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  #31  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Ricoh View Post
I'm not sure. I'm viewing images presented for web using an iPad, very difficult to make a judgement. If people do no more than present web-grade images, most cameras are capable, the iPhone 6 being more than capable.
Paul has presented 100% crops albeit with the Sony resized to match the image area of the E-M1, which does make sense given that's how you would view a comparative print (for example).
I wonder how popping the 12-40 on the E-M1 and zooming to 17mm would stack up. I'm pretty sure it's a better performer than the worst of the Oly primes at their respective focal lengths.
As an alternative the 25 (Oly or Panny) verses the 55 would be interesting.
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  #32  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Greytop View Post
Paul has presented 100% crops albeit with the Sony resized to match the image area of the E-M1, which does make sense given that's how you would view a comparative print (for example).
I wonder how popping the 12-40 on the E-M1 and zooming to 17mm would stack up. I'm pretty sure it's a better performer the worst of the Oly primes at their respective focal lengths.
As an alternative the 25 (Oly or Panny) verses the 55 would be interesting.
The 2 images I posted earlier today compared the Pany 25 f1.4 and Ziess 55 f1.8.
Here, I've resized them in Photoshop so they are the same size then taken a crop of each.

Oly + 25 F1.4



A7ii + 55 f1.8



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  #33  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by birdboy View Post
It not about sensor size per se or pixel density. The A7R has a pixel density of 4.8 micron /pixel whereas the EM1 has 3.75 the E5 has 4.3 and the E3 4.7 so the E3 is close to the pixel density of the A7R! When one looks at the images then it is not FF or pixel density that is determining the noise the trick lies in the electronics that measure the photons in the photsites and the Olympus sensor and electronics is doing an admirable job at reducing noise and I would say better than the Sony A7R.
Sorry, that is wrong. All other things being equal, a larger sensor will have less noise as it captures more light.
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Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Kiwi Paul View Post
The 2 images I posted earlier today compared the Pany 25 f1.4 and Ziess 55 f1.8.
Here, I've resized them in Photoshop so they are the same size then taken a crop of each.

Paul
Thanks post these Paul
Are these 100% or larger? They look too sharp to be 100% for either lens camera combination to me
Oh and this was with your A7 II 24MP (now returned) and not the A7R II correct?
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  #35  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Kiwi Paul View Post
The 2 images I posted earlier today compared the Pany 25 f1.4 and Ziess 55 f1.8.
Here, I've resized them in Photoshop so they are the same size then taken a crop of each.


Paul
The thing that strikes me most about those is the difference in processing. Don't know if they are jpgs or raw but there ar some massive differences in the curves in them. Sony is slightly warmer too, or the sun came out a bit.
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  #36  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by birdboy View Post
Ross How would you explain the lower read noise figures for the EM1 shown on the sensorgen web pages? I am beginning to think that the generally accepted WWW view that FF must be less noisy than cropped sensors is suspect. I accept that the final image does appear clearer in FF but that image has been produced by a sensor and lens and I currently support the view that the lens plays a bigger part in this than the sensor.
Thanks, but I had deleted my post, but obviously not soon enough.

I love my E-M1 & am not (can't afford to if I wanted to) going to get into anything different anyhow.

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  #37  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

It seems that Paul's comparison is being questioned for several reasons but I think it is important to realise that it was never intended to be a scientific test, merely an observation based on several real life situations.

It may well be true that the lenses used are not an equal match in terms of quality, but who's fault is that? If the 17mm f1.8 is the best prime of that focal length Olympus can produce they must expect to be judged upon it. Actually, I perceive that although perhaps not quite top draw it's still a more than capable lens.

As for resizing the Sony images before cropping giving that camera an advantage, Paul could have done it the other way - upsizing the Olympus files to match the Sony before taking 100% crops. I expect that would have been far less kind to the E-M1.

Regarding the confusion over f-stops, I think we can accept that, regardless of the physical diameter of the aperture, in terms of light gathering f2.8 is the same for any lens on any format. We don't need to involve ourselves in complicated physics equations, the lens designers have already done that!

