Yep, look at the DPreview link imposed above, it shows effective aperture and the LX100 I s a full stop ahead so it is just like comparing a crop To a FF DSLR.
Pound for pound best point and shoot.
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Yep, look at the DPreview link imposed above, it shows effective aperture and the LX100 I s a full stop ahead so it is just like comparing a crop To a FF DSLR.
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No. The stop difference is only relating to DoF. It says so below their comparison.
http://www.dpreview.com/reviews/panasonic-lumix-dmc-lx100/images/Equiv_Ap.png
If you got a stop more of light on the LX100, it would be a f1.2 lens, not f1.7.
What you should say is that for the same exposure, the images from the LX100 will be less noisy. That's not the same as the lens being faster. DPReview seem to get a little confused about these concepts.
https://photographylife.com/sensor-crop-factors-and-equivalence
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Ricoh GR. Very sharp lens/sensor combo, very responsive to use. I carry mine everywhere, it's about as thick as a deck of cards/pack of cigs and about as long as an iPhone 5:
I get some really nice B/W conversions out of it which is typical for Ricoh cameras as well:
I get some really nice B/W conversions out of it which is typical for Ricoh cameras as well:
I don't think you understand. If there is a stop difference in DoF there is also a stop difference in the amount of light the sensor receives. That is just a cold hard fact based on physics.
Remember, the dpreview link is talking about FF equivalent aperture, that applies to both the equivalent amount of light and the equivalent DoF. If you shoot a crop DSLR at f/2.8 and a FF DSLR at F2.8 the the sensor in the FF camera is receiving 1 additional stop of light, spread over the larger area of the sensor so the exposure remains the same. That extra stop of light directly corresponds to the lower noise that the larger sensor exhibits. If both cameras had identical sensor technology, e.g Nikon D7000 and D800 (more or less), then the FF has 1 stop better noise performance, so ISO 3200 on the FF gives the same signal to noise ratio (SNR) as ISO 1600 on the crop sensor.
If you are claiming the Sony RX100 and the Panasonic LX100 have the same light gather potential then you are also claiming a crop DSLR and FF DSLR have the same light gathering potential for the same lens physical aperture. That is blatantly false, a larger sensor collects more photons. It is also physically impossible to have an imaging system that affords a shallower DoF at equal subject size without also having a higher light gathering ability because the 2 are intrinsicly linked. It is like saying a jug of water has a weight independent of the volume of water it is storing, no, the change in water volume is directly proportional to the weight of water and vice versa.
And lastly, read again what it says in the DPReview graph:
The low-light image quality is related to effective aperture, the camera with the larger sensor collects more light and offers a higher SNR and lower noise at equal apertures.
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Good call, I meant to mention that yesterday. The Nikon Coolpix A is almost as good and is sometimes cheaper to buy.
Soldato
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I don't understand, you're right. How can the f-stop (the ratio between focal length and diameter) change based on sensor size?
I understand that a larger sensor will capture more light, but I don't think you're right in describing that in stops. I noticed that every other DPReview aperture equivalent chart or table mentions that it's only in terms of DoF or with a specific caveat regarding low-light abilities.
Here for example: http://www.dpreview.com/articles/0692551582/2015-roundup-advanced-zoom-compacts
DoF changes with sensor size as a function of the circle of confusion, correct? I don't see how that changes the speed of the lens. Maybe I just read your post wrong in the first place but it seems to me that it's certainly not a cold hard fact of physics that the LX100 captures 1 stop more light than the RX100. I'd agree if you'd said that the LX100 captures more light than the RX100, though it's an incalculable amount.
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The f-stop doesn't actually change, because as you say, that is a just a physical measurement, morove the f-ratio is exactly that a ratio so even if the aperture increased if the focal length increases in proportion then the f-ratio stays constant. However, what Dpreview is displaying in its graph, and what people commonly talk about when comparing cameras with different sensors, is "effective aperture", i.e. what would be the equivalent aperture to obtain the same DoF AND the same light gathering on a camera with a different sensor size. Th graph from DPreview is showing what the effective aperture would be if the sensor was FF sized, this gives a standard normalization of the different physical apertures and sensor sizes facilitating a simple comparison.
