Nikon F-mount 2x teleconverters

Through the years, Nikon marketed several models of 2x teleconverters in Nikon F mount. For a more-or-less complete history of these teleconverter models, see e.g. Wikipedia. On this page, i discuss three of these teleconverters, of which two are legacy models only available on the second-hand market.

On another page, I briefly discussed the TC-20E, relatively modern 2x model for AF-I lenses that also works with AF-S lenses. Like most other Nikon teleconverters, the front mount of the TC-20E is equipped with an extra tab than allows mounting on this teleconverter only a few, mostly telephoto lenses specified by Nikon as compatible. That page also shows how the front mount of this and similar teleconverters can be modified to use them with lenses not originally approved by Nikon. Even after modification, however, not all lenses can be mounted on this teleconverter, because the front element of the TC-20E moderately protrudes from its front mount, colliding with the rear element of many lens models.

Another page of my site discusses the TC-14E III and TC-17E II teleconverters. Yet another page discusses the TC-14x for the Nikon Z system.

Many of the photographers who have a practical experience with Nikon 2x teleconverters in F mounts are aware than it can be difficult or impossible to use autofocus on lenses mounted on these teleconverters. In some cases, the teleconverters simply lack the mechanical and electronic couplings required by the different types of Nikon autofocus. In other cases, this difficulty is not intrinsic to teleconverters, but stems largely from three facts:

1 - The autofocus detectors of many legacy Nikon DSLRs begin to struggle at effective lens speeds just above f/5.6. This implies that only f/2.8 or faster lenses can provide a reliable autofocus on these cameras once mounted on a 2x teleconverter. Some modern high-end Nikon DSLRs provide a reliable AF with lenses with effective speed up to f/8, which means in practice up to f/4 native speed when a 2x teleconverter is added.

2 - Macro lenses are a special case, because their effective aperture almost always increases when focusing closer, and additionally these lenses have very long focusing helicoids that require an extensive travel of the AF motor when racking back and forth looking for something to lock focus onto. Both factors can make autofocus problematic when a 2x teleconverter is added to a macro lens. Engaging a focus limiter that reduces the focusing range of the lens can make the autofocus faster, but rarely solves the problem completely.

3 - Nikon never marketed teleconverters equipped with a mechanical transmission for the "screwdriver"-type autofocus actuator of AF and AF-D lenses. Legacy third-party teleconverters with this type of mechanical pass-through coupling were made e.g. by Kenko. The only recourse for ths type of autofocus is purchasing these teleconverters on the second-hand market.

As discussed below, an important use for autofocus in macro lenses is to allow in-camera focus bracketing. For this use, it does not matter whether autofocus is able to lock focus on the subject. The starting focus position of the sequence, its number of shots and the amount of focus travel between successive shots are manually chosen by the photographer, and the camera operates the AF motor of the lens according to these parameters. The autofocus detectors of the camera are never used in this process.

Incidentally, the legacy Nikon TC-16 and TC-16A teleconverters contain a built-in focusing mechanism, AF motor and battery, and bring AF to manual-focus lenses when mounted on the Nikon F3AF SLR camera. The focusing range is somewhat limited and varies with the lens focal length. Among the limitations of these teleconverters is that they appear to only work on a specific SLR camera model, and that they underexpose with lenses faster than f/1.8.

None of the teleconverters discussed on this page are weather-proof.

TC-200 and TC-201

It can be useful to begin the present discussion with the Nikon TC-200 (1977-1983) and TC-201 (1984-2001) teleconverters, which are legacy 2x models that lack protruding front elements. They also lack the additional front bayonet tab that allows mounting only Nikon-approved lenses. In other words, the TC-200 and TC-201 teleconverters can be used straight out of the box with virtually all lenses in Nikon F mounts, and even with accessories like extension rings and bellows, if you so desire.

These two models differ in details of their aperture control mechanical transmissions, but are optically identical. In particular, the TC-200 is compatible with AI lenses, and the TC-201 with both AI and AI-S lenses. This difference only matters when the lenses are used on certain legacy film SLR cameras.

The optical scheme uses 7 elements in 5 groups. The distance between front and rear mounting flanges is 44.1 mm, with a barrel diameter of 64.5 mm. The weight of the TC-201 without caps is 245 g. As a result of their "fully ordinary" front lens mounts, these teleconverters use the same front caps that fit on Nikon F camera bodies.

The TC-200 and TC-201 are designed for use with lenses of focal lengths lower than 200 mm. However, these teleconverters are also compatible with the legacy Reflex-Nikkor 500mm f/8.0 (not the earlier 50 cm f/5 model). As a whole, these teleconverters are of high quality and typically give good results when used with compatible lenses of reasonably high quality. They also tend to be cheap on the second-hand market. When used with lenses faster than f/2, however, these teleconverters limit the resulting lens speed to f/4. In other words, it makes little sense to use these teleconverters with f/1.2, f/1.4 or f/1.8 lenses, because they are all limited to f/2 by the teleconverter. This is a speed limitation of the teleconverter optics and, unlike what some wild rumors say, cannot be magically removed by tweaking some of the mechanical couplings of the teleconverter.

The TC-201 is equipped with a thin extra pin located near the locking pin of the front Nikon F bayonet. This extra pin is mechanically coupled to a prong on the rear mount of the teleconverter, and is of no consequence with modern DSLR and mirrorless Nikon cameras, and reasonably modern lenses.

These teleconverters cannot be used with G lenses.

A copy of the Nikon documentation of the TC-201 is available here.