It was no surprise to me that the full frame Sony beat the MFT Olympus in all of Paul's examples; what did surprise me was how little the differences were in terms of real world usage.
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  #38  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Nawty View Post
Sorry, that is wrong. All other things being equal, a larger sensor will have less noise as it captures more light.
I agree - all other things equal, that's exactly true. However, whether that's because it "captures more light" or whether it's because it needs less magnification is definitely up for debate.

Try this thought experiment:

- Imagine two sensors made with the same pixels (same technology, pitch, size), but one u43 and the other FF

- Put a lens in front of each with the same field of view and set the same f-stop

- Set them both to the same ISO and take a shot with the same exposure time

Now, each pixel would receive exactly the same light intensity on both sensors and would therefore yield the same noise.

However, the u43 image would need more magnification so whatever noise was there would be magnified. That's got nothing to do with the sensor itself capturing more light per se has it?
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  #39  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Nawty View Post
The "shrinking" was nothing to do with your post but the link to Clarkvision website where he (for example) took a milky-way photo with a 15mm and 35mm lens and then showed them at the same framing and then compared the noise between them, which to me seems rather disingenuous.
Ah, apologies - I thought you were referring to my post!
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  #40  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

The larger lens will indeed capture more light but when that light is focussed on the larger sensor it will be spread over a larger area, so all other things being equal (aperture, euqivalent focal length etc) surely the light intensity per unit area at the sensor will be the same?

Anyway, on the evidence of this thread I won't be changing to a Sony system as the differences seem very small. Thanks for the demo Paul .
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  #41  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

What if all the sensor data from both cameras was printed such that each pixel was produced by one "dot" of the printer head.

4800 x 3200 @ 300dpi = 16 x 10.67

4608 x 3456 @ 300dpi = 15.36 x 11.52

Could you see a difference? Perhaps the colours would be slightly different, any specular highlights may look dissimilar, whites whiter, blacks blacker, etc., etc., et...

Hang on a minute, we had all this with film choice, grain size, speed, backing colour, and all the wonderful variations that came from chemistry

We still discus the colour richness of the E-1 & E-500 sensor and all the various stages that have brought us to where we are today with the "mysterious" unknown PEN-F sensor.

I do enjoy a good technical discussion, and this forum seems to be able to do it so well, with hardly any Teddies being harmed.

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  #42  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by birdboy View Post
Ross How would you explain the lower read noise figures for the EM1 shown on the sensorgen web pages? I am beginning to think that the generally accepted WWW view that FF must be less noisy than cropped sensors is suspect. I accept that the final image does appear clearer in FF but that image has been produced by a sensor and lens and I currently support the view that the lens plays a bigger part in this than the sensor.
Read noise is only half the story. What's important is the signal to noise ratio so you need to look at the max saturation (also called the pixel well capacity) as well. Both are measured in electrons (created by photon interaction) and the ratio gives you the s/n. As the sensor size (area) increases so does the well capacity. Although the read noise is lower on the E-M1, so is its well capacity. The Sony has a well capacity three times bigger than the E-M1 but the read noise is only about 50% higher. This means the Sony has a better s/n ratio. In heavily filled pixel wells the s/n will be low for either camera, but as the well gets more lightly filled (in low light) the s/n increases. Since the larger area of the FF pixel and its larger well capacity are able to capture more photons, more electrons accumulate in the well leading to lower s/n ratios.

And in fact, there are other sources of noise than read noise - "shot noise" being the main one which is random quantum fluctuation in the capture and conversion of photons into electrons in the well. Shot noise becomes the biggest contributor to noise in the darker parts of an image.

As regards lenses, since we're magnifying a 4/3 image twice as much as FF (in linear dimensions, not area), any lack of sharpness is exaggerated. Lenses for smaller formats need to have higher acuity to deliver the same perceived sharpness in the final image. I reckon the Oly 12mm f2 lens is one of the sharpest in the u43 system, but at the same final viewing size, an old OM 24mm f2.8 (when stopped down to f8) delivers an apparently sharper image from the Sony.
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  #43  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Greytop View Post
Thanks post these Paul
Are these 100% or larger? They look too sharp to be 100% for either lens camera combination to me
Oh and this was with your A7 II 24MP (now returned) and not the A7R II correct?
They are 100% crops or there abouts, and yes with the A7ii.

