Quite so, Doctor, but it isn't just a question of DoF at the 3m setting.
There's the usability factor too. With a too-thin adapter, there is a
tendency to set the lens to focus beyond infinity, with the result that the
effective DoF for earthly subject is much reduced. And with super wide
angle lenses, it can be very difficult to spot that on the focusing screen.
But I don't have any experience with a 5D, so it may not be as much of a
problem as I had with an 8mm on an E-1 (even wider angle, even smaller
screen).
Buzz Lightyear
-----Original Message-----
From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx]
Sent: 22 January 2009 13:36
To: Olympus Camera Discussion
Subject: Re: [OM] OM-5D, part II, Winter Pear Orchard
The hyperfocal distance of an 18mm lens at f/3.5 (wide open) is only 2.8
meters. Infinity is certainly already in focus at 3 meters... as is
everything back to 1.5 meters. Not to worry about the adapter.
Dr. Focus
Piers Hemy wrote:
> If the 8mm focuses at infinity when the lens shows 3m, I think you
> need a thicker adaptor, not a thinner adapter.
>
> Piers
>
> -----Original Message-----
> From: iwert bernakiewicz [mailto:zuikooh@xxxxxxxxx]
> Sent: 22 January 2009 11:01
> To: Olympus Camera Discussion
> Subject: Re: [OM] OM-5D, part II, Winter Pear Orchard
>
> --snip
>
> The 18mm is very critical in focussing, I think the focussing ring on
> my copy is a bit off maybe, being the 3m mark is already infinity. It
> might as well be the adapter, I have ordered a second one which should
> be thinner (adapter that is).
>
> --snip
>
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