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KenkoTeleplus MC4 DGX converter - AF's at f8? (1 Viewer)

Just acquired the Kenko MC7 2X DGX converter (and I think there is a MC4 2X version too). Had a brief test on my 300 f4 with my 50D. It does AF and the focusing speed is not too bad either.
EXIF showed f8 at wide open and focal length 600mm, but no mention about the converter. Initial images are a bit soft. Will try it out on birds in a bright day.
 
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Tried it out on 5D with 300 F4L, Initial results are soft and washed out. AF did work, but through the view finder, it looks "jumpy" (Not with my Canon 1.4X) and its better if turned IS off, so don't know if it is th IS group that's affected. Looks better to crop from the 300 + 1.4X combo than using it. Will try out again on a tripod, and may be also on my 300 f2.8 and see.
 
The DGX MC7 2X on my 300 f2.8 gives shots of very low contrast, and the sharpness dropped quite a bit. May be the Pro 300 DGX 2X will fare better. Interestingly, from some sites, the Pro-version do have the full number of contacts in the Canon version, while the non-pro one has only5 + 3.
 
I have tried the Kenko Pro 300 DGX 2X on a Canon EF 100-400mm at max zoom with my Canon EOS600D/Rebel T3i. Although it has the full range of pins, it will AF (and AF fast and accurately) in good light even with the EXIF data showing F11.3. In dimmer light, it does hunt a bit but the focus still locks on accurately after a second or so. Contrast does take a hit and the image appears as lighter or washed out. However, by underexposing by -2/3 to -1 1/3, these effects are reduced somewhat. I hope to compare results with the Canon EF 400mm F5.6 prime lens, which I expect to perform better than the zoom. Did not manage to try any other Kenko TC though, but would like to know the results.
 
Hor Kee said:
I have tried the Kenko Pro 300 DGX 2X on a Canon EF 100-400mm at max zoom with my Canon EOS600D/Rebel T3i. Although it has the full range of pins, it will AF (and AF fast and accurately) in good light even with the EXIF data showing F11.3. In dimmer light, it does hunt a bit but the focus still locks on accurately after a second or so. Contrast does take a hit and the image appears as lighter or washed out. However, by underexposing by -2/3 to -1 1/3, these effects are reduced somewhat. I hope to compare results with the Canon EF 400mm F5.6 prime lens, which I expect to perform better than the zoom. Did not manage to try any other Kenko TC though, but would like to know the results.
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Interesting, and thanks for the information. I got the non Pro version because I thought that the Pro one will not AF, so from the beginning, I should have got the latter. Anyway these are funny toys that are not too costly. I may try to get the other later.
 
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Hor Kee said:
I have tried the Kenko Pro 300 DGX 2X on a Canon EF 100-400mm at max zoom with my Canon EOS600D/Rebel T3i. Although it has the full range of pins, it will AF (and AF fast and accurately) in good light even with the EXIF data showing F11.3. In dimmer light, it does hunt a bit but the focus still locks on accurately after a second or so. Contrast does take a hit and the image appears as lighter or washed out. However, by underexposing by -2/3 to -1 1/3, these effects are reduced somewhat. I hope to compare results with the Canon EF 400mm F5.6 prime lens, which I expect to perform better than the zoom. Did not manage to try any other Kenko TC though, but would like to know the results.
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Interesting, this is certainly different to what others have reported with the same converter but maybe on different Cameras. Even with the 1.4x Kenko pro DGX most say that AF is almost a non starter with the centre focus point on Cameras like the 40D, 50D and 7D.
BTW the EXIF should show f11 and not f11.3 shouldn't it.
 
Roy C said:
Interesting, this is certainly different to what others have reported with the same converter but maybe on different Cameras. Even with the 1.4x Kenko pro DGX most say that AF is almost a non starter with the centre focus point on Cameras like the 40D, 50D and 7D.
BTW the EXIF should show f11 and not f11.3 shouldn't it.
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My guess is that it is down to the advanced features of the Eos 600D. I've just had this camera for 2 months and it never ceases to amaze me. Again, it may be down to an individual trait of the camera, TC or even the 100-400mm lens that I borrowed for the test (a mint 2nd-hand copy).

I'm not sure how the EXIF recorded as F11.3. I'll try to find out why this was the case.

