We ’ll compare theCanon 24 - 70 f/2.8 Mk II , theNikon 24 - 70 f/2.8 AF - S , and theTamron 24 - 70 f/2.8 Di VC .
This will for the most part examine the electro - mechanical mechanisms in the lenses . But just for completeness here are the optical diagram for all 3 . The Canon is the most optically complex , moderate 18 constituent in 13 chemical group . The Tamron has 17 element in 12 groups , while the Nikon has 15 elements in 11 groups . ocular diagrams for ( top to bottom ) the Tamron 24 - 70 f/2.8 VC , Nikon 24 - 70 f/2.8 AF - S , and Canon 24 - 70 f/2.8 Mk II ( not to scale ) .
The Front Group
One affair that all 3 of these crystalline lens have in unwashed is a large front chemical group at the end of an extending gun barrel . They all disassemble the same way – a makeup doughnut is removed exposing the screwing that let us take the front radical from the genus Lens . The Canon front group is pictured below but they ’re all very exchangeable – 2 or 3 glass elements permanently arrange in a plastic case .
Canon 24 - 70 f/2.8 Front Group
I will include an image of the Tamron front chemical group below to show the variable thickness shims used to obtain right space ( two on the element , one lying beside it ) . Both the Tamron and Nikon lens utilise shims to space the front chemical element . The Canon does not .
Tamron 24 - 70 f/2.8 VC front group with shim
I also want to show one closing curtain - up of the Tamron front group because the back element of the first mathematical group ( element # 2 ) was the one we had reported coming loose in a duet of former copies . This transcript ( which is more recent ) shows a very heavy plastic sealing wax rather than the softer glue we had seen in those early ones . We may have gotten a duet with defective seals in those other copy , or Tamron may have changed things . Either way , we have n’t seen that problem in a long sentence now .
Closeup of the second element seal in Tamron lens .
Opening up the Back
Since we ’re doing this to show internal differences , I should commence with some generalisation . The Canon 24 - 70 f/2.8 II is typical of most newer ( last 5 - 6 geezerhood ) Canon designs . The Nikon 24 - 70 is quite typical of a Nikon lens system , which have n’t changed very much in the last decade . Sony lens system lean to be very much like Nikon lenses . Sigma and Tamron lens used to be much like Nikons , too , but recently are morphing and use up on some of the characteristics of Canon lenses .
Nikon Preliminaries
For all 3 lens , open up up the back involves removing the piece of tail that hold the bayonet mount and electrical connections in position . For the Nikon there is an extra step : the rear chemical element of this lens is attached straight to the inside of the bayonet mount and is remove first . This is a bit unusual but it is convenient if you want to clean the inside of the rear element .
Rear element removed from bayonet mount .
The Nikon lense also has electronic position - sensing brushes under the zoom and focus closed chain that have to removed before any dismantling takes place .
Nikon zoom brush
The focusing brush is smaller and deeper , so it ’s difficult to show you until it ’s removed .
Focus electronic skirmish being removed .
Under the Bayonet Mount
OK , once we ’ve got the Nikon de - accessorized , the rear bayonet mount of all three lenses is removed the same mode . ( You ’re also start to see why it take a petty more time to solve on a Nikon genus Lens . )
Nikon
The bayonet saddle horse contains the long lever that trigger the mechanically skillful aperture mechanism .
Nikon mount showing long aperture lever tumbler .
There ’s a spring in the backing that return the aperture lever to neutral position if the tv camera is n’t actively move it . Some Nikon electron lens have two springs , some just one .
Underneath the bayonet setting are more shim . For most lenses shim thickness at the bayonet mountain aline proper eternity nidus . If you change a bayonet mount , you ’ll generally want to vary the shim thickness , etc .
Shim between bayonet mount and lens
Canon
There ’s not much to show with the Canon bayonet mount . There are no shims . Canon bayonet mounts come in various thicknesses , so rather than shimming they simply choose the correct thickness mount when they foregather the lens .
There are no aperture mastery lever and bound because the aperture is controlled electronically . Springs and levers bend and break , but electronics burn out . If there ’s any reliableness remainder between electronic and mechanical aperture control I ’ve never noticed it .
With the bayonet mount and rearward gun barrel mount removed from the Canon electron lens we ’re looking straight at the PCB ( printed circuit board ) where all the electric connections live – typical for Canon lenses . If you scroll back up , you ’ll notice the Nikon lens does n’t have a PCB .
Main PCB of Canon 24 - 70 f/2.8 II
Tamron
We dissected a Canon - mount Tamron , so it does n’t have a mechanically skillful aperture lever tumbler . Had we done a Nikon - mount version then the bayonet mount would have had an aperture ascendancy lever , like the Nikon . Like Nikon , however , the Tamron ( and most third - party lenses ) employ shim under the bayonet backing to attain right spacing .
Rear shim under bayonet mount of Tamron 24 - 70 f/2.8 VC
Under the shim , however , the Tamron has a PCB like the Canon . Older third - party lenses generally did n’t have PCBs , but in recent years most are using them . I particularly wish Tamron ’s because they are a very nerveless black colour . I assume the plug with light-green marks on it is a computer connexion for factory adjustment .
Tamron PCB look powerful fine in introductory inkiness .
The black PCB also makes for adorable bokeh from the electronic component if we take a through - the - lens barb of my work bench .
Removing the Rear Zoom Components
With this one I ’ll start with the Canon genus Lens , since it ’s the most straightforward . After the PCB is off we remove several screws . . .
