Mike Cohen

Photographing the moon

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When I attempt to take a photo of the moon, it usually comes out as a featureless white blob, due to being overexposed. Thanks to a tip on Flickr, I discovered that the secret to taking a photo of the moon that doesn’t suck is to use spot metering rather than matrix.

With matrix metering, the camera will use both the dark sky and the bright moon to determine the exposure, which usually ends up overexposing the moon to avoid underexposing everything else. Spot metering lets you use only the moon to determine the exposure, which avoids the usual blown out appearance.

Moon & Star

For this shot, I used my Sigma 70-300mm lens with shutter priority. Since I wasn’t using a tripod and this lens doesn’t have VR, I used a shutter speed of 1/250 with ISO 3200.

iDjembe News

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I have been working on a major update to iDjembe for several weeks. The major new feature is Virtual Drum Circle, which lets you broadcast to other players on the local network using Bonjour.

I’ve also drastically improved the responsiveness, and in the process learned a lot about iPhone audio. The current version uses the simple Audio Services to play the sounds, which has some major limitations such as being able to play only one sound at a time. Since the samples have a long trailing end as they fade to complete silence, during that time it isn’t possible for any other sounds to play, which makes it unresponsive.

I did a lot of experimentation with different sound APIs and I’ve settled on using OpenAL which seems to give the best performance and is the least ugly.

In the current version, I handle taps in a single view, where I do my own hit testing to determine the location to decide which sound to play. I’ve changed it to use custom buttons, which performs just as well and gives a nice highlight effect for the tapped area.

I hope to have this update out in 2 weeks or less.

links for 2009-02-26

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  • Public Data Sets on Amazon Web Services (AWS)
    Public Data Sets on AWS provides a centralized repository of public data sets that can be seamlessly integrated into AWS cloud-based applications. AWS is hosting the public data sets at no charge for the community, and like all AWS services, users pay only for the compute and storage they use for their own applications. An initial list of data sets is already available, and more will be added soon.
    (tags: web reference free ec2 aws datasets research)

Safari 4 is a winner

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After trying Safari 4 on another machine yesterday, I got brave enough to install it on my main system today. I still don’t care for the tab bar at the top of the window, so I used these patches to restore the old style tab bar and the blue progress bar.

I find that Safari 4 is a lot faster than either Safari 3.x or Firefox 3. It also uses a lot less CPU than any of the other browsers. So far I haven’t seen any crashes or incompatibilities. New versions of SAFT and 1Password were released today, so I have all of the functionality I’m accustomed to.

Simple fix for 1Password & Safari 4

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When Safari 4 was released today, a lot of people reported that 1Passsword won’t work with it. Since I rely on 1Password, I was very reluctant to upgrade. The developers of 1Password came up with an easy work around, which must be re-applied with every 1Password update until they officially support Safari 4. I came up with a simple automatic patcher, which you can download here, including full source code.