Bruce Varner Photography BruceVarner.com


 

Zeiss Ikonta B (Pre War)

Rangefinder Prisms Out of Adjustment 

 

Problem: Camera produces sharp exposures when focused at known distances using the lens distance scale as a guide.  When using the rangefinder to attempt focus, the setting is off a consistent amount at each distance.

* Caution!! If the amount of error in the rangefinder is large and not consistent throughout all distances, the below procedure will not probably not resolve the problem.  See "Rangefinder Prisms Out of Adjustment" for such problems.

* Caution!! Be sure the shutter is not cocked.  Set the focus on the lens to infinity.  Set the shutter speed to B.

* Caution!! Have the proper small screwdrivers before attempting this repair.  Use a tray, such as a TV tray, with a white towel placed in the tray.  Remove all parts from the camera over this tray so any small pieces can be caught & seen if dropped!

* Caution!! Be sure you know how your camera is mis-aligned before beginning repair!  Example: Does it indicate a focus of 15 meters when in reality the distance is 8 meters.

* Caution!!  Caution!! If you do not have familiarity with small mechanical items and a lot of patience, do NOT attempt this repair!  Please read through this entire article before attempting, and then make the decision whether to proceed at your own risk!  I am NOT a camera repair man.  I was in a position where I had trouble finding anyone I would trust that was willing to work on my camera and talked to some who had bad experiences with others attempting repair on their Zeiss camera.

--The following assumes that the camera front lens elements are in the correct helical.  You either need a ground glass to check this or already have exposures from known distances while the lens was set to those distances.  If the photos are tack sharp, the elements should be correct.

--Facing camera lens, remove the small screw at 4 O’clock & the other at 8 O’clock on the black face plate.

--Facing camera lens and looking down onto the top of the lens, remove two screws at 12 O’clock on the top of the black face plate.

 --Remove the black face plate.  There is a lip on the plate at the 8 O’clock position.  Therefore remove the faceplate by lifting from the 1 O’clock position of the plate (where your finger normally focuses the rangefinder) & carefully removing the plate from the camera.

 * Caution!!  The Face plate is extremely fragile & bends easily.  You will know if this happen as the lens will focus with much more difficulty when the plate is replaced and the plate has been bent.  Be careful!

 --Take some kind of marking material and mark the two prisms and that exact spot on the frame.  I used fingernail polish to make the marks then scribed a light line in the polish after it was dried to identify the exact position of the prisms in the frame.

 * Caution!! Do not move the prisms or focusing gears at all until this temporary mark has been made!  This is the only way you will know the position from which the prisms started!

*When working the gears they may appear loose or bind.  This is probably because the face plate is removed and nothing is holding the large gear that surrounds the lens flat.

--With the lens still at infinity and the camera on its back, remove the two screws from the brass plate holding the prisms in place. Carefully lift the plate away.With this plate removed you can freely move either the front or back prism.* Caution!! If you turn the camera, these two prisms will fall out. (This is why you marked them initially!)

 * Caution!! The exposed prism gears could fall out also.  I found however that the center gears are staked onto the back metal plate and could not be removed.

 --If only the front prism is misaligned you should be able to resolve the issues by moving only the front prism in one direction or the other in small increments.

--To do this remove the prisms so they will not fall out of the camera.  Remove any prism gears that may fall out.

 --Set up a tripod to mount the camera on and be able to look through the viewfinder at something at least 200 meters away.  The further the better and preferably aimed at an elevated object so the camera will be tilted back somewhat to better allow the back prism to stay in its normal position.

 * Caution!! Before mounting the camera, place a white towel or sheet under the tripod as insurance to catch anything that might inadvertently fall from the camera front such as prisms or gears.

 --Mount the camera on the tripod and adjust through the viewfinder so you are looking at the distant object.  Insert the rear prism in the exact position in relation to the mount as when it was initially removed.

 --Now hold the front prism over the rear prism in their normal relationship to each other and turn the front prism only, both ways until the infinity object is focused.  Mark the spot to ensure that when you reassemble the prisms they go in the needed positions.

 --Screw the brass plate back onto the prisms after replacing any gears you may have removed and while the prisms are in the correct alignment.

 --Carefully place the faceplate back over the front lens and test the focus at all distances while holding the plate on with your fingers.  (No need to have to remove the face plate screw again if you do not get satisfactory results.)

 --If this does not result in proper alignment recheck your assembly and try again until resolved.  When completed replace the screws that hold the faceplate on the camera.

 --DONE, unless.......

 --If you were unable to get the prisms to focus correctly, you will have to adjust both the back and front prisms.

 --To help facilitate this, you should be able to remove the large center prism gear.  Once removed, this will disrupt the geared connection between the lens gear and the prisms allowing the rear prism to be rotated without having to move the lens at the same time.

 --Moving both the rear and the front prism, turn each until you have the infinity object in alignment.  Mark the spot on both prisms.  Install the removed gear and replace the brass plate that holds the prisms in place.  Test throughout the distance range.

 --If the camera still does not focus at the other distances or is just slightly out of focus at all distances try moving the front or rear prism one notch and retest.

 --If during testing the camera is in focus when set at infinity but unable to focus at all for any other distance try the following.

 --Move both prisms 90 degrees in opposite directions. That is 180 degrees total.  Move the rear prism 90 degrees to the left and the front prism 90 degrees to the right when looking from behind the camera.

 * This is my experience.  I do not know if this applies under all circumstances!  You may have to use trial and error to find the correct alignment between the two prisms.

        --Once focus testing is successful, replace the screws that hold on the front plate and you should now have a correctly focusing Zeiss rangefinder camera.

 DONE

 I am not sure if this procedure will work with Zeiss rangefinder cameras other than the 532/16 Super Ikonta B.  I wish to thank Mike Elek who provided initial detailed information and suggestions for this repair.  I would also like to thank Austin Franklin for the information he provided.  Good Luck.

 

 

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