10-13-2010, 04:57 PM
[quote name='Brightcolours' timestamp='1286971556' post='3606']
Hello Reinier,
There is no significant difference. The lens is optically the same. The non-DG is just older.... when Sigma started to introduce "digital" lenses (APS-C lenses), they needed a way to differentiate the lens lines in nomenclature. APS-C lenses got a "DC" addition. Sigma also added a new coating to the back element because sensors reflect a lot more light back than film, to for instance fight "purple fringing".
Lenses for full frame also got that coating, and got "DG" added to their name. But non-DG lenses perform still very well, one can not tell the difference.
I do believe you have a Canon EOS, I am correct? The only thing you should make sure of is that the lens actually is compatible with the modern EOS digital SLRs. Lenses from before 2003 or so would be incompatible with the aperture communication signals, generating an "Err99" on older DSLRs and a "Lens error" on newer DSLRs. Sigma used to offer "re-chipping" to make that problem disappear, but re-chipping is not possible anymore, as far as I know.
So... just make sure that the lens is either already compatible, or has been re-chipped in the first half of this decade. Easily tested too (and you can ask the seller. of course). Just make a picture, not wide open. If the camera locks with an error, it is not compatible electrically. If it normally exposes a photo, all is well.
[/quote]
Just one addition: DG generally also means that the rearmost lens element has been coated if that wasn't the case already.
You can check this by shooting with a bright light just outside the frame, and compare the shots against another lens, known to be of DG (any Canon EF lens) under the same conditions. If you do get a lot of flare, glare of veiling, it likely isn't coated, and may cause similar effects under "normal" shooting circumstances, if les spronounced. This because for film there wasn't the necesaity to do extensive coating on the back of the last element: film only reflects 2 to 3 % of the light received, while a digital sensor reflects about 40 to 60 %.
In short, check that it works with your camera, adn check that it doesn't show any significant amount of veiling, flare or glare.
Kind regards, Wim
Hello Reinier,
There is no significant difference. The lens is optically the same. The non-DG is just older.... when Sigma started to introduce "digital" lenses (APS-C lenses), they needed a way to differentiate the lens lines in nomenclature. APS-C lenses got a "DC" addition. Sigma also added a new coating to the back element because sensors reflect a lot more light back than film, to for instance fight "purple fringing".
Lenses for full frame also got that coating, and got "DG" added to their name. But non-DG lenses perform still very well, one can not tell the difference.
I do believe you have a Canon EOS, I am correct? The only thing you should make sure of is that the lens actually is compatible with the modern EOS digital SLRs. Lenses from before 2003 or so would be incompatible with the aperture communication signals, generating an "Err99" on older DSLRs and a "Lens error" on newer DSLRs. Sigma used to offer "re-chipping" to make that problem disappear, but re-chipping is not possible anymore, as far as I know.
So... just make sure that the lens is either already compatible, or has been re-chipped in the first half of this decade. Easily tested too (and you can ask the seller. of course). Just make a picture, not wide open. If the camera locks with an error, it is not compatible electrically. If it normally exposes a photo, all is well.
[/quote]
Just one addition: DG generally also means that the rearmost lens element has been coated if that wasn't the case already.
You can check this by shooting with a bright light just outside the frame, and compare the shots against another lens, known to be of DG (any Canon EF lens) under the same conditions. If you do get a lot of flare, glare of veiling, it likely isn't coated, and may cause similar effects under "normal" shooting circumstances, if les spronounced. This because for film there wasn't the necesaity to do extensive coating on the back of the last element: film only reflects 2 to 3 % of the light received, while a digital sensor reflects about 40 to 60 %.
In short, check that it works with your camera, adn check that it doesn't show any significant amount of veiling, flare or glare.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....