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Canon T2i/550D Practical Video Review

4volt — Fri, 26 Feb 2010 10:58:56 GMT

I got my hands on the Canon T2i and I ran it though it’s paces, the things I was most interested in was the video modes and low-light performance.

To see the HD version downsized to 720p, you have to load the video from vimeo directly: Canon T2i, 550D Practical Video Tests.

T2i Vs. 7D

First a quick word about the T2i vs. the 7D. The T2i does not have that pro-feel that the higher level cameras have. The body is fairly light and it is most defiantly made of plastic, and you can tell when you hold it. For me that is not a big deal, it’s not worth nearly double the price to step up, though I do see the appeal.

Compared to “real” video cameras

In general I’ve been very impressed with the video shooting mode, in practice shots are easy to setup and the manual control works great. This camera lacks some features that a pro video camera may have, like a smooth auto focus, XLR audio inputs, and a power zoom.

Paired with a decent lens I feel that the video quality is just as good as the Canon XH-A1, a $3,000 HDV camera that I used in my last video shoot. In fact I would wager that the T2i is better in low-light, but I have no direct comparisons to show.

About the video codec

Video is captured in h264, at a high bit rate that is variable between 40 to 60 mb/s in 1080/30p and 1080/24p. I was unable to see any noticeable compression marks.

Needless to say, the video files are huge, order extra SD cards. A 4gb card is good for about 8 minutes of footage. Even though I knew that the files are big, I was surprised when the “No Space on Card” error came up, and it did twice while I was testing.

RAW still photos are about 20mb each.

I do wish that the camera settings like shutter speed, aperture and other EXIF properties were saved into the video, or at least the settings when video recording started. This is a minor issue barely worth mentioning.

Live View

A important feature for me is the ability to preview footage as it’s being shot, Live View mode in the EOS Utility works well, and a laptop would make a decent field monitor. The downside is that when recording the live view slows down to about 10-15fps, and motion is not a good representation of what is being recorded.

Another possibility is a HDMI field monitor, though I suspect a decent one would cost more then a average laptop.

When using live view and recording footage, the video file is written to the SD, not to your computers disk.

Capturing Video

Capturing video on the camera is easy and the manual controls are more familiar to me with my photography background then the manual controls on a pro-video camera.

Things that I wish it has was a live audio monitor and histogram, but those are minor things.

Auto-focusing is something that you will want to avoid when taking video, each time I tried this the lens over focused before it found it’s place. USM lenses are better, but I will probably still manually focus in most cases.

There is also a handy magnification button you can press for detail focusing that switches your live view on the lcd to 5x and 10x magnification.

Edit: You can start movie shooting with a remote, but you have to use the 2-sec delay setting on the remote, "immediate" mode on the remote takes a photo.

Another feature I missed is the power zoom for those very slow zooms, doing a slow zoom by hand is fairly difficult.

Audio

I have not yet had the chance to do detailed tests on audio quality, but my old Rode VideoMic works very well with it.

When the rest of my gear arrives, I may do another review of just audio qualities.

Editing Video

My computer is relatively good, a dual core 3.2 with 4gb of memory, a 4-disk raid 10 array and a GeForce 6200, and I've never had issues with editing 720p mpeg2 video. But my computer just doesn't have the power to keep up with the 50mbit 1080p stream. The video is fairly watchable in VLC, but in Premiere Pro 4.0 playback is very slow, perhaps about 3-5 fps. Editing this demo video was very tedious.

I’ll be looking to options for a new video card, and see what plugins are available that may be able to help.

Demo Video

See the video at: http://vimeo.com/9753969 (Or above)

I’m also publishing some of my test videos in a little collection. Most shots were done with the Canon 50mm f1.8 (non-usm) lens. The extreme close up shots were done with the same lens with a screw-on macro adapter.

Their is also one shot with the Sigma 70-300mm f4-5.6 lens.

It was important to me to do tests without any expensive specialty lenses. I believe both of these lenses are valued under the $100 USD mark.

All of these shots were setup in 5 minutes or less, on special rigs or setup was needed.

Room lighting is 4x65w flood bulbs, recessed.

No lights were used in the lit candle shots.

A 14w CFL desk lamp was used in the candle smoke shots.

Shutter speed was 1/30sec for all shots.

Conclusions

This is a great camera for a great price, it’s not perfect, but there’s also no un-resolvable issues.

