You are comparing a 300/4 MTF to a 600/4 FF lens. The relevant comparison is a 300/4 MTF lens to a 600/8 FF lens. That would match FOV, DOF, light-gathering, and diffraction.
Or, you could compare a 600/4 FF lens to a 300/2 MFT lens.
Jim
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How m4/3 got the reputation it have good lens?
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Or, you could compare a 600/4 FF lens to a 300/2 MFT lens.
Jim
sportyaccordy
Forum Pro
Now you dun did it!!! :-D
drmarkf
Leading Member
.....
Can of worms opened. So, here's the thing. When it comes to extreme telephoto there's a very clear advantage to a crop sensor. It's a 300mm f/4 lens, 100% usable at f/4, sharp edge to edge that gives an identical image as a center crop of a 300mm f/4 FF lens would if it was usable at f/4 and equally sharp AND the sensor behind it had similar pixel density (no such sensor exists).
So no, it's not equal to a 600/4 FF but it's not equal to a 300 f/4 FF either for it's intended usage (birding). Is it equal to 600/8? No, because shutter speed is very important for its intended usage and light intensity matters more than total light gathered.
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O
OlyPent
Guest
blue_skies
Forum Pro
Hmm, you think in 2D, think in 3D instead. What angle do the rays form from the exit pupil to the corner?
The circle has to cover the diameter of the sensor, and a 3x2 rectangle has a larger diameter, relative to area, than a 4x3 rectangle. Can you understand this difference?
It leads to larger lenses, relative to the larger format, because of corner performance.
In addition, widest aperture being similar, causes major problems for the larger sensor/lens. Example: f/2 in MFT correspond fo f/4 in FF. FF lenses at f/4 are easier to design, and will be sharper and faster than f/2 FF lenses. Few will purchase those, rather they will spend extra for sharp 'edge-to-edge' (and corners) f/2 lenses.
Not quite the same challenge, now is it?
I dunno, do you understand the relative formats and size differences?
Perhaps you keep forgetting sensor sizes?
M43 can be thought of as merely the center section of the FF,
Look at the image below, can you see the difference?
If you cannot see the diameter difference, and the corresponding impact on lens design.
Yes, I know that FL in M43 is half that of FF, but exit pupils being pushed forward is easier in smaller lenses. If FF only had to worry about center sharpness, lens design would be easy, right?
But again, how about that 'perfect' f/2 lens on FF, does M43 have a corresponding f/1 lens? And this disregards the sensor sensitivity fall-off that plays an inherent part.
Again, not quite the same. Or, designing FF lenses with high center sharpness and max aperture of f/4 sounds like quite a different challenge, yet this is what M43 lenses effectively are.
PDAF in DSLR was done by dedicated photo-receptor 'stripes', that could be sensitized in different directions. They used the mirror in a different path and this allowed fast and accurate AF, at the drawback of micro-calibration requirements.
In mirrorless, PDAF has to be done with the main sensor itself, so any PDAF solution is compromised and cannot be dedicated, as it would block sensor pixels.
Today's solutions are rather innovative, but are not the same as the DSLR approach. Some argue that they are getting better (no calibration), and they have only become feasible as in-camera processing power has increased and sensitivity of the sensors has been increasing (enabling small cells to work). Still, the EV sensitivity of mirrorless PDAF solution trail those of DSLRs.
Some vendors to 'cook' the RAW, so yes, DxO is measuring this. Plenty of discussions about that here in the past, where were you then?
That is the estimate loss to software correction (don't have a link), but only affecting certain parts of the image.
Also read e.g. http://admiringlight.com/blog/zeiss-batis-25mm-f2-vs-sony-fe-28mm-f2/
- "Overall, I feel the Batis 25mm is the better performer. It’s sharper over a much larger aperture range across the frame, and while the bokeh is a bit rougher at f/2, the better sharpness and distortion control make it a winner. I also prefer the slightly wider field of view that a 25mm lens brings. However, when it comes to the big question, it’s much harder to answer: Is the Batis worth almost $900 more? For my needs: No."
Sorry, almost all modern lenses, including and especially MFT, are designed WITH software correction in mind.
Good lenses without correction means going back in time, or opt for Otus' type solutions.
What is wrong with software correction?
DxO does see the software correction: e.g. the E1650 lens has bad distortion, and this now 'baked' into the RAW, similar to how MFT handles some lenses. The resulting quality is much better. See all the early E1650 reviewers shooting the lens down because its RAW was distorted. Yet, no customer ever saw this, as flows (in camera or in post) do hide this.
Speculation??????
There are facts for everything but I don't have the time for research.
Spend more time on this forum, you'll agree with most, if not all.
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Cheers,
Henry
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that's a totally unsubstantiated generalization.
birding is hardly the only reason to use long lenses... i shoot sports at 600mm on ff, and the last thing i want to deal with is a weak little m4/3 sensor, that won't let me use fast shutter speeds.
what part of 36-42mp, vs. 16-20mp, is so difficult to understand?
credit where it's due...
this shot is 600/7.1 on ff, the equivalent m4/3 lens would be 300/3.5...
as mentioned above, i can use a canon 600/4, which is a 300/2 on m4/3... that'll never happen.
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dan
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I was in the middle of editing that post due to really poor choice of words when you replied. You can read the updated version.
It's not equal to 300/4 FF because of pixel density, not equal to 600/4 FF because of noise, not equal to 600/8 FF because of exposure. Equivalence isn't an easy concept.
