So, I guess there is two different types of Sigma teleconverters. DG and non-DG. DG would be the identifier for use with digital cameras. Their website states this line has better lens coatings to reduce glare and ghosting with a digital sensor.

So, I accidentally ordered a non-DG TC. And, it already shipped by the time I realized it and called them.

Do I need to worry about this, or is it a load of crap? I'm thinking it's BS. Just wanting to know if anyone else has had experience with this.

Anytime you have an air/glass surface you get some reflection of photons (anywhere from 10-30% on average) due to the differences in indeces of refraction. Special coatings that are microns thick ( about 1/4 the wavelength of average visible light ) enable transmission of up to ~99% of photons. Engineers spend a lot of time designing lens elements to maximize their transmission of light to the sensor.

The teleconverter adds another hunk of glass between the objective and the sensor so the chance of photons going astray is increased. Eg, IQ loss, lens flare, other internal reflections, etc. I'm not familiar with the quality of the Sigmas, but I'd be willing to bet it if you want the best possible images then it's worth it to get the one with coatings.

I understand what coatings are, and I'm sure the glass is coated. I'm just asking if I need to worry about these specail "digital" coatings they talk about.

Also, there is no price difference or anything. I just don't want the hassle of shipping things back and forth.

Well then, I have no idea. I mis-understood and thought one had coatings and the other didn't.

The only thing I can think of is that a digital sensor has an inherent reflectance that may not be an issue with film. Those special coatings may stop the reflections from being bounced straight back to the sensor. But that's just my best guess without any real knowledge on the issue.

Note: The DG denotes added coating that achieves the best color balance whilst cutting down on ghosting caused by reflections from the digital image sensor.

I'm probably over-thinking this...


Thanks for the detailed reply, Ted.

Originally Posted by LateApex

Note: The DG denotes added coating that achieves the best color balance whilst cutting down on ghosting caused by reflections from the digital image sensor.

I'm probably over-thinking this...


Thanks for the detailed reply, Ted.

Yeah, sorry about that. Sometimes I tend to spout off like I actually know what I'm talking about. Luckily, in this case, I was right

people tend to say the dgs a slightly better, but i've never seen anything to prove it either way... I only have dgs, but only because they were the same price so why not... the biggest negative to the non dgs imho is their resale value...

I was kind of hoping you would chime in. I may still send it back, who knows. I think I have something like 7 days to return it if I don't like it. Thanks.

heh... they ended up sending the DG version anyway.

nice kill!

awesome.

woot