JP Image Book 2009

4volt — Mon, 22 Feb 2010 09:42:56 GMT

Every year I release a small “Image Book” of my favorite pictures, images and art. Some of the images I’ve published here, some are new to you.

To see last years edition see: Image Book 2008

As always I’m releasing the PDF for free, download and enjoy it.

I also have a printed version in limited quantity, and if you like my work and want to support what I do. I’m offering a printed version of this book as a thank-you for US donors, while I still have supplies.

Soon I'll be buying a new camera, my old camera is now about 5 years old, and has served me well over that time, but it is time for a new one. Any money you donate, I'll put right towards that camera.

So donate and and I’ll send you one! Be sure to mention it in your note, and include an address.

Otherwise here’s the files, download and enjoy:

Image Book 2009 (Print Quality, 56MB)

Image Book 2009 (Web Quality, 12MB)

The “Cheap and Easy” Photo Backdrop

4volt — Mon, 11 Jan 2010 08:50:00 GMT

Every now and then everyone needs to take a photo of something small, there’s an easy (and cheap!) way to get a great looking photo with a white background.

As soon as you see the technique, it’s hard to forget, it’s a plain white poster board propped up against a wall or whatever you have handy. Fill your camera’s view with the poster board and take the photo.

For lighting you’ll need a reflected flash or some bright lights, but that is not the focus of this article. I’ll soon do an article on my flash bouncer.

Below are a few photos of the setup, it’s easy to understand once you see it in action.

This technique works great for smaller items that are not too shiny. If the item is too big, you’ll have a tough time covering the edges.

If the item is shiny you’ll be able to see in the reflection of the object the rest of your room and camera. For those kinds of things a light tent would be better. (and more costly)

Warning Label Generator

4volt — Wed, 19 Aug 2009 20:32:43 GMT

So today a friend of mind sent me this image, I’m not sure where it came from exactly, but I knew I need one for my laser room.

After doing a quick search for examples to make mine, I came across this Warning Label Generator site, it’s not new, but is useful.

You can choose the sign type and an icon, and enter your own text. A custom graphic might be better, but this is quick and easy.

That is all.

Abandoned House

4volt — Tue, 21 Jul 2009 07:19:18 GMT

A few weeks ago I had the opportunity to take a bunch of photos in a turn of the century abandoned farm house, and it was very cool. It was out in the middle of nowhere, Minnesota.

The house was in disrepair and was pretty treacherous, but not seriously dangerous. Some walls were smashed, garbage strewn around, and there were trees that had not been trimmed back in years. But no graffiti or fire damage.

Check out the full galley here: Abandoned House

Also, if you’ve been missing the lack of cool new DIY projects and laser related goodness, it’s because of a house remodel that’s been taking up all my extra project time. But, I do have some very cool stuff in the works, so stay tuned.

Photos: Running a exposed hard drive, and then ruining it

4volt — Mon, 06 Jul 2009 05:31:11 GMT

Way back in 2002, I ran an experiment with a hard drive to see how durable the inside actually is, mostly curious to see how easy it is to ruin a drive.

In the 2nd above photo you can see the drive arm moving, all of these photos were taken while the drive was being used in a live system.

We removed the cover of a old IDE hard drive and proceeded to format and install windows. We didn’t make any attempt to protect the drive, and the office we worked in at the time was pretty dusty. The format and install did work with some errors, and eventually we got the computer to boot in safe mode. The computer worked but just barely, it was plain to see it wouldn’t last for long.

After that crude test, we decided to take it to the next level and pour water into the running drive, mostly just to see what would happen. We covered the live pc with plastic, and took some other electrical safety precautions.

We started with just a few drops on far side of the arm, the water more or less sprayed right off of the moving platter. Later I made a quick calculation and found that the edge of the platter at 5400rpm moves at an estimated 56 miles per hour (90kph).

After the water the drive arm moved wildly, and eventually went back to the edge. A few quick tests showed the hard drive had more or less failed at that point, but continued to spin and try to seek. Since most of the drive electronics are on the circuit board underneath, that’s not too surprising. Although if a drive fails catastrophically, usually they stop the spin. I’m sure it would be possible to retrieve the data if the drive heads were not damaged.

After the light dousing, we decided to pour the whole glass on the drive, and like before it more or less just splashed off the drive, but was exponentially cooler.