For the above test, I didn't tape the pins at all. I was told by the shopkeeper that there is no need to do so with the 600D. How and why, that I'm still trying to find out. I'm interested in getting a copy of the 2X TC after I get a telephoto lens (gunning for the 400mm F5.6). I'll probaby use it as an 'emergency' extender when the birds are just too far. I hope to test the 1.4x Pro soon on a similar lens and will report my findings.
 
Hor Kee said:
My guess is that it is down to the advanced features of the Eos 600D. I've just had this camera for 2 months and it never ceases to amaze me. Again, it may be down to an individual trait of the camera, TC or even the 100-400mm lens that I borrowed for the test (a mint 2nd-hand copy).

I'm not sure how the EXIF recorded as F11.3. I'll try to find out why this was the case.

For the above test, I didn't tape the pins at all. I was told by the shopkeeper that there is no need to do so with the 600D. How and why, that I'm still trying to find out. I'm interested in getting a copy of the 2X TC after I get a telephoto lens (gunning for the 400mm F5.6). I'll probaby use it as an 'emergency' extender when the birds are just too far. I hope to test the 1.4x Pro soon on a similar lens and will report my findings.
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It is well documented that the Kenko DGX series of converters do not need to be taped in order for the Camera to attempt to AF even when the f stop takes it past the Cameras specification. This is the same with any lens or Camera. This is done by the converter hiding itself from the Camera's AF system while still reporting the correct aperture (some clever jiggery pokery by Kenko) .

On any Canon Camera fitted with a DGX converter it will attempt to AF without taping the pins but how well it does it is another matter, The 600D AF system has 9 AF points with just one centre cross type sensor so therefore the general AF system is nowhere near as good as, say, the 7D that has 19 points, all cross type sensors. If it does AF at over f5.6 any better than the more expensive Cameras it is probably down to the fact that the AF system is not as advanced as most Cameras (as silly as this may sound). AF at, effectively, f8 was pretty good up to the 30D Camera but after that the centre point was enhanced to work better with f2.8 lenses.

Sorry to be so negative but I would be most doubtful that the Camera will AF consistently well at f11, especially on the the centre focus point - if it did it would makes it far and away the best DSLR AF system ever produced and the price does not reflect this.
 
Thanks Roy for your helpful insight to AF past F8. The 600D's AF at F11 is good only in bright light, otherwise it hunts about for a couple of seconds or so and will take longer with poorer lighting. In that case its AF performance is consistent with its predecessors of its class of Canon DSLRs. It is very interesting how a less advanced AF system with less AF points can give different results.
 
Tried out the MC7 2X DGX again today on my 7D and 300 f4 (effectively at f8, like the 1.4 on 1-400 as I don't have the 1.4 MC4). At close range, on big object, it AF well with the centre point, and image quality is considered quite good. (it was a slightly overcasted day, but still with good light.) But on smaller and distant objects, it doesn't autofocus so well, and image quality dropped wuite a bit. The young tree swall is a full frame resized and slightly sharpened, taken at a distance of about 15 foot. But then I guess we don't have to use 600 mm for it at this distance. So need more testing with distant objects, (which is the main reason I bought it for.)
 

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Just got my long-awaited Canon EF 400mm F5.6L lens. Tried a Kenko Pro 300 DGX 1.4 TC on it but it didn't autofocus. Strange that its 2x cousin did autofocus as stated in my earlier posts. A used non-reporting 8 pin Vivitar 1.4x (similar to the old MC4 and probably rebadged or otherwise derived from it) made the camera try to autofocus but it was jumpy and could not lock on at all. Both attempts were done in good light. Any idea why?
 
eastwood said:
Interesting, and thanks for the information. I got the non Pro version because I thought that the Pro one will not AF, so from the beginning, I should have got the latter. Anyway these are funny toys that are not too costly. I may try to get the other later.
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Sorry. I need to revise my opinion after going back to my local shop today. I tried the Kenko Pro 300 1.4x DG and not the DGX version. I got confused between the two versions.
 
Hor Kee said:
Sorry. I need to revise my opinion after going back to my local shop today. I tried the Kenko Pro 300 1.4x DG and not the DGX version. I got confused between the two versions.
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Right on, HK. micloi has a very clear description of the DGXs in the Canon Forum. That helps a lot.
 
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