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autotak
Joined: 04 Dec 2009 Posts: 15
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Posted: Sun Jul 25, 2010 10:13 am Post subject: Cleaning lens elements and de-centering / collimating? |
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autotak wrote:
All,
I spent the past few hours reading about cleaning lens elements and many people advised against taking lens elements out of a group because they claimed the elements will be de-centered when replaced and the groups would need collimation.
Any truth to this? My goal is to clean an SMC Pentax 50/1.4 front & rear element and judging by the 50/2, the elements are placed into "holders" with rings keeping them in place. I'm confused how de-centering can occur since the elements fit cleanly into the holding assembly.
Would love to hear your insights on this!
Thanks,
autotak. |
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Scheimpflug
Joined: 06 Feb 2010 Posts: 1888 Location: New Zealand / USA
Expire: 2011-11-18
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Posted: Sun Jul 25, 2010 1:36 pm Post subject: |
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Scheimpflug wrote:
Many people are afraid to open lenses in general, and will come up with any excuse they can to avoid it.
How badly does it need cleaning? _________________ Sigma DP1, Nikon D40 (hers ), Polaroid x530, Pentax P30t, Pentax P50, (P30t/P50 K-A to Nikon F body mount conversion)
Nikon: 18-55/3.5-5.6 "G ED II DX" (F) Soligor: 28/2.8 (FL->F converted), 135/3.5 (F), 3x TC (F, modified) Kalimar: 28-85/3.5 (F)
Vivitar: 70-210/2.8-4.0 Version 3 (F), Tele 500/6.3 Preset (F), 19/3.8 (F) Minolta: 300/5.6 (SR/MC/MD pending F conversion)
Tamron: 28/2.8 (Adaptall) Panagor: 28/2.5 (FD) Aetna: 300/5.6 (F) Osawa: MC 28/2.8 (F)
Vintage Lenses: Dallmeyer: 1940s A.M. 14in 356mm f4 (ULF->M42) 1930s Adon Telephoto Taylor, Taylor & Hobson: 1880s Rapid Rectilinear 8 1/2 x 6 1/2 11.31in f/8 (LF->?)
Parts Lenses: Nikon 35-135/3.5-4.5 (F), Sigma 70-210/4.5 (F), Nikon 50/1.8 Series E (F) |
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visualopsins
Joined: 05 Mar 2009 Posts: 10462 Location: California
Expire: 2021-06-22
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Posted: Sun Jul 25, 2010 2:58 pm Post subject: |
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visualopsins wrote:
Collimation is a concern primarily with elements cemented surface to surface when the mating surfaces are not flat. Imagine two bowls, one inside the other, how it is possible to tilt them in relation to each other while maintaining rounded surfaces in contact. Proper collimation makes the lips of the bowls (lenses) parallel. Modern lens designs use flat mating surfaces between group component lenses to avoid the labor intensive collimation step.
Your 50mm iirc has one cemented group; I don't know if the mating surfaces are flat -- check a lens diagram. If they are curved and get separated, collimation will be necessary on re-assembly to insure alignment.
You are correct -- camera lens rings and seats typically can hold collimation between individual elements within acceptable limits. _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony A7Rii, Spotmatics II, F, and ESII, Nikon P4
M42 Asahi Optical Co., Lenses:
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
Other lenses:
Carl Zeiss Jena Flektogon 2.4/35
SMC PENTAX 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto
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fstop
Joined: 11 Apr 2010 Posts: 29
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Posted: Mon Jul 26, 2010 2:04 am Post subject: Re: Cleaning lens elements and de-centering / collimating? |
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fstop wrote:
autotak wrote: |
All,
Any truth to this? My goal is to clean an SMC Pentax 50/1.4 front & rear element and judging by the 50/2, the elements are placed into "holders" with rings keeping them in place. I'm confused how de-centering can occur since the elements fit cleanly into the holding assembly.
autotak. |
If you must open it for cleaning, then you must.
