I recently asked a question about a particular zoom lens. That lens is available as the 35mm version or with the special DG designation..light output sized for the digital sensor.

Does that make any difference? Is "digitally optimized" a marketing buzz word? Why would manufacturers make lenses with light areas to fit digital sensors if that is not a good thing?

I am confused. Perhaps some of you who have DSLR cameras and use the lenses you already had for 35mm can tell me if it makes any difference.

I wondered if it affected the actual f value..then figured that is the light "output received", not the light "area" struck.

So, if I use a 35mm lens on the DSLR and a similar one with a light area cut down to sensor size, does that make any difference at all in the final image?

Since one of the first brags about the DSLR was to be able to use lenses already on hand from the 35mm..I wonder about the value of the special "digital" lens.

Any thoughts at all will be appreciated. TomDart.

Message edited on: 06/13/2005 19:08

I've read a couple articles, but do not claim to be an expert. I'd think I'd not get an SLR lens if it could ONLY be used on a digital back, (though if the cost was really low, it still may not be a bad deal). It'd be smaller, lighter, faster. Not sure we will ever see cheap sensors approaching film size, particularly if the digi-optimized lenses prove to be a lot better. Otherwise, digital optimized lenses in theory bend the light so it hits the sensor at a more perpendicular angle than is needed for film. Supposed to more evenly illuminate the frame. Also, have anti-reflective coating on INTERNAL metal parts to reduce reflections.

Misha, that bit of info helps clear the fog...salesmen who do not have the "digital" version in stock claim no difference..that is why I asked. I hope to see on the shoot experience and not believe all the hype, either way! Then again, if I am not shooting film( or plan to with the particular lens) the digital version may be the best way. I am wanting a nice telephoto zoom and that is pricy. And like all of us, do not want to be disappointed with the lens. Thanks for the imput. This does help! Tom. PS the part of light orientation is new to me. Thanks for that and light is something I do understand.

While I haven't seen any of the new Digital lens, I do believe they may help in a small way. (Maybe more than I think) but I am going to be very hesitant to purchase any, since lens can last for years, I do believe that in the not to distant future that full size sensors will be the norm. I have no fact on the above statement, just a feeling.

I use a 17 -35 mm bought with my DSLR about 2 years ago and a 60 mm macro lens a very early version approx 8 years old for all my shots, both lens were designed to work with full frame film cameras, I cannot see any problems quality wise though scientific tests have shown lens designed for digital use are better but marginally. My feelings are if I was to purchase an outfit from scratch I would go with the appropriate digital version but the improvement in quality is not enough to make me change my present lens selection. I would really like the manufacturers make lens that gives the same focal lengths relative to 35 mm cameras i,e for a wide angle zoom of 17 - 35 not to turn into a 26 - 45 mm, please make us a true wide angle lens in the range of say 12 - 30 mm, then I would be ready to purchase a new lens.

MGTF: the reason the focal lenghts are different to SLR is because of the sensor size...the 'magnification' factor brings the smaller sensor up to the same size as 35mm. It looks like a magnification but in actual fact, is a field of view crop. Smaller the sensor, more 'magnification). My dslr has a 1x3 'mag' as oppossed to the standard 1x6, 1x5...due to the larger sensor size than the 10D, 20D, 350D etc. Hence, the full frame sensors cams(Canon IDS, IDs mk11 etc) have no 'magnification'.

Attached Link: http://www.sigma-imaging-uk.com/support/faq_lens.htm

I think that digitally optimized lenses can be made to suit the smaller sensor size so therefore can be made smaller and cheaper there should be little difference in quality.. However if you get a full frame camera at another date you will not be able to use them at the wide angle as you will get some vignetting

the most important difference is the fact that the optical quality of a digitally optimized objective is better than a "normal" one - due to the fact - a regular print film is never that perfect flat that a chip is... so if you use a DSLR you would get sharper images with an optimized objective than with a normal one. if you use regular print film it doesn't matter... my 10 cent -christian

jimry : Thanks, I understand the reason for the magnification factor, my point is that even though camera companies are making lens designed for the digital format they are still sticking to the focal length markings relevant to 35 mm full frame cameras, this can sometimes be a disapointment if purchasers are not aware of the magnification factor.

An interesting point about film but I think it is not the case that digitally optimised lenses are better quality it depends what you mean by normal? For example Canon do not make a L series lens in the EFS mount which are digitally optimised, the point is that they can be made smaller and so less expensive glass is needed in theory they should be able to make them better or as good but no doubt the big makers are not interested as it would require enormous investment.. And in the end they have the full sized 1DS etc as the main pro camera which has the same 35mm frame which is standard unlike the 1.3 1.5 or 1.6 sensors on the best digital SLR

Attached Link: "For Digital" Lenses

@danob - if you refer to what i wrote... i was told the optical quality is better to get a more precise picture over the whole chip - which is not that important if you use normal film! so they're optimized to minimize the distortion at the plane of the chip... which is also important because the chip is bigger as the film. also a digital SLR seems to have a "sharper" image - simply because you always have the same (exactely same) distance between lenses and chip... which may differ some micrometers if a (not flat) film is used... it's the same as if you compare a reflector telescope with a refractor telescope... the refractor is optically more precise and you need better objectives to get out the full precision in the pic... and it's the same with the objectives for cameras... again my 5 cent ;)

Kort my dear, a huge thx for that link that just clarified things for me in a sec!!! Simply explained and beautifully pictured!!! Yep!

I agree with Misha, if you are going to spend out on a lens, you might as well have a lens that can be used both on film/full frame and the smaller sensors. I have used both a digital lens (not mine) and my own full fame lenses. I have seen little difference, except for the full lenses tending to look a little sharper. Ok to be fair I have only used one digital lens so cant make a real comparison. Ok if using a full frame style lens, on a DSLR with a smaller sensor, the outer portion of the optic in not used due to the crop, so IMO and as I understand it, the outer portion of a lens is less sharp than the inner portion of the lens and therefore using a full lens should produce a better quality image!?! Based on conversation and images that I have seen/shot

Yikes! This tread has grown...and I say hurrah to that. My primary concern is image quality. The fact that the smaller digital(I can spell it when I try) lens is a possible burden in the future if and ever if full frame sensors drop in price, or if I need to trade or sell the lens to get another one... It seems the full frame 35mm size is the way to go, the best of the compromises. I simply did not want to purchase an expensive lens and be disappointed with the results. This input has been quite varied and much for thought. TomDart.

I am very much of the same train of thought and have avoided buying a digital lens for that very reason. Although the quality seems to be mostly comparable to standard lenses in the same class, a lens should last for years after the camera is in the antiques archives. Keeping an open option on a full frame digital if they come down to a reasonable price.