A New EF 50 f/1.8 IS? [CR1]
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robbinzo said:
I am in no super rush to go with a prime, and yeah, if the 1.4 becomes a 1.8 with IS and is priced like the other new IS primes (guessing it will land at around $850) then for sure the 1.2 starts looking a lot more worth it. If I go with a prime though....its part of a larger shift in gear. I am currently rocking the 10-22, 24-70, and 70-200. The 10-22...sigh, got it last year because my main body was a 7d. Now I have the mk3 and am kind of betting that the 7d may end up not getting much use. So the idea is to trade up on a few things...swap 10-22 for 16-35 (of course, not a fair even swap). Then maybe drop the 24-70 in favor of the 50mm prime. Well, that was the old plan, its funny how FF changes things because the 24-70 is like a new lens to me now...lol
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Just so nobody is harmed by this breathtakingly assured response:markd61 said:
I must affirm that what I write is true. I can mention some useful resources for understanding related phenomena: Expose-to-the-right and the non-linear response curves of digital camera sensors; the most relevant information for persuading you is in this thread and especially here. In short, you, sir, are completely wrong.
If you would like to test it out, it is simple to see it in action:
Find a recent Canon camera, set ISO manually, and switch to A/v mode. Slap a lens faster than f/2.8 on it (I thought it was f/2; it might actually be wider, I'll have to look at this again). Shoot at f/2.8 and then shoot at the widest setting. You will notice that the image is noisier (and, depending on the lens used, there may be vignetting as well, but this is not the important effect to notice). By the theory, image brightness and noise should remain constant, since we are holding ISO constant, and exposure is simply light intensity * duration. But quite obviously that is not what happens; the image becomes noisier.
In truth, the manufacturer's declared ISO settings are not scientific measurements - the scientific measurements given by DxOMark show that for every camera (regardless of manufacturer) the ISO sensitivities are not linear or even very predictable compared to what they "should" be.
I do not consider mentioning this issue to be a burden to other users, since it's fairly easy to comprehend (I gather that it is due to the narrow angle of current photosites restricting the angles at which light is effectively gathered, but in any case the effect is clear).
Digital SLRs are not film cameras, and the final image brightness and grain is affected by much more than just the user's selected settings.
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To the gentle users of the forum in general, I will leave with this final thought - DSLR "best practice" can be confusing to master. The main thing to consider, if you want to have clean files, is to get as much information into the highlight section of your RAW by keeping the image bright without burning out highlights. The second thing, of course, is to use low ISOs when possible. Finally, there is a limit to how high you should crank ISOs in most Canon DSLRs; it is not necessary to get the image looking bright enough on the camera's preview screen, because that is not the final version of the image. Instead, you may brighten the image afterward to retain your settings and a reasonable ISO.
How do you find the point at which brightening in post is better than pumping the ISO (obviously, if you just shoot JPEGs or can't be bothered, don't worry, but your image quality won't be as good as possible)? Look at the sensorgen charts from the DxOMark data, specifically the point at which the "read noise" curve goes flat, no improvement (or even shoots upward). On the 7D, that point is ISO 800 or 1600. On the T1i, it was ISO 800.
How do you brighten the image? Not with DPP. Daniel Browning recommended RawTherapee last year; there is also The GIMP, Lightroom, or Darktable (a Lightroom replacement for Linux boxen).
It is worth mentioning that there are other losses at High ISO: Dynamic range and saturation capacity (I believe saturation capacity is essentially a measure of how even the image is, since it measures the number of pixels that reliably reflect a gray target, instead of appearing in the final image to be some other shade).
The culprit, as Daniel Browning mentions, and also Gregg Siam, is that the photosites of Canon DSLRs don't respond equally well to light coming in from unusual angles. In fact, slight purple and green fringing in some lenses has been blamed on this, as well.
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P
pulsiv
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it seems as if we should get used to the fact that canon will not give its fans/customers what they want... but something close to that... and then some 1 or 2 years later the "real deal" may come... but in the meantime we bought something we didn't really want, just because its a tiny bit better than the "old" stuff.
I'm dissapointed, if this 1.8 IS lens is becoming the replacement for the 1.4
there would be no benefits from that lens (and from my point of view).
