August 23, 2014, 03:19:11 PM

Author Topic: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C  (Read 31268 times)

TWI by Dustin Abbott

  • 1D X
  • *******
  • Posts: 1555
    • View Profile
    • dustinabbott.net
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #135 on: April 22, 2013, 09:42:46 AM »
If nothing else, the new Sigmas are beautiful looking pieces of kit.  I love the look compared to the old "crinkle finish" design.  The new lenses are so clean and professional looking.
6D x 2 | EOS-M w/22mm f/2 + 18-55 STM + EF Adapter| Rokinon 14mm f/2.8 | Tamron 24-70 f/2.8 VC | 35mm f/2 IS | 40mm f/2.8 | 100L | 135L | 70-300L -----OLD SCHOOL----- SMC Takumar 28mm f/3.5, Super Takumar 35mm f/3.5, SMC Takumar 55mm f/1.8, Helios 44-2 and 44-4, Super Takumar 150mm f/4

TWI by Dustin Abbott

  • 1D X
  • *******
  • Posts: 1555
    • View Profile
    • dustinabbott.net
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #136 on: April 22, 2013, 09:47:57 AM »
The sample images at that site look pretty good.  Resolving power looks pretty impressive.  If I were a crop user I would be getting very interested about now.
6D x 2 | EOS-M w/22mm f/2 + 18-55 STM + EF Adapter| Rokinon 14mm f/2.8 | Tamron 24-70 f/2.8 VC | 35mm f/2 IS | 40mm f/2.8 | 100L | 135L | 70-300L -----OLD SCHOOL----- SMC Takumar 28mm f/3.5, Super Takumar 35mm f/3.5, SMC Takumar 55mm f/1.8, Helios 44-2 and 44-4, Super Takumar 150mm f/4

Mantanuska

  • PowerShot G1 X II
  • ***
  • Posts: 48
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #137 on: April 22, 2013, 12:34:43 PM »
Regardless of all this arguing over APS-C vs FF noise, fact of the matter is this lens is not only  capable of doing f1.8 at 18mm, but it looks pretty good wide open based on those sample images. 

f1.8 is still f1.8 don't muddy the waters by bringing sensors into the picture

rs

  • 6D
  • *****
  • Posts: 599
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #138 on: April 22, 2013, 02:13:35 PM »
I know I said I'm done, but just one quick last post from me on the subject. DPReview have a hands on preview of this lens up on their website, and on the first page they wrote this:

Quote from: dpreview
Sigma's choice of F1.8 as maximum aperture isn't a coincidence; it means that the lens will offer the same control over depth of field as an F2.8 zoom does on full frame. What's more, it will also offer effectively the same light-gathering capability as an F2.8 lens on full frame. By this we mean that it will be able to project an image that's just over twice as bright onto a sensor that's slightly less than half the area, meaning the same total amount of light is used to capture the image. This is important as it's a major determinant of image quality. Essentially it means that APS-C shooters will be able to use lower ISOs when shooting wide open in low light and get similar levels of image noise, substantially negating one of the key advantages of switching to full frame.

http://www.dpreview.com/previews/sigma-18-35-1-8
5D II | 24-70 II | 70-200 II | 100L | 40 | Sigma 50/1.4 | 40D | 10-22 | 17-55 | 580 EX II | 1.4x TC II

Wildfire

  • EOS M2
  • ****
  • Posts: 170
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #139 on: April 22, 2013, 02:17:56 PM »
Yes, once again you're correct that the 1.8 crop lens has the same light-gathering ability as the 2.8 FF lens.

However, the important fact (to me, at least) is that the exposure from the 1.8 lens will be twice as bright-in camera than the 2.8 lens at the same ISO -- for low-light shooting this is more important to me than depth of field.

Albi86

  • 1D Mark IV
  • ******
  • Posts: 837
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #140 on: April 22, 2013, 02:28:49 PM »
Yes, once again you're correct that the 1.8 crop lens has the same light-gathering ability as the 2.8 FF lens.

