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Category Archives: Technical Discussions

The Sky is Falling and the Light is Leaking: the A7r Anti-Massacree

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Anti-Massacree - A humorous anti-war movement from the 1960s, suggested in the Arlo Guthrie song Alice’s Restaurant. The song, like many of my posts, was criticized for being overly long. Believe it or not, I’m mostly a lurker in online forums. I read the hysteria of the day mostly for my own amusement. Sometimes I type a [...]

A 24-105 Comparison

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Sigma has been releasing one great lens after another for a while now. Some, like the 35mm f/1.4 and 18-35mm f/1.8 zoom, have created feeding frenzies soon after (or even before) their release. Others, like the 24-105 f/4 OS, haven’t created a whole lot of fuss. So I thought we would do a little optical [...]

Examples Using an Optical Testing Station

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OK, I’ve done a couple of posts about critical focus for testing, and setting up an optical testing station.  This post will provide some demonstrations about actually using it. I’m going to use lenses that we optically adjusted back into proper alignment as examples. I’m doing this because it’s a great opportunity to show you [...]

Setting Up an Optical Testing Station

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There are a lot of right ways to do optical testing. The gold standard is to put the lens on a $150,000 optical bench or run it through a well-equipped Imatest lab. But unless you have an optical bench or Imatest lab handy, that’s not practical. We have to optically test around 400 lenses a [...]

Why You Can’t Optically Test Your Lens with Autofocus

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By far the most common email and PM I get basically says, “I think my lens is optically out of sorts. What do you think?” The second most common is, “So what’s the best way to optically test my lens without a ton of equipment.” Years ago I wrote an overly long post about testing [...]

The A7R teardown: A look inside Sony’s awesome full-frame mirrorless camera

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The usual warnings apply: Do not try this at home. This post was made by semi-trained, semi-professional repair technicians who sort of know what they’re doing. The following blog post contains graphic images of the inside of a very nice camera. If such things make you squeamish, don’t read further.  No cameras were harmed in [...]

Tamron 150-600 Telezoom Shootout

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There’s been a lot of interest in the newly released Tamron 150-600mm f/5-6.3 SP Di VC USD lens. (For those wondering what the initials mean, VC means vibration compensation, the others all read ‘marketing drivel’.) But meaningless initials or not, with a price under $1,100, a superior range, and vibration compensation, this lens has created a lot [...]