In the end it was just for fun, and it produced some interesting photos.

John Aho’s 3rd PSCombine Set

4volt — Fri, 22 May 2009 16:15:34 GMT

It’s been a while since I’ve posted anything PSCombine related, if you are not familiar here is a short blurb:

PSCombine is a program that will import your collection of images or photos and randomly combine them in Photoshop with a random blending, opacity, and filters. I like to think of it as "Computer Assisted Art".

It’s free to use, all you need is photoshop, go check out the PSCombine project page for more detail. If you have a PSCombine gallery let me know, I would love to see it.

John just posted a new gallery on flickr and I wanted to post my favorites here.

Pi Pie

4volt — Mon, 18 May 2009 05:43:01 GMT

This isn’t incredibly unique, but while searching for photos on another post I wanted to share it with the world. It’s a pie, with the number of pi around the edge, plus the pi symbol is carved in the lid.

Also, apple pie is awesome. I want some now.

Modifying Micro Servos for Continuous Rotation

4volt — Sun, 19 Apr 2009 04:29:43 GMT

There are many ways to power your next project but I’m quite partial to the continuous rotation servo because it’s very easy to hook up to your micro controller, you don’t need to build or buy a separate controller or h-bridge to power the motor. In a servo all that is built in. All you need to do is connect the power directly to your battery and send a low-voltage control signal to tell it what you want it to do.

Servos out of the box are meant to rotate in a fixed range of 180 degrees, but modifying them for continuous rotation is easy, my first servo took about 30 minutes, and now I can do them in about 15 with no problems.

Take the back cover off
You’ll need a small jewelers screw driver. There is one long screw in each corner.
Take out the gears
The gears will slip out easily from the casing, you may need a small pliers for the main (largest) gear.
Make sure that the largest gear has teeth all around the outside of large part of the gear. I've recently come across some micro servos that do not have teeth all the way around and are impossible to modify for continuous rotation.
Cut the mechanical stops off
Usually there is a small tab on the inside of the gear cover, easily removed
There may also be a stop inside the potentiometer, since the pot is essentially also the axel you’ll have to leave it in, but make sure that it can rotate all the way around. You may need to snip off some small metal tabs on the inside of the pot.
Add some resistors
There are three wires coming off of the pot, snip all three off and solder two resistors starting from the middle wire, connecting one to each of the other wires. In these photos the wires are Green Red and Yellow.

I used 1.75k resistors, but your servo may be different, use a multimeter to determine what is best for you.

Note: I hoped to take to pot off the axle and glue it into it’s center point, but that’s impossible with most micro servos since the axle is part of the pot.
Re-assemble
Center

The one thing about modifying servos for continuous rotation is that when you use the resistor method it's likely that they are not perfectly balanced. You can tell if you have that problem when the center PWM value sent to the servo and it starts rotating, when it should be stopped. I use the SoftwareServo.h library that lets you adjust the center PWM value to compensate in software

If your using the Arduino, here is a script that uses the SoftwareServo library and a loop to continually adjust the “setMaximumPulse” property on the servo object.

Upload the sketch, open your serial monitor pane, and wait for the servo to stop spinning, when it does write down the last number shown in the serial monitor and use it in the setup of your servo. For more details see the script source:

Continuous_Rotation_Servo_Test.pde

Jansen Walker: The story so far

4volt — Sat, 18 Apr 2009 07:33:42 GMT

Update Note: While I'm keeping this post for historical value, this post is not kept up to date with my Jansen Walker, look at the Jansen Walker project page for the latest details and plans.

Original Post:

If you’ve been following my posts lately I’ve been putting a bunch of my time into a robotics project that uses the Jansen mechanism for movement, if your not familiar look below for an animation.

I've spent quite a bit of time on the mechanical design on this robot, maybe more then was strictly necessary since I used this opportunity to learn SolidWorks, and since all the parts are laser cut, absolutely everything must be modeled.

The pictures you see here are from the assembly of the 2nd prototype and so far I'm pleased with how it’s turned out. I've successfully driven it around on my coffee table, but very little electrical work has been done on it yet other then a closed-loop test script.

I’m still planning to publishing the plans open-source style as soon as I’m happy with everything. there’s also the possibility of a kit in the works.

Videos and more details soon, so stay tuned.