. . . and the entire rearward barrel assembly comes off as a building block . This comprise rapid climb mechanism and key , the rapid growth brush forum , and the lens system switches .
The optical elements and ultrasonic motor ( silverish thingie with slots near the top ) rest behind .
Notice the small , categorical leaping washer between two plates at the top of the motor . Adjusting this adjusts the motor tension . A undecomposed affair to leave alone , ordinarily .
Removing one more set of screws removes the ultrasonic autofocus motor division from the visual portion of the lens . Simple , fresh , and lucid . It ’s a dream to break apart . Most recent Canon lens system have this type of modular meeting place .
The Nikon 24 - 70 f/2.8 AF - S come aside a chip differently . The zoom headstone is removed first .
Then the zoom pack is removed simply by delineate everything up properly and lifting .
Then we can remove the screws holding the mid barrel in berth and slither it off .
With the mid barrel removed we now see why the Nikon lens does n’t have a PCB at the back . Nikon apply several lowly electric circuit boards connected by flex cable system and even some solder wires , wrapping them around the inner barrel . It does n’t front quite as elegant but it make for just o.k. . This is how lenses have been made for geezerhood .
you may also see the Nikon ultrasonic motor toward the bottom of the picture . Notice the tension washer between two home base and low down the expansion slot of the motor .
On the other side of the crystalline lens we can also see the GMR ( Giant MagnetoResistor ) social unit – the slivery piece held on by two screws at the left of the image below . The GMR is the position sensing element Nikon and many third - company lenses use . In the spirit of ‘ do n’t do what I did , do what I say ’ , I ’ll tell you do n’t ever touch that with a finger . If you do the crystalline lens no longer works and the unit of measurement has to be replaced by Nikon and Aaron will give you that look he gives when you ’ve done something really stupid .
Nikon inner barrel showing one of the circuit board , some flex cables , and the GMR sensor .
Newer Canon lenses practice a smaller optic sensing building block tucked inside the barrel of the focusing building block we removed above . Even though this is the Nikon section , I ’ll show it below for comparison . The modified research I ’ve done found that both types of units are available in a wide motley of accuracies , so I do n’t know that one character is better than another . The optical social unit are a portion small and out of the way if you open up a lens , but I doubt many of you care about that .
Canon ’s optical focus posture sense unit .
The Nikon supersonic motor is the next disassembly footstep . Unlike the Canon lens it does n’t add up off as a unit – it has to be disassemble piece by piece . Underneath it there is a soldered wiring harness so complete dismantling involves desoldering some wiring , too . That ’s a time down process that we ’re not croak to go through for a demo .
Once it ’s PCB is remove , the Tamron shows some trait similar to both the Nikon and the Canon lenses . It does n’t come apart modularly like a Canon , but it is a mo more organized inside than the Nikon . The aperture Francis Scott Key ( screwdriver is remove it ’s screw ) ask to be removed , along with 4 climb up screws , then the mid barrel comes off .
The mid - barrel contain the Tamron ’s GMR social unit .
With the mid gun barrel removed we can see the Tamrons ultrasonic motor , which is very similar to the Nikon and Canon motors .
Tamron USM exposed . Forceps are removing the focus tonality .
USM remotion leaves the optical essence of the Tamron intact .
The Tamron is n’t quite as modular as the Canon , but the USM gathering does come off well as a unit .
Optical Element Adjustments
While we ’re not getting into the optical elements too much in this teardown , I will take a minute here to march one of the main differences between the lens . Notice the rear part of the Tamron visual assembly two images above ( the picture with the forceps ) and you ’ll see several screws holding the rearmost group onto the optic forum . If we take those screw out we remove the rear mathematical group .
As shown in the mental image below , under each ass is a exercise set of shim – unlike thickness of the three shims could both space and right disputation of the rear element . Notice also there are three more screws holding the next constituent in place ( each of these screws is just to the left wing of the rearward element screw Emily Post with the establishment shims still in place ) .
private shims for the three screw of the Tamron rear end element .
move out these screws lets us remove the next constituent , which testify a set of spacing shims . alter shims here would aline the spacing between elements , but not the element ’s tilt .
Spacing shim under next visual group .
Most lenses ( include most Nikon and Sigma ) expend shimming to line up most of the opthalmic factor . canyon lenses run , instead , to have helical collars on the lens element . Rotating the collar lean the element forward or backwards .
spiral apprehension for adjusting elements in a Canon lens .
Conclusion
Well , if you ’ve gotten this far , you have earned the Geek Scout Merit Badge for lens teardown . You may ( or may not ) have also gained some grasp for why it costs so much to do a ‘ simple ’ fixing on some genus Lens .
There are for certain differences in how the various manufacturers design the non - optic portions of their lenses . Third - political party lens used to be very standardized to Nikons but recently are starting to , uhm , borrow some of the designs Canon has used .
From an lensman ’s point of view , one design is n’t better or worse . They all make lenses that work just fine .
But a figure of you have asked us to demonstrate why we call some designs ‘ clean ’ or more organized than others . Hopefully this demonstrate that , at least to some extent .
Roger Cicala and Aaron Closz
Lensrentals.com
January , 2013
Posted inTechnical Discussions » Teardowns and Disassmebly , Technical Discussions
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Dr. Roger Cicala is the founder ofLensrentals.com . Since the company has long since outgrown his ability to oversee it , he is now the Director of Research and Quality Assurance for Lensrentals , meaning he spends all twenty-four hours accept photography thing apart and figuring out how they work .
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