April 28, 2011#

DSLR.Bot and Venice HDR Images

In the on-going battle between Nikon and Canon owners as to which camera is better, one feature that I, a devoted Canon owner, have lamented is Nikon’s ability to bracket to 5 images as opposed to Canon’s 3, which becomes a real drawback when making High Dynamic Range (HDR) images. But now there is a new iPhone/iPad app that allows me to extend the number of images captured for HDR to as many as 20, and I have only begun to experiment with it.

Daniel Rucci told me about DSLR.BOT, a $5 app for your iPhone or iPad that gives you remote (via infra red) control of your camera for regular shooting, long exposure, time lapse, HDR and video. It has some pretty cool features like Geo Tagging in Shoot mode or creating an exportable shot list in Movie Mode, and as I explore this app more I may post about the other features, but the Bracketing mode is what I was initially excited about.

HDR photography is based on capturing identical images with bracketed exposure values so you can, in effect, extend the dynamic range of your camera. This can be done by altering the aperture, the ISO or shutter speed on your camera. You don’t really want to alter the aperture in this case as you want your depth of field to remain the same. Altering ISO is a viable option, but you will incrementally increase noise throughout the bracket. Changing the shutter speed is the most reliable method of producing HDR images, and this is where DSLR.Bot shines because it uses an infra red signal to control your camera’s shutter, and allows for up to 20 brackets per image.


The interface is pretty simple: you set the number of brackets you want, then you set the shutter timing for the first and last frames and DSLR.Bot fills in the rest. There are a couple of drawbacks to this app and the first one becomes apparent here, as the fastest shutter speed available is only .3 of a second. I do a lot of my work at night and with a fat stop so this is not a huge set back, but it is very limiting if you want to do any daytime work. According to the developer this has to do with IR signal processing and won’t get any faster.

The other really cool feature is the ability to create HDR time lapse with the repeater function. Simply set how many times you want it to repeat and the delay between each bracket. In the illustration I have it set to repeat 96 times with a 30 second delay which, at 24 frames per second, would compress 45 minutes of action into a 4 second clip.

I mentioned this app uses Infrared signals, but there is no IR transmitter on the iPhone or iPad. The solution is very simple and cheap. I followed the instructions from Instructables and made a transmitter that plugs into the headphone jack, using parts I bought from Radios Shack for around $4. You could also by one from the developer for $20 with shipping.

So, with my newly made IR transmitter and iPhone in hand I went to the beach to try it out and created the two images below.

I think the developer came up with an ingenious way of controlling a DSLR but I’m not sure I would trust IR for a daylight shoot, as the very next day after making the images above, I tried it out during the day and had a problem getting the app to trigger the camera in daylight. That aside, this is a great app. There is a ton of functionality built in and it is very easy to operate. I am glad people are thinking up ways to integrate the power and portability of the iPhone with our cameras and it is important to support them in their efforts. For the price of this app, you can’t afford not to have it as part of your kit.

*UPDATE* I found a way around the problem of using IR during the day by simply using some black camera tape to attach the IR LED’s directly to the camera in front of the IR sensor. It blocks out the daylight and lets the camera see the LED’s. So far it’s worked perfectly.


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