Kenko Teleplus PRO 300 DGX 1.4x
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viper_biker
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I was using one on a 70-200VRI yesterday and wasn't happy with the images (quite soft) but it works really well on the 300 prime.
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Confirmed Richard.....here's the text from Kenko's press release a while back
The DGX TelePlus converters have updated circuitry to record exif data more accurately. In the exif exposure data (meta-data recorded with a digital picture) DGX converters record the equivalent aperture and focal length of the lens setting plus teleconverter. Optically and mechanically they are identical to the prior high-quality DG series converters.
( http://www.thkphoto.com/news/news-pr012010-10.html )
Bob
tdodd
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Yes, but the DG version does that as well. I should know. I've got one. I haven't seen anything in the specs of the DGX version that clearly states specifically what the differences are. Certainly the text quoted above implies nothing new or different.
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Tim,
I suspect that Nikon control is different to Canon in this respect and the update will be more obvious there.
T/C's on Canon equipment are recognised by the lens and not the body...the lens then sends modified data to the body. The extra three pins on the forward end of the T/C are simply a common and two contacts...one is wired for a 1.4x and the other for a 2x. When the lens sees one of these contacts made then it adjusts the aperture and focal length data sent back to the body.
Bob
micloi
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I have the DGX's (both 1.4 and 2x). It shows the focal length correctly BUT it does not compensate for the exposure so I need to underexpose 1 stop for the 1.4 and 2 stops for the 2x or the photos come out too bright. This is not an issue witth my Sigma teleconverters.
I am using the DGX's on a Canon, on both Sigma and Canon lenses.
I am using the DGX's on a Canon, on both Sigma and Canon lenses.
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I guess that's down to the lens/lenses in question. All Canon EF lenses that are "T/C friendly" have 11 electrical contacts whilst the "non-T/C friendly" ones only have 8. A lens with 11 contacts should work fine without EV correction.
Bob
micloi
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I am sure you are right concerning the Canon lenses. The Sigma lenses still work without any adjustment with the Sigma TC's but not the Kenko TC's, that is something to be aware of.
HoppyUK
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That seems right Bob. I've just tried my Kenko 1.4x DG and with a 70-200L with 11 pins it reports both f/number and focal length correctly. On my "non-T/C friendly" 24-105L (which it also fits - just!) with only eight pins, it doesn't report either of the changes.
Both deliver correct exposure though, as you would expect.
The TC only has eight contacts though
:shrug: Edit: both Canon lenses.
HoppyUK
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I get correct exposure at all times, regardless of what is being reported. I can't think why that would be otherwise with any lens/TC combo, as the light transmitted to the camera is reduced and it cannot do anything but compensate for that.
For example, I get correct exposure even with a set of fully manual extension tubes at 1:1 (2 stops loss) that receive no lens data at all. The viewfinder reads f/0.0 and so does the Exif, but exposure is correct.
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The exposure would be correct shooting wide open as the metering aperture and the shooting aperture are the same. It's when the metering is done wide open and then the lens stops down for the shot that the error would occur.
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HoppyUK
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That's not what I'm getting Bob.
Even on the non-TC friendly 24-105L which reports one stop out with the Kenko DG 1.4x, the exposure is correct at all f/numbers.
The light is reduced by the TC regardless of what the camera has been told, so it reduces the shutter speed one stop to compensate, throughout the aperture range.
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My deduction is that you have your metering on the shutter button then and aren't using AE lock.
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HoppyUK
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Yes, but not sure how that would make any difference.
The point I make is that the metering system doesn't need to know what the actual f/number is. That's just for information. It works by adjusting the relative number of stops from the starting point rather than by specific f/numbers. It measures the light though the lens, which is already reduced by the TC, calculates the adjustment necessary for correct exposure in terms of a stops shift, and sets the appropriate aperture/shutter speed.
gpa
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As have I and concur, works well with my 200-400mm
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My assumption (and it is just that) is that the viewfinder info is just a visualisation of the likely outcome....which invariably occurs when all the hardware is up to the task. The real metering occurs after the aperture stops down) just before the mirror lifts) and any offsets (manually set or calculated as required) are applied at this time.
Maybe you could peer through the viewfinder with the Kenko in situ and then see if the EXIF shows the same aperture/speed as the forecast showed....I suspect that it will differ by the expected amount.
If you were to use AE lock then the final exposure would likely be out by one stop even though the metering prediction looked good.
