Moose is correct but still underplaying the distance you need for
infinity focus with a 600mm lens at f/8. If you're shooting 35mm (30
lines/mm resolution) then the hyperfocal distance (the minimum distance
at which infinity is in focus) for 600mm f/8 is 4,431 feet or more than
8/10 of a mile. If you put a 2X on it (still on 35mm) or have the lens
on an E-thing (where you need 60 lines/mm resolution) then the
hyperfocal distance doubles and moves out to 8,862 feet. If you combine
2X and an E-thing the hyperfocal distance doubles again and moves out to
17,720 feet or about 3-1/3 miles!
Long lenses can be hard to use. At 200 feet this lens only has about 18
feet DOF for 35mm and only about 9 feet on an E-thing. Good luck
Chuck Norcutt
Moose wrote:
> Scott Peden wrote:
>> A bit over a week ago I lucked into a Sigma 600/8.
>>
>> I noted immediately that at 200 or so feet, infinity was to far of a focus,
>> I had to back off a bit.
>>
>> Last weekend It was just barely focusing all the way over to infinity.
>
> 2. 200 feet isn't infinity for a 600 mm lens I don't know the exact
> numbers, but for a lens that long, 200 feet should focus closer than
> infinity. You need more like half a mile to be certain of infinity.
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