NikonGear'23
Gear Talk => Lens Talk => Topic started by: jhinkey on February 14, 2016, 17:37:24
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For those of us with "old" non-G Nikkors that have aperture rings, the new TC14E-III is not very compatible with our lenses.
Thus has any enterprising soul tried to transplant the optical cell from the -III version into the -II version (or the TC14B for that matter) in order to gain the optical goodness in a TC body that's compatible with our great older lenses?
I know there would be some significant tinkering and you'd have to get the axial position of the optics just right, but with careful measurements before tearing things down I would think it possible to be done.
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There's not much a difference between TC14vII and vIII, IQ wise.
And the previous TC version is easily converted to accept all lenses, caution should be taken to some lenses that protrude the rear elements more than expected.
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There's not much a difference between TC14vII and vIII, IQ wise.
And the previous TC version is easily converted to accept all lenses, caution should be taken to some lenses that protrude the rear elements more than expected.
Some people say there is a significant difference, depending on the lens, especially off-center. The off-center part is what I'm interested in for long distance landscapes with my tele lenses.
Can you even mount an AI or AIS lens on this TC (assuming you file off the small mount tab like on the -II version) and not have the lens indexing tab jam on the TC lens mount?
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Some people say there is a significant difference, depending on the lens, especially off-center. The off-center part is what I'm interested in for long distance landscapes with my tele lenses.
Never used TCs for landscape, only for birds, so only the center is of interest for me. Other usages can't comment.
Can you even mount an AI or AIS lens on this TC (assuming you file off the small mount tab like on the -II version) and not have the lens indexing tab jam on the TC lens mount?
To my knowledge yes.
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I never found edge resolution to be a problem with my two 300mm versions, AF 300mm f/4 (non-D), AFS 300mm f/4 E PF, with or without TC14E (I). The TC seems to introduce or enlarge effect of spherical aberrations just a little, but that is it. Then of course I am on a DX sensor, so it is hard to say how it would be on FX.
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Unfortunately with such things, it's hard to know how good the TC14EIII would be with a specific lens until you've modified it and there's no going back, unless it will in fact mount an AI or AI-S lens as is with just the mounting tab removal.
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There is too little IQ difference to even start to think of this project, besides they are not the same length, and length matters a lot for a TC...
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Although I have shorted a TC-14B to fit the Enigma project,,, But that's another story ;)
Link to the old site
http://www.fotozones.com/live/index.php/topic/48368-lord-of-the-rings-a-progress-report/?p=388922
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There is too little IQ difference to even start to think of this project, besides they are not the same length, and length matters a lot for a TC...
You are saying that the flange distances are different?
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First, Mongo has not noticed a great deal of difference between the two converters - although , it may depend upon the lens you use it with.
Secondly, the two converters are different lengths (the III version being shorter than the II). In theory, you would have to transplant the version III optics together as a combined group with perfectly exact distance from element to element as in the version III itself. Even if this were possible, you then have to try and get the rear element of the converter to be in a position ( in its new body) from the sensor that is exactly equal to the distance it would been in its original casing from the sensor AND at the same time, have the front element of the transplanted elements group the same distance from the rear element of any lens that would be fitted to that which it would have been in the original series III converter. Mongo cannot see how this is practicably possible becuase the body length of the converters is quite different. Therefore , Mongo thinks it is not technically possible and maintain the ability to focus the lens at all distances to the subject.
Mongo would love to know what NG's lens doctor thinks about this.
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There is too little IQ difference to even start to think of this project, besides they are not the same length, and length matters a lot for a TC...
Both are 24.5mm from front to rear mount so a transplant is theoretically possible (or the specs in my database are wrong...)
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When I measure I get 24.75mm is the TC14E Mark I
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Mongo's previous view was on the basis that the converters are different lengths from front to rear mounts. If they are the same, then, it is theoretically possible to do this.
Mongo must say that when using them, he got the impression they are different lengths but admits he has not actually measured them.
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Is 0.15mm significant? The focus system will easily compensate for the slight difference in extension. These TCs are designed to fit multiple lenses, I find it hard to believe they all need the same precise camera - TC - lens spacing to work perfectly...
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Well, as any hard-core lens modder can tell you, while 0.15 mm might not appear to be much, it is also many times larger than any factory tolerance of the flange distance. So is bound to generate troubles.
