If the marketing is misleading to people who don't fully understand the whole situation except to people with enough knowledge to do alternate calculations... then it's pretty much lying IMO. Posting full frame FL equivalents without posting full frame aperture equivalents makes it seem like smaller cameras can perform as good (or even better) than bigger cameras with those lenses, but it's simply not the case.warpdrive wrote: ↑Dec 9th, 2014 9:26 pmI think Tony saying the equivalence marketing is a lie is too extreme, because full frame equivalence is only useful for determining focal length, DoF and comparison of total light gathering in terms of the arbitrary 35mm reference point. Yes the marketing might be a bit misleading to the person who takes the marketing at face value without understanding how different camera system render images, so that's why the article I posted is so important to understand.
The physics demands that a crop system camera be disadvantaged by the crop factor by exactly the math calculated. There is no doubting that. If your sensor is 1/4 the size, it will perform 1/4 as good because it is collecting 1/4 as much light. Any case where this does not follow would be differences in sensor technologies used, which differs from manufacturer to manufacturer. This doesn't mean that the calculations are flawed or unrepresentative. The article tries to say that calculations doesn't matter by comparing the newest Panasonic sensor with 3-5 year old Canon (the worst manufacturer) sensors, which is a bit misleading. The example of the D5300 vs D810 ISO scores clearly show that similar sensor tech will be almost exactly affected by crop factor by the calculations. Theoretically you could put a number to "sensor efficiency" too (and I think Tony does that in one of his other videos), but that's purely academic.warpdrive wrote: ↑Dec 9th, 2014 9:26 pmThe issue the article points out is that full frame equivalence tends to be used to bash crop system cameras. It implies that a 2X crop factor means the camera is 2X inferior. Some people take it to a ridiculous level and say that a high end m43 lens with expensive glass elements is overpriced because it only gives the same equivalent aperture as some cheap slow full frame lens, which is the ultimate fallacy because equivalence doesn't apply to all other parameters of a lens' performance
Low light performance is typically compared via the ISO spec, which generally favors bigger sensors. DR is usually more important for low ISO shots, which is more sensor tech/tuning dependent but still generally benefits from bigger sensors. I feel like with the D4S sensors they tuned the sensor performance for higher ISO by sacrificing some dynamic range, which would make sense given the D4S has slightly better ISO performance but worse DR than the D810. With the D810 being more of a landscape camera, the DR is more important. I agree there's a lot of factors to consider for low light performance, but I think in this case the D5300 will easily be the clear winner.warpdrive wrote: ↑Dec 9th, 2014 9:26 pmRe: the whole issue of DR vs pixel density. As your DP comparison numbers show, DR does not scale to pixel density when comparing different sensors, even though both are made by Sony in this case. That's why the OP's question of what formula can be used to determine which camera will perform better in low light is impossible to answer accurately. The author comparing the Canon to the Panasonic sensor was used to prove his point that equivalence of sensitivity is at best, loose due to different designs of sensors. You can never be sure there isn't something else masking the differences like a change in the fabrication/design process which produces different grouping of pixels or using a completely different diode material.