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Author Topic: A New EF 50 f/1.8 IS? [CR1]  (Read 20486 times)

Rocky

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #90 on: July 10, 2012, 03:32:42 PM »
With current Canon cameras (up to the 7D at least), reports put the fastest aperture that increases light to the sensor at f/2.  If you shoot at f/1.4, the ISO is "invisibly" bumped (it still reports as say ISO 100 but the files are noisier than they should be).

I'm sorry but this is simply not true in any way shape or form. The f stop is a ratio that describes the light transmission (I know T-stops are the real deal but we are working in the vernacular here) of the lens. Saying that an f1.4 lens doesn't pass any more light than an f2 lens is nonsense. To suggest that a camera would "know" that an f1.4 lens or faster was mounted and would choose to "throw a way the extra light is also ludicrous.

Can't find the source at the moment, but the original claim was that the additional light coming through hits the sensor at such an oblique angle, that it doesn't go into the pixel wells.
This explanation applies only to the corner and the edge of the sensor. Does not apply to the middle of the sensor.  Therefore you can end up with a highly vignetted at the corners.  Canon user with f 1.4 lens does not really complaining about serious vignetting. Therefore your reasoning is questionable.
M9 uses offset microlens  progressively to take care of the vignetting problem due the the large incident angle at the corner of the frame (this is the nature of the M mount short lenses). Then M9 do a double take correction on camera to each specific lens.

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #90 on: July 10, 2012, 03:32:42 PM »

briansquibb

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #91 on: July 10, 2012, 05:36:16 PM »
With current Canon cameras (up to the 7D at least), reports put the fastest aperture that increases light to the sensor at f/2.  If you shoot at f/1.4, the ISO is "invisibly" bumped (it still reports as say ISO 100 but the files are noisier than they should be).

I'm sorry but this is simply not true in any way shape or form. The f stop is a ratio that describes the light transmission (I know T-stops are the real deal but we are working in the vernacular here) of the lens. Saying that an f1.4 lens doesn't pass any more light than an f2 lens is nonsense. To suggest that a camera would "know" that an f1.4 lens or faster was mounted and would choose to "throw a way the extra light is also ludicrous.

Can't find the source at the moment, but the original claim was that the additional light coming through hits the sensor at such an oblique angle, that it doesn't go into the pixel wells.

Crop sensors are less impacted by the vignetting as they get their light from the middle of the lens so the light path is less oblique

Edwin Herdman

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #92 on: July 10, 2012, 06:42:28 PM »
We're not talking about vignetting at the edges of an image.  We're talking about photosite wells blocking photons arriving at oblique angles, "per photosite vignetting" or shadowing, if you like.

Up until I wrote that post I thought that the cutoff was at f/2, but apparently it's actually f/2.8.  That's rather disappointing.  It probably changes from camera to camera slightly, depending on the sensor and photosite design (at the very least, it could change or someday be "fixed" in a new design).

Etienne

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #93 on: July 10, 2012, 06:54:50 PM »
We're not talking about vignetting at the edges of an image.  We're talking about photosite wells blocking photons arriving at oblique angles, "per photosite vignetting" or shadowing, if you like.

Up until I wrote that post I thought that the cutoff was at f/2, but apparently it's actually f/2.8.  That's rather disappointing.  It probably changes from camera to camera slightly, depending on the sensor and photosite design (at the very least, it could change or someday be "fixed" in a new design).

The center of the sensor does not see the large angle of incidence that is seen in the corners, and even the corners only see this large angle of incidence for perhaps 1/3 or less of the light. The center should be relatively unaffected even down to f 1.2.

Besides if that was the whole story then we would not see a big difference in bokeh between f 2.8 and f1.4. But we do. In fact there's a very noticeable difference in bokeh between f 1.8 and f 1.4.

This doesn't add up.

Wideopen

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #94 on: July 10, 2012, 06:57:31 PM »
Ill take one of these. IS does help me alot for night time street photography

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #95 on: July 10, 2012, 07:52:21 PM »
We're not talking about vignetting at the edges of an image.  We're talking about photosite wells blocking photons arriving at oblique angles, "per photosite vignetting" or shadowing, if you like.

Up until I wrote that post I thought that the cutoff was at f/2, but apparently it's actually f/2.8.  That's rather disappointing.  It probably changes from camera to camera slightly, depending on the sensor and photosite design (at the very least, it could change or someday be "fixed" in a new design).


I think what Edwin is referring to are these findings from DxO and Luminous Landscapes back in 2010.

http://www.luminous-landscape.com/essays/an_open_letter_to_the_major_camera_manufacturers.shtml
http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues

Ellen Schmidtee

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #96 on: July 11, 2012, 02:28:00 AM »
Can't find the source at the moment, but the original claim was that the additional light coming through hits the sensor at such an oblique angle, that it doesn't go into the pixel wells.
This explanation applies only to the corner and the edge of the sensor. Does not apply to the middle of the sensor.  Therefore you can end up with a highly vignetted at the corners.  Canon user with f 1.4 lens does not really complaining about serious vignetting. Therefore your reasoning is questionable.

It's neither my reasoning nor complaint - I just recalled the web page the other participant based his complaint on.

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #96 on: July 11, 2012, 02:28:00 AM »

Morsing

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #97 on: July 11, 2012, 06:49:11 AM »
Quote
Quote from: Edwin Herdman on July 10, 2012, 06:42:28 PM
We're not talking about vignetting at the edges of an image.  We're talking about photosite wells blocking photons arriving at oblique angles, "per photosite vignetting" or shadowing, if you like.

