Tamron DiII vs non Di lens

Shane422

So I found the Tamron 28-200 F/3.8-5.6 XR SUPER for $149 new. I've heard pros and cons to this lens, but it fits the budget and has a nice range, so I'm thinking of getting it. But I know Tamron makes DiI and DiII lenses. Since this will be fitted to a Nikon D50, will I be missing and functions that a Di lens would have? or is this simply a marketting tool? I do know about the conversion factor 1.5X with digital.

cmason

from what I read on their website, the Di lens has special coatings to reduce glare and other issues more common on digital cameras, while the Dii is a true crop sensor sized lens.

TristanP

Here's the info right from Tamron:

http://www.tamron.com/lenses/di/di_slide1_diII.asp

It's just like the Canon EF/EF-S difference - Di lenses will work on all dSLRs, while the DiII only work on crop factor cameras. The advantage of using EF (Canon)/Di (Tamron)/DG (Sigma) lenses on a crop factor camera is that you're only using the central part of the lens, so there's less (if any) vignetting and fewer issues with aberrations and image quality at the edges than there would be on a full frame camera.

Shane422

I was thinking just that. That the Non Digital lens would be using the center portion of the lens and therefore have less distortion. So why would anyone ever want a Digital or cropped lens. It seems that simply putting on the correct filter would solve any flare issues.

TristanP

Designed-for-digital lenses (EF-S, DiII, DC) are typically smaller, lighter, and cheaper. If ultimate IQ is the need, then yes, the regular lenses are usually much better.

mercphoto

Shane422 wrote:

It seems that simply putting on the correct filter would solve any flare issues.

Because the glare they are trying to reduce is off the back element of the camera. Therefore a filter does no good. Film is reflective to a certain extent, but a digitel sensor much more so. Therefore an anti-reflectivce coating on the back lens element is rather beneficial.

I've also heard that "digital lenses" try to direct the light rays to the sensor at a more perpindicular angle to the sensor. Again, film is rather forgiving of the angle of incidence, but due to how a CCD or CMOS sensor is made, its best that the light strikes the sensor more head-on.

Then again I use "film" EOS L-lenses on my 20D and don't notice any of these issues. So while all the above is likely technically true, I don't know how large a problem it truly is.