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JohnBar
Joined: 21 Jun 2012
Posts: 581
Location: Liverpool
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 Posted: Thu Feb 27, 2014 4:44 pm Post subject: Chromatic Aberration |
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JohnBar wrote:
Is CA a lens design issue or can it vary from sample to sample within a given design? In other words is it down to design or down to manufacturing tolerances and factory assembly?
I have acquired a lens with blue fringing in high contrast areas and I am contemplating trying another copy. Would this be wise? It is quite cheap to buy although its retail price was high back in the day.
The lens is ISCO AV Cinelux 3.5/110-200 for 35mm projection
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SXR_Mark
Joined: 12 Jun 2010
Posts: 506
Location: England
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| Posted: Thu Feb 27, 2014 9:50 pm Post subject: |
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SXR_Mark wrote:
Of course, sample variation can have an effect on CA as it can with any aberration. However, I would say CA is primarily a function of the optical design. Note, though, that the interaction with the micro-lenses on the sensor array of a digital camera can make the inherent CA of lens worse. It is therefore possible, in principal, for a given lens to give different CA on different (digital) cameras.
As you find your current sample of this lens unsatisfactory, I would think you would be unlikely to find another sample appreciably better.
Mark
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frenched
Joined: 16 Feb 2013
Posts: 395
Location: MD USA
Expire: 2014-06-17
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| Posted: Fri Feb 28, 2014 1:00 am Post subject: |
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frenched wrote:
Manufacturing tolerances have improved over the years, so yes I think there are variances with any old lens designs. I don't know this lens but CA is generally trivial to fix in post these days. No sense chasing a "perfect" copy if you otherwise like the results of what you have. |
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mo
Joined: 27 Aug 2009
Posts: 8982
Location: Australia
Expire: 2016-07-30
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| Posted: Fri Feb 28, 2014 1:32 am Post subject: |
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mo wrote:
I think a cine/projection lens would possibly behave differently than a lens designed for a slr. Read up about Rudolf kingslake and lens designs...he is an amazing man,very easy to read.
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David
Joined: 13 Apr 2011
Posts: 1869
Location: Denver, Colorado
Expire: 2013-01-25
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| Posted: Fri Feb 28, 2014 2:45 am Post subject: |
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David wrote:
Mostly, lens design. CA stems from light focusing at different points as it bends through the lens (because of wavelengths). So blue light being a shorter wavelength bends more than green and red causing the different color spectra to be in different places on the media. Stopping down can largely rectify CA.
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Langstrum
Joined: 16 Feb 2014
Posts: 351
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| Posted: Fri Feb 28, 2014 6:00 am Post subject: |
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Langstrum wrote:
I also have few lenses with CA and I wanted to find better copies but then I decided to live with that. With Photoshop you can remove CA easily. Also the use of filter, like the Haze 2A in the link below, may help.
http://www.dpreview.com/forums/thread/3515049
I got a Tiffen Haze 2A filter and it actually can reduce 30-50% CA depending on the lens. Maybe it's because of different coatings.
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AF Lenses:
Canon EF 50/1.8; EF 200/2.8 L, EF 200/1.8 L, EF 300/4 L Sony E mount SEL 50/1.8 OSS, SEL 16/2.8 Fuji X mount XF 35/1.4 R
MF Lenses: Peleng MC 8/3.5, 17/2.8 Samyang 14/T3.1, 35/T1.5, TS 24/3.5 ED, 85/T1.5, Polar 85/1.4 Auto Revuenon 28/2.8; MC 50/1.4 Vega11U 50/2.8 Carl Zeiss Tessar 50/2.8 (exakta mount) Auto Chinon 50/1.9 Zenitar ME1 50/1.7 Sears Auto Sears 55/1.4; Sears 135/2.8 Auto Yashinon DX 50/1.4; Tomioka 50/1.2 SMC Pentax 50/1.7; 50/1.4 Canon FD 50/1.4 S.S.C; 55/1.2 S.S.C; FD 50/1.2 L; FD 85/1.2 L; 85/1.2 S.S.C Aspherical; FD 80-200/4 L 300/2.8 S.S.C Fluorite FD 300/2.8 L FD 200/1.8 LCosina-S 50/1.2 Helios Helios 44 Chrome f/22, 44-2, 44-3, 44M-4, 44M-7 (58/2), Helios-40 85/1.5 Jupiter Jupiter-9 85/2; Jupiter-37A 135/3.5; Jupiter-21M 200/4 Nikon Ai 105/2.5 Tairs-3S 300/4.5
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JohnBar
Joined: 21 Jun 2012
Posts: 581
Location: Liverpool
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| Posted: Fri Feb 28, 2014 7:34 am Post subject: |
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JohnBar wrote:
The strange thing is there is no other CA like magenta green yellow etc. It is only blue and only in specular and around borders of white on black.
Otherwise the lens is remarkably sharp and easy to mount
Perhaps I can disassemble it and spin the elements around a bit in their retainers to see if it makes a difference...
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Langstrum
Joined: 16 Feb 2014
Posts: 351
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| Posted: Fri Feb 28, 2014 8:19 am Post subject: |
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Langstrum wrote:
| Quote: |
The strange thing is there is no other CA like magenta green yellow etc. It is only blue and only in specular and around borders of white on black.
Otherwise the lens is remarkably sharp and easy to mount
Perhaps I can disassemble it and spin the elements around a bit in their retainers to see if it makes a difference... |
My Pentax and Samyang lenses also show only green CA. I had the same thought and tried disassembling, rotating, cleaning, and finally, the CA is still there 
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Camera: Sony A7 mark III, A6300
AF Lenses:
Canon EF 50/1.8; EF 200/2.8 L, EF 200/1.8 L, EF 300/4 L Sony E mount SEL 50/1.8 OSS, SEL 16/2.8 Fuji X mount XF 35/1.4 R
MF Lenses: Peleng MC 8/3.5, 17/2.8 Samyang 14/T3.1, 35/T1.5, TS 24/3.5 ED, 85/T1.5, Polar 85/1.4 Auto Revuenon 28/2.8; MC 50/1.4 Vega11U 50/2.8 Carl Zeiss Tessar 50/2.8 (exakta mount) Auto Chinon 50/1.9 Zenitar ME1 50/1.7 Sears Auto Sears 55/1.4; Sears 135/2.8 Auto Yashinon DX 50/1.4; Tomioka 50/1.2 SMC Pentax 50/1.7; 50/1.4 Canon FD 50/1.4 S.S.C; 55/1.2 S.S.C; FD 50/1.2 L; FD 85/1.2 L; 85/1.2 S.S.C Aspherical; FD 80-200/4 L 300/2.8 S.S.C Fluorite FD 300/2.8 L FD 200/1.8 LCosina-S 50/1.2 Helios Helios 44 Chrome f/22, 44-2, 44-3, 44M-4, 44M-7 (58/2), Helios-40 85/1.5 Jupiter Jupiter-9 85/2; Jupiter-37A 135/3.5; Jupiter-21M 200/4 Nikon Ai 105/2.5 Tairs-3S 300/4.5
Voigtlander 15/4.5 Aspherical; Ultron 35/1.7
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