Graflex.org

[campy]

I am new to large format and am interested in how to increase depth of field
by using drop bed. After dropping bed do I tilt lens back and forth to find my focus point? Do I focus at the closest spot or the furthest away? How much of an increase should I expect? Also when the bed is down the short focus rail comes out of it's groove and seems to lock up. Is there a certain sequence I should do?

[Discpad]

Start here at http://www.largeformatphotography.info/articles/bond-checklist.html
and continue here
http://www.trenholm.org/hmmerk/

[Discpad]

Also, click here for "View Camera Focus and Depth of Field — Part I by Harold M. Merklinger"
[http://users.snip.net/~joe/Focus_tilt_&_swing-VCFaDOF1.pdf]

[FrankS]

Campy,

I'm new to LF too and I went through a similar problem with my Speed Graphic and 135mm lens. To focus on infinity with the bed dropped, the focussing rail hinges were in the way of where the lens standard had to go. This is true for a 135mm lens on a thicker bodied Speed, and (I believe) for a 90mm lens on a thinnner bodied Crown.

To work around that problem, I do this:
1.) open the camera bed
2.) with lens still retracted into body as it is for storage, I rack out the focus so that the rear focus track and the hinge is on the camera bed tracks and totally out of the camera body tracks.
3.) unlatch the lens standard and move it onto the hinge area of the focussing tracks and lock it there
4.) now drop the camera bed
5.) tilt the lens back so it is upright
6.) focus the lens back towards the film plane to get infinity focus
7.) raise the lens so it is centered (dropping the bed lowers the lens, though focussing it back brings it up, depending on how far back you go)
8.) tilt the lens standard forwards about 5 to 10 degrees while looking at the groundglass with lens aperture wide open to assess the focus plane
9.) adjust focus and tilt until desired result is achieved

This works for my 135mm lens on a Speed. A 90mm lens on a Crown has a similar problem, but I don't know first hand if this will work for you. Play around with where you lock the lens standard near the hinge between the front and rear focussing rails. The trick is to release the rear rails from the camera body tracks by racking out the focus before dropping the bed. (at least with my combo) Please let us know if it does or does not work!

_________________
...preferring to be on the shiny side of the film, Frank S.

[campy]

Thanks I will try that.