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  #44  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by Nawty View Post
The thing that strikes me most about those is the difference in processing. Don't know if they are jpgs or raw but there ar some massive differences in the curves in them. Sony is slightly warmer too, or the sun came out a bit.
Shot as RAW and processed in LR CC, shot on a different day, so the colour temp wouldn't be the same, the compositions aren't exactly the same as I weren't standing in exactly the same place either. The processing was done independently but I used the same process and the difference in the LR sliders isn't that great, even with the sliders set the same there is still a difference in the histogram, different day, different composition, different cameras and lenses, there will be a difference in the curves / histogram not necessarily attributable to processing.

Paul
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  #45  
Old 7th February 2016
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Re: E-M1 and Sony A7R comparison (warning - lots of images)

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Originally Posted by pdk42 View Post
On this issue of aperture size and f-stop I can assure you all that the light intensity reaching the sensor is proportional to the f-stop, not the absolute aperture size. A moments thought makes this obvious - if it were just the size of the aperture alone, then why do longer focal lengths have bigger glass for the same f-stop? Look at your 17mm f1.8 lens and the aperture size is about 1.25cm. Now look at your 75mm - here it's more like 5cm and yet both are f1.8 and both will give the same exposure when used for a photo at the same shutter speed and ISO.

The logic of it in more mathematical terms is due to the inverse square law. The inverse sq law states : "The intensity of the light is inversely proportional to the Sq of the distance it travels."

That is I is proportional to 1/(D * D)
where
D is the distance and
I is the Intensity

For a 32mm lens at f/8
Diameter is 32/8 = 4 mm, therefore radius = 2mm
The area of the aperture is then 2 * 2 * pi = 4pi
The focal length of the lens is 32mm so
the intensity of the light = 4pi/(32 * 32) = 0.01227 .............. A

For a 80mm lens at f/8
Diameter is 80/8 = 10 mm, therefore radius = 5mm
The area of the aperture is then 5 * 5 * pi = 25pi
The focal length of the lens is 80mm so
the intensity of the light = 25pi/(80 * 80) = 0.01227.............. B

A and B are the same - the same intensity at the same f-stop, but the aperture size are 4mm and 10mm respectively.

Absolute aperture size matters for the amount of blur for out of focus parts - hence the reason why FF cameras show more blur than u43 cameras.
Paul my reasons for questioning what you did because I am trying to fully understand this FF versus cropped sensor issue because I have thought about going FF. I wonder where you got your suspect formula from maybe http://www.photographycorner.com? I was not going to do this but I feel it is so wrong that it needs to be corrected before more folk believe in your formula. I say its suspect because you state "The intensity of the light is inversely proportional to the Sq of the distance it travels." and that the intensity = 0.01227 yet your formula can be simplified to pi/4/(fstop)^2 which contradicts your statement as there is no distance in the equation! Intensity is a measure of watts per area.

I would guess that few on here have read the clarkvision article and properly digested it. But I would like to highlight some of the important statements made in it. For those who still think he is wrong would do well to look at his background.

http://clarkvision.com/rnc/

“The prevailing view by photographers is that faster f/ratios delivers more light. I will show you in this article that is not necessarily the case. This bucks the prevailing view in photography, but is not the prevailing view in imaging science. This article will explain why.”

The clarkvision article explains all those issues that folk have raised on here. He uses the same exposure settings (ISO aperture and shutter speed) but the conclusions are that f/stop does not tell the whole story and that a truer exposure is described in his Etendue equation.

“There are three factors that determine the true exposure in a camera +lens. 1) The lens area, or more accurately, the lens entrance pupil, which is the effective light collection area of a complex lens. The area determines how much light the lens collects to deliver to the sensor. 2) The angular area of the subject. The product of these two values is called Etendue, or A*Ω (A*Omega) product. (A= the lens entrance pupil area, and Ω, omega = the angular area of subject). The third value is 3) exposure time, the length of time the sensor is exposed to light.”

“We have shown 3 examples where f/ratio does not indicate the true amount of light in a recorded image. The true exposure is better described by Etendue, the A*omega product, or EtS. This is the case for all photography.

But one need not do EtS calculations. Given a choice for imaging a subject, use the lens that has the largest aperture diameter, not the fastest f/ratio. Of course this applies only if the selected lens will fit the subject in the frame, or else you may need to do a mosaic.”
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