two quick questions..

[chopper5654]

i have been searching, to no avail, for two topics i've seen covered. i cant remember where i saw them and the search feature isnt narrowing things down enough. so, experts......

1) building distortion and the avoidance of? i know it has to do with how close i stand, but sometimes (in the case of urban churches with tall steeples) i can't stand back far enough because of other city buildings. how do i stop the curvature of the vertical features?

2) hyperfocal distance? its time i get better at this. i've seen it referenced hundreds of times, and have read articles, but cannot find one tonight for some darned reason.

thanks a mill for any help. (i would post photos of today's distortion, but i need to upgrade flickr to "pro" first.)

[sued5320]

1) I could try to help with this one but not sure I have the right answer. If I remember correctly from an Ansel Adams books, the film plane has to be parallel to the building in order to avoid convergence. (I'm not sure if that works if you use an UWA lens.)

2) http://www.dofmaster.com/hyperfocal.html

HFD is a specific focus distance for a specific aperture, focal length and camera (CoC) which results in the maximum depth of field. This DOF is equal to 1/2 focus distance to infinity.

The online DOF calculator will show you the HFD when you select the camera, f-stop and focal length.

There are lots of HFD charts available. Which one you use depends on your approach.

There are 3 variables and you have to determine which two you will choose and then use a chart to give you the third. Most people select the f-stop and focal length and then calculate the focus distance. You can also select focal length and HFD and use a chart to tell you which f-stop will give you maximum DOF.

[Todd Lambert]

#1 can really be helped by using a Tilt/Shift lens.

[chopper5654]

Originally Posted by Todd Lambert

#1 can really be helped by using a Tilt/Shift lens.

..for a price

i think i've found what i am looking for. thanks guys.

yes, you must be parallel to focal plane. easier to shoot shorter buildings or to step way back. obv, or correct in pp, which is what i will have to investigate since i shoot in really cramped downtown quarters at the moment. yes, tilt/shift will do it, but those are specialty lenses i will have little use for in the long-term.

HFD is exactly that. thanks for the link. i found it shortly after asking by searching google. potn's search engine couldnt compete, so i went outside the site.

but yes, the easiest way to shoot on the fly with HFD is to put your foreground object where you want it and focus on double the distance away. for instance, a rock is 10 feet from you, pick something close to 20 feet away and focus on that. crude, but effective.

thanks again, guys. i know i can always count on potn'ers.