Front lens caps are nicely protecting your lens… until you accidentally scratch the front glass element by misplaced cap border in the photo bag. I also don’t like front caps for the extra time required to take them off.
Protective filters solves that concerns. However I often don’t like how the lens look with filter, and that it becomes slightly longer.
Here’s my experimental modification – embedding filter glass directly into the lens filter thread. I don’t use hoods/polarizers/ND/etc. so don’t need filter thread to be used for something else. It should work for any lens that has front element positioned deep enough to not touch the filter glass. And frame around front glass should be able to support the filter.
Fortunately, my favorite lens Mitakon ZhongYi 35mm F0.95 Speedmaster MK-II fits that criteria : ) And here is final result – pricy Schneider B+W XS-Pro UV glass sits firm and protects the lens from dust, dirt and scratches. It’s also easy to clean it.
All is needed for such modification:
- Good quality filter glass (I prefer B+W XS-Pro nano UV filters)
- Cheap filter with fastener ring located inside filter front thread
- Spanner wrench
- Rocket blower or any alternative dust remover
- Rubber disc (do gently disassemble B+W filter brass frame)
First step is to carefully disassemble B+W filter by unscrewing fastener ring at the rear area. I don’t know for sure but it may be important to remember which filter glass surface is the front one.
Next step is to blow out all the dust and carefully locate filter glass at the lens front frame.
Now it’s time to disassemble the cheap filter (I purchased $2 one from eBay) using spanner wrench. Make sure you don’t damage the thread.
Put the fastener ring from cheap filter on the lens thread, center the filter glass and slowly fasten the ring by hand. You may gently secure it with spanner wrench.
NOTE: the filter coating may be slightly scratched, or even damaged if you push too hard.
Filter is inside, but lens keeps its size and shape. I like that!
B+W filter frame
UPDATE (Oct 2019) – few more details on B+W filter disassembly.
The frame of B+W UV filters is made of brass and has laser engravings. It can NOT be disassembled from the front. Even slim frame of B+W Nano series is made of brass.
Very thin ring with smooth surface is securing the glass in frame from the rear area.
To unscrew the ring use rubber disc or two-side adhesive foam. Unscrew it in CCW direction. Tread is much more thin than regular filter thread.
Securing ring is also made of brass.
Securing ring is just little thicker than filter glass.
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