Sony Alpha a7RIII vs. a7III

Discussion in 'Mirrorless Digital Cameras' started by gary_anthes, Mar 5, 2018.

  1. I was about to buy the a7RIII but now that the a7III is out, I'm having second thoughts. Is the R worth an extra $1,200 bucks? I don't make huge prints, but I occasionally do crop extensively. I'm most interested in very good low-light performance. Any thoughts?
  2. It's a tough call. If you shoot a lot of static objects, the A7rIII is the best choice. It has a high-res mode that rivals medium format, if your lenses are good enough. Otherwise, the A7III is the better choice. Steve Huff has written at least two pieces about it, and he has used both cameras as well as the A9:

    Steve Huff Photo – Real World Camera and Lens Reviews
  3. The 7Riii has much higher resolution than the 7iii, 42 MP v 24 MP, and no anti-aliasing filter. Both have a silent shutter option, but 5 fps v 10 fps, respectively. The R also has a higher resolution viewfinder, which makes viewing and focusing stunningly clear.

    If you shoot landscapes and travel photos, then the R3 is probably the one to get. 24 MP with an AA filter is sharp enough for many applications, but the R is significantly sharper, and better suited for highly detailed subjects and big enlargements The difference is noticeable even in an 8x10 print. Pixel-Shifting is probably not very useful outside of the studio, but it's there if you want it. There are also more and better video options in the R3, especially 4K video.

    I had an A7ii, but very seldom used it after getting an A7Rii. The A7ii did not have a silent mode, which was a significant factor in its disuse, but mostly it was the image quality. Image-wise, the R3 appears to be the same as the R2. I traded in the A7ii to buy an A9, which I now use more than the R2. It has a high speed silent mode (the R2 is singles only), better color, and nearly instantaneous focusing, shared by the R3.
  4. The difference is noticeable even in an 8x10 print.
    Interesting. At that size, something other than pixel count must be at work, yes?

    Thanks for your comments.
  5. I print at 2400 dpi, which is equivalent to 19,200 pixels on the short side - nearly four times that of a 42 MP image. You notice the difference in fine details, like eyelashes, and in a strong sense of texture in surfaces like stone, leather and skin. You don't have to be able to read fine print to recognize it as print. The same for details.

    At ISO 25,600, with IBIS, I get acceptable noise in light too dim to see the control settings. The A7iii is supposed to do that at two or three times the sensitivity.
  6. That is the inkjet dpi, a property of the print head, it is not the same as pixels per inch. I can't see how you can notice a difference, unless your printer can meaningfully print more than >300-400 ppi, which I doubt. There will be an advantage for a very large print, but for an 8 x 10 and any half decent camera today I can't see it.
  7. In the worst case, it takes three color dots to produce one pixel, that is still 800 PPI. In practice, the ink dots are much closer together, because each color is produced at 2400 to 4800 dpi in the same pass. Although a 24 MP camera is 4000x6000 pixels, the short side resolution in an 8x10 is less than 500 dpi because of the AA filter, which brings it down to the equivalent of 333, compared to 668 for a 42 MP sensor. The printer's resolution exceeds both, so It's not hard to see a 2:1 difference between cameras.

    Without a tripod and/or image stabilization, camera shake reduces the effective resolution to about 6 MP, if you use the 1/f rule for shutter speed. That is often the weakest link in the chain, and makes it impossible to make a real comparison between cameras. It's also important to use output sharpening, to mitigate the effect of dot gain.
  8. "is the inkjet dpi, a property of the print head, it is not the same as pixels per inch. I can't see how you can notice a difference, unless your printer can meaningfully print more than >300-400 ppi, which I doubt" Robin

    Marketing for simple minded folks

    This has been proved time and time again.

    On a 8 by 10 print and much larger, photographers do not have a clue what sensor size, camera, or how many pixels you can count on a pin head :photographers.

    Joe Public just looks at the photo and decides if it is interesting or not. I go with Joe Public hate counting anything.
  9. Some do and some don't, but all photographers, even "simple minded" ones, care about the quality of their prints, even 8x10 ones.
    Ed_Ingold likes this.
  10. The all-electronic shutter is a great feature of Sony cameras. However there is a down side - the time it takes to read the entire sensor.

    How fast is the Sony a7RIII silent shutter?

    Electronic shutters in CMOS sensors work like focal plane shutters. Both scan the sensor from top to bottom, exposing/reading the results row by row. The mechanical shutter takes 1/250 second to traverse the sensor. The electronic shutter in A7m3 takes 1/18 seconds (55 msec). The A7Rm3 takes1/100 second (10 msec) and the A9 1/150 (6.7 msec). Longer scan time means more rolling shutter effect in moving subjects. This appears as a strongly bent shaft during a golf swing, or sickle-shaped helicopter blades.

    The A7Rm2 has the same scan time as the A7Rm3. I have not been troubled by the rolling shutter effect, mainly because I rarely shoot action photos. Motion parallel to the scan direction show up blurred rather than curved (e.g., a conductor's baton). Most of the problem goes away if you simply switch to the mechanical mode. Unlike the newer cameras, the A7Rm2 doesn't shoot in continuous mode with the electronic shutter. None are able to use flash in the electronic shutter mode mode - it's disabled in the camera.

    All rows in a CCD sensor are read at once, but AFIK none have a selectable silent shutter. A Nikon D1x has a CCD sensor, and uses the electronic shutter for all speeds faster than 1/250 second. If you use a flash in manual mode, it works at any speed, until the shutter shorter than the flash duration. Sony made a news release last week that they have developed a CMOS sensor with global reading.
  11. Ed, all these "downsides" result in a fps faster than any competition. With my a7RIII, if concerned about potential rolling-shutter, I go to the excellent mechanical shutter, at 10-fps. If I need 20-fps, I put the lens on my a9, with no rolling-shutter, even at 20-fps, silent shooting.
  12. As shown, the electronic shutter on the A7iii is very slow by comparison to the A7Riii. Perhaps not the defining specification, but something to consider.

    Even at 1/18 second for my A7Rii it's not a problem. I only use the electronic shutter when silence is demanded. For one thing, the dynamic range is less (12 bit v 14 bit). Secondly, most of my subjects are either motionless or without straight lines in motion.I usually keep the A9 in Auto mode - silent for continuous, mechanical for single frames.

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