Here are some tips that will reduce the risk, if not remove it altogether, of misconfiguring the lens during reassembly:
1. Do not work in a dusty environment.
2. Use a paper and pencil and take note of each disassembly step. Better still, take photos.
3. Be sure to use the proper screw drivers and tools.
4. It is a good idea to work in an area where there is no chance of losing any bouncing screws or flying springs. You have a shoe box like enclosure and open the lens in it, for example.
5. When you disassemble the elements, draw clearly (photos can be confusing!), and with exaggerations (especially curves), how the elements were arranged. By drawing, you can depict the order and orientation of lenses quite nicely and without confusion.
Clean the elements and reassemble. With the above tips, it is not that difficult a process if you know your way around mechanical things (it is not easy either, but demands care and attention to detail).
Good luck! |
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autotak
Joined: 04 Dec 2009 Posts: 15
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Posted: Mon Jul 26, 2010 6:14 am Post subject: |
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autotak wrote:
Thanks all for the tips. I've been playing with a junker SMC Pentax 50/2 and have learned some of the advice the "hard way".
If I get a lens wrench, is there any benefit in taping the end so if I do slip with it, I don't gouge the lens or delicate rings? I'm guessing the tape would have to be thick like duck tape or quality packing tape so the sharp edges can't poke through.
Thanks,
autotak. |
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Scheimpflug
Joined: 06 Feb 2010 Posts: 1888 Location: New Zealand / USA
Expire: 2011-11-18
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Posted: Mon Jul 26, 2010 7:29 am Post subject: |
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Scheimpflug wrote:
Might be better to tape the lens and the trim rings instead. If you put any tape on the end of the tool, you would probably just make it more likely to slip out. _________________ Sigma DP1, Nikon D40 (hers ), Polaroid x530, Pentax P30t, Pentax P50, (P30t/P50 K-A to Nikon F body mount conversion)
Nikon: 18-55/3.5-5.6 "G ED II DX" (F) Soligor: 28/2.8 (FL->F converted), 135/3.5 (F), 3x TC (F, modified) Kalimar: 28-85/3.5 (F)
Vivitar: 70-210/2.8-4.0 Version 3 (F), Tele 500/6.3 Preset (F), 19/3.8 (F) Minolta: 300/5.6 (SR/MC/MD pending F conversion)
Tamron: 28/2.8 (Adaptall) Panagor: 28/2.5 (FD) Aetna: 300/5.6 (F) Osawa: MC 28/2.8 (F)
Vintage Lenses: Dallmeyer: 1940s A.M. 14in 356mm f4 (ULF->M42) 1930s Adon Telephoto Taylor, Taylor & Hobson: 1880s Rapid Rectilinear 8 1/2 x 6 1/2 11.31in f/8 (LF->?)
Parts Lenses: Nikon 35-135/3.5-4.5 (F), Sigma 70-210/4.5 (F), Nikon 50/1.8 Series E (F) |
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autotak
Joined: 04 Dec 2009 Posts: 15
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Posted: Mon Jul 26, 2010 8:13 am Post subject: |
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autotak wrote:
OK,
Maybe this is a wild idea, but what about using liquid latex to coat the lens element area before using the lens spanner?
I would only worry if the latex is too thin, but it *sounds* like a good idea.
Thanks,
autotak |
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ZoneV
Joined: 09 Nov 2009 Posts: 1633 Location: Germany
Expire: 2011-12-02
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Posted: Tue Jul 27, 2010 12:52 pm Post subject: |
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ZoneV wrote:
I don´t dink thats a wild idea.
I read such things from people who filed down the rear element of a lens mount, without dissmanteling. One used record cleaning solution (-> sensor film) for that. _________________ Camera modification, repair and DIY - some links to look through: http://www.4photos.de/camera-diy/index-en.html
I AM A LENS NERD!
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