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Knoppow on Kalert RF
This stuff works fine and is the right thickness. The
piece costs about $15 US and is enough to make several mirrors. I've meant to write a procedure for replacing it to supplement the one already on the Graflex.org site. That one says you must break out the old mirror. This is not so. the mirror is held by two spring clips but it has some wax like material to cement it. This can be removed by using a little acetone or even lighter fluid. The clips are removed carefully because you will reuse them. Note how they are oriented. Use the old mirror as a pattern to cut the new one. Use a carbide scribe to mark the glass, it will snap at the scratch. I got my scribe at Home Depot for $5 US. This is also the right tool to use for ground glass. Its much easier to remove the old mirror and replace it if you remove the entire mirror assembly. However, once its remounted you must make sure the mirror is at an exactly 45 degree angle. A small drafting triangle will work for this. When the mirror is replaced place a drop of cement at the corners to make sure it doesn't drift with time. Airplane glue works fine and is easily removed if you have to. If the mirror is cut accurately it will just drop in. The coated surface of the mirror must fact the eye window of the rangefinder. Because it is a 50%-%50% splitter is difficult to see which side the mirror is on. However, this can be done by looking at the reflection of a small light placed near the mirror. When the mirror is facing you light must travel through the mirror coating twice to be refected by the inside surface of the glass so the second reflection will be much dimmer when viewed this way. The other way the two reflections will be nearly equal in strength. If the mirror is placed backward it will throw all the adjustments way off plus it may result in a double reflection. Once the mirror is mounted the mirror assembly is replaced (held by one screw) and adjusted for 45 degree angle. Then you will probably have to readjust everything although you may be lucky. Start with the lateral coincidence adjustment. I've posted instructions on setting up Kalart rangefinders to the Graflex.org site, but again want to post a revised and clarified version. The key is to get the infinity adjustments right to begin with. This involves making sure the actuating arm is set right and the initial infinity setting of the lens frame are correct. On Speed and Crown Graphics using the Kalart the infinity stops should be set so that the camera must be racked out perhaps 1/16th inch from the mechanical stop. I recently posted a letter to the Graflex.org help board in the Speed Graphic section on how to set the actuating arm correctly. Faded beam splitter mirrors seem to be very common on Graphics of a certain age. I don't know what happens to them. Fortunately, they are easy to replace and once done will probably never have to be done again. A makeshift fix is to place a neutral or colored filter over the upper window of the RF. This will increase the contrast of the two images although it is no substitute for replacing the beam splitter. There is no eyepiece on the rangfinder but most came with a plain tube to shield image. This was not supplied on all Graphics or it may be missing. Some RFs have coarse threads in the eyepiece for this to thread into, some have a bracket on the back of the camera in line with the eye window of the RF for this tube. There were also telescopes made to fit the Kalart. One was made by Kalart but there were others. I've never managed to find one. A telescope on the eye window has the effect of having a greater base distance for the rangefinder and thus increasing its accuracy. Back when the Contax camera came out to compete with Leica it advertised it had a greater RF base so was more accurate. The Leica, however, had a 2X telescope built in so the _effective_ base of the two was about the same. The Kalart is very accurate when set up correctly. Correct set up is tedious but once done will not have to be done again unless the lens is changed. |
#2
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Sorry folks, I was just sending Richard's directions to myself but
forgot to delete the news group address. Jim Jim Hemenway wrote: This stuff works fine and is the right thickness. The piece costs about $15 US and is enough to make several mirrors. I've meant to write a procedure for replacing it to supplement the one already on the Graflex.org site. That one says you must break out the old mirror. This is not so. the mirror is held by two spring clips but it has some wax like material to cement it. This can be removed by using a little acetone or even lighter fluid. The clips are removed carefully because you will reuse them. Note how they are oriented. Use the old mirror as a pattern to cut the new one. Use a carbide scribe to mark the glass, it will snap at the scratch. I got my scribe at Home Depot for $5 US. This is also the right tool to use for ground glass. Its much easier to remove the old mirror and replace it if you remove the entire mirror assembly. However, once its remounted you must make sure the mirror is at an exactly 45 degree angle. A small drafting triangle will work for this. When the mirror is replaced place a drop of cement at the corners to make sure it doesn't drift with time. Airplane glue works fine and is easily removed if you have to. If the mirror is cut accurately it will just drop in. The coated surface of the mirror must fact the eye window of the rangefinder. Because it is a 50%-%50% splitter is difficult to see which side the mirror is on. However, this can be done by looking at the reflection of a small light placed near the mirror. When the mirror is facing you light must travel through the mirror coating twice to be refected by the inside surface of the glass so the second reflection will be much dimmer when viewed this way. The other way the two reflections will be nearly equal in strength. If the mirror is placed backward it will throw all the adjustments way off plus it may result in a double reflection. Once the mirror is mounted the mirror assembly is replaced (held by one screw) and adjusted for 45 degree angle. Then you will probably have to readjust everything although you may be lucky. Start