Graflex.org

[essessem]

I'd like to use both a 135mm WF Ektar and 203mm Ektar on a 4x5 Crown. I currently have a side mount RF model, so I'd have to get a top mount model to do this.

Question is, is it really practical to open up the RF mechanism, swap out the cam, and expect it to work smoothly, i.e. without having to recalibrate each time? Any personal experience anyone has would be appreciated.

Alternately, I've been thinking maybe I could add a top RF to my current camera and use it for the 2nd lens, retaining the side RF for the 135mm.

Thanks for reading...
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Speak softly and carry a big camera.

[45PSS]

If you have a side rangefinder, calibrate it to one lens or the other.
Make an accurate focusing scale for that lens.
Make an accurate focusing scale for the second, third, fourth or however many lens you wish to use.
Focus using the RF, read the scale, transfer the distance to the other scale and shoot.

Focus scale should have Infinity, 100 ft., 50 ft., 25 ft., 15 ft., 10 ft., and 1 foot markings thereafter to the closest focusing distance of the lens, usually 3 to 6 feet for most before requiring bellows extension factor compensation for correct exposure.

Finding and installing a Top RF on side RF body will be a major undertaking. Buying a repairable Top RF Crown will cost about the same.
Once a top RF is calibrated it does not have to be recalibrate for other lens but you must have a cam made for that lens for it to be accurate.
Lens production can be anywhere from 1% to 5% tolerance of the stated focal length.
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The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[Les]

[1banjo]

hey essessem

just get top RF the cams are not hard to change out
Its getting the cams to match your lens that mite be hard
now its easer to make cam to match your lens on a super
speed or super graphic cameras then a pacemaker
I have made cams for both now it mite take 2 hr to make
a cam to match a super with having to make 5 or 6 cams to
get it right were as it mite take 6 to 8 hr's for a pacemaker
& 10 or 12 cams to get it right
BUT one you have done it one the next one will not take
long to make

banjo

[essessem]

Wow, great feedback, guys.

So far I'm likin' Les's idea the best, with separate RFs. Swapping out cams sounds good in theory, but I foresee lots of readjusting. Although it sounds as if banjo either hasn't had this problem or else is OK with tweaking adjustments a lot.

45PSS's idea is great for its simplicity, but for shooting people it wouldn't be so practical for me. Plus my DOF tends to be pretty shallow, so using a scale would be pretty hit or miss.

Which leads to a related question: when determining focal distance, do I measure lens-to-subject or film plane-to-subject?

Thanks again...
_________________
Speak softly and carry a big camera.

[45PSS]

Focal length of a lens is measured from its nodal point to the film plane when the lens is focused at infinity.
http://reallyrightstuff.com/pano/05.html
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[1banjo]

hey essessem
cams are great once you get them adjusted to the lens {NOT ADJUST THE CAMERA
MAKING THE CAM MACH THE LENS & ONLY THAT LENS} & only use that lens with that
cam !! once I got them adjusted I have never had any problums never had to do any
adjustemts when changing from lens / cams to other lens / cams as long as you never
use a different lens to that cam

BANJO

[essessem]

I just ordered a dial calipers & will give cam-making a shot. Oh yeah, and I plan to get hold of a top RF Crown as well. I've an idea about laying out the cam shape using a computer graphing program & will post results if I'm successful. Thanks all!
_________________
Speak softly and carry a big camera.

[45PSS]

http://graflex.org/helpboard/viewtopic.php?t=4653&highlight=super+graphic+cams

may be of interst to you.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[essessem]

Great article 45PSS (or, Charles, I presume.) For which lens did you make this cam? I'd be curious to get your measurements for the focus scale (either multiplied by 1.058 or not) so I could plug all the numbers into a graph, which I could PDF and send to you to see if it matched to your cam.

Plus I noticed we're practically neighbors--I live in SF, work in Cupertino.
_________________
Speak softly and carry a big camera.

[45PSS]

203 f7.7 ektar; 165 f4.5 paragon; 100 f6.3 wide field ektar for starters.
I used a 50 foot tape measure, several copies of the 1951 Air Force lens resolution chart attached to an artist canvas attached to a portable light stand and measured from the surface of the target to the film plane on the camera for all the distances and focused on the sun with a special mylar filter over the lens for infinity.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[essessem]

Is it just me, or does it seem that there is an inordinately large number of both top RF Crowns AND Kalart RF assemblies showing up on The Popular Auction Site?
_________________
Speak softly and carry a big camera.