However, the important fact (to me, at least) is that the exposure from the 1.8 lens will be twice as bright-in camera than the 2.8 lens at the same ISO -- for low-light shooting this is more important to me than depth of field.

Which is what I also said. What matters is not the total amount of light, but the luminance on the sensor surface.

Do you understand the otherwise self-contradiction of saying that it gathers the same light but it delivers a twice as bright image....?

Wildfire

  • EOS M2
  • ****
  • Posts: 170
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #141 on: April 22, 2013, 03:15:27 PM »
Right, the FF lens "gathers" twice as much light, and then spreads the "gathered" light over a much larger sensor. The crop lens "gathers" less light, but then focuses the light onto a small sensor, creating a brighter exposure than the full frame lens despite having "gathered" less actual light.

TrumpetPower!

  • 1D Mark IV
  • ******
  • Posts: 951
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #142 on: April 22, 2013, 03:29:32 PM »
Right, the FF lens "gathers" twice as much light, and then spreads the "gathered" light over a much larger sensor. The crop lens "gathers" less light, but then focuses the light onto a small sensor, creating a brighter exposure than the full frame lens despite having "gathered" less actual light.

...but only when shot at an f/number sufficiently smaller such that the actual physical aperture is the same.

In other words, the APS-C camera shot with a 50mm lens at f/1.8 gathers the same amount of light as a 135 camera with an 80mm lens at f/2.8, and framing and depth of field and the rest are also comparable.

50 / 1.8 = 27.8
80 / 2.8 = 28.6

Cheers,

b&

Kit.

  • PowerShot G1 X II
  • ***
  • Posts: 41
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #143 on: April 22, 2013, 05:49:54 PM »
I've decided to offer some help to Sigma with an FAQ set for potentially confused customers.


Nope, comparing shutter speeds of 70/2.8 to shutter speeds of 35/1.8 is not helping at all.

You seem to think that all that matters is the amount of light falling on a square micrometer of the sensor.
While it doesn't. We don't shoot sensors.
What really matters is the amount of light that is gathered from a square millimeter of the subject.

AdamJ

  • Guest
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #144 on: April 22, 2013, 06:56:15 PM »
Nope, comparing shutter speeds of 70/2.8 to shutter speeds of 35/1.8 is not helping at all.

I didn't compare it specifically with 70mm, I compared it with a 24-70mm, because that was the comparison others made that started the debate.

You seem to think that all that matters is the amount of light falling on a square micrometer of the sensor.

If you read the thread, you'll understand that my objective was to dispel the notion that f/1.8 on APS-C is in effect the same as f/2.8 on full frame. That notion is actually an unhelpful and circuitous way of saying that APS-C sensors are, because of their typically smaller pixels, usually noisier than full-frame sensors - simple as that.
« Last Edit: April 22, 2013, 06:58:23 PM by AdamJ »

Mantanuska

  • PowerShot G1 X II
  • ***
  • Posts: 48
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #145 on: April 22, 2013, 07:24:15 PM »
Quote from: AdamJ

If you read the thread, you'll understand that my objective was to dispel the notion that f/1.8 on APS-C is in effect the same as f/2.8 on full frame. That notion is actually an unhelpful and circuitous way of saying that APS-C sensors are, because of their typically smaller pixels, usually noisier than full-frame sensors - simple as that.


^^ THIS

And that FAQ table. All that needs to be said.

Kit.

  • PowerShot G1 X II
  • ***
  • Posts: 41
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #146 on: April 22, 2013, 07:48:26 PM »
Nope, comparing shutter speeds of 70/2.8 to shutter speeds of 35/1.8 is not helping at all.
I didn't compare it specifically with 70mm, I compared it with a 24-70mm, because that was the comparison others made that started the debate.
While you should be comparing pictures/scenes shot with both and then presented on comparable mediums (screen or paper).

Otherwise the comparison is meaningless.

