Originally posted by beholder3 Do you understand that by allowing higher exposure times you loose any relevant comparability with regards to noise? Longer shutter times on any sensor reduce noise.
If you're already at your best ISO on your small-sensor camera, longer shutter times merely blow out highlights (because you're overexposing). The larger-sensor camera will be set to a higher ISO, so you'll be able to reduce ISO and therefore reduce noise.
Originally posted by beholder3 No. Just habe a look at dynamic ranges here:
DxOMark - Compare cameras side by side
And also look at noise values.
You will see the two FF sensors are 2-3 EVs
behind the APSC model in dynamic range. This is significant.
At the same time the old FF model has pretty much the same noise values as the newer APSC.
And again the newest FF sensor has about 1 stop noise advantage to the older APSC.
For the nth time, you have to compare like technologies. Pentax's Sony sensor technology appears to be far in advance of Canon's. Have a look at DxOMark's figures for the Pentax Q and you'll get a better comparison.
Originally posted by beholder3 There is a lot more detail to be seen for the tiny sensor.
All I see is a pair of images - no explanation, no test conditions. I'm going to make a guess here (deduced from the statements you made): the one on the left is a Pentax Q with a mounted DA*300, on the right the same lens on an APS-C camera. The photos were taken with the same subject to camera distance, and crops of the crab subject taken. The reason the crops show the subject the same size is that the APS-C image is blown up about 4x more than the Q's.
So, the images don't compare like for like - the original APS-C image would have 4x the AOV of the Q's. If the APS-C camera had the same pixel pitch as the Q (i.e. 4x the pixel-count), the 2 crops would have been identical in quality. A like-for-like test would involve a 75mm lens on the APS-C camera and correspondingly closer subject-to-camera distance.
Assuming your tests were carried out with rigour, the result would suggest the DA*300 was rather out-resolving the APS-C camera's larger pixels, so it's obviously a good lens.
Originally posted by beholder3 It might be counter intuitive, but the small sensor gives much more detail than the larger one. And yes the tolerances are smaller / the quality requirements are higher for smaller sensor lenses.
I was saying that it was counter-intuitive that a lens intended for a Q-type sensor could have 4x the resolution of the lens intended for the APS-C camera (which it would need for the same overall end-resolution).
You keep making statements that small sensors and their lenses give more detail. Until you show me a lens intended for a Q-sized camera with a measured MTF50 of 200 lp/mm (which would be needed to equal the resolution of a decent, i.e. 50 lp/mm, lens on an APS-C camera), then the statements aren't true.
Originally posted by beholder3 Going back to the sample turtle pictures: Its is much more than a ergonimics question.
- size / weight much less will lead to people with heavy equipment not taking it with them. No photo taken. No photo = total quality fail. It cant get worse.
- Many tele reaches are not available at all. Just not. Again the Q example. Adapting a commonplace 300 mm lens lead to 1,600mm FF equivelant reach. Go find a 1,600mm lens for your FF. If you find one: Consider what happens if you use a new 560mm lens on the Q...
- Lets assume you actually find a 1,600mm tele lens for your FF. Price? Anywhere comparable even if it is not totally out of reach? Unaffordable means no lens in reality. No lens in reality means no picture. Again: total quality fail as anything is better than no picture.
- Light. F4 on the Q still gathers light as you expect at F4 and gives you those shutter times. Now finding a 1,600mm F4 on FF might be somewhat difficult...
Yes, you've found a nice use for the Pentax Q - obviously the DA*300 works well when mounted (though surely you need to be tripod mounted - particularly as there's no viewfinder). Of course, you'd achieve exactly the same result if you had an APS-C or FF camera with the same pixel pitch as the Q - you'd just crop your image. Note though that the equivalent (1600mm) lens for FF wouldn't necessarily be much bigger or heavier than the DA*300, because its max aperture would be about f22! It's just that no-one makes one.
If it weren't for time and storage constraints, the larger sensors would have the same size pixels of the Q-type cameras (resulting in enormous pixel-counts), and the process of binning prior to printing would restore the low noise levels expected from the larger sensors.
Originally posted by beholder3 Ah, I found some more real life data as help for understanding the differences between noise and dynamic range limitations.
Definition:
Dynamic Range (at given ISO)
= ratio of the lightest to the darkest possible impression.
= saturation level (at given ISO) divided by read noise (at given ISO)
Now look at the sensor data of a little older K-5 APSC vs. new 5D3 FF:
Sensorgen.info data for Pentax K-5 Sensorgen.info data for Canon EOS_5D_MkIII
If you compare them you will see the larger 5D sensor can cope with a little more photons and can go about half a stop higher on the upper end, but has rather dismal read noise at low ISO < 1600 (more than 3 stops worse).
And that even though the pixels are 40% larger.
As I explained above, the Sony sensor technology is superior to Canon's - it's nothing to do with sensor size.