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Miljenko Devcic | profile | all galleries >> tech >> Lens reviews and tests >> Kenko vs Sigma TCs >> DG vs non-DG TCs tree view | thumbnails | slideshow

DG vs non-DG TCs

Some time ago Sigma introduced DG lens series that differ mostly in improved coating that minimizes sensor to lens elements reflexions. Many lens models received that treatment including their two teleconverters: 1.4x and 2.0x. How that different coating influences pic quality and is it really an improvement, I have explored simply by shooting the same subject while switching teleconverters. Here only 1.4x TC was used, both DG and older non-DG versions. Two very different Sigma lenses were used, along with Nikon D200: 150mm f/2.8 APO Macro DG and 50-500mm f/4-6.3 APO RF. All the camera settings (like aperture, exposure, white balance) were equal.
Pics are equaly processed, the same picture crop extracted and assembled side by side. Here just two comparisons are presented but all the other made lead to same conclusions:
DG version betters in contrast, but fails in colour fidelity. It has pinkish colour cast, while non-DG converter gives more neutral colour. Resolution seems to be equal. SO if you are into buying Sigma teleconverter and can get (cheaper) old non-DG version, go for it. Despite all the efforts, I couldn't provoke situation where DG version would show any significant advantage over older non-DG version.
Side by side
Side by side		 Crops
Crops		 With Sigma 150mm Macro
With Sigma 150mm Macro		 With Sigma 50-500mm
With Sigma 50-500mm

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Guest 11-Mar-2016 23:06
Oh by the way. I just left the previous post. I have the 2x TC and using it on a Sigma SD14 camera with a 150mm-500mm OS Sigma lens. Works great, except the AF doesn't work with these big lenses. AF and OS both work very well without the TC.
Guest 11-Mar-2016 22:57
I know this is an old thread, but I was happy to find it. Thank you . Nice comparison. I too have just purchased a used nonDG for $85. USD in like-new condition. It was advertised at Adorama as a DG model, even had the correct mfg.# for the DG. After seeing this test, I'm glad I didn't spend the extra money. I am happy with it, by the way. I just had concerns as to whether the coatings were worth complaining to Adorama. Thanks.
Iain 01-Aug-2015 17:20
Thank you! I bought the non DG 2X converter yesterday cheaply (£85 second hand) but didn't know if I needed DG or not. Yours is the first site I've found which actually answers the question and I'm very happy I went with the cheap one. Regards, Iain
Guest 13-Feb-2009 02:46
Also, if you look closely at the yellow car, there is much less reflection on the yellow panel in the non-DG version. It's almost as if a polarizer was used. I don't know if this is good or bad though.
Guest 13-Feb-2009 02:42
That's an interesting comparison. I can see the color cast also in the DG version. For some reason, I see more noise in the first pic in the non-DG version but there is also a very slight increase in detail retrieval. Look carefully at the tire threads (rear left tire) on the silver car. It's a minute difference but I can see it on this monitor (a Samsung XL20).
click on thumbnails for full image