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Easy to test, shim the TC14E Mark III until it's 24.7mm and see what happens. It's well within the pins of the contact blocks tolerances to move the male F mount on the TC out.
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When a TC is used on a unit focusing lens, the lens elements move much more than 0.15mm during focusing.
Granted, most telephotos used with TCs are IF ...
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Well, as any hard-core lens modder can tell you, while 0.15 mm might not appear to be much, it is also many times larger than any factory tolerance of the flange distance. So is bound to generate troubles.
Obviously someone needs to measure the E-III accurately to see what the dimension actually is.
0.15mm is 0.0059" BTW for us English unit challenged. Two pieces of somewhat thin-ish paper.
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Thinnish maybe, but that is about the depth of focus of say a 400 mm f/2.8 lens wide open. Should give the proper perspective of things.
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Correct dimensions of the TC-14E III
Front element protrudes - 2,5mm (including protective rubber)
Front to rear mount - 24,11mm (with compressed rubber seal)
Don't have here the vII
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Thanks Pedro. Please measure at the indicated point on the flange ;) that's the mating point of the Nikkor F-mount.
The Mark I and Mark II are identical length and optics.
Edit. I'll upload a new image!
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When a TC is used on a unit focusing lens, the lens elements move much more than 0.15mm during focusing.
Granted, most telephotos used with TCs are IF ...
When you mount a unit focusing lens on a TC the new combined lens becomes a lens with floating elements similar to an IF lens. Thus also you loose Focal length as you focus closer with a TC attached, for some lenses especially IF lenses a lot of focal length is lost as you focus up close actually!
Please see 1.4.2 and for instance Fig. 25 on this amazing reference page
http://www.pierretoscani.com/echo_focal_length.html
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Thanks Pedro. Please measure at the indicated point on the flange ;) that's the mating point of the Nikkor F-mount, you can also see that's where lenses get 'brassing' from wear,,,
The Mark I and Mark II are identical length and optics.
Hi Eric,
That measures 25,07mm
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Sorry Pedro, I think I was wrong, I will upload a new drawing! I think your first measurement was about right, I got thrown off by the stated 24.5mm!
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Here is the 85mm 1.4 showing M B f 46.5mm, top right of the drawing, to the wide surface of the mount, so that's where we should measure.
The measurement of 24,5mm is an overall length of the housing, has nothing to do with the optics,,,
Sorry for the confusion! I was calibrating Leica lenses last night so my head was in Leica mode :o ::)
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24.71mm - 24.74mm is the TC14E Mark I and II
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My TC14EII measures 24.63 to 24.66mm depending on where you take the measurement - yes that's 0.0012 of an inch non-parallel.
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Thanks, well I'm measuring with a cheap digital caliper and an old-school one of good quality,,, ;)
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Thanks, well I'm measuring with a cheap digital caliper and an old-school one of good quality,,, ;)
My quick measurement is with my not-so cheap digital caliper (supposedly good to 0.0005 inch resolution) that should be close.
I will re-check with my 0.0001 inch resolution caliper later today . . . .
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My TC14EII measures 24.63 to 24.66mm depending on where you take the measurement - yes that's 0.0012 of an inch non-parallel.
If these firgures are accurate, they imply the mount(s) are warped and well outside factory tolerance.
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Don't know how you have made such measurements, but mine have been made with a Mitutoyo with constant pressure and accurate until 0,005mm.
Mine measures across the mount in 8 different points always 24,11mm...
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If these firgures are accurate, they imply the mount(s) are warped and well outside factory tolerance.
Yeah, I'll check it later as I said with a more accurate 0-1" micrometer. However I've found this kind of non-parallelism common with many adapters, etc. with no correlation between degree of non-parallelism and cost.
As a side note, I'm working on trying to develop a method to quickly measure flange to sensor parallelism as a way to do a self check w/o having to send the body in to a shop.
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OK but we end up at about 0.6mm difference between the two versions, that's 6 pieces of normal printing paper, a lot,,,
However - I don't see the IQ that would make this worth doing,,, several hours dismantling the two then machining, positioning and centering and reassembly of one converter and one into the parts bin,,,
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Quickly taking a screen shot of Erik’s images (which hopefully are to scale with each other), Mongo overlaid one on the other.
