But, the x100 is so slow.... almost as bad as the X1...can you elaborate on this a bit more?
July 28, 2014, 06:38:16 AM
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Topic: G1X Prime? (Read 4514 times)
wickidwombat
- Canon EF 400mm f/2.8L IS II
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APS-H Fanboy
Edwin Herdman
- 6D
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If the G1 X had a prime lens, say 35mm f/1.8 or 50mm f/1.8 (which would be beyond 80mm equivalence - it's not a simple crop factor anymore because the new sensor is a different image ratio, I believe), the lens would still be too large for a compact camera - in fact it would be larger, because not only would the front element still have to extend as far from the sensor (60.4mm), it would have to be much wider around, meaning that the lens would probably have to be wider around than the camera is tall (considering that even on many "fast" primes the front element is nowhere near the total diameter of the actual lens housing)!
The essential fact of cameras with smaller sensors, while they may have fast apertures and narrower fields of view (same nominal field of view as a longer focal length on a larger camera), there is still less depth of field control. And while you can get an equally "fast" aperture with a shorter focal length while keeping the same field of view with a smaller sensor, the total amount of light hitting the sensor is only equivalent to that of a longer focal length lens at a smaller aperture in a system with a larger sensor - meaning that if you have the same focal length, the larger sensor can receive more light even with a smaller relative aperture (remembering for a moment that f-numbers are a ratio, not a fixed size).
If the larger format has a longer focal length and the same aperture, it actually is at a significant advantage in terms of the amount of light reaching the sensor. This will mean that you get greater control over depth of field (see how deep depth of fiels is with a wide lens versus a super telephoto of the same focal length) and, crucially, the image can be cleaner.
Going to a small format does not give you a free lunch here.
Since it has a sensor closer in size to APS-C cameras, to get the same depth of field and light intensity you need a lens much closer in size to APS-C cameras. The genius of the G1 X is that it is taking what is essentially the usual DSLR and kit lens combination and putting it in a smaller and probably more rugged package.
The essential fact of cameras with smaller sensors, while they may have fast apertures and narrower fields of view (same nominal field of view as a longer focal length on a larger camera), there is still less depth of field control. And while you can get an equally "fast" aperture with a shorter focal length while keeping the same field of view with a smaller sensor, the total amount of light hitting the sensor is only equivalent to that of a longer focal length lens at a smaller aperture in a system with a larger sensor - meaning that if you have the same focal length, the larger sensor can receive more light even with a smaller relative aperture (remembering for a moment that f-numbers are a ratio, not a fixed size).
If the larger format has a longer focal length and the same aperture, it actually is at a significant advantage in terms of the amount of light reaching the sensor. This will mean that you get greater control over depth of field (see how deep depth of fiels is with a wide lens versus a super telephoto of the same focal length) and, crucially, the image can be cleaner.
Going to a small format does not give you a free lunch here.
Since it has a sensor closer in size to APS-C cameras, to get the same depth of field and light intensity you need a lens much closer in size to APS-C cameras. The genius of the G1 X is that it is taking what is essentially the usual DSLR and kit lens combination and putting it in a smaller and probably more rugged package.
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BaconBets
- Guest
Going to a small format does not give you a free lunch here.
Since it has a sensor closer in size to APS-C cameras, to get the same depth of field and light intensity you need a lens much closer in size to APS-C cameras. The genius of the G1 X is that it is taking what is essentially the usual DSLR and kit lens combination and putting it in a smaller and probably more rugged package.
I'm pretty sure the G1X lens is already physically as long or longer than the 35mm and 50mm slr primes. Rangefinder type primes tend to be fairly compact.
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Edwin Herdman
- 6D
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Of course that is the case. Focal length is merely the distance from the sensor to the rear nodal point (and if the lens is the same type of design on both systems, as is likely to be the case, there will be no difference in length to account for telephoto or reverse telephoto designs). It is the relative aperture that is the problem here. However, as I have stated, you are still likely better off when using a nominally slower aperture lens of a longer focal length on a larger sensor. The smaller sensor cameras must rely on photosites of a much smaller pixel pitch to have as high a megapixel count; given the same level of technology, larger photosites will do better. Sorry if I made my original reply overly complicated.
« Last Edit: January 16, 2012, 08:07:05 PM by Edwin Herdman »
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elflord
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If the G1 X had a prime lens, say 35mm f/1.8 or 50mm f/1.8 (which would be beyond 80mm equivalence - it's not a simple crop factor anymore because the new sensor is a different image ratio, I believe), the lens would still be too large for a compact camera -
Yes, it would have to be about 12mm aperture max -- about 35mm f/3 or 24mm f/2 or similar, like existing pancake primes
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Edwin Herdman
- 6D
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12mm for the entrance pupil, right? 12mm doesn't seem like much, but it has to be matched with a larger front element. Pancake primes for m4/3rds have tended to be much shorter focal length than the OP is asking for - remember that he's stating that at f/5.8 or so the 50-60mm range is a bit slow for portraits. You can't really do a pancake prime for 50mm or beyond while keeping up a fast aperture.
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