[x-vision]

While the new Sigma is an impressive feat of optical engineering,

I also fail to see the appeal of this lens … for stills.

 

It’s bulky and heavy and will likely be expensive. So, one might indeed

consider FF alternatives before spending money on this lens.

 

I’m wondering, though, if Sigma is eyeing budget cinema systems

with the new lens - like the BCC (Blackmagic Cinema Camera) or

even the Canon EOS-C.

 

For these systems, the new lens is currently peerless, as the

FF alternatives are DSLRs, not cinema cameras.

[Brightcolours]

With all this math mambo-jambo you, popo and brightcolours, just seem to forget:


There's not such a lens for APS-C like there are some very pricey ones for FF - and to use them, you just need to get an also pricey FF-body. Which, following Klaus' post are overrated and overpriced anyway, so all the people buying these are just wasting money?

 



I don't get the point trying to calculate equivalence for FF, this is not a question for an APS-C shooter how "lame" this lens is compared to what is available for FX. At the moment it's just outstanding for APS-C and if it can be used at open aperture, it still gives 1.5 f-stops more than the usual 17-50/2.8 "fast standard zooms" which I don't find that overpriced (except a Nikon 17-55/2.8, ok, point taken).


And DoF? At 18mm and open aperture it's 0.86m, not breathtakingly narrow. f/2.8 (with APS-C and same focal length) would give 1.47m.

You can not talk about DOF as something set like you do. There is no such thing as a DOF of 0.86m at 18mm, or something like that. DOF is really always only immeasurably thin, and it will appear bigger depending on many factors, which include projection size and spectator distance. Without stating those two, one can't put a figure at how deep DOF appears to be. Any DOF calculators that do are not right.

One can ask if a Sigma 17-70/2.8-4 OS couldn't be a bit more useful, because of the OS which compensates more than the 1.7 missing f-stops (I was interpolating until 35mm) - but there's no other way to get a narrow DoF and short shutter speeds.


And, by the way, it's not correct to calculate those ISO differences like you did: the borders between the sensels keep the same size, more or less, so in reality the sensitive area decreases more when the sensors get smaller with the same pixelcount.


"The sensor gets MORE sensitive. If you have more surface, the sensor will catch more light. If you have bigger pixels, the pixels will catch more light. Hence: the FF sensor is MORE sensitive by definition."


So a film 8×10 inch and 100 ISO is per your definition much more sensitive than a film 135 with 100 ISO?

So you keep thinking ISO on digital says something about the sensitivity of the sensor? 

 

1. With film, the grain size changes with the sensitivity. Low sensitivity film has a much finer grain than high sensitivity film. 

2. With digital, we can set whatever ISO-setting we want. Film... well, film has its own sensitivity.

3. With 8x10 inch plates/film and 135 format film of the same era you get similar sized grain. Think about that. 

4. In the film era the sensitivity was not a variable. In digital the amount of signal amplification is a variable. Why feel the need to stay stuck in your ways which made working with film easier?

5. Back to that grain size of equal ISO films on different formats. You really want to talk about sensel size here? Then how do you handle a 6mp APS-C sensor, a 10mp APS-C sensor, a 12mp, 16mp, 24mp APS-C sensor? All those will have different sensitivities.

6. ISO in the digital age is NOT about the sensitivity of the sensor. 

 

A FF sensor is more sensitive than an APS-C sensor, no matter how you look at it. If you look at it from a pixel POV, and take similar sensel counts (for instance 12mp): the FF sensor will have 1.5x1.5 times the surface.

If you look at it from an image POV too, the image gets formed with 1.5x1.5 the amount of light over the same exposure period.

 

That you can't get your head around that ISO is not about sensitivity in the digital age, and around the idea of equivalent ISO settings for different format sensors, does not mean it is wrong.

Strange - my old spotmeter didn't list film formats as parameter. Must've been a cheap one...