with the lateral coincidence adjustment. I've posted instructions on setting up Kalart rangefinders to the Graflex.org site, but again want to post a revised and clarified version. The key is to get the infinity adjustments right to begin with. This involves making sure the actuating arm is set right and the initial infinity setting of the lens frame are correct. On Speed and Crown Graphics using the Kalart the infinity stops should be set so that the camera must be racked out perhaps 1/16th inch from the mechanical stop. I recently posted a letter to the Graflex.org help board in the Speed Graphic section on how to set the actuating arm correctly. Faded beam splitter mirrors seem to be very common on Graphics of a certain age. I don't know what happens to them. Fortunately, they are easy to replace and once done will probably never have to be done again. A makeshift fix is to place a neutral or colored filter over the upper window of the RF. This will increase the contrast of the two images although it is no substitute for replacing the beam splitter. There is no eyepiece on the rangfinder but most came with a plain tube to shield image. This was not supplied on all Graphics or it may be missing. Some RFs have coarse threads in the eyepiece for this to thread into, some have a bracket on the back of the camera in line with the eye window of the RF for this tube. There were also telescopes made to fit the Kalart. One was made by Kalart but there were others. I've never managed to find one. A telescope on the eye window has the effect of having a greater base distance for the rangefinder and thus increasing its accuracy. Back when the Contax camera came out to compete with Leica it advertised it had a greater RF base so was more accurate. The Leica, however, had a 2X telescope built in so the _effective_ base of the two was about the same. The Kalart is very accurate when set up correctly. Correct set up is tedious but once done will not have to be done again unless the lens is changed. |
#3
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Sorry folks, I was just sending Richard's directions to myself but
forgot to delete the news group address. Jim Jim Hemenway wrote: This stuff works fine and is the right thickness. The piece costs about $15 US and is enough to make several mirrors. I've meant to write a procedure for replacing it to supplement the one already on the Graflex.org site. That one says you must break out the old mirror. This is not so. the mirror is held by two spring clips but it has some wax like material to cement it. This can be removed by using a little acetone or even lighter fluid. The clips are removed carefully because you will reuse them. Note how they are oriented. Use the old mirror as a pattern to cut the new one. Use a carbide scribe to mark the glass, it will snap at the scratch. I got my scribe at Home Depot for $5 US. This is also the right tool to use for ground glass. Its much easier to remove the old mirror and replace it if you remove the entire mirror assembly. However, once its remounted you must make sure the mirror is at an exactly 45 degree angle. A small drafting triangle will work for this. When the mirror is replaced place a drop of cement at the corners to make sure it doesn't drift with time. Airplane glue works fine and is easily removed if you have to. If the mirror is cut accurately it will just drop in. The coated surface of the mirror must fact the eye window of the rangefinder. Because it is a 50%-%50% splitter is difficult to see which side the mirror is on. However, this can be done by looking at the reflection of a small light placed near the mirror. When the mirror is facing you light must travel through the mirror coating twice to be refected by the inside surface of the glass so the second reflection will be much dimmer when viewed this way. The other way the two reflections will be nearly equal in strength. If the mirror is placed backward it will throw all the adjustments way off plus it may result in a double reflection. Once the mirror is mounted the mirror assembly is replaced (held by one screw) and adjusted for 45 degree angle. Then you will probably have to readjust everything although you may be lucky. Start with the lateral coincidence adjustment. I've posted instructions on setting up Kalart rangefinders to the Graflex.org site, but again want to post a revised and clarified version. The key is to get the infinity adjustments right to begin with. This involves making sure the actuating arm is set right and the initial infinity setting of the lens frame are correct. On Speed and Crown Graphics using the Kalart the infinity stops should be set so that the camera must be racked out perhaps 1/16th inch from the mechanical stop. I recently posted a letter to the Graflex.org help board in the Speed Graphic section on how to set the actuating arm correctly. Faded beam splitter mirrors seem to be very common on Graphics of a certain age. I don't know what happens to them. Fortunately, they are easy to replace and once done will probably never have to be done again. A makeshift fix is to place a neutral or colored filter over the upper window of the RF. This will increase the contrast of the two images although it is no substitute for replacing the beam splitter. There is no eyepiece on the rangfinder but most came with a plain tube to shield image. This was not supplied on all Graphics or it may be missing. Some RFs have coarse threads in the eyepiece for this to thread into, some have a bracket on the back of the camera in line with the eye window of the RF for this tube. There were also telescopes made to fit the Kalart. One was made by Kalart but there were others. I've never managed to find one. A telescope on the eye window has the effect of having a greater base distance for the rangefinder and thus increasing its accuracy. Back when the Contax camera came out to compete with Leica it advertised it had a greater RF base so was more accurate. The Leica, however, had a 2X telescope built in so the _effective_ base of the two was about the same. The Kalart is very accurate when set up correctly. Correct set up is tedious but once done will not have to be done again unless the lens is changed. |
#4
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I had problems with 'drift' in a Kalart.
