Educate me: Mirrorless vs. DSLR - PDAF and Contrast Detect (Basics and Beyond)

Started 8 months ago | Questions thread
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dance2jam Forum Member • Posts: 57
Educate me: Mirrorless vs. DSLR - PDAF and Contrast Detect (Basics and Beyond)

IT ALL STARTED WITH A SIMPLE QUESTION: Why do mirrorless cameras that are focused on a near object, after jumping to the background, find it impossible to return to the original near focus point. It happened to me a number of times on the Z9 (my first mirrorless camera - arriving there from the D850/D500). I was amused to see two YouTuber bird photographers have the same issues.

THE BEGINNING OF A RABBIT HOLE: So this started a dive into what the difference was between DSLR AF systems and Mirrorless. (off sensor vs on sensor). On the difference between PDAF (Phase detect AF) vs. Contrast Detect (DCD) AF. Brand specific "get arounds" focusing issues (duel pixel, quad pixel, linear etc.) and which systems worked best and why.

WHAT'S THE POINT?: I am a relatively new amateur photographer (3+ years) who enjoys understanding the equipment in my hands. In my humble opinion, it does improve how I use the camera. I asked some very knowledgeable people to help me understand, as though I were a talented 8 year old, in English, why this problem exists in mirrorless cameras and not DSLRs, explain it in simple terms from the ground up, and then how companies like Sony a1, Canon R5 and Canon R3, and Nikon Z9 deal with the issue, the discussion quickly elevated from basic math (for 30 seconds) into a discussion of Fourier transformations. Now, I jest, but you get the point. I know it can be broken down to be clear, detailed, but basic enough that someone without detailed knowledge of sensor design can understand the answer to the original question. I have had wonderful chemistry/physics teachers make the complex so simple. I know someone can do it.

WHAT IS MY REQUEST? If you have the ability, time, energy and like to teach, please take the challenge and I will be eternally grateful. If you have reference material that is more detailed than Phase detection is faster, Contrast more accurate, please feel free to reference it. Right now I'm trying to form building blocks for deeper learning, and I have to start somewhere. This is the first thread/question I've asked in DP review forum, and I just know there is someone out there that can answer the call!

Thanks in advance.


 dance2jam's gear list:dance2jam's gear list
Nikon D500 Nikon D850 Nikon Z9 Nikon AF Nikkor 180mm f/2.8D ED-IF Tokina AT-X Pro 100mm f/2.8 Macro +6 more
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Canon EOS R3 Canon EOS R5 Nikon Z9 Sony a1
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