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I've decided to get a Sony Alpha and am trying to decide which. At this point I'm leaning towards the A7S (original). I know it does better on video with the way its pixels are setup compared to an A7ii. What I don't know and haven't been able to really find is how the lower pixel count affects the still side of things.

Main questions: How big of a print is the A7S capable of before it really gets degrading? How does the larger pixels effect things?

Example a 300ppi image that's 3" by 3" would need to be 900px by 900x. The A7S is reported to have larger pixels so what does that mean for this calculation?


Just to make sure, the A7Sii is the same pixels and therefor same size print correct? So its kinda deciding between the A7S and getting better video quality or the A7ii / A7R for better print quality, would that be accurate?

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The core of your question is:

...a 300ppi image that's 3" by 3" would need to be 900px by 900x. The A7S is reported to have larger pixels so what does that mean for this calculation?

The basic answer is: it means nothing. In the final image, a pixel is a pixel. I see where your confusion comes in, but this is entirely about the size each of each photosite on the sensor. Since there are many, many different sensor sizes, and many different sensor resolutions, there are many, many different sizes for photosites. But when an image is produced, the resulting image is just an array of pixels, and the basic math you're quoting is only concerned with that.

That said, once you're over a certain threshold (and it's somewhere below 300 pixels per inch, depending on how closely you're looking), ppi isn't the most relevant factor. When you're way, way on the low end, you worry about visible jagged pixels. But that was basically a worry from a decade ago. 12mpix is enough for decent prints below poster size without worry about that. Going to a higher sensor resolution may enable larger prints, but not necessarily, as focus, lens sharpness, camera stillness, and other factors become more important limits.

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12 megapixels are 12 megapixels of resolution. At base ISO, it will do just as well as any other 12 MP camera and at higher ISOs it will do even better since its pixels are larger than most cameras. This in particular will result in higher dynamic-range and smoother rendition of details.

For a general formula in what print sizes are possible see this question. Basically, expect a 15" x 10" print to stand close inspection and larger prints to be usable at further viewing distances. Remember, there isn't one limit of print-size, it depends on viewing distance.

The A7S and A7S II have the same pixel size and will perform the same at their base ISO. At higher sensitivities, it is possible the A7S II will deliver improved quality due to technological improvements but the difference should not be that significant.

  • Yeah its the "larger pixel" part that confuses me. Say 300ppi then 3" x 3" would be 900px x 900px using normal pixels. I don't know what the A7S' larger pixels means for this calculation. I'll edit my question to state this. – RyanFromGDSE Dec 7 '15 at 21:44
  • Sorry, typo, corrected. @Ryan Larger pixels do not influence maximum print sizes, just noise and dynamic-range. They do help maintain print sizes at high ISO though. – Itai Dec 7 '15 at 22:53

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