This is exactly the concept as when people talk about "equivalent focal length", e.g. if a lens is 100mm fitted on a 1.5x crop DSLR then the "FF equivalent" focal length is 150mm. Likewise, if the f-stop is 4.0 on the 1.5xcrop DSLR, then the "equivalent aperture on FF" is f/5.6.
A photographic 'stop' is simply a doubling of exposure . A sensor with twice the area has 1 stop of additional light gathering ability, a lens with twice the front area has 1 stop of additional light gathering. A FF DSLR has 1 stop more light gather ability than a crop DSLR.
yet again you have misunderstood the DPReview image captions, look closely:
Equivalent apertures, what I described above, gives the same DoF (as you say), and crucially "similar total light capture", which is exactly what I am saying. If 2 camera + lens systems have the same equivalent aperture then they have the same DoF and same light gathering potential, or as in terms of the Panasonic vs Sony, if 1 system has a 1 stop larger equivalent aperture then it has 1 stop shallower DoF and 1 stop more light gathering ability.
yep, something I point out a lot on this forum to much bewilderment because the smaller the sensor the shallower the DoF (that is because when producing a final image of a certain size like an 8x10"print the smaller sensor had to be blown up to a larger ratio than the bigger sensor, the bigger sensor capture more detail so actually has a deeper DoF!).
However, in the real world you have to do one of 2 different things when photographing a subject with a bigger sensor to ensure the same composition and framing. You either have to move closer to the subject, or you have to use a longer focal length. Doing either of these 2 will reduce the DoF, and that is why people who like shallow DoF portraits prefer FF cameras.
As explained above, it doesn't change the speed of the lens, it changes the effective speed of the lens, just like mounting an f/2.8 lens on an APS-C DSLR gives an effective aperture of f/4.0 on a FF DSLR. Th effective aperture describes both the DoF and the light gathering potential.
You are simply wrong, it is basic physics and thus a fact. A camera with a sensor twice the size captures twice the number of photons per second. The Panasonic LX 100 sensor is nearly twice as large and the aperture are similar, the effective aperture difference is 1 stop, therefore twice the number of photons hits the Panasonic sensor and thus it has in theory 1 stop better light performance assuming the sensor is the same technology (technically has the same quantum efficiency, the ability to turn photons into electrons).
It is not incalculable, it is very calculable with very straight forward math.
Here is an example to illustrate. You put 2 square plastic trays on your front lawn, one has twice the area of the other. It is raining, in 5 minutes how much more water has the bigger plastic tray collected? easy, twice the volume because it has twice the area.
Remember also that the Panasonic camera has a longer physical focal length and the physical aperture (lens diameter) is bigger. Lets say the Sony had a focal length of 100mm and a diameter of 25mm, the f-ratio is f/4.0. To give the same image the Panasonic (if it had twice the sensor area) would need a 141mm lens with a 35.4mm diameter to give the same f/4.0 aperture (141/35.4).
Both system have the same f-ratio on the lens, but the Panasonic has a bigger diameter. With a 35.4mm diameter the Panasonic lens' front area is A= PI*(D/2)^2 = (313*PI) mm^2, the Sony in this case would be (156.3*PI)mm^2 I.e, the camera with twice the sensor area has a lens with a larger diameter that is twice the area and allows in twice as many photons per a second. Doubling the photons gives a 1 stop exposure difference.
We can go backwards and forwards over this all day but I suggest you look at why people would buy a FF DSLR over a crop. The FF camera has 1&1/3 stop larger sensor giving 1&1/4 stop effective difference in both DoF and light gathering. that exact same logic applies when comparing cameras with any different sized sensors.
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That's what I thought but the rx100 is worlds apart from the lx100 in real size terms
The lenses aren't the same, they may have the same physical aperture but the image circle is larger on the lens designed for the larger sensor so it lets in twice as much light at the same aperture.
To be precise the lens that is projecting a larger image circle will have a larger physical diameter and a larger focal length, so the f-ratio is the same. They both might be f/1.8 but the lens projecting a larger image has a larger diameter aperture.