You seem to think that all that matters is the amount of light falling on a square micrometer of the sensor.
If you read the thread, you'll understand that my objective was to dispel the notion that f/1.8 on APS-C is in effect the same as f/2.8 on full frame. That notion is actually an unhelpful
Just the opposite. The end result is about the same, because it is mostly limited by purely optical considerations. No matter what technical solutions are employed between the subject and the final image on paper or on monitor.

and circuitous way of saying that APS-C sensors are, because of their typically smaller pixels, usually noisier than full-frame sensors - simple as that.
Nope. They aren't noisier "because of their typically smaller pixels". Given the same size of the lens' entrance pupil (i.e. the same amount of light captured by the lens from an area on the subject), the same angle of view and enough of pixel well depth, they all will provide about the same amount of noise on the final medium.

They are noisier because the entrance pupils of their smaller lenses are generally smaller than on the lenses that provide the same angle of view for larger sensor formats. There are physical limitations in making large entrance pupils for smaller focal lengths, as pupils bigger than f/0.5 are impossible even theoretically.
« Last Edit: April 22, 2013, 07:50:02 PM by Kit. »

Mantanuska

  • PowerShot G1 X II
  • ***
  • Posts: 48
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #147 on: April 22, 2013, 09:13:07 PM »


They are noisier because the entrance pupils of their smaller lenses are generally smaller than on the lenses that provide the same angle of view for larger sensor formats. There are physical limitations in making large entrance pupils for smaller focal lengths, as pupils bigger than f/0.5 are impossible even theoretically.

You still get more light from a smaller focal length (at the same pupil size) .  Thats why we describe the amount of light coming through the lens as a function of the focal length and pupil size, or in other words we use F-stop notation.

a 10mm aperture on an 18mm lens that gives a certain fov on APS-C lets in more light than a 10mm aperture on a  28mm lens that would produce the same fov on FF.

Thats why zoom lenses that aren't constant aperture get darker when you zoom in. The pupil isnt getting smaller, you just have less light entering the lens because you are constricting the FOV.

An F-stop is and F-stop regardless of format or focal length
« Last Edit: April 22, 2013, 09:20:00 PM by Mantanuska »

wickidwombat

  • Canon EF 400mm f/2.8L IS II
  • *******
  • Posts: 4457
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #148 on: April 22, 2013, 09:19:08 PM »
personally i see the f1.8 light gathering ability and effective wider depth of field as a benefit not a negative
the only issue is having a good high iso APS-C sensor to pair it with currently there isnt one in canons line
APS-H Fanboy

9VIII

  • 6D
  • *****
  • Posts: 547
    • View Profile
Re: Sigma Announces 18-35 f/1.8 DC HSM Art for APS-C
« Reply #149 on: April 23, 2013, 12:47:07 AM »
Nope, comparing shutter speeds of 70/2.8 to shutter speeds of 35/1.8 is not helping at all.

I didn't compare it specifically with 70mm, I compared it with a 24-70mm, because that was the comparison others made that started the debate.

You seem to think that all that matters is the amount of light falling on a square micrometer of the sensor.

If you read the thread, you'll understand that my objective was to dispel the notion that f/1.8 on APS-C is in effect the same as f/2.8 on full frame. That notion is actually an unhelpful and circuitous way of saying that APS-C sensors are, because of their typically smaller pixels, usually noisier than full-frame sensors - simple as that.

Unfortunately I think that may actually still hold true.

http://www.geofflawrence.com/inverse_square_law.html

To get equivalence you need to account for the smaller surface area and the extra distance from the subject. Using a shorter focal length to make up for the tighter FOV effectively puts you farther away from the subject.


If someone would actually make a lens that gives the same FOV at the same focal length instead of throwing all the extra light away in FOV reduction, then we'd have an amazing short focal length lens. Right now wide angle on crop cameras just seems like a waste.

I do agree that everything would be better off with smaller pixels though, and that people should stop equating MP count with noise.
-100% RAW-