mosc

marike6, sensor size has everything to do with it because all these cameras have dynamically set ISO speeds. You hold exposure the same by changing the ISO. The larger sensor can be more sensitive...

f4.9 is not dark. Quit saying that. Do people call f5.6 FF "dark"? No. They consider sensor size.

and I'm sorry bout f2.3 1/1.7" and f4.9 1" are very very similar. Their wide angle, which is far...

and since I was obviously being sarcastic, what the hell other purpose does this thing serve! I mean, how about a half of a stop faster for say, half the zoom range would be more than a fair trade...

You know I often find myself on a sunny day, shooting handheld, wanting infinite depth of field, at 720mm, and wondered why I need all this massive gear? I mean, everyone shoots 720mm on a sunny...

I'm looking for the 70-210 f4, not the longer one.

Threat title says it all. I'm looking at all these wonderfully priced lenses on ebay but how do I know what I'm getting optically/mechanically? I don't care about scratches to the paint but will it...

It's kind of clear their focus was on ignoring weight and size with this thing despite it being APS-C. It's focus is on delivering pro performance to APS-C with pro weight/size as a non-restriction.

How low you can go ideas:
Use a tiny checkerboard black and white in a studio setting with controllable light. Put both cameras at the same distance and hold exposure time to something reasonable...

Naveed you're crazy. This lens isn't stabilized. That makes it better suited for Sony and Pentax than Canon and Nikon even. Sony sold a lot of SLT's in recent years. I think the odds of this NOT...

Andy, too bad they didn't make an a-mount version of this sigma yet lol!

Thanks DPR for continuing to try and explain total light to people. Also seems like there will be more to this when you get a real copy, specifically focusing on comparing it to f2.8 FF which I am...

We won't know anything until there is a price and some information on how sharp this thing is wide open across it's range. If it's soft at f2.8 and costs $2000, it's not going to change much. If...

Timmbits, this is already the fastest aperture zoom ever in terms of aperture * crop. Asking for it to be faster is... naive.

Yes. Lenses should be pushing sensor sizes SMALLER! This is an excellent observation. If the lens can deliver proportionately faster apertures as it reduces image circle for the same...

Now have Sigma make a f1.0 9-19mm 1" lens for it and we'll talk ;)

People keep bickering over equivalent f-stops. Both sides are clearly right and clearly not accepting the other side is talking about a different aspect of photography.

From an exposure...

widest aperture*crop on a zoom in history, right?

This lens weighs almost 2lbs...

Exposure depends on sensitivity, ISO. DSLR's have very flexible ISO's. In other words, you raise the ISO on the FF f2.8 lens and it matches the exposure on the crop f1.8 lens.

And because you...

You're right, that lens is the right length and aperture for me. It's just expensive and I want A-mount.

I wish the original non-IS version was available used for a-mount. With the IBIS already...