E-M1 AA filter and sensor size differences vs E-PL5 (E-M5)

[Ulfric M Douglas]

Using CZJ 135mm and a tapemeasure taped to a plank.

e-P2 had a view of 512mm of the target,

e-pM2 had a view of 503mm of the target, making it approx 98.2% of the e-P2's sensor size.

Am I interested enough to repeat at varying distances and narrow the error? No.

 

[micksh6]

Using CZJ 135mm and a tapemeasure taped to a plank.

e-P2 had a view of 512mm of the target,

e-pM2 had a view of 503mm of the target, making it approx 98.2% of the e-P2's sensor size.

Thanks. You were saying that you wouldn't allow focus ring to move, so you were focusing by unscrewing lens from adapter, right?

In this case optical configuration would be the same between cameras and the measurement should reflect sensor size differences (if distance from sensor to subject is the same, of course).

Am I interested enough to repeat at varying distances and narrow the error? No.

 

[Ulfric M Douglas]

...

Thanks. You were saying that you wouldn't allow focus ring to move, so you were focusing by unscrewing lens from adapter, right?

In this case optical configuration would be the same between cameras and the measurement should reflect sensor size differences (if distance from sensor to subject is the same, of course).

...

I simply focused (normally) while on the first body,

then replacing bodies I did not touch the focus ring.

 

[micksh6]

I really wanted to get to the bottom of this. Now, tests with manual lenses, so no distortion correction.

Here are comparison shots with Samyang 7.5mm fisheye, E-M1 and E-PL5. Both are carefully focused at longest visible tree, close to infinity. On E-M1 I had to move focus ring a bit closer to infinity stop than on E-PL5, by almost half a millimiter or so. So, there is flange distance difference between cameras.


E-M1




E-PL5

I drew 1 pixel wide pink vertical lines on photos - these show where I measured distance, you can see it when you download full size image.
Distance: E-M1: 4539-1231=3308, E-PL5: 4475-1063=3412
Difference - 3.0%, E-M1 can capture image wider by 3%.

Since flange distance is different, lens focusing element position is not the same - optical configuration differs. So, we can't realy be sure if optics results different image sizes or sensor sizes are different.

Here are tests when lens opical configuration is the same. I used m42 Helios 44-2 58mm F2 lens. m42 mount is unique because it's a screw-mount (well, C-mount is too, maybe some others, but I had a good m42 lens with adapter).

As opposed to bayonet mount it allows to adjust focus by unscrewing the lens from adapter.

By screwing the lens I compensated for flange distance differences. Both shots are focused well and lens focus element stayed at the same position for both cameras (at 10 meter mark on the lens).


E-M1


E-PL5

The distance to fence where I focused is 18 meters, not infinity, but, I think it's far enough to estimate magnification.

Because the lens is not firmly screwed to adapter it's tilted a bit, you can see that the right side is softer than the left one, focus plane is tilted. This doen't happen when the lens is firmly in place. But, since the picture looks similar for both cameras I hope it's a fair test.

E-M1: 3719-280=3439, E-PL5: 3802-263=3539
Image on E-PL5 sensor is larger, so E-M1 sensor must be larger. Difference - 2.8%.
No matter how I measure it, the difference is always almost the same.

Conclusions:

• EM1 sensor does seem to be larger than E-PL5 (E-M5) sensor by about 2.7-2.8% linearly, but I'm open to critique of my test. I'm skeptical myself, the difference seems to be large enough that somebody else should have noticed it.
• On the other hand, the difference may be small enough so most will not care. I probably will not care either, unless I'm stressed to capture something really big and I need to squeeze everything from UWA lens.
• There are flange distance differences between cameras. They may affect results too, and amplify sensor size differences sometimes. At close (2-3 feet) focus distance the difference in magnification may exceed 5% as I showed in 17mm F1.8 test. E-M1 will see much farther to the edges of the frame than E-PL5, this should explain its lower scores in DXO mark tests as edge resolution will be lower with the same lens. But this may vary between camera samples so people should test it by themselves.
• AA filter strength (and sharpness) is probably the same on all Olympus cameras since E-M5 until now.

 

[axlotl]

http://cameraergonomics.blogspot.com.au/2013/04/lumix-gh3-review-part-5-field-of-view.html

Hi Mick, With regard to sensor size, Your observations are exactly the same as mine. I reported the finding on this forum last year and got no reaction at all. Maybe nobody believed me.

In standard 4:3 ratio capture the Panasonic sensor in GH2, G5 G6 (and now apparently GM1) produces a field of view about 2.5%-3% linear greater than the field of view gained with a camera using the Sony M43 sensor (Pana GH3, Olympus EP5, OM5, OM1 etc) using the same lens at the same focal length on the same tripod with sensor the exact same distance from the subject.

Your finding is real and anybody with due diligence and access to the requisite cameras, can confirm it by careful observation. The finding refers to the size of the effective sensor, not necessarily the dimensions of the total sensor. It means that the pixel pitch of the Panasonic sensors must be slightly greater than the pixel pitch of the Sony sensors.