TC-300 and TC-301

The TC-300 (1977-1983) and TC-301 (1984-2001) are compatible with AI lenses, and the TC-301 is additionally compatible with AI-S lenses. Aside from this, the two models are identical. They are 2x teleconverters (not 3x as occasionally reported).

The TC-300 and TC-301 use 5 elements in 5 groups and are designed for lenses of focal length 300 mm or higher. In practice, their usability is limited by the exceptionally high length of their protruding front optics (23 mm past the front mounting flange). These teleconverters use the special Nikon BF-2 front cap. Most of the protruding optical barrel is covered by a rubber sleeve that helps to protect the rear of the lens from damage if the lens is incompatible, or if the photographer is attempting to attach the teleconverter to a lens in a haste.

Like the TC-201, the TC-301 is equipped with a an extra, thinner pin near the locking pin of the front Nikon F bayonet (see above). This pin has no function on modern Nikon DSLRs and Z mirrorless cameras.

The TC-300 and TC-301 lack the extra tab present on the front mount of more modern Nikon F teleconverters, but extreme care must be used when attempting to attach one of these teleconverters to a lens for the first time.

In lenses with rear elements that move when focusing or zooming, extra care must be used because the teleconverter may appear to attach successfully to the lens when the latter is set at a certain focus or zoom setting, but subsequently operating the focus or zoom mechanisms of the lens may cause its rear optics to collide with the teleconverter optics.

The distance between front and rear mounting flanges is 83 mm, with a barrel diameter of 64.5 mm. The weight without caps is 330 g. Speed of the connected lens is limited to f/2.8 or slower. A faster lens will lose more than the expected 2 stops of speed with this teleconverter.

These teleconverters can be used with the Micro Nikkor 200 mm f/4 IF (the older, AI version of the Micro Nikkor 200 mm, not the AF-D model) to reach 1x. Additionally, these teleconverters can be used with the Nikkor 135 mm f/3.5, 180 mm f/2.8 non-ED, 200 mm f/2, and Medical-Nikkor 120mm f/4. Aside from these lenses, the TC-300 and TC-301 are only meant to be used with extreme telephoto lenses (excluding catadioptrics), where they indeed perform very well in most cases. These teleconverters, however, may cause vignetting or dark corners if the lens is stopped down past f/11.

These teleconverters cannot be used with G lenses.

A copy of the Nikon documentation of the TC-301 is available here.

TC-20E III

This is the only 2x teleconverter in F mount still marketed by Nikon at the time of writing. It was introduced in 2009 and is specifically marketed as compatible with AF-S lenses, but according to Nikon it supports autofocus only on a limited range of lenses (see the table published by Nikon). Autofocusing capabilities with this teleconverter on a given lens and camera are in reality not always clear-cut, and depend on the illumination level of the subject, on the desired AF speed, on whether AF-C or AF-S autofocus is used, and on whether the photographer can tolerate occasional or frequent AF misses and "hunting" (see also below).

I expect that this teleconverter will eventually be discontinued by Nikon, together with most of the F-mount lenses still in production.

This teleconverter is equipped with 10 electrical contacts on its rear and front mounts.

The TC-20E III is designed mainly for lenses of focal length 300 mm or higher. The list of compatible lenses, however, contains several lenses shorter than 300 mm, in particular the Micro Nikkor 105 mm f/2.8 G IF-ED, which with this teleconverter becomes a 210 mm f/5.6 (at infinity focus) 2x macro lens. With the teleconverter and at effective 2x, it is an effective f/9.6 lens fully open. With the teleconverter and at effective 1x, it is an effective f/7 lens. Nikon specifies that AF cannot be used on this lens when mounted on this teleconverter, but the documentation of the teleconverter is not updated with subsequent cameras. I tested this lenses with the TC-20E III on FTZ adapter and Z8 camera, and can report that AF is enabled with this combination.

The 105 mm G, even without teleconverter, is not a fast autofocusing lens, and with this teleconverter it autofocuses remarkably slowly and with a definite tendence to hunt, especially in the close-up and macro range. Engaging the focus limiter helps a little. Activating the AF after manually focusing at approximately the right distance also helps. As a whole, shooting in autofocus with this lens and the teleconverter would not be my first choice, but it is possible if necessary.

On the Z8, AF must be active to shoot focus-bracketing sequences. Using the teleconverter allows focus bracketing with this lens at a magnification up to 2x (it is, in fact, the only lens in my possession that allows me to do this at 2x on my Z8). For my use of this lens, in-camera focus bracketing is far more important than autofocus in itself. The alternative is focus bracketing by using a motorized micrometric focusing rail and an external controller to operate the rail and the camera trigger, which is impractical to use in the field and is slower by one or two orders of magnitude.

The optical scheme uses 7 elements in 5 groups, of which one aspheric element. The BF-3B special gray front cap is necessary to accommodate the moderately protruding front optics. Older models of the same cap, also suitable for this teleconverter, include the BF-3 and BF-3A. This teleconverter is a complete optical redesign of the earlier TC-20E II. The external appearance also differs from earlier Nikon teleconverters (compare with the TC-20E shown here). Image quality on good lenses is generally high to very high.

The rear element of this teleconverter is deeply recessed within the rear bayonet.

The Nikon documentation of the TC-20E III is available here.

Conclusions

Multiple models of Nikon 2x teleconverters in F mount have different characteristics and are suited for different uses.

The TC-20E III is the only of these 2x teleconverters in F mount still marketed by Nikon.

Among Nikon 2x teleconverters in F mount, all the more modern models are equipped with a special front bayonet, to restrict its use to Nikon-approved lenses. It is possible to remove this restriction, but the modification is permanent.

None of these 2x teleconverters is weather-proof.