Monday, 2 November 2009

A 2x Teleconverter for the 500mm AF Minolta Relfex lens (Sony SAL-500F80)

Its my birthday and guess what my sweet wife has gifted me. A 7 element 2x teleconverter ! As they say a bird photographer can never have enough focal length. My main birding lens is the Minolta 500mm F8 (AF) reflex lens – the older equivalent of the Sony SAL-500F8 and I`m quite happy with it but I`ve always got one eye on expanding the focal length.

I had read that it was possible to add a teleconverter to this lens and get a whopping 1000mm focal length for the lens or an effective focal length of 1500mm when you take into account the 1.5x crop of the Sony A200’ s sensor! However, it was also known that not all teleconverters are compatible with it. Also if you add a 2x teleconverter to this lens, it loses two stops of light thus making it F16.

Carl from did a review of this lens, after which he tried a 2x Pro-optic teleconverter with it, and it worked. I had been looking for a pro-optic teleconverter but couldn`t find one in the U.K. A reader on the former site left a comment that he had tried and successfully used a Kenko Teleplus MC-7 2x teleconverter with the same lens. I therefore was quite eager to try it out.

The Kenko Teleplus MC7 DG 2x teleconverter is one of the best generic makes of teleconverters available on the market. It is multicoated for high resolution, Digital Compatible and has 7 elements in 5 groups. It has a length of 35.7mm, weighs 170g  and has a light loss of 2 f/stops. Full AF operation with the Teleplus 2x MC7 is possible on camera lenses with a maximum aperture f/3.5 or faster.

Kenko Teleplus Mc7 DG teleconverter

Above is an image of the TC with front and back caps on. Below are images of its front and back (click for larger image) As you may able to see from the contact points, it has a Gate Array IC (Integrated Circuitry) which means that the converter maintains signal integrity between the camera body and lens in the same way an original manufacturer's converter would.

Kenko Teleplus Mc7 DG teleconverter      Kenko Teleplus Mc7 DG teleconverter

The Minolta 500mm F8 fits in perfectly into the Kenko Teleplus 2x TC. Once in and attached to the camera body, you notice an instant elongation of the lens making the compact 500mm look and feel more like a 500mm glass lens, only, now it is no longer 500mm. It has become a 1000mm lens!

Kenko Teleplus Mc7 DG teleconverterKenko Teleplus Mc7 DG teleconverterKenko Teleplus Mc7 DG teleconverterKenko Teleplus Mc7 DG teleconverter

With the TC in place, the camera itself feels very front heavy. You could still use one hand to hold the camera but and using one hand to support the TC region of the camera will stabilise it and leaves you less concerned  about the strain on the lens joints.

When I switched on the camera I was pleasantly surprised that the AF motor started to whirr and try to focus. It almost succeeded but then could not lock on. I didn’t think it would even budge at F16! Anyway, I switched into manual focus and that worked just fine.

Now for some test shots. I was at work all day and got back late in the afternoon and the weather has been really awful, with drizzle lasting the entire day (not to mention the snow from two days back), so the light was very poor….a good test for an F16 lens!

All the below shots were taken either hand held or resting on my window sill in Aperture priority mode without flash (except for the kingfisher figure where flash was used). All images with the lens only were taken with autofocus while with the teleconverter in place, I had to resort to manual focus.You do see blur in the images and I would blame it more on my shaky hands rather than on the lens itself. Oh yeah, all shots were taken through a glass window so keep that in mind too. None of the images have been altered except to convert it from RAW to JPEG.

Kenko Teleplus Mc7 DG teleconverter

Above the Minolta 500mm by itself, below with the Kenko 2x teleconverter.

Kenko Teleplus Mc7 DG teleconverter

Below is a 100% crop of the above image taken with the teleconverter.


Moving a little closer onto a different subject. Below is the Minolta 500mm by itself.

Kenko Teleplus Mc7 DG teleconverter

..and again with the 2x teleconverter:

Kenko Teleplus Mc7 DG teleconverter

Next, even closer

with the lens alone:

Kenko Teleplus Mc7 DG teleconverter

with the 2x converter:

Kenko Teleplus Mc7 DG teleconverter

Finally, I brought it indoor to test it on my Kingfisher figure. This time flash was used but the camera was handheld.

Kenko Teleplus Mc7 DG teleconverter

Above shows an image with the lens only and below with the 2x teleconverter in place.

Kenko Teleplus Mc7 DG teleconverter

Below is a 100% crop of the above shot with the 2x converter.

You can see a definite loss of light with the teleconverter, but that is only expected. I didn’t think that the images would be half as good. There is a reduction in sharpness but keeping  in mind that the outdoor images were taken in horrible lighting across a dirty glass window, handheld they are not bad at all. There is little or no evidence of chromatic aberration – one thing I expected to creep in. I have a feeling this combination could get me some awesome bird photos if used in good daylight. The true test will be when I take it out birding, but for that the weather has to get better first before I begin really enjoying my birthday gift.


Meanwhile here is what the Kenko 2x teleconverter does to a 50mm f1.4 lens ( which I also got as another birthday gift) for macro shots:


Kenko Teleplus Mc7 DG teleconverter

Above with just the Sony SAL50F14 50MM lens and below with the Kenko teleconverter in place.

Kenko Teleplus Mc7 DG teleconverter


  1. Dear Sir,
    Article is perfect! Thank you!
    I need this TCs!
    I have SAL 500mmF80 mirror-SONY.
    Somewhre I reed tha tho KNO doesnt fit on ths lens, becuse it is not deep enough for bajonet.
    Please, adwise.
    Krešimir Pregernik,

  2. The SAL500mm and the Minolta 500mm are the same. The Kenko MC7 will fit both lenses, but the image quality is not great as you can see above.

  3. Dear Sir, thanks.
    Did' you take a picture at sunny day ... for F16 and ISO 100 1/125- with TC2X at distance 30meters?
    Sincerelly yours,
    Kresimir Pregernik,,


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