I traced it to the screw that aligns the lower prism. The screw bears against the back of the prism, which is held against the screw tip by its springy sheet metal mount. In my case there was an air gap between the screw and the prism bracket, allowing the prism mount to 'twang'. It wasn't the twang, but the gradual shift of the prism with temperature, storage position and phase of the moon that kept the rangefinder from holding calibration. Solution (probably not the best one) was to turn the screw in 1.5 turns so the prism was pressing back against the screw. At a guess the proper method would be to remove the metal bracket and bend it back so it tensions against the screw - but I was afraid I may bend some skew into the bracket and never get anything to like up again. After the repair, I found _all_ the alignment settings needed tweaking. I also had a problem with the spring that tensions the prism assembly so that it bears against the cam. The end of the spring had slipped from its proper position against the back of the prism assembly. This caused the prism to not follow the cam, leading to a lot of hair pulling as nothing ever lined up the same way twice. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#5
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I had problems with 'drift' in a Kalart.
I traced it to the screw that aligns the lower prism. The screw bears against the back of the prism, which is held against the screw tip by its springy sheet metal mount. In my case there was an air gap between the screw and the prism bracket, allowing the prism mount to 'twang'. It wasn't the twang, but the gradual shift of the prism with temperature, storage position and phase of the moon that kept the rangefinder from holding calibration. Solution (probably not the best one) was to turn the screw in 1.5 turns so the prism was pressing back against the screw. At a guess the proper method would be to remove the metal bracket and bend it back so it tensions against the screw - but I was afraid I may bend some skew into the bracket and never get anything to like up again. After the repair, I found _all_ the alignment settings needed tweaking. I also had a problem with the spring that tensions the prism assembly so that it bears against the cam. The end of the spring had slipped from its proper position against the back of the prism assembly. This caused the prism to not follow the cam, leading to a lot of hair pulling as nothing ever lined up the same way twice. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#6
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"Nicholas O. Lindan" wrote in message nk.net... I had problems with 'drift' in a Kalart. I traced it to the screw that aligns the lower prism. The screw bears against the back of the prism, which is held against the screw tip by its springy sheet metal mount. In my case there was an air gap between the screw and the prism bracket, allowing the prism mount to 'twang'. It wasn't the twang, but the gradual shift of the prism with temperature, storage position and phase of the moon that kept the rangefinder from holding calibration. Solution (probably not the best one) was to turn the screw in 1.5 turns so the prism was pressing back against the screw. At a guess the proper method would be to remove the metal bracket and bend it back so it tensions against the screw - but I was afraid I may bend some skew into the bracket and never get anything to like up again. After the repair, I found _all_ the alignment settings needed tweaking. I also had a problem with the spring that tensions the prism assembly so that it bears against the cam. The end of the spring had slipped from its proper position against the back of the prism assembly. This caused the prism to not follow the cam, leading to a lot of hair pulling as nothing ever lined up the same way twice. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ The screw that bears on the prism is the basic infinity adjustment for the rangefinder. The spring metal bracket for the prism should follow it right down to the boss its threaded into. Probably the prism got bent up at some point. The bracket and prism are held in place by two tiny screws on the bottom of the same boss the adjustment screw is in. Normally the screw will be about helf way so a turn and a half is acceptable. If you have a rangefinder where the adjustment is questionable the way to set it is to make sure the rangefinder actuating arm is installed correctly as I described in my previous post. Then make sure the infinity stops for the lens standard are set so that infinity focus on the ground glass requires racking out the focus track about 1/32 inch from its back stop. This should also put the distance scale on Anniversary Graphics about in the right place. The scale on a Pacemaker can be put anywhere so is not useful as a guide unless you know for certain its in the right place. In any case, with the infinity stops in the right place, the eccentric on the bed at center position (slot straight up and down) the rangefinder should indicate infinity. If it doesn't adjust the little screw until it does. The mid and close distance adjusters should not have any effect on this but they should be on the starting values for the particular focal length lens given in the Kalart manual. If this set up is done carefully sometimes the rangefinder will come right in on the starting values. Usually it doesn't. After setting the mid and close distances so they are correct the rangefinder should be checked at intermediate distances. Sometimes it will be correct at infinity, 15 feet and 4 feet but not at 6 or 8 feet or at 30 feet. This is an indication the infinty adjustments are off somehow. The position of the actuating arm is critical. Some instructions say to place the end of the arm against the back of the camera. This may work but the correct position is the greatest rearward position the cam on the camera bed can have when the camera is folded. This is actually a little forward of the back of the camera box. The eccentric should be set at its maximum rearward adjustment and the end of the arm held against it with a rubber band while the set screw is tightened. Then the eccentric is moved back to its center position. This method of adjustment gives the greatest range for the cam in the rangefinder. Actually, this is not a single cam but a couple of coupled cams. The slider adustments adjust where they overlap and how much allowing the approximation of a range of cams to cover the focal length range of the rangefinder. If the infinity and arm settings are not right the curvature of the cam is wrongm, or rather, you will be working on the wrong part of the cam, so the coincidence with the lens will never be right. It is also important to watch for backlash when making adjustments to the sliders. Work the focus arm back and forth a few times after each step to make sure it really is where you want it. The adjustment procedure is tedious as hell but does work and when done right the RF is very accurate down to quite close distances. It is interesting that in the patent literature it is stated that the rangefinder was never intended for close use. Nonetheless it does work down to 4 feet, sometimes even down to the limit of movement of the arm, about 3-1/2 feet for a 4x5 camera with a 135mm lens on it. -- --- Richard Knoppow Los Angeles, CA, USA |
#7
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"Nicholas O. Lindan" wrote in message nk.net... I had problems with 'drift' in a Kalart. I traced it to the screw that aligns the lower prism. The screw bears against the back of the prism, which is held against the screw tip by its springy sheet metal mount. In my case there was an air gap between the screw and the prism bracket, allowing the prism mount to 'twang'. It wasn't the twang, but the gradual shift of the prism with temperature, storage position and phase of the moon that kept the rangefinder from holding calibration. Solution (probably not the best one) was to turn the screw in 1.5 turns so the prism was pressing back against the screw. At a guess the proper method would be to remove the metal bracket and bend it back so it tensions against the screw - but I was afraid I may bend some skew into the bracket and never get anything to like up again. After the repair, I found _all_ the alignment settings needed tweaking. I also had a problem with the spring that tensions the prism assembly so that it bears against the cam. The end of the spring had slipped from its proper position against the back of the prism assembly. This caused the prism to not follow the cam, leading to a lot of hair pulling as nothing ever lined up the same way twice. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ The screw that bears on the prism is the basic infinity adjustment for the rangefinder. The spring metal bracket for the prism should follow it right down to the boss its threaded into. Probably the prism got bent up at some point. The bracket and prism are held in place by two tiny screws on the bottom of the same boss the adjustment screw is in. Normally the screw will be about helf way so a turn and a half is acceptable. If you have a rangefinder where the adjustment is questionable the way to set it is to make sure the rangefinder actuating arm is installed correctly as I described in my previous post. Then make sure the infinity stops for the lens standard are set so that infinity focus on the ground glass requires racking out the focus track about 1/32 inch from its back stop. This should also put the distance scale on Anniversary Graphics about in the right place. The scale on a Pacemaker can be put anywhere so is not useful as a guide unless you know for certain its in the right place. In any case, with the infinity stops in the right place, the eccentric on the bed at center position (slot straight up and down) the rangefinder should indicate infinity. If it doesn't adjust the little screw until it does. The mid and close distance adjusters should not have any effect on this but they should be on the starting values for the particular focal length lens given in the Kalart manual. If this set up is done carefully sometimes the rangefinder will come right in on the starting values. Usually it doesn't. After setting the mid and close distances so they are correct the rangefinder should be checked at intermediate distances. Sometimes it will be correct at infinity, 15 feet and 4 feet but not at 6 or 8 feet or at 30 feet. This is an indication the infinty adjustments are off somehow. The position of the actuating arm is critical. Some instructions say to place the end of the arm against the back of the camera. This may work but the correct position is the greatest rearward position the cam on the camera bed can have when the camera is folded. This is actually a little forward of the back of the camera box. The eccentric should be set at its maximum rearward adjustment and the end of the arm held against it with a rubber band while the set screw is tightened. Then the eccentric is moved back to its center position. This method of adjustment gives the greatest range for the cam in the rangefinder. Actually, this is not a single cam but a couple of coupled cams. The slider adustments adjust where they overlap and how much allowing the approximation of a range of cams to cover the focal length range of the rangefinder. If the infinity and arm settings are not right the curvature of the cam is wrongm, or rather, you will be working on the wrong part of the cam, so the coincidence with the lens will never be right. It is also important to watch for backlash when making adjustments to the sliders. Work the focus arm back and forth a few times after each step to make sure it really is where you want it. The adjustment procedure is tedious as hell but does work and when done right the RF is very accurate down to quite close distances. It is interesting that in the patent literature it is stated that the rangefinder was never intended for close use. Nonetheless it does work down to 4 feet, sometimes even down to the limit of movement of the arm, about 3-1/2 feet for a 4x5 camera with a 135mm lens on it. -- --- Richard Knoppow Los Angeles, CA, USA |
