Focusing Very Wide Lenses

[rupal]

I have been reading the article "How to focus the view camera" (Specifically Procedure II) & i noticed near the end of the article it says that with very wide lenses, it does not apply to focus half way in between the focus spread.

( "However, the only case when the median rule is not a good approximation is when the two magnifications are significantly different and at least one of them is comparable to 1 which is only the case for close-ups with very wide lenses, so in practice one needs not worry about this technicality" )


Can Someone explain this in more detail, And what would be considered "Very Wide" ? Or have i not understood it correctly.

[John Brady]

Hi Rupal, some of us here lean more to the technical side and others to the artistic side. I can't help you with the technical reasons but I use very wide lenses and will share my experience with you.

As far as very wide goes, on 4x5 I would consider a 47mm to a 72mm to be very wide.
I shoot 8x10 so for me a 90xl to 150mm would be very wide.

When I focus for a landscape scene with a super wide lens I am usually very close to a dominant subject in my image yet there are probably trees way off in the distance. I usually set the camera up with the front and rear level and apply a small amount of rise or fall if the lens allows it and then stop way down. I find a point just past my near subject and focus on it. Thats usually about 15 to 25 ft or so into the scene. That's way less than half and usually less than a third into the scene.

Anyway, this method has worked very well for me and maybe it will help you. Here is an example of an image I made last week using the described method.

www.timeandlight.com

[rupal]

Thanks John, i will try the method you described. I have a "Super Angulon 65mm f5.6" & i find it very hard to get it sharply focused. By the way Beautiful photography you have there.

thanks - Rupa

[Arne Croell]

I have been reading the article "How to focus the view camera" (Specifically Procedure II) & i noticed near the end of the article it says that with very wide lenses, it does not apply to focus half way in between the focus spread.

( "However, the only case when the median rule is not a good approximation is when the two magnifications are significantly different and at least one of them is comparable to 1 which is only the case for close-ups with very wide lenses, so in practice one needs not worry about this technicality" )


Can Someone explain this in more detail, And what would be considered "Very Wide" ? Or have i not understood it correctly.

To paraphrase, it refers to the case when the magnifications of the near object and the far object on the film differ widely - this condition can only be fulfilled if you are close to lifesize for the near object and much smaller for the far object. These two conditions can only be reached simultaneously with a wide angle - for a long lens the magnifications for both objects will not differ much for any focus spread that can realistically be used within a normal f-stop range. How wide? No clearcut answer, but 90mm and smaller for 4x5 maybe a good rule of thumb. Now those wide angle lenses were never designed for magnifications close to unity and will not be that great if (ab)used that way anyway, so its mostly a hypothetical situation.