You base your judgements on a mistakend notion that sensor size is to be taken into account when calculating the lens speed.
Consider situation when you're using XZ-2 @ISO800, f2.4, l=100mm eq. Taking the same scene with RX100 would require you to use IS3200.
That's a lot of a difference, don't you think ?
The fact that f-number equivalence applies only to DOF calculation and not to the shutter speed, is just plain fact in photographic optics. Anybody knowledgeable in the photooptics will confirm that.
My point is that: RX100 and XZ-2, when both set to f4.9, ISO1600, taking the same scene, will require the same exposition time. But with XZ-2, you have freedom to go f2.4, and select ISO400 - without actually changing the shutter speed ! In other words, XZ-2 is two stops faster @100mm eq
There is not any ISO tweaking going on. It rather has something to do with focal lengths:
f-number is "the ratio of the lens's focal length to the diameter of the entrance pupil". Without going into detail (you can find it here http://en.wikipedia.org/wiki/F-number), you can notice f-number is dependent upon the focal length used.
The confusion wrt sensor size is thus caused by the usage of the "equivalent focal lengths", which IMHO is a bit misleading from optics point of view. It is better to trear small sensors in term of cropping.
Try it experimentally: take a full-frame camera and a pinhead compact (both should be well calibrated), set both to fully manual mode, select the same ISO, same f-number, same shutter speed. Do a shot of the same scene with both cameras.
You'll see the scene is exposed roughly the same - no sensor size was taken into account.
Both DOF and shutter speed (exposition) are influenced by the f-number. But while for DOF calculation you have to factor-in the sensor size, shutter speed is unaffected by it.
Tape5: It was nice seeing RX100 at the end of the list which is what you expect if it is the best in the list right? Best IQ and smallest.
The sensor size is NOT to be taken into account ! That means, if a scene requires 1/30s @ISO800, f/1.8 for 5DMkIII (full frame), then it requires the same 1/30s @ISO800, f/1.8 for G15.
In other words, f-number has twofold impact on your photography: a) it determines DOF, b) it influences shutter speed.
But while for a) you have to account for the sensor size, b) is not influenced by the sensor size.
"Best IQ" is oversimplification. RX100 has best IQ under two conditions:
- you stay away from the subject (the lens does not like close-ups)- you avoid tele-end (the lens is quite a lot slower @tele than the LX7, XZ-2, P7700 and G15, forcing you to use high ISO).
Do we have any English or Latin linguists around here ? I am neither (not even a native speaker), so I am confused:
"Compact" surely implies "holding together". Does it also necessarily mean "small" ?
I sympathize with DPR staff, really. First, they are nice guys and they do the very good job !
But this article just feels like an (hopeless) attempt to tame the rabid RX100 fans who polute all the comment sections with their resolute demands for an immediate annihilation of every camera with sensor smaller than 1".
At the same time, the article falls victim to the absurdities of the camera industry terminiology that developed over the years. "Compact" and "P&S" are terms introducing far more confusion than benefits in camera categorization.
- "P&S" is a terminological fossil from 1960s, as instead of camera's capabilities it describes the camera's operating mode.
- the disadvantage of the term "compact" is that one is not clear whether it describes the size or atomicity of a camera.
I think the most reasonalbe way out of this mess is to accept the situation that we have several (possibly overlapping in particualr aspect) categories of cameras.
FartIng: i bought and returned the G15 for a G1X - Why?Articulated screen, larger sensor, but I found the G15 still has awful noise on photographs and HD video above 800 ISO (like the G12 I had before that).
The only awful thing now I find about the G1X - Macro close up photography is impossible which is heartbreaking.
Now I use my Nokia Lumia 920-which seems to take better photos than the G1X!
Do you really suppose anybody can take you seriously here when you claim 920's 1/3"-sized sensor takes better pictures than APS-C ?
Rachotilko: I still don't get how so many people can't get that capability to shoot in low light can be achieved by any of these:a, high ISO,b, fast lensc, efficient image stabilization.
In case you have b) or c), you don't need a).
In the ideal world, all of us would get a)-z). But in this world it is pretty expensive to do a), and if b) provides the same benefits with lower cost, I am glad that b) exists.
Stephen_C: Given the RX100 and the G1X, why does this camera exist? The RX100 has pocketable with great IQ nailed perfectly. The G1X is larger with an articulating screen. The G15 is large with a small sensor and no articulating screen. Also, giving the G15 a gold and the RX100 a silver looks very much like favoritism.
This camera has better IQ on than RX100 in some situations (such as shooting @ tele end or closeups)
I still don't get how so many people can't get that capability to shoot in low light can be achieved by any of these:a, high ISO,b, fast lensc, efficient image stabilization.
Unbelievable, the herd mentality experiment has got out of control ! I just hope this RX100-obsessed mob will tame itself soon.
Anyway, I want to thank the DPR team for a nice G15 review !
tron555: In the studio scene comparison shots the FZ150 look MUCH sharper and clearer to my eye in both JPEG and RAW to my eye. Is anyone else seeing what I am seeing?
FZ150's shot was taken at f/3.5, FZ200's at f/2.8
Could be that the constant range brought with itself some compromises. But it'd be interesting to see FZ200's image taken at f/3.5
New batch of small sensor cameras (with bright lens and BSI-CMOS 1/1.7") has advantage when shooting at above 60mm eq - the faster lens kick in. Their lens designs seem to perform well in wide range of scenarios (including closeups or telephoto).
The "invention" - on the other hand - can use the advantage of the larger sensor when shooting wideangles (below 50mm eq) but the lens sharpness drops (quite a lot) for close-ups.
Summary.For shooting wideangle distant shots (such as family shots or sunsets), RX100 is a definite low-light king. In other scenarios (portraits, concerts), high quality bright lens still have some edge.
Rachotilko: Guys, stop the RX100 BS, please !
With its f/4.9 at tele end, it has to resort to ISO1600 when these small-sensor marvels can use ISO400 to keep the same shutter time for the same scene.
This ISO1600 vs IS0400 handicap can not be offset by the advantage provided by its larger sensor.
So: enjoy your "invention", and let the rest of us enjoy the fast lens.
@iudex:Tak predsa sme to tu rozprúdili ...Áno, ISO1000 je limit, ale s G15 a podobnými strojčekmi najnovšej generácie (XZ-2, P7700) si vystačíš s odosť nižšími hodnotami.
peevee1: High ISO looks worse than Nikon P7700, but better than Fuji X10, which is commendable.Look at the globe for clear difference in readability.
RX100 is of course much better.
concerts ? parties ? ... Bright lens allow you to use it in not so good light as well
Well, depends on focal length. At tele end (100mm) it's f2.5 vs f4.9. That translates to 2 stops in lens speed, ie. comparing ISO800 vs ISO3200.
iudex: When comparing RAWs at ISO1600, G15 delivers decent quality, no other competitor is noticeably better. Unlike many others I do not see the omission of articulated screen as a big problem; it enabled to make the G15 thinner and more pocketable.
I was comparing the low-light capabilities at focal length 100mm eq.
G15 is f2.8 at 140mm eq., so I presume it is around f2.4 @100mm
RX100 focal length maxes at 100mm, with max aperture f4.9
S100 has prohibitively slow lens at tele end. So there is a substantial usability gap between G15 and S100, despite similar sensors.