[Klaus]

This is 100mm f/1.8 on the EOS 5Ds R (quick n' dirty).

 

 

 

 

[Rover]

Let me answer that question for you:

https://dustinabbott.net/2016/05/sigma-5...rt-review/

Scroll down to the "Mounted on Full Frame" section.

I would've totally got this for use on the 1D series but I'm already pretty well set lens-wise.

[Klaus]

On their website, they only advertise APS-C. You also don't know whether a full format lens isn't full format+ (e.g. in order to achieve better vignetting/bokeh).

[JJ_SO]

So?

 

You can do the same game with a 300 mm on a FF and on a 4×5" camera. The FF lens will give a worse picture than yours on the 4×5" camera.

[Klaus]

Which is why it is pointless to have a debate - the Sigma 50-100mm is an APS-C format lens. The 1.5x (Sigma figure) applies and from here on we can do the equivalence game again - like it or not.

[Brightcolours]

1.6 to 1.34! The lens also covers the new Sigma Foveon APS-H. 

 

You were referring to the lens, not to the limits or crop factor of Canon APS-C size. Ignoring the speed of the lens, which is the reason for it's size, price and weight is the result of this silly equivalence games.

 

You also would not "equivalent" a remote controlled model racing car going up to 100 km/h to be 2000 km/h fast because the genuine "FF"-car model is 20 times bigger. 100 km/h = 100 km/h.

 

Also, FF is just one of many sensor sizes. Given the amount of phone cameras and their sensor sizes, there's no reason to declare FF to a reference. Not many of today's daily camera users ever took pictures on film - or full frame cameras, which are NOT the center of photographic world anymore. So, I think it's better to use the true specifications and not equivalence numbers.

Very often we talk about cellphone cameras in equivalent to FF terms. 

 

"True specifications" say NOTHING what so ever, without reference point. In fact it says so little, that Apple will not even bother mentioning the focal length(s).

Sorry that it irks you so much, when people want to know what a lens compares to on other formats. But yeah, people DO want to understand how lenses compare. They DO want to know that an iPhone 6s has a "31mm FF equivalent" lens, so they understand "ohhh ok, so kinda moderate wide angle".

 

But you say you rather have the "true specifications". Ok, the iPhone 6S has a 2.65mm lens. That is not that informative, is it?

 

And that is just for the front lens. The back lens is 4.15mm. Informative, right? And what does that tell you? 

Hmm.. not much. It seems much less wide. But luckily, we can talk about what it is equivalent to. 29mm FF equivalent. So, wider instead of less wide. Yay for equivalence!

 

We just use FF as reference point, because it is an easily understood reference point. But we can use any other reference point. But none make more sense, most just make things less clear. Because most people with any idea about photography do know what 35mm on FF will mean, or 50mm, or 200mm.

[Brightcolours]

This is 100mm f/1.8 on the EOS 5Ds R (quick n' dirty).

Thanks for the quick and very dirty info, Klaus!

[JJ_SO]

f/1.8 = f/1.8 and remains so, no matter which sensor is used - like it or not. 

 

On Sigma's website they already show the massive vignetting at f/1.8 - so the few millimiters more from APS-C to APS-H will not impact much.

[Brightcolours]

Let me answer that question for you:

https://dustinabbott.net/2016/05/sigma-5...rt-review/

Scroll down to the "Mounted on Full Frame" section.

I would've totally got this for use on the 1D series but I'm already pretty well set lens-wise.

Thanks Rover! So yeah, heavy vignetting, but usable in certain cases. 

[Brightcolours]

f/1.8 = f/1.8 and remains so, no matter which sensor is used - like it or not. 

f1.8 for 50mm = 27.77777777777777777777

f1.8 for 100mm = 55.55555555555555555555