I feel, an updated 50mm 1.4 with real USM and better built quality would find a lot of fans.
(maybe canon feels, the "old" 1.4 was a too good bargain...)
but I guess thats what canon wants: if you need a faster lens, you will have to buy an L...
I'm dissapointed, if this 1.8 IS lens is becoming the replacement for the 1.4
there would be no benefits from that lens (and from my point of view).
I feel, an updated 50mm 1.4 with real USM and better built quality would find a lot of fans.
(maybe canon feels, the "old" 1.4 was a too good bargain...)
but I guess thats what canon wants: if you need a faster lens, you will have to buy an L...
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I noticed NO ONE seems to have mentioned the best part about IS lenses: they also stabilize video extremely well. Even an optically-impossible F/0.6 isn't going to keep a sharp steady image when shooting video handheld at 50mm!
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markd61 said:
Can't find the source at the moment, but the original claim was that the additional light coming through hits the sensor at such an oblique angle, that it doesn't go into the pixel wells.
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This explanation applies only to the corner and the edge of the sensor. Does not apply to the middle of the sensor. Therefore you can end up with a highly vignetted at the corners. Canon user with f 1.4 lens does not really complaining about serious vignetting. Therefore your reasoning is questionable.Ellen Schmidtee said:
M9 uses offset microlens progressively to take care of the vignetting problem due the the large incident angle at the corner of the frame (this is the nature of the M mount short lenses). Then M9 do a double take correction on camera to each specific lens.
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We're not talking about vignetting at the edges of an image. We're talking about photosite wells blocking photons arriving at oblique angles, "per photosite vignetting" or shadowing, if you like.
Up until I wrote that post I thought that the cutoff was at f/2, but apparently it's actually f/2.8. That's rather disappointing. It probably changes from camera to camera slightly, depending on the sensor and photosite design (at the very least, it could change or someday be "fixed" in a new design).
Up until I wrote that post I thought that the cutoff was at f/2, but apparently it's actually f/2.8. That's rather disappointing. It probably changes from camera to camera slightly, depending on the sensor and photosite design (at the very least, it could change or someday be "fixed" in a new design).
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Edwin Herdman said:
The center of the sensor does not see the large angle of incidence that is seen in the corners, and even the corners only see this large angle of incidence for perhaps 1/3 or less of the light. The center should be relatively unaffected even down to f 1.2.
Besides if that was the whole story then we would not see a big difference in bokeh between f 2.8 and f1.4. But we do. In fact there's a very noticeable difference in bokeh between f 1.8 and f 1.4.
This doesn't add up.
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Edwin Herdman said:
I think what Edwin is referring to are these findings from DxO and Luminous Landscapes back in 2010.
http://www.luminous-landscape.com/essays/an_open_letter_to_the_major_camera_manufacturers.shtml
http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues
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Rocky said:
It's neither my reasoning nor complaint - I just recalled the web page the other participant based his complaint on.
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M
Morsing
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I had never hear of this before, and was sceptical at first, however it does make sense. However, people are clearly overreacting. If you take the time to examine the graphs on the DxO-site, you will see, that by going from f4 to f2.8 on the 7D, you up the gain with about 0.04 eV thus gaining a total of 0.96 eV of light gathering ability instead of 1 eV as expected. This is marginal and of no consequence. Going from f2.8 to f2.0 up the gain by 0.05 eV gaining 0.95 eV in light gathering power, again very little effect. Going from f2.0 to f1.4 ups the gain with 0.25 eV thus gaining only 0.75 eV of light gathering instead of 1 eV. This is worse, but you still get a three fourths of 'what you pay for', not, as indicated, nothing. In going from f1.4 to f1.2 the gain is upped by 0.2 eV giving only 0.13 eV of light gathering power instead of the expected 0.33 (a third of a stop) so this is clearly getting worse.
In total, going from f4 to f1.2 (3.33 stops) you get about 0.6 eV of sensor gain and thus, only get 2.73 eV of light gathering instead of the full 3.33 eV.
Of course the manufactures are still 'cheating', but it is not like you get nothing from using faster glass, you just get (a little) less than you thought you would.
Hope this clears things up a bit
//Morsing
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