It does allow you to use different ISO settings to get appropriate exposure time figures. So it is not yet useless, even in the digital age. In the film age, different sized grain would give different ISO ratings for films. Ask yourself why that is not the case with digital cameras with different sized pixels/sensels (big hint to what has changed in the ISO standard).

It will capture more photons, in absolute numbers - but not more on the same area than the smaller frame will catch, too.

In the film era, ISO/ASA was about the film getting exposed right. With digital that is not the case at all, anymore. Manufactures can apply whatever amplification they deem necessary, and top that with extra amplification via "ISO settings". One camera's ISO 100 may mean way more amplification than an other camera's ISO 100.

 

So stop placing importance on the ISO figure, it has no importance. 

 

For equivalent images (FOV and DOF wise), multiply the focal length and f-value by the crop factor.

If you also want a similar exposure time, use an equivalent ISO setting by multiplying the ISO setting value by the crop factor squared.

[popo]

With all this math mambo-jambo you, popo and brightcolours, just seem to forget:

As I said, if you don't care about strict equivalence, that's fair enough. You can use whatever you like, how you like. Just don't pretend it is something it isn't by making selective or partial comparisons. It is what it is, whether you choose to understand it or not.

[JJ_SO]

And you can ride the horse named "equivalence" until it's completely dead

 

Tell me one good reason to erase the difference between two different sensor sizes? Do you think it will be possible one day in future to get an APS-C camera completely equivalent to a FF or even to Medium format DSLR? It's pointless in my eyes, the advantages are so different as they are and will stay that way, not matter of equivalence equations. There are reasons to buy FF and other reasons to go bigger or smaller.

 

'sides, if you don't know about different ways to develop film to different sensitivities, that's alright for me, you're right, the sensors are not films, but 100 ISO gives even in the senor age at the same amount of light the same combination of shutter speed and aperture and that fact doesn't care much about equivalences.

 

Don't you realize we're saying the same? You try to bring in an equivalence to FF format, I say, yes, it's different but nonetheless it is the only fast wide-angle zoom for APS-C and I like to pay respect to Sigma because they just did it? And somebody who needs one for his APS-C cam doesn't have much of a choice, especially because nor Canon neither Nikon have something like that to offer.

 

If somebody's an APS-C shooter with a need for a fast wide angle: Here's one

If somebody's a convinced FF shooter with a fine 24-70 (*overrated* /2.8) lens, great, keep it and shoot happily ever after.

 

Now, the combinations FF/APS-C will weigh

D800+24-70: 1900 grams

D7100+18-35: 1575 grams*

D7100+17-70: 1230 grams

 

* the difference is tiny - but it saves some fast primes which might even not be in the same performance league as this zoom is.

[popo]

And you can ride the horse named "equivalence" until it's completely dead

It's already dead. I think I ate it the last time I had a burger.

Do you think it will be possible one day in future to get an APS-C camera completely equivalent to a FF or even to Medium format DSLR?

Within some limitations, we may already be at a day when a mirrorless APS-C system can be near enough full frame equivalent. Just add one of these. Ok, the limitation is currently that you have to use EF lenses on a NEX unless you like manual options. But in principle other full frame lenses could be used on more APS-C sensor mirrorless systems. With this reducer it is (near enough) equivalent to the native full frame system. You may start arguing about quality now.

[thxbb12]

And you can ride the horse named "equivalence" until it's completely dead

 

Tell me one good reason to erase the difference between two different sensor sizes? Do you think it will be possible one day in future to get an APS-C camera completely equivalent to a FF or even to Medium format DSLR? It's pointless in my eyes, the advantages are so different as they are and will stay that way, not matter of equivalence equations. There are reasons to buy FF and other reasons to go bigger or smaller.

 

'sides, if you don't know about different ways to develop film to different sensitivities, that's alright for me, you're right, the sensors are not films, but 100 ISO gives even in the senor age at the same amount of light the same combination of shutter speed and aperture and that fact doesn't care much about equivalences.

