As I have leanred a great deal about the lens' based on many of your comments and advice, I was wondering if anyone wouldn"t mind telling what the abbreviations mean when lenses are identified. For example:
Di
Li
APO
IF (I think this means Inside Focus)
D
DG
ASPH
HSM
EX
I AM GOING TO GET THE BOOKS SEVERAL OF YOU MENTIONED ON LENSES AND DIGITAL PHOTOGRAPHY... THX
Posted by Basil Greber on June 16, 2006 at 1:10 AM
I suggest you check the websites of Nikon, Tamron and Sigma. These things are nicely explained there. These abbreviations tell you about the coating of the lens, how it focuses, whether it measures distance, and whether it contains special lens elements.
Basil
Posted by Kent Staubus on June 16, 2006 at 5:04 AM
Di--A Nikon lens that does not cover 35mm film. Digital only.
Li--Don't know. Canon equiv. of above?
APO--Apochromatic. Uses special glass to reduce purple fringing. A good thing to have.
IF--Internal focussing. Means the filter won't turn as you focus. Good to have.
D--A Nikon lens that uses distance info. Good for flash calculation.
DG--A Sigma digital lens? (Will not cover 35mm film.)
ASPH--Aspherical. Has special glass in a lens to reduce distortion. Used in wide angle zooms, mostly.
HSM--High speed motor. A Sigma lens with a motor in it for faster focussing. Nikon equiv. is "S", Canon equiv. is "USM".
EX--Sigma designation for their better quality lens.
Kent in SD
Posted by Basil Greber on June 16, 2006 at 9:37 AM
Kent, I think what you are talking about is DX. Di is Tamronish for something like digital integrated coating or so...
Unfortunately different manufacturers will use different insignia for similar features (e.g. "ED", "L", and "APO" mean pretty much the same thing - special glass used to focus all colors at the same plane).
My suggestion is to first pick out a focal length that interests you, then read reviews of lenses in that area. It will narrow things down and keep you from going crazy trying to learn everything about every lens. Also figure out what's important to you in a lens (e.g. resolution, maximum aperture, focus speed, zoom range etc.) and make sure to give those characteristics higher priority over other features. The goal is to have something that will work for the type of images you want rather than just the one with the most acronyms (and usually the higher price tag to go with them). Some are significant, some are nice-to-have, and others may be completely meaningless for the way you plan to use the lens. Make sure you understand what you need before reading the marketing hype.
Kent wrote: HSM--High speed motor. A Sigma lens with a motor in it for faster focussing. Nikon equiv. is "S", Canon equiv. is "USM".
Not quite true. First, HSM is Sigma's Hyper Sonic Motor. Secondly, all lenses for a Canon EF or EF-S mount have motors in them. The HSM, or USM if you buy Canon, motors are different than the standard in-lens motors. They are faster, quieter, and will allow you to make manual adjustments to the focus without switching to manual mode.
Kent also wrote: DG--A Sigma digital lens? (Will not cover 35mm film.)
No, that's a DC lens in the Sigma world--appropriate only on 1.5/1.6 crop factor cameras--vignetting will occur on film or larger sensors.
The DG lenses have coatings which are optimized for digital sensors. They will work fine on film cameras--the coatings will not degrade performance on film; they just aren't needed for film. (Film is much less reflective than sensors; the DG coatings are on the back elements to reduce problems caused by light reflecting off the sensor and then off the lens again.)
Some companies use RF instead of IF. The effect is the same--the filter doesn't turn and the length doesn't change when you focus. There are lenses where the filter won't turn, but the length will change. I don't think it's fair to call these IF/RF.
Discussion
6 repliesDi
Li
APO
IF (I think this means Inside Focus)
D
DG
ASPH
HSM
EX
I AM GOING TO GET THE BOOKS SEVERAL OF YOU MENTIONED ON LENSES AND DIGITAL PHOTOGRAPHY... THX
Basil
Li--Don't know. Canon equiv. of above?
APO--Apochromatic. Uses special glass to reduce purple fringing. A good thing to have.
IF--Internal focussing. Means the filter won't turn as you focus. Good to have.
D--A Nikon lens that uses distance info. Good for flash calculation.
DG--A Sigma digital lens? (Will not cover 35mm film.)
ASPH--Aspherical. Has special glass in a lens to reduce distortion. Used in wide angle zooms, mostly.
HSM--High speed motor. A Sigma lens with a motor in it for faster focussing. Nikon equiv. is "S", Canon equiv. is "USM".
EX--Sigma designation for their better quality lens.
Kent in SD
Basil
My suggestion is to first pick out a focal length that interests you, then read reviews of lenses in that area. It will narrow things down and keep you from going crazy trying to learn everything about every lens. Also figure out what's important to you in a lens (e.g. resolution, maximum aperture, focus speed, zoom range etc.) and make sure to give those characteristics higher priority over other features. The goal is to have something that will work for the type of images you want rather than just the one with the most acronyms (and usually the higher price tag to go with them). Some are significant, some are nice-to-have, and others may be completely meaningless for the way you plan to use the lens. Make sure you understand what you need before reading the marketing hype.
Guy
Not quite true. First, HSM is Sigma's Hyper Sonic Motor. Secondly, all lenses for a Canon EF or EF-S mount have motors in them. The HSM, or USM if you buy Canon, motors are different than the standard in-lens motors. They are faster, quieter, and will allow you to make manual adjustments to the focus without switching to manual mode.
Kent also wrote: DG--A Sigma digital lens? (Will not cover 35mm film.)
No, that's a DC lens in the Sigma world--appropriate only on 1.5/1.6 crop factor cameras--vignetting will occur on film or larger sensors.
The DG lenses have coatings which are optimized for digital sensors. They will work fine on film cameras--the coatings will not degrade performance on film; they just aren't needed for film. (Film is much less reflective than sensors; the DG coatings are on the back elements to reduce problems caused by light reflecting off the sensor and then off the lens again.)
Some companies use RF instead of IF. The effect is the same--the filter doesn't turn and the length doesn't change when you focus. There are lenses where the filter won't turn, but the length will change. I don't think it's fair to call these IF/RF.
-Paul
-Paul