. If I’m shooting hd with a high iso (lots of detail make a hard to compress image) then I absolutely need to have a fast card. Of all of the cards tested, the Sandisk extreme class 10 45mb/sec is a clear winner for dslr video. It is 166% the speed of the pny card, despite only being 120% the price. If I were a stills-only shooter, then I would consider trading volume for speed.

In the future I’m interested in testing out different priced cards in the same class to see what the speed / price curve looks like. Lastly, it brings up the interesting idea that a slow enough card can almost replace an intervalometer. My super old sandisk 1Gig card took almost 3 seconds between shots! That could make for an acceptable time lapse interval in a pinch. Do you have a brand that you love or hate? post it in the comments and I’ll try to see if I can test it.

Note – I know that there are much more precise ways you can actually test cards using a computer. I don’t want that. I wanted to test both my camera and sd cards simultaneously.

DIY Rotary turntable

I have wanted to build a rotary turntable for quite a while. With it I can shoot 360 degree product shots, I can set the camera up on it and shoot panoramas. I can use it with my timelapse setup to put motion into a long shot. I also have an idea about trying to use it to build a masterlock picker!

There is a stepper motor connected to a sparkfun easydriver via an arduino (not shown) The motor has something like 1.5 degrees per step and it is geared down heavily via the rubber belt, so it is very precise.

I used a table saw to cut this notch. Not something that I would recommend for the faint of heart.
Here is the easy driver on the breadboard.

This shot shows the bottom of the board. I used a “lazy susan” bearing from Home Depot to keep the turntable rolling smoothly. One thing I did wrong is that it was mounted several times while I was sanding or grinding and I definitely got a bit of grit in the bearings.
more info after the break