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Partial / tactical teardown, for cleaning and quick repair.
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Face lens down, (front on table)
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Remove 3 screws on the lens mount
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Remove lens mount
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Pull / push trpod mount towards back of the lens, and remove it. Be patient, it is very precisely assembled.
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Loosen tripod ring, till it can rotate.
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Remove tripod ring. Be aware, the is a 90 degree stepping steel ball inside.
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Do NOT remove 3 focus scale calibration screws. I actually did that when attempting disassembly. And luckily, I also marked the original position before that.
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Remove focus ring rubber. Take your time, it's a huge piece and might be glued.
I perform the teardown in order to clear and regrease the helicoid. It's ok now, but ... the Infinity port moved by 3 inc. Should I remove the 3 focus scale calibration screws and rotate the focus flange?
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Remove 2 focus stop screws. Your's might be in different holes. Also you may like to calibrate that. There 3 holes at the infinity end, and 2 at the close-up (8m / 25 ft) end.
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Rotate the rear half of the lens, towards close-up direction (CW as looking downwards), pass 8m/25 feet mark and continue, while applying gentle force pulling rear part up, until they separate, mark the point.
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When assemble them back, attach from this angle/point.
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The front tube, thread on the inner side.
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The rear tube, thread on the outer side.
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This is just a partial tear down. This lens is extremely well made, and very very precise.
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Until this point, this is a reasonable "maintenance teardown". And you can do most mirror and lens cleaning and grease replace.
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Putting them back from the point/angle you marked in previous step, the focus scale does not need a calibration.
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To reassemble your device, follow these instructions in reverse order.
To reassemble your device, follow these instructions in reverse order.
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I am looking for more understanding of this breakdown. I have questions about the fragility of the components and how to clean the interior of the front glass of mold spores. Additionally i would love to understand how to calibrate its focus. Can you advise?
This is a professional lens, built very tough. Primary mirror cleaning is quite easy. but front element is kind of tricky. because there’s an inner thread there covered by damping oil/grease. Maybe you should try remove it from the front. remove the filter/cap thread ring first(My cap used to stuck with this ring so I‘ve got this far)…
In step 3, there are 2+3 screw holes at each end , those are for focus ring stopping screws. 3 for inf end and 2 for close end (if my memory is correct). But this is for adjustment instead of “calibration“. By my guess a giant lens like this could never be calibrated due to the TCE of aluminium tube. that’s why the focus ring is allow to go beyond inf.
Terrance -