Bob
HoppyUK
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Viewfinder readout and Exif are the same Bob, with or without TC. Sometimes it's right (TC enabled lens) and sometimes it's a stop out (non TC enabled). In the latter case, if the f/number is adrift of what it should be, the shutter speed will drop accordingly to compensate, so that exposure is always correct.
All metering is done at full aperture.
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micloi
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UPDATE: Tried both the Kenko 1.4x DGX and the 2x DGX as well as the Sigma 1.4x DG and 2x DG on a Canon lens with 11 electrical contacts.
All teleconverters report the correct focal length and aperture.
ONLY the 2 Sigmas expose correctly.
The 1.4x Kenko is wrong by 1 stop
The 2x kenko is wrong by 2 stops
HoppyUK
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That's interesting. Which of your lenses does this apply to? I'm wondering if this is maybe one of those odd 'new camera/old 3rd party lens' problems that needs the lenses rechipping.
Just a wild guess but that's not my experience using a Canon 40D and 5D2, with Canon lenses and the Kenko DG. Exposure is always correct, regardless of whether or not it is reported properly.
micloi
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Just tried it on a Canon 300mm 2.8 IS and a 7D, same problem, so not a case of old lens here :shrug:
Please do not forget that I am using a DGX and not a DG TC so maybe it is an issue with the new teleconverters?
yangzijohn
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I am planning to buy a kenko 2x for my canon 70-200 f4L on EOS 500d. In order for the AF to work, I need to tape the first three pin. In this case the tc will not report back to camera, right? Can I assume that after I tape the first 3 pins, it doesn't matter whether DG or DGX and I can safely buy a cheaper DG instead DGX?
Thanks in advance!
Thanks in advance!
HoppyUK
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The pins taping trick can work, with some cameras, but it's far from ideal.
What it does is fool the camera into thinking there is no TC in place, therefore it doesn't know the f/number has gone over f/5.6 and so it still tries to focus.
However, since the f/number actually has gone over f/5.6, it will struggle. It's more the diameter of the aperture that the camera sees which is the problem, and that has been reduced by the TC. That's why Canon switches it out. You can usually get away with f/6.3 or so (which is the little bit of headroom that Sigma and others use with their lenses that run to f/6.3) but at f/8, which is what you're looking at, it might not focus at all. It will certainly try, but might hunt back and forth a lot, perhaps in vain.
This seems to be different with different cameras. My 40D would not tolerate anything over f/6.3 max at all, but my old 350D would have a go and get it right a lot of the time even at f/8 if you give it a nice contrasty target in good light. But it's slow and a bit unreliable even then.
puddleduck
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Agreed. It always did that for my Nikon lenses, at least with AF-S lenses.
micloi
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Tried the 1.4x DG as well and still need to compensate for the exposure, it seems like that is how these work which is fair enough. The DG did not report the correct exposure but did report the correct focal length so the plot thickens!
It does not matter really as it is so easy just to dial the exposure down one or two stops and leave it there, I was just curious to see if this is a generic thing or not, it seems it is.
Anyway I only have one lens left that can take teleconverters so I am selling all of them except the one Sigma TC I will use, I just wanted to do some testing before they are gone!
It does not matter really as it is so easy just to dial the exposure down one or two stops and leave it there, I was just curious to see if this is a generic thing or not, it seems it is.
Anyway I only have one lens left that can take teleconverters so I am selling all of them except the one Sigma TC I will use, I just wanted to do some testing before they are gone!
micloi
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I would not use the 2x on an f4 lens if you are not using an 1 series camera.
You will lose AF (even if you tape the pins, AF will only work in very good light and won't be as accurate, making you miss many shots). Also image quality will suffer considerably with an f4 zoom lens.
Also by taping the pins you are losing reporting of all information in the Exif data which will make it very difficult later when you will be trying to see info for aperture and length in your photos, except if you do not care about this :shrug:
Here is an interesting comparison test of most teleconverters:
http://www.traumflieger.de/objektivtest/open_test/telekonverter/overview.php
The new Kenko 1,4x MC4 DGX (cheaper and inferior model to the 1.4x PRO DGX) gets the first place in the main test.