1.4 III - dark rose coloured elements with grey body
1.4 II - pink coloured elements with dark body
You will see from the edited diagram that some things line up and some do not. The rear mount lines up on one side but not the other. This must be an error in the diagram because the rear mount is perfectly parallel to the body. So, there is some diagram error or distortion in the proportions or the scale somehow. It is difficult to know what parts may be just housing and not the mount itself.
In Mongo’s view, you must be able to:-
1. transplant the whole of the version III elements and groups exactly as they are.
2. ensure that the front and rear elements of the converter are exactly the same distance from the front and rear mounts respectively as they had on the Version III converter
It looks like you can fit all the version III elements/groupings into the version II housing IF you can overcome the slightly smaller housing at the front of the converter. If you can, then, it seems possibly to get that front element the correct distance from the front mount. However, it looks like the rear element will protrude a little too much from its required distance to the rear mount.
A lot of this is pure speculation without having precise scale diagrams and measurements.
Last point .........is it really worth this incredible trouble ??????
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Quickly taking a screen shot of Erik’s images (which hopefully are to scale with each other), Mongo overlaid one on the other.
1.4 III - dark rose coloured elements with grey body
1.4 II - pink coloured elements with dark body
You will see from the edited diagram that some things line up and some do not. The rear mount lines up on one side but not the other. This must be an error in the diagram because the rear mount is perfectly parallel to the body. So, there is some diagram error or distortion in the proportions or the scale somehow. It is difficult to know what parts may be just housing and not the mount itself.
In Mongo’s view, you must be able to:-
1. transplant the whole of the version III elements and groups exactly as they are.
2. ensure that the front and rear elements of the converter are exactly the same distance from the front and rear mounts respectively as they had on the Version III converter
It looks like you can fit all the version III elements/groupings into the version II housing IF you can overcome the slightly smaller housing at the front of the converter. If you can, then, it seems possibly to get that front element the correct distance from the front mount. However, it looks like the rear element will protrude a little too much from its required distance to the rear mount.
A lot of this is pure speculation without having precise scale diagrams and measurements.
Last point .........is it really worth this incredible trouble ??????
You can't really use those cross sections for anything accurate. Measurements will tell.
Only way to know is to modify a TC14E-III to accept lenses that have aperture index tabs and do an A/B comparison on your favorite lenses.
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Indeed, these are not to scale,,,
The aperture follower 'shadows' the lower part,,, on the Mark I and II
It's an E converter - No linkage at all so I don't think you can fool it,,,
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As a side note, I'm working on trying to develop a method to quickly measure flange to sensor parallelism as a way to do a self check w/o having to send the body in to a shop.
Please enlighten us if you find a way. I have in the past returned two bodies due to incorrect register distance/misaligned mount; it would be great to have a better way than repeated comparison of infinity points or focus points with focus ring taped in fixed position.
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Please enlighten us if you find a way. I have in the past returned two bodies due to incorrect register distance/misaligned mount; it would be great to have a better way than repeated comparison of infinity points or focus points with focus ring taped in fixed position.
I'm not working on measuring the distance, but rather the variation in the distance - i.e., non-parallel sensor and mount surface.
Two ways are interferometric and laser proximity probe (which is related to the first). The goal is to make these simple and cheap, though that might be tough . . .
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To get the absolute register distance would be complicated by the UVIR filter/dust shaker that could reflect light back, and also the thickness of those that would have to be subtracted if light is reflected off the actual surface of the sensor. Anyone know how Nikon service do these tests?
My second problematic case was just incorrect register distance in a refurbished D7100 body, which did not show any signs of misalignment as far as I could tell, but the latter can be very hard to judge based on resulting captures at infinity. My feeling is that very short focal length lenses are more sensitive to misalignment of the mount than longer lenses due to the small movements necessary to effect focusing.
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To get the absolute register distance would be complicated by the UVIR filter/dust shaker that could reflect light back, and also the thickness of those that would have to be subtracted if light is reflected off the actual surface of the sensor. Anyone know how Nikon service do these tests?
My second problematic case was just incorrect register distance in a refurbished D7100 body, which did not show any signs of misalignment as far as I could tell, but the latter can be very hard to judge based on resulting captures at infinity. My feeling is that very short focal length lenses are more sensitive to misalignment of the mount than longer lenses due to the small movements necessary to effect focusing.
Yes, measuring the absolute distance is very very difficult to do accurately - no idea how Nikon does it - likely indirectly. Thus I'm just looking for non-parallelism . . . . much easier (but maybe not easy) to do.