By the way this phenomenon is entirely different from that which forms the basis of the multi aspect ratio sensor found in the GH1 and GH2. These cameras have an 18 Mpx sensor which is readily seen to be physically larger than sensors which have native 4:3 aspect ratio only. The MAR sensor uses a different crop from the larger sensor for each aspect ratio. I would very much like to see a return of this feature in Panasonic cameras, as I used it frequently with the GH2.

With regard to resolution my tests find that the GH3, GX7 and G6 each have exactly the same RAW resolution.

 

[Fredrik Glckner]

Since flange distance is different, lens focusing element position is not the same - optical configuration differs. So, we can't realy be sure if optics results different image sizes or sensor sizes are different.

This is a good comment. Most M4/3 lenses are internal focusing, and exhibit "focus breathing". This means that as you change the focus, the field of view changes as well. You can see this illustrated with the 20mm f/1.7 (which is not internal focus) and the 25mm f/1.4 (which is) here:

http://m43photo.blogspot.com/2013/11/focus-breathing-with-leica-25mm-f14.html

So this could be the cause of the change in "zooming" you see: A small change in the flange register distance causes different focus settings, which in turn changes the field of view.

 

[micksh6]

http://cameraergonomics.blogspot.com.au/2013/04/lumix-gh3-review-part-5-field-of-view.html

Hi Mick, With regard to sensor size, Your observations are exactly the same as mine. I reported the finding on this forum last year and got no reaction at all. Maybe nobody believed me.

In standard 4:3 ratio capture the Panasonic sensor in GH2, G5 G6 (and now apparently GM1) produces a field of view about 2.5%-3% linear greater than the field of view gained with a camera using the Sony M43 sensor (Pana GH3, Olympus EP5, OM5, OM1 etc) using the same lens at the same focal length on the same tripod with sensor the exact same distance from the subject.

Your finding is real and anybody with due diligence and access to the requisite cameras, can confirm it by careful observation. The finding refers to the size of the effective sensor, not necessarily the dimensions of the total sensor. It means that the pixel pitch of the Panasonic sensors must be slightly greater than the pixel pitch of the Sony sensors.

By the way this phenomenon is entirely different from that which forms the basis of the multi aspect ratio sensor found in the GH1 and GH2. These cameras have an 18 Mpx sensor which is readily seen to be physically larger than sensors which have native 4:3 aspect ratio only. The MAR sensor uses a different crop from the larger sensor for each aspect ratio. I would very much like to see a return of this feature in Panasonic cameras, as I used it frequently with the GH2.

With regard to resolution my tests find that the GH3, GX7 and G6 each have exactly the same RAW resolution.

Thank you. It's good to know that my tests make sense. So, basically, E-M1 returned to sensor size of Panasonic sensors.

BTW, your blog is very useful. I read some articles in the past but haven't seen sensor size article. Added RSS subscription now.

 

[Steen Bay]

http://cameraergonomics.blogspot.com.au/2013/04/lumix-gh3-review-part-5-field-of-view.html

Hi Mick, With regard to sensor size, Your observations are exactly the same as mine. I reported the finding on this forum last year and got no reaction at all. Maybe nobody believed me.

In standard 4:3 ratio capture the Panasonic sensor in GH2, G5 G6 (and now apparently GM1) produces a field of view about 2.5%-3% linear greater than the field of view gained with a camera using the Sony M43 sensor (Pana GH3, Olympus EP5, OM5, OM1 etc) using the same lens at the same focal length on the same tripod with sensor the exact same distance from the subject.

Your finding is real and anybody with due diligence and access to the requisite cameras, can confirm it by careful observation. The finding refers to the size of the effective sensor, not necessarily the dimensions of the total sensor. It means that the pixel pitch of the Panasonic sensors must be slightly greater than the pixel pitch of the Sony sensors.

By the way this phenomenon is entirely different from that which forms the basis of the multi aspect ratio sensor found in the GH1 and GH2. These cameras have an 18 Mpx sensor which is readily seen to be physically larger than sensors which have native 4:3 aspect ratio only. The MAR sensor uses a different crop from the larger sensor for each aspect ratio. I would very much like to see a return of this feature in Panasonic cameras, as I used it frequently with the GH2.

With regard to resolution my tests find that the GH3, GX7 and G6 each have exactly the same RAW resolution.

Thank you. It's good to know that my tests make sense. So, basically, E-M1 returned to sensor size of Panasonic sensors.

Seems that the E-M1 has a Panasonic sensor, so not that surprising.

http://www.dpreview.com/forums/post/53072123

But rather strange that the (Sony?) sensor in e.g. E-M5 is (a bit) smaller than a mFT sensor should be (assuming that the E-M1 sensor has the 'correct' size (diagonal app. 21.63mm)).

BTW, your blog is very useful. I read some articles in the past but haven't seen sensor size article. Added RSS subscription now.