Jul 252015
Kowa telephoto lens 500mm f5.6

Kowa telephoto lens spottings scope

Kowa is a huge optical company mainly known for spotting scopes among birders. The company is among the best in the field together with Swarowsky or Nikon among others. The company based in Japan, was founded in 1894. This is not a small garage tuning company, the company has 2000 employees. This new telephoto lens / spotting scope is an interesting option. To the main body of the lens which is a prime lens, there are three different adapters allowing to use the lens in three different focal lengths with different brightness:

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350mm f/4

This is the brightest combination with the shortest adapter. Kowa T07

500mm f/5.6

According to my opinion this combination by far the most interesting, 500mm focal length with a relatively bright f/5.6 aperture. The adapter is longer. Kowa Tx10

850mm f/8.9

It is the longest combination for small birds, the adapter is the longest, but brightness is reduced, it is only good for bright sunlight. Kowa Tx17

Prism unit for scopes

Kowa TP-88EC1 Prism Unit

Manual focusing only

This lens is a manual focusing only, this is a huge drawback according to my opinion, but the main thing is the price and optical quality here. The price of the lens/scope is 2900 USD, the adapters cost 340 USD each for 500mm (the Pentax is 325 USD), 510 USD for 350mm. I’d probably go with the 500mm f5.6 and forget the two other. (For birding, the 350 f/4 is little short, but perhaps also interesting if it sharp, the 850mm is a little dark, especially for viewfinder image)

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Lens parameters

The weight of the lens is app. 2kg (4 pounds) and has a filter diameter of 95mm. This weight is handholdable, although I don’t know the adapter is included or not in the weight. What is unique is the fluorite optics which only present in the highest quality products. The lens has 9 aperture blades and can be stopped down to f/11. This is not so common, for macro f/16 or f/22 preferred, but this is not the macro lens, the lens minimum focusing distance is 3m (10′). This is usual for such a lens. The lens is significantly more expensive than the Tamron 150-600 or the Sigma 150-600mm lenses (the difference is not so huge compare to the Sports version of the Sigma). The question how is it compare to the image quality. The autofocus and the stabilizer is a big plus for the other two lenses. The lens has 7 elements in 7 groups.

The 2900 USD perhaps first seems very high and it is, but this optics uses fluorite elements. We cannot checked it yet, and in Hungary to chance such a thing is quite little in the near future. On dpreview there is an opinion it is quite good, comparable to Canon L primes, which costs significantly more.

Available mounts

Canon Nikon Pentax Micro 4/3 and Sony alpha as well. Seems can be used on many systems. It is perhaps very interesting on a Micro 4/3 giving a huge focal length (500mm will be 625 equivalent).

500mm f/5.6

It is interesting why Canon nor Nikon doesn’t have 500mm f/5.6 lenses. Both wants to sell the super expensive f/4 versions instead. Would be nice to have a cheaper version though. Pentax has a 560mm f/5.6 for 5000 USD.

sample images and opinion on dpreview From the sample images the lens looks quite sharp according to my judgement.

The lens can be used as a spotting scope as well with an adapter

The price if I am guessing right on par with the Sigma 300mm f/2.8 lens. The Sigma lens has autofocus, bright f/2.8 aperture. The real question how is it compared at 500 or 600mm in case of the Sigma. At 420mm the Sigma is quite good I am sure. As I see if the Kowa has very good image quality, there is a market for the lens. The 500mm f/5.6 looks a desirable combination, as well the 850mm is quite unique. Such lenses are incredibly expensive in the Canon or Nikon lineup, even for Pentax.

In the box

-Removable tripod adapter
-Front and back lens cap

BH order link for the lens

500mm f/5.6 FL Telephoto Lens/Scope
As I understand the lens is the same for all mounts, just the adapters are different.

Separetely purchased elements

For the lens at least one adapter is needed, which costs 340 USD.
Kowa 500mm f56 2

Official Kowa website

Official Kowa website and video



Kowa 500mm f/5.6 Fl

Canon Nikon Pentax Micro 4/3
Filter size:
95 mm front
Lens elements / groups:
7 / 7
Exotic Lens elements:
1.97 kg (4.34 lbs. )
Appr. 4.0 x 13.4″ (10.16 x 34.04 cm)
Close focus distance:
3 m (9.84′)
No / manual focus only
Front element rotates:
Moving barrel elements during focusing:
Focus preset modes:
Lens Mount:
Full frame
Reproduction ratio:
Aperture blades:
9 diaphragm blades
Distance scale:
Yes in m and feet
Manual focus override:
Focal length:
350, 500, 850 mm
Max Aperture:
f/4, f/5.6, f/8.9 respectively by focal length
Min Aperture:
Angle of view:
FTM (Manual focus override):
Focus limiter:
Tripod mount ring:
Lens hood:
Tilt / shift: