The information contained in this post is in addition to what was provided in an earlier blog to cover subtle differences between two otherwise identical procedures, one covering the 28mm lens and the other (here) the 50mm lens. Since I can no longer edit that post, I hope you find it useful.
I am adding this addendum to point out the minor physical differences that might become an issue or a surprise for some lens owners. It’s best to start from my earlier blog here and return here to continue your work on Ricoh GR Lens A12 50mm F2.5 Macro. Up to this point everything is identical.
DISCLAIMER: I’m providing this procedure only for informational purposes and take no responsibility whatsoever for any damages to the lens or the person who tries it. Please bear in mind that no engineering degree is required to follow these instructions, however, it helps to have a technical background or hands on experience with fixing things. Also please practice working with small screws before opening this lens up, they can be very tricky.
The subtle differences are noted once the procedure for lifting the top circuit board and arriving at the sensor board starts. Please refer to the following image for explanation.
- The type and color of the three large screws to be removed are different. Whereas the screws were black in the A12 28mm case, here they are silver and slightly different looking. Other than that they perform exactly the same function. They are all spring loaded, sitting on loose spacers with washers. Please remove them carefully so that they won’t jump out due to the spring action and get lost
- The three smaller screws holding down this board are black here whereas they were silver in A12 28mm case. Also one of the screws is actually under the yellow protective film covering the ribbon cable. To unscrew it, pull back the yellow film slightly.
- Once all 6 screws shown above are removed, you’ll be able to lift up the circuit board in exactly the same manner as we did for A12 28mm lens.
- Once this circuit board is lifted, we arrive at the sensor board plus the AA filter/UV block filter sitting on the opposite side of it. Please refer to the following image for explanation that follows.
Inspect the sensor and remove any foreign objects, etc. that might be sitting on it. Most small particles can be easily removed using a cotton swab or an air blower (manual or pressurized can type) without touching the sensor or the need for any liquids or alcohol
- Next, inspect the AA + UV block combo glass filter on the opposite side. If it’s clean, it best be left alone. If you see any dust or other particles on it, again, a cotton swab or an air blower are the best options. If, however, there are particles under the glass or on the back of the lens, the AA + UV block filter needs to be removed for cleaning.
- Unlike the same filter in A12 28mm lens, this filter is not attached to the white frame holding it in place. There are several parts to remove. To remove the filter:
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- Using a tweezer, remove the loose foam washer shown in the image above
- Remove the three small screws holding the white frame. Do not lose these screws!
- Using the tweezer, remove the white frame, you may have to dislodge it by applying a small amount of force
- Remove the loose black elastic washer sitting directly beneath the white frame
- Keep all these parts in a secure place for later reassembly
- Wearing your vinyl gloves at this point, carefully remove the glass filter (Do not touch the filter with bare hands, the smudge it causes will be pretty difficult to remove). You may have to nudge it a bit to lift it off as it is tightly sitting in its frame. You can also use a pressurized can of air blower to make it jump out, it worked for me
- Note that this glass filter combo has a shiny coat of orange hue on one side and is plain on the other. At reassembly time, remember that the shiny side faces away from the sensor and looks into the back of the lens. In reality it shouldn’t matter since the light will pass through it either way, but Ricoh installed this filter the way I described, so I recommend doing as Ricoh did
- Once you’re finished with cleaning, the reassembly is simply the above steps along with the respective steps given in the A12 28mm sensor cleaning described in my earlier here , in reverse
Good luck and god bless.