1 Kenko 1,4x MC4 DGX..............2.000
2 Canon Extender 1,4x II...........1.848
3 Kenko 1,4x Pro 300 DG...........1.830
4 Sigma 1,4x APO EX................1.744
5 Canon Extender 2x II.............1.666
6 Kenko 1,5x MC DG ................1.596
7 Kenko 2x MC7 DGX................1.576
8 Kenko 2x Pro300 DG..............1.549
9 Kenko 2x MC7 DG..................1.468
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Reading the text in the Traumflieger report, the 1.4x MC4 DGX didn't produce the correct EXIF data with their test setup....a 70-200/4 L IS on a 5DMkII....which seemed to be the whole point of the new release.
Bob
HoppyUK
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I'm not making sense of this. I have that same lens and camera, and it works fine with a Kenko Pro 300 1.4x DG. Correct exif, and correct exposure both indicated in the viewfinder, and delivered. As it did on my 40D.
I am not understanding why Micloi is not getting correct exposure at all. That doesn't seem to me to be dependent on any reporting - the light is reduced by the TC, that's all the camera needs to know to adjust the shutter speed accordingly
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I've just dug out my old Kenko 1.4x PRO DG and done some metering tests with a 70-200/4 IS on the 5DII and then compared them to a Canon 1.4x T/C. The Kenko and the Canon 1.4x are giving me identical metering (tested at various apertures) when targetted on my lightbox.
A further test, which Micloi might try, is to meter at f/8 or f/11 and then press the DoF preview button....the metering shouldn't change (mine doesn't)
Bob
A further test, which Micloi might try, is to meter at f/8 or f/11 and then press the DoF preview button....the metering shouldn't change (mine doesn't)
Bob
lostsoulal2
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The marketing material for the MC4 DGX 'hints indirectly by only mentioning prime lenses' that there could be issues with zoom lenses whereas they say "The PRO 300 family are designed to work best with telephoto zoom lenses of 100mm and above. The PRO 300 can be used with telephoto zoom lenses as well as prime lenses, however Kenko does not recommend them for zoom lenses that have a range starting at under 50mm."
Perhaps the MC4 DGX range may be more suitable for prime lenses?
puddleduck
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No the MC4 range are budget options and should be avoided. The Pro 300 DG series can match Nikon or Canon TCs in optical performance. The MC4 are not as a good and are a reduced 4 element optic.
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That's certainly always been the case Andy but the Traumflieger tests have put the MC4 at the top of the pile (optically)....based on the copy they tested. A lucky sample perhaps :shrug:
Bob
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I'm finding those Traumflieger tests hard to believe. They can say what they like, but no way is a cheap 4-element telecon better than the pukka Canon L version. It's only been recently upgraded to a MkII model and although they left the optics alone (only adding weather-proofing I think) they surely would have upgraded the glass if there was any benefit to be had.
Maybe if they tested it with a few different lenses their findings would be more consistent. There may be other issues with their test procedure also - mthe German translation I'm reading is a bit confusing. Also, while it is possible that they got a poor copy of the Canon 1.4x (though most unlikely I think) it is not possible for them to have got an exceptionally good copy of the Kenko. A poor copy can be worse, but even the best copies can never be better than 100% of design specification.
Edit: just a thought. I've got a lot of respect for those Traumflieger reviews in general and he seems to know what he's doing. I'm wondering though if the design of the 4-element Kenko compared to the much longer 5-element Canon makes it more receptive to the way the light cone of the 70-200L 4 IS test lens presents itself to the telecon. I've often read that the Canon telecons are optimised around the 300L 2.8 and the Canon version apears to be more highy 'corrected'. When you do that, lenses tend to perform better in their specific area of application, but perform relatively worse when you move too far away from that. I can think of other examples, such as the highly regarded Canon 17-55 2.8 which when given the test treatment on the-digital-picture.com (which I believe is highly questionable with wide-angles) performs significantly worse than the humble 18-55 kit lens. But in the real world of course, the better lens shines through.
Trig's
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Darren,
Was this the Kenko DGX 1.4x & did or have you uesd it on Nikon's 70-200mm VR (Not the newest VII) as was looking at getting the older DG version from OSD but they are discontinuing it now for the newer DGX model....
So no doubt a uesd DG will go up in price if they have better IQ than a DGX..
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It is the DG model that I have. I have only used it with the 80-200 in order to take actual photos but I have attached it with all my other lenses just to have a play and it works with them. I have not used the DGX model so cannot comment on any comparison and unfortunately I don't have a 70-200.