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DConvert
Joined: 12 Jun 2010
Posts: 921
Location: Essex UK
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 Posted: Tue Nov 03, 2015 7:35 pm Post subject: Adding a shim to an adapter |
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DConvert wrote:
I've just brought a 10mm UWA lens (in Sony A mount) and an adapter to fit it on micro four thirds.
As is common with cheap adapters it's been made slightly short to ensure infinity focus is maintained.
Unfortunately with such a short FL lens this error is significant I need to turn the focusing ring nearly all the way to closest focus to bring the actual focus down to infinity!
the DOF is such that I can get most shots in adequate focus by shutting down the aperture to around F8, but I'd like to have some focus movement available!
From what I've found on the internet relevant BFLs are:
Sony A 44.5mm
µ4/3 19.25mm
While my vernier calipers indicate the adapter is ~23.2mm
From these measurements adding 2 mm of shims under the body mount in the adapter should pretty much correct matters. That seems rather a lot to me, about 10 times what I would have expected.
Before I get going
Can anyone familiar with these shimming operations suggest any tips or ideally a complete procedure?
What are the best materials to use for shims?
Can anyone find fault with my calculations??
Many thanks
Mike
Last edited by DConvert on Thu Nov 05, 2015 2:12 pm; edited 1 time in total |
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visualopsins
Joined: 05 Mar 2009
Posts: 11020
Location: California
Expire: 2025-04-11
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| Posted: Tue Nov 03, 2015 7:51 pm Post subject: |
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visualopsins wrote:
2mm does seem like a lot of shim.
Tissue, Paper, Cardboard, etc., are easy to make into shims for testing...
For final, copper sheathing works great. Obtain different thicknesses at building supply hardware. Or Arts & Crafts Supply.
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Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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DConvert
Joined: 12 Jun 2010
Posts: 921
Location: Essex UK
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| Posted: Thu Nov 05, 2015 2:10 pm Post subject: |
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DConvert wrote:
| visualopsins wrote: |
2mm does seem like a lot of shim.
Tissue, Paper, Cardboard, etc., are easy to make into shims for testing...
For final, copper sheathing works great. Obtain different thicknesses at building supply hardware. Or Arts & Crafts Supply. |
Thanks. 
A quick trial with paper (0.1mm thickness) made no noticable difference. Using aq piece of card from a document wallet (0.35mm thick) has moved infinity focus about half way round the focusing ring, so hopefully double that thickness will get it right.
FWIW using a ink pad for rubber stamps made it much easier to mark out the shims for cutting. I'm not sure I'd want to try that if working from a lens but the adapter has nothing that will get damaged by the ink. |
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visualopsins
Joined: 05 Mar 2009
Posts: 11020
Location: California
Expire: 2025-04-11
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| Posted: Thu Nov 05, 2015 3:46 pm Post subject: |
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visualopsins wrote:
| DConvert wrote: |
...
FWIW using a ink pad for rubber stamps made it much easier to mark out the shims for cutting. I'm not sure I'd want to try that if working from a lens but the adapter has nothing that will get damaged by the ink. |
brilliant!
_________________
☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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