Up until I wrote that post I thought that the cutoff was at f/2, but apparently it's actually f/2.8.  That's rather disappointing.  It probably changes from camera to camera slightly, depending on the sensor and photosite design (at the very least, it could change or someday be "fixed" in a new design).


I think what Edwin is referring to are these findings from DxO and Luminous Landscapes back in 2010.

http://www.luminous-landscape.com/essays/an_open_letter_to_the_major_camera_manufacturers.shtml
http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues


I had never hear of this before, and was sceptical at first, however it does make sense. However, people are clearly overreacting. If you take the time to examine the graphs on the DxO-site, you will see, that by going from f4 to f2.8 on the 7D, you up the gain with about 0.04 eV thus gaining a total of 0.96 eV of light gathering ability instead of 1 eV as expected. This is marginal and of no consequence. Going from f2.8 to f2.0 up the gain by 0.05 eV gaining 0.95 eV in light gathering power, again very little effect. Going from f2.0 to f1.4 ups the gain with 0.25 eV thus gaining only 0.75 eV of light gathering instead of 1 eV. This is worse, but you still get a three fourths of 'what you pay for', not, as indicated, nothing. In going from f1.4 to f1.2 the gain is upped by 0.2 eV giving only 0.13 eV of light gathering power instead of the expected 0.33 (a third of a stop) so this is clearly getting worse.
In total, going from f4 to f1.2 (3.33 stops) you get about 0.6 eV of sensor gain and thus, only get 2.73 eV of light gathering instead of the full 3.33 eV.

Of course the manufactures are still 'cheating', but it is not like you get nothing from using faster glass, you just get (a little) less than you thought you would.

Hope this clears things up a bit

//Morsing

mememe

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #98 on: July 11, 2012, 08:09:11 AM »
I dont like that "We put IS in EVERYWHERE" thing...

Cause it makes them very expensive lenses.

Marsu42

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #99 on: July 11, 2012, 10:14:42 AM »
I dont like that "We put IS in EVERYWHERE" thing... Cause it makes them very expensive lenses.

Like the 24-70ii :-o ?

markd61

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #100 on: July 11, 2012, 10:29:38 AM »
I stand corrected. :-\

Robsenn

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #101 on: July 11, 2012, 10:45:12 AM »
In regards to the price moaning. Consider that you are comparing lenses that are brand new with lenses that are way over 10 years or older. They have already recouped their research and tooling costs and therefore cost has come down over time.

At the time they came out they were the same price as the newly released lenses.

I bet in ten years time the 24-70 II will cost about as much as the 24-70 I and everyone will start moaning about how much its successor is going to cost. I guess most of the forum goers here (me included) have started their interest in photography when the 24-70 was already an old dog and they have no reference points for brand new lenses.

Marsu42

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #102 on: July 11, 2012, 12:14:13 PM »
I bet in ten years time the 24-70 II will cost about as much as the 24-70 I

I'm not so sure about that - quality optics (I suppose, the mk2 isn't reviewed yet :-p)) like on the new Canon are damn expensive to produce, and this will stay this way even if other tech parts like IS (= not on the new 24-70) and r&d costs are left out of the equation.

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #102 on: July 11, 2012, 12:14:13 PM »

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #103 on: July 11, 2012, 12:27:48 PM »
I had never hear of this before, and was sceptical at first, however it does make sense. However, people are clearly overreacting. If you take the time to examine the graphs on the DxO-site, you will see, that by going from f4 to f2.8 on the 7D, you up the gain with about 0.04 eV thus gaining a total of 0.96 eV of light gathering ability instead of 1 eV as expected. This is marginal and of no consequence. Going from f2.8 to f2.0 up the gain by 0.05 eV gaining 0.95 eV in light gathering power, again very little effect. Going from f2.0 to f1.4 ups the gain with 0.25 eV thus gaining only 0.75 eV of light gathering instead of 1 eV. This is worse, but you still get a three fourths of 'what you pay for', not, as indicated, nothing. In going from f1.4 to f1.2 the gain is upped by 0.2 eV giving only 0.13 eV of light gathering power instead of the expected 0.33 (a third of a stop) so this is clearly getting worse.
In total, going from f4 to f1.2 (3.33 stops) you get about 0.6 eV of sensor gain and thus, only get 2.73 eV of light gathering instead of the full 3.33 eV.

Of course the manufactures are still 'cheating', but it is not like you get nothing from using faster glass, you just get (a little) less than you thought you would.

Hope this clears things up a bit

//Morsing

I think the important thing that camera manufacturers do is to preserve the relationship between ISO, f-stop and shutter speed.  Digital systems are not always linear over the entire operating range.  If the gain has to be increased to preserve the photographic trades that we are familiar with, then it makes our lives easier.  But it is good to know that shots wide open with fast lenses might have slightly more noise because of the boosted gain.

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #104 on: July 11, 2012, 12:32:35 PM »
I stand corrected. :-\

Markd61, I hope you read this and decide to rejoin the forum.  Discussions are useful and we learn from them and improve our craft.  That's what the forum is for.

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Re: A New EF 50 f/1.8 IS? [CR1]
« Reply #104 on: July 11, 2012, 12:32:35 PM »