Fast "prime" telephoto lenses with tons of glasses are considered as benchmark of optical quality among photographers. The new released Tokina 400mm f/8 mirror lens is a "prime" lens itself, but due to its reflective catadioptric optic and slow f/8 aperture, the target design of this lens is not definitely a new flagship on optics, but instead it is a super compact alternative for such heavy telephoto lenses! I decided to review this exciting lens with an unusual objective; exploring characteristics of this lens respect to professional goals to define the border line in which this lens could act unique and brilliant in the field!
First of all, with 355g in weight and 76.8mm in length, lightness and compactness are main characters of Tokina SZX 400mm f/8 mirror lens, so it is the only super-tele lens which could carry on photo equipment compartment of my photo sport 300 back-pack to carry far distances atop mountains without risk of broken back of heavy lenses! The following pictures show the resolving power of Tokina SZX 400mm f/8 mirror lens from a location atop mountains on the subject three kilometers away.
At same location but in opposite direction to the city, the peak of Tochal mountain with nearly 4000 meters in height was composed with stars. Tokina SZX 400mm f/8 mirror lens act very well on sequences of exposures, finally composed as a star trail over the peak. I really praised this compact lens on resolution fine details of ice, snow and shelters at top of mountain.
The exceptional portability of Tokina SZX 400mm f/8 lens is a privilege for those professionals who plan on photo and video projects in remote areas. But let me introduce those circumstances when the output quality of this mirror lens could compete with superior glasses. In this respect, we should first precisely investigate optical characteristics of the Tokina SZX 400mm f/8 mirror lens.
Sharpness is an always important wordiness among photographers and mirror lenses have less sharpness and contrast respect to state of the art professional glass telephotos. However, the final sharpness of a photo does not depend only on lens optical characteristics; instead it depends on many more parameters like vibrations, ISO sensitivity, distance of the subject, and atmospheric transparency. Respecting turbulence's presence in the atmosphere, professionals like bird photographers typically hesitate on distancing their subject because the sharpness is easily ruined for those subjects in low altitude above horizon. Far distancing mountain landscapes and celestial bodies like the moon and sun near the horizon are among those subjects that atmospheric turbulence decreases sharpness on them and there is no escape from this issue! This phenomena leads to an interesting fact for both Astro-photographers and close up landscape photographers; the simple Tokina SZX 400mm f/8 mirror lens could lead to very close result outputs on those subjects like high end glasses in terms of sharpness!
Moreover, the distribution of sharpness across the image is another important aspect to study. Typically due to lens aberrations, sharpness decreases in far corners of the image. To examine the amount of sharpness variation of the Tokina SZX 400mm lens in practice, I perform a consequential photograph of the moon high above the horizon passed through the frame as follows.
Crop of top left corner
Crop of center
Crop of bottom right corner
Respecting the above test, lens sharpness is very good and the distribution remains constant across the frame and even on far corners, any deterioration of image is barely visible. The mirror optical design reduces color aberrations practically to zero, also optical designers seem to do a fantastic job on controlling other types of aberrations too. Moreover, this test reveals another fact on the amount of high vignetting of Tokina SZX 400mm f/8 mirror lens on full frame sensors. As you can see on the background light, a strong darkening rises from half of the frame. We can conclude that the image circle of this lens is full frame with robust sharpness distribution across but a strong vignetting is also present from halfway to corners. In some cases like creating mosaic panorama images, this vignetting is a problem but on other cases as following video time lapse and photos, it could even make nice effects and strong emphasizes on subject composition.
This video time-lapse consists of 230 single exposures through Tokina SZX 400mm f/8 mirror lens on Nikon D3s full frame body.
Kenko Tokina always produces high quality lens converters for lenses and recently I received a 2X converter, named "SZ 2X EXTENDER for T-mount (TA-020)", which is mainly designed for Tokina SZX mirror lens. This converter is compact and solid in build quality, but there is a very interesting fact about the combination of Tokina SZX 400mm f/8 mirror lens with this converter. Let's take a look at the following images taken with/without SZ 2X Extender attached.
With SZ 2X EXTENDER
Comparison of using SZ 2X Extender on Tokina SZX 400mm f/8 lens
Apart from doubling the focal length of SZX 400mm f/8 lens with SZ 2X converter, it is very exciting that there is almost no vignette at the image circle of the lens-converter combination! So this lens also gets rid of the strong vignette on full frame sensors with SZ 2X converter. Tokina SZX 400mm f/8 lens acts as an 800mm f/16 lens with this converter, so special considerations should be taken for a proper focus and vibration free exposures. Albeit the slow f16 aperture of this lens-converter combination, it is definitely a suitable optic catching mesmerizing photos of sun and full moon at horizon.
In conclusion, this new Tokina SZX 400mm f/8 mirror lens is a compact lens with unique characteristics. On Size and weight side, this lens is unrivaled and it is the only option for a backpacker to carry a super telephoto for DSLR or Mirror less system on long travel routes. Moreover this mirror lens could produce very close outputs with respect to benchmark glasses on subjects at far distances close to the horizon like distant mountain landscapes, bright celestial bodies like the sun, moon and planets above the horizon.