People get confused that f-ratio is aperture but it is only a ratio of aperture to focal length so 2 lenses with the same f-ratio can be very different in size.
Two lenses with the same focal length and f-stop can have different size image circles and let in different amounts of light. For example Nikon produce a 35mm f/1.8 for DX and FX, the coverage on both the lenses is quite different, the FX lens lets in around twice as much light at the same aperture size by using larger elements which gather more light, resulting in an increased intensity of light passing through the diaphragm compared to the DX version, the larger projection of course results in the same intensity of light hitting the sensor as the DX version, thus the same exposure.
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All this talk of 'effective aperture' is just ridiculous. Aperture is aperture, it doesn't change. If you want to say that a sensor is better in low-light, be it due to sensor size or other attribute, then just say so.
FWIW my RX100 Mk i has been my only digital camera since it launched a few years back...it goes everywhere with me, including stuffed in my pocket while snowboarding. It's worked in -25C and 40+, sand, jungles trekking in days of rain and mist, snow. The low-light performance is as good as any crop DSLR I've owned, the video is excellent, 20mp of resolution to crop with. Can't fault it really.
FWIW my RX100 Mk i has been my only digital camera since it launched a few years back...it goes everywhere with me, including stuffed in my pocket while snowboarding. It's worked in -25C and 40+, sand, jungles trekking in days of rain and mist, snow. The low-light performance is as good as any crop DSLR I've owned, the video is excellent, 20mp of resolution to crop with. Can't fault it really.
Equivalent aperture is a very important concept when comparing DOF and exposure and allows an easy comparison of image quality across a range of cameras with very different sensor sizes.
yes, I was just referring to the camera comparison in discussion.
for lenes of the same focal elngth one has to consider that the lens projecting the larger image circle has a wider angle of view, it is effectively collecting light form a larger image cone and then projecting that backwards to a larger circle., which as you say maintains the same intensity.
Another interesting result comes from zooming in/our with a zoom lens, or walking closer/further away with a fixed lens. 50mm at f/5.6 has the same light intensity as 100mmf/2.8, because although at 50mm there is 2 stops == 4x the light gathering the field of view is 4x larger, conversely the 100mm lens is only capturing 1/4 of the scene so receives 1/4 of the light of the 50mm lens. It s kind of obvious when you think about it, a lens with a very narrow field of view can only let in light from that small area.
Like it or not that is the terminology the industry and photographers y= use by standard.
Ever seen a P&S that said something like "24-100mm equivalent lens", or simply "24mm wide end". The actual lens might only be 4.5 - 19mm big in reality. It would be incredibly hard to constantly have to bring a calculator with you when shopping for different camera with different sensor sizes and lens and doing all the math yourself so it makes sense that camera manufacturers and camera review sites talk about equivalent aperture, because it is just a very useful way to make comparisons.
You talk about aperture but lenses are rarely if every advertised by aperture, the f-number is not the aperture but the aperture ratio. Aperture would be the diameter of the front lens element which might be 28mm on a nifty fifty but no one adversities that or thinks in terms of photography in that way, largely because the physical aperture is not a useful concept in determine exposures in the field, even although it the main criteria.
Think you're getting your semantics in a twist. Lenses are always described by aperture.
'Effective aperture' doesn't mean anything. "One stop greater light-gathering performance" on a sensor means something. You can't talk about aperture being anything but the absolute, quantitative value that it is!
Think you're getting your semantics in a twist. Lenses are always described by aperture.
'Effective aperture' doesn't mean anything. "One stop greater light-gathering performance" on a sensor means something. You can't talk about aperture being anything but the absolute, quantitative value that it is!
I have never seen a 24-70mm f/2.8 lens sold as an 8.5-25mm aperture lens. F/2.8 is a ratio, not the actual aperture.
Effective aperture does mean something, you just don't understand it. Effective aperture is a simple method to allow accurate comparison of lenses and sensors, I suggest you keep reading up on it until you understand the concepts, that way it should make it easier to make future camera purchases with fair comparisons. If a sensor and lens system has 1-stop effective larger aperture then that tells you a lot about the expected depth of focus, light gathering potential and sensor noise.
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