Rachotilko

To DPR team:

to reduce the confusion, would you not consider an article about the f-number equivalence ?

The question "does the need to apply f-number equvalence apply to DOF calculation only or to shutter speed calculation as well" has been hotly debated here for quite a long time.

Some basic lesson in photooptics would silence this, I hope.

@Beach Bum

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.

@noirdesir:

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 ?

@noirdesir:

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.

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 ?

@Samuli Pulkkinen

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.

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 lens
c, efficient image stabilization.

In case you have b) or c), you don't need a).

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 !

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

My conclusion:

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.

@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

concerts ? parties ? ... Bright lens allow you to use it in not so good light as well

@TrojMacReady

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.

I was comparing the low-light capabilities at focal length 100mm eq.