David Alan Harvey has used a variety of camera gear throughout his career, often favoring a minimalist approach with a "one-camera, one-lens" philosophy. 
Here's a summary of the equipment he's known to have used:
Cameras
-  Leica Rangefinders: He started with a Leica IIIF when he was 14 and later used an M6 for 25 years. He has also mentioned using a Leica Monochrom and Leica M series cameras more recently.
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| Leica IIIf | 
- Fujifilm: He often uses Fujifilm cameras, including the X-T1, X-Pro1, X-Pro2, and X100. He takes the X-T1 when a smaller size is useful.
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| Fujifilm X-T1 | 
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| Fujifilm X-Pro 2 | 
- Nikon: He has used Nikon cameras, including the D800 and previously a D100.
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| Nikon D800 | 
- Canon: At one point, he used a Canon EOS 1D X.
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| Canon 1Dx | 
- Medium Format: He has experience with medium format cameras, specifically mentioning the Fuji 6x9 and Mamiya 7.
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| Fuji 6x9 | 
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| Mamiya 7 | 
- Other: He has also mentioned using a Panasonic GF1 and even an iPhone.
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| David Alan Harvey and an iPhone | 
- Epson: He used the Epson R-D1.
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| Epson R-D1 | 
Lenses
- His most frequent lens choice throughout his career has been the 35mm focal length
- More recently, he has grown fond of the 50mm too, and sometimes uses a 28mm.
- Specific lenses mentioned include the Leica Summilux 50mm f/1.4, Fujinon XF 35mm f/1.4 R, and Zeiss Touit 32mm f/1.8 (in Fuji X mount).
Flash
-  He uses a flash indoors quite a bit, specifically a Vivitar 2800 with a warming gel for nighttime street photography, often using a "dragging the shutter" technique.
Bags
-  He designed camera bags with Filson, emphasizing portability, durability, and a discreet appearance.
It's clear that while he has preferred certain setups (especially Leica with a 35mm lens), he is adaptable and emphasizes creating images over specific gear, stating that he doesn't care what camera he shoots with, only that he can create images.