 

Don't you realize we're saying the same? You try to bring in an equivalence to FF format, I say, yes, it's different but nonetheless it is the only fast wide-angle zoom for APS-C and I like to pay respect to Sigma because they just did it? And somebody who needs one for his APS-C cam doesn't have much of a choice, especially because nor Canon neither Nikon have something like that to offer.

 

If somebody's an APS-C shooter with a need for a fast wide angle: Here's one

If somebody's a convinced FF shooter with a fine 24-70 (*overrated* /2.8) lens, great, keep it and shoot happily ever after.

 

Now, the combinations FF/APS-C will weigh

D800+24-70: 1900 grams

D7100+18-35: 1575 grams*

D7100+17-70: 1230 grams

 

* the difference is tiny - but it saves some fast primes which might even not be in the same performance league as this zoom is.

 

Regarding the comparison, you forgot to mention this combo which is much more relevant:

 

D600 + Tamron 28-75 f/2.8: 1268 grams

 

Lighter than the APS-C version while offering much better range.

[Brightcolours]

Regarding the comparison, you forgot to mention this combo which is much more relevant:

 

D600 + Tamron 28-75 f/2.8: 1268 grams

 

Lighter than the APS-C version while offering much better range.

Indeed. Or just look at the Canon EOS 60D and Canon EOS 6D. They have almost the same weight. With the Canon EF 24-70mm f2.8 L USM II the FF combination will similar as the 60D with new Sigma, and yet will offer a bigger focal range. Imagine the difference with the Tamron 28-75mm.

[thxbb12]

Indeed. Or just look at the Canon EOS 60D and Canon EOS 6D. They have almost the same weight. With the Canon EF 24-70mm f2.8 L USM II the FF combination will similar as the 60D with new Sigma, and yet will offer a bigger focal range. Imagine the difference with the Tamron 28-75mm.

 

Absolutely.

The fact is, for equivalent DOF control, larger formats allow for smaller lenses.

There are many examples out there.  Classic small primes such as 50 f/1.8, 35 f/2, 20 f/2.8, etc.

If you were to build equivalent lenses, say for MFT, these would translate to 25 f/0.9, 17.5 f/1, 10 f/1.4. How big would these lenses be? Certainly larger and heavier than their FF counterpart (which are older designs too)!

 

I'm still waiting for a manufacturer to build a FF mirrorless with small pancake lenses (f/2.8 ones would be enough). Surely, such a system is doable and it would combine small factor with very high IQ while allowing one to put faster glass for DOF control if needed.

 

Am I the only one to think such a system would be great? Why no manufacturer is doing it?

[Brightcolours]

I'm still waiting for a manufacturer to build a FF mirrorless with small pancake lenses (f/2.8 ones would be enough). Surely, such a system is doable and it would combine small factor with very high IQ while allowing one to put faster glass for DOF control if needed.

 

Am I the only one to think such a system would be great? Why no manufacturer is doing it?

Obviously the very expensive Leica M9 series fits the bill. Combine it with a Voigtlander 35mm f2.5:



or if you like things very wide, the Voigtlander 21mm f4 or inbetween the 25mm f4.

 

Not all pancake lenses give very high IQ (in fact, some have quite nasty bokeh).

[thxbb12]

Obviously the very expensive Leica M9 series fits the bill. Combine it with a Voigtlander 35mm f2.5:



or if you like things very wide, the Voigtlander 21mm f4 or inbetween the 25mm f4.

 

Not all pancake lenses give very high IQ (in fact, some have quite nasty bokeh).

 

Yes, there is obviously Leica, but this is not exactly for everyone. I'd like a camera with "modern" (I'll get flamed) specs and ergonomics, with AF (similar to MFT), an integrated viewfinder and that is less expensive than a 2 carat diamond. Basically MFT with a FF sensor.

 

I'm aware pancake designs are often not as good as regular design, but if it's good enough I'm happy.  Panasonic, Samsung and Pentax have nice example of good designs. And if one is looking for ultimate IQ, they would still be able to mount a regular lens.