Sensor/pixel question: I have an OM-1 and a Sony aR7ii. Looking at the option on the Sony to shoot at APS-C produces an image of approximately 18 MP while the OM-1 produces a similar...

Rileychas Loc: San Diego, California

I have an OM-1 and a Sony aR7ii. Looking at the option on the Sony to shoot at APS-C produces an image of approximately 18 MP while the OM-1 produces a similar perspective image of approximately 24 MP. So my question would be does the full frame image from the Sony at 42 MP have an inherent IQ advantage or am I just using those extra MPs to produce a larger image? Another way of looking at it would be does the part of the FF sensor used for an APS-C shot have roughly the same pixel density of the MFT 24 MP sensor?

I hope that this is not a stupid question.

R.G. Loc: Scotland

An APS-C sensor is bigger than a m4/3 sensor. The sensor pixel size is just the starting point where IQ is concerned, but as a general rule, bigger is better. But in-camera processing is also a factor, as is the sensor type (recent, stacked, BSI etc).

BebuLamar

Rileychas wrote:

I have an OM-1 and a Sony aR7ii. Looking at the op... (show quote)

The M4/3 sensor in this case has significantly higher pixel density. Higher pixel density sensor needs higher resolution lens to make use of its higher density.

Rileychas Loc: San Diego, California

I realize that the MFT and APS-C are not equal in size but both are in the "crop sensor" category and my question is generic to FF vs crop pixel density..

Longshadow Loc: Audubon, PA, United States

Not sure where you are going with the question.
Manufacturer 1 can make a sensor of X by Y dimensions with a pixel density of Q per mm².
Manufacturer 2 can make a sensor of M by P dimensions with a pixel density of R per mm².
It depends on the sensor used (made). All sensors are not necessarily created equal.

What are you trying to compare?
Crop sensor just means that the sensor is smaller than "24x36".

Rileychas Loc: San Diego, California

I thought the question was clear, no need of lesson on sensor size. Simply put does a FF sensor used in crop mode utilize the part of the sensor roughly equal to that of a dedicated crop sensor? If so then the additional MPs are only used in FF mode.

SuperflyTNT Loc: Manassas VA

The OM-1 has a 20mp sensor, not 24, but it’s also not similar in AOV to the ASP-C crop. Now that AOV is based on the diagonal measurement of the sensor, so although the the crop factor for APS-C is 1.5 and the M4/3 is 2 they have different aspect ratios. 3:2 vs 4:3. So the ASP-C would natively print to 8x12 the M4/3 would natively print to 9x12. So any additional cropping to a different aspect ratio would have to be taken into account.

Longshadow Loc: Audubon, PA, United States

Rileychas wrote:

I thought the question was clear, no need of lesson on sensor size. Simply put does a FF sensor used in crop mode utilize the part of the sensor roughly equal to that of a dedicated crop sensor? If so then the additional MPs are only used in FF mode.

If only a portion of the SAME sensor is used in crop mode, the pixel density for the sensor remains the same, simply less of the pixels are utilized (the ones that are ignored).
I couldn't figure out if he was referring to the same sensor or different sensors.
I can set the "format" in my bridge camera and it shades the area of the image that will NOT be utilized to create the image.

SuperflyTNT Loc: Manassas VA

Rileychas wrote:

I thought the question was clear, no need of lesson on sensor size. Simply put does a FF sensor used in crop mode utilize the part of the sensor roughly equal to that of a dedicated crop sensor? If so then the additional MPs are only used in FF mode.

Well if that’s the question didn’t you answer it yourself when you stated that crop mode was about 18mp?

Strodav Loc: Houston, Tx

IQ is made up of several different factors. Start with detail, which is different from sharpness. The detail a camera and lens can capture depends on the number of sensor elements you have on the subject and the quality of the lens. I think this is where the op is going with the question. If the number of sensor elements between a FF and crop sensor camera are forced to be equal, then the FF camera sensor usually has an advantage because the sensor elements are larger and can capture more photons. Noise and low light capability depends on size of the sensor element and the sensor's readout electronics. So you can have a crop sensor camera with better electronics that makes up for the smaller sensor element size. Then there is the quality of the Bayer filter and lens elements, ... There are no hard and fast rule rules, especially as technology advances. You have to measure the "IQ" of each camera to see how it performs.

Rileychas Loc: San Diego, California

OK, forgot exact MP of the OM-1 but that's not critical to the question which I evidently answered myself.

User ID

Rileychas wrote:

I have an OM-1 and a Sony aR7ii. Looking at the op... (show quote)

APSC is about 1/2 the area of FF and m4/3 is about 1/4.

Based on a 60MP FF camera, 1/2 is 30 and 1/4 is 15. You dont see many 30MP APSC cameras, but nearly all m4/3 are above 15MP.

No need to know or calculate the exact pixel densities. Theres too many other variables more important than fussing over really precise math. Full, 1/2, and 1/4 ... easy numbers and close enuf for rock and roll.

Rileychas Loc: San Diego, California

In retrospect I guess it really was a stupid question after all. Putting an APSC lens on a FF camera would require either disabling the pixels that fall outside of the image cast by the lens or disregarding their data when processing the image.

Longshadow Loc: Audubon, PA, United States

Rileychas wrote:

In retrospect I guess it really was a stupid question after all. Putting an APSC lens on a FF camera would require either disabling the pixels that fall outside of the image cast by the lens or disregarding their data when processing the image.

Cropping when processing.

SuperflyTNT Loc: Manassas VA

I wouldn’t say it’s a stupid question. You can still get some very good images with less megapixels. If you already have an ASP-C lens and want to use it on your FF body go ahead, but I wouldn’t buy a crop lens to use on it. Even then unless it forces you to use crop mode I wouldn’t change it. Often those crop lenses will cover much more of the sensor than the crop. You should at least be able to shoot a square crop at full height. I would do all cropping in post where you have more control.