It's not equal to 300/4 FF because of pixel density, not equal to 600/4 FF because of noise, not equal to 600/8 FF because of exposure. Equivalence isn't an easy concept.
sportyaccordy
Forum Pro
Equivalence is really easy. For sensors within a generation light related noise is inversely proportional to aperture diameter x shutter speed.... so in that context a shot on MFT through 300/4 is the same as 600/8 on FF if shutter speeds are the same.
Thing is, most modern lenses are sharp at F/8 (unless diffraction kicks in)... same can't be said at F/4 (though F/4 usually is sharp). And larger sensors enable higher native resolution, which also helps.
Admittedly long reach stuff is where smaller formats shine... a 600mm lens just sounds miserable to lug around. But that's solely due to size/weight/cost.... not anything IQ related. At best smaller systems will match... at best.
While I am not a fan of, or a user of, MFT, I think that Stejo's statement is neither a generalization nor lacking the potential for substantiation. Note the artful wording that constrains the performance of the 600/4 lens. There is a slightly buried assumption that the pitch of the FF and MFT sensors are the same, but if you add that, it's hard to argue with.
From a practical point of view, I have long argued that the best 1.5 x teleconverter for the a7 is an a6300.
Jim
"potential" is not the same thing as substantiation.
pandering to that kind of nonsense just encourages the spread of misinformation.
"identical image" does infer that, but do people really think that ff always has the same pixel pitch as m4/3?
afaik, it's an argument in theory only.
in order to back up the claim, you'd have to post up the specific m4/3 vs. ff cameras that had identical pixel pitches.
if anything, the argument for crop sensors has always been in favor of higher pixel density, not equivalent pixels...
i'll point you to the review of the same lens that i just posted, crop vs. ff... dpr pitted a 20mp crop camera against a 23mp ff camera, and the ff camera had a significantly higher mtf rating, across the entire image plane:
Loading…
www.dpreview.com
sometimes life isn't always what theory tells us that it's going to be...
i'll try and post an example of why ff is better, at all focal lengths... same picture, ooc vs. raw... exactly how far can you push an m4/3 base iso image in post? i really don't know.
dxo says that it's a 2.73-stop push? with a bunch of brightening and processing... i've done it at four stops before, with room left over.
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dan
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pocoloco
Guest
In fact... it is a fake system... and when they produce lenses... they don't sent us their best... no... they send us their worst... they are nasty small light weight lenses... nothing like our huge lenses... and i hear a lot of people say that huge lenses are great and the best... they potrait the light so beautifully.
blue_skies
Forum Pro
I have done similar things, to get higher SS, but essentially this is the same as choosing a higher ISO.i'll try and post an example of why ff is better, at all focal lengths... same picture, ooc vs. raw... exactly how far can you push an m4/3 base iso image in post? i really don't know.
dxo says that it's a 2.73-stop push? with a bunch of brightening and processing... i've done it at four stops before, with room left over.
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dan
So, you push four stops, ie. from base ISO 100 to ISO ISO 1600.
Yup, I'd expect M43 to be able to handle ISO 1600 as well.
The A7x has more lattitude here, but only if you start at a higher ISO...
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Cheers,
Henry
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blue_skies
Forum Pro
Lol, the first couple of posts were from M43 users.
Ask yourself why M43 users show up in an FF forum, and why their posts come up first.
(And if they didn't post here, these threads would be more readable/informative - void from comments such as yours?)
I'm not willing to get in the bickering game. There's advantages and disadvantages both ways.
For example, shooting f/8 the amount of light that reaches the sensor *per pixel* is not enough when lighting conditions are not good, making it hard (if not impossible) for the camera to lock focus. This is very important for birding. You can't compensate for actual exposure with ISO.
As I said before, equivalence is not an easy subject. You can compare 2 different lenses on the same sensor or 2 different sensors on the same lens. Comparing 2 different sensors with 2 different lenses it really is apples and oranges.
I'm happy to concede that a 600/4 FF lens (of equal sharpness) is in all ways, shapes and forms better than a 300/4 MFT lens for those that don't have an issue with it's size, weight and price.
For example, shooting f/8 the amount of light that reaches the sensor *per pixel* is not enough when lighting conditions are not good, making it hard (if not impossible) for the camera to lock focus. This is very important for birding. You can't compensate for actual exposure with ISO.
As I said before, equivalence is not an easy subject. You can compare 2 different lenses on the same sensor or 2 different sensors on the same lens. Comparing 2 different sensors with 2 different lenses it really is apples and oranges.
I'm happy to concede that a 600/4 FF lens (of equal sharpness) is in all ways, shapes and forms better than a 300/4 MFT lens for those that don't have an issue with it's size, weight and price.
i think that it depends on whether or not the sensor is iso-invariant: https://www.dpreview.com/articles/7450523388/sony-alpha-7r-ii-real-world-iso-invariance-study
with the right sensor, the cost to underexpose at low isos is minimal, compared to what can be gained with protecting the highlights.
i can see that at higher isos, depending on which m4/3 sensor is used: http://photonstophotos.net/Charts/PDR.htm#Olympus OM-D E-M1 Mark II,Sony ILCE-7R
the problem is that the m4/3 d.r. is lower by over 1.5 stops at base iso... can you shoot the a7r at base iso, and take advantage of that in darker conditions?
https://www.dpreview.com/reviews/im...normal&normalization=compare&widget=1&x=0&y=0
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dan
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