#8
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"Nicholas O. Lindan" wrote in message nk.net... I had problems with 'drift' in a Kalart. I traced it to the screw that aligns the lower prism. The screw bears against the back of the prism, which is held against the screw tip by its springy sheet metal mount. In my case there was an air gap between the screw and the prism bracket, allowing the prism mount to 'twang'. It wasn't the twang, but the gradual shift of the prism with temperature, storage position and phase of the moon that kept the rangefinder from holding calibration. Solution (probably not the best one) was to turn the screw in 1.5 turns so the prism was pressing back against the screw. At a guess the proper method would be to remove the metal bracket and bend it back so it tensions against the screw - but I was afraid I may bend some skew into the bracket and never get anything to like up again. After the repair, I found _all_ the alignment settings needed tweaking. I also had a problem with the spring that tensions the prism assembly so that it bears against the cam. The end of the spring had slipped from its proper position against the back of the prism assembly. This caused the prism to not follow the cam, leading to a lot of hair pulling as nothing ever lined up the same way twice. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ The screw that bears on the prism is the basic infinity adjustment for the rangefinder. The spring metal bracket for the prism should follow it right down to the boss its threaded into. Probably the prism got bent up at some point. The bracket and prism are held in place by two tiny screws on the bottom of the same boss the adjustment screw is in. Normally the screw will be about helf way so a turn and a half is acceptable. If you have a rangefinder where the adjustment is questionable the way to set it is to make sure the rangefinder actuating arm is installed correctly as I described in my previous post. Then make sure the infinity stops for the lens standard are set so that infinity focus on the ground glass requires racking out the focus track about 1/32 inch from its back stop. This should also put the distance scale on Anniversary Graphics about in the right place. The scale on a Pacemaker can be put anywhere so is not useful as a guide unless you know for certain its in the right place. In any case, with the infinity stops in the right place, the eccentric on the bed at center position (slot straight up and down) the rangefinder should indicate infinity. If it doesn't adjust the little screw until it does. The mid and close distance adjusters should not have any effect on this but they should be on the starting values for the particular focal length lens given in the Kalart manual. If this set up is done carefully sometimes the rangefinder will come right in on the starting values. Usually it doesn't. After setting the mid and close distances so they are correct the rangefinder should be checked at intermediate distances. Sometimes it will be correct at infinity, 15 feet and 4 feet but not at 6 or 8 feet or at 30 feet. This is an indication the infinty adjustments are off somehow. The position of the actuating arm is critical. Some instructions say to place the end of the arm against the back of the camera. This may work but the correct position is the greatest rearward position the cam on the camera bed can have when the camera is folded. This is actually a little forward of the back of the camera box. The eccentric should be set at its maximum rearward adjustment and the end of the arm held against it with a rubber band while the set screw is tightened. Then the eccentric is moved back to its center position. This method of adjustment gives the greatest range for the cam in the rangefinder. Actually, this is not a single cam but a couple of coupled cams. The slider adustments adjust where they overlap and how much allowing the approximation of a range of cams to cover the focal length range of the rangefinder. If the infinity and arm settings are not right the curvature of the cam is wrongm, or rather, you will be working on the wrong part of the cam, so the coincidence with the lens will never be right. It is also important to watch for backlash when making adjustments to the sliders. Work the focus arm back and forth a few times after each step to make sure it really is where you want it. The adjustment procedure is tedious as hell but does work and when done right the RF is very accurate down to quite close distances. It is interesting that in the patent literature it is stated that the rangefinder was never intended for close use. Nonetheless it does work down to 4 feet, sometimes even down to the limit of movement of the arm, about 3-1/2 feet for a 4x5 camera with a 135mm lens on it. -- --- Richard Knoppow Los Angeles, CA, USA |
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