@Mitch_P wrote:
Interesting. I moved on to the wonderful RF 100-500 L and have not kept up with this issue. Just out of curiosity, what was my "user error"? Also, the people complaining were experienced photographers, not beginners. I'm glad there's a solution now, but I absolutely don't regret upgrading 🙂 I had also mentioned the Irix issue and somebody must have found it in a search.
The YouTube videos that I watched were created by an amateur wildlife photographer. Over the years he has made several videos that are supposedly documenting some “pulsing” bug he had discovered, which was associated with Canon camera bodies beginning with his 40D.
This content creator felt he had discovered a bug that thousands and thousands and thousands of other users had never experienced. His discoveries were based on testing methods that were flawed due to a fundamental lack of understanding of how camera gear works.
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As you noted in your original post, the pulsing would occur at or near the MFD of the lens. This was the same issue that was demonstrated in the videos that I had seen. The content creator did not know or understand that the MFD specification for consumer grade zoom lenses is not constant across the entire zoom range. Typically, the MFD specification is only valid at the minimum zoom setting. As you increase the zoom setting, the MFD increases by some amount that manufacturers almost never tell you about.
https://en.wikipedia.org/wiki/Parfocal_lens
That is how a non-parfocal lens works. A parfocal lens maintains focus as focal length is changed. When it comes to MFD, this means that MFD will change as the focal length is changed. The content creator did not understand that MFD increases as you increase focal length.
In other words, he was trying to focus on subjects that inside the MFD specification for the lens.
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The content creator I watched experienced the pulsing issues with several different cameras. He blamed the Canon camera bodies, although he would admit that the issue could be related to something that he was not aware of. He was unaware of something every EXPERIENCED photographer is aware of. You should turn off Image Stabiization when you mount your rig on a tripod. The following article has a 2015 release date. It describes how a typical IS system works.
https://www.bhphotovideo.com/explora/photography/tips-and-solutions/image-stabilization-when-to-use-...
When you do not disable a IS when using a tripod, a feedback loop is created. One common result is the autofocus system will being to oscillate. The article describes in detail the basics of how a typical Image Stabilization works.
Most of the older designs such as those used by Sigma work by “hunting” for camera movement. This achieved by slightly and slowly defocusing the image and then reacquiring a focus lock. When the camera is perfectly stationary, this lends the appearance that the image is going in and out of focus.
His older 40D camera body would exhibit this behavior rather slowly. The image would drift in and out of focus in just under a second. Newer camera bodies feaure newer, faster AF systems. This drifting in and out of focus occurs faster. In the most recent generations of camera bodies, this phenomenon manifests itself has high speed focus pulsing.
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This is pretty basic stuff that experienced photographers should be fully aware of. Let me stop and draw the line here. There is no need to describe additional basic mistakes he was making. I’ll summarize by simply saying that his scientific methods are highly flawed.
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"Enjoying photography since 1972."
