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Messages - neuroanatomist

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7816
Software & Accessories / Re: FoCal Pro version 1.5 and the 5D Mark III
« on: August 06, 2012, 06:14:57 PM »
A quick questions about when to register a lens with the camera - is that only when you have multiple copies of the same lens?

Optional. I don't see any downside, though. I entered mine, on the off-chance I mount a different lens of the same type, or someone wants to try my 1D X with one of their lenses.  In some cases, the serial number is stored, but it's irrelevant since multiple copies can't be registered - that's indicated by an asterisk next to the boxes on some older lenses (135L and 100-400L showed that, IIRC).

7817
EOS Bodies - For Stills / Re: 5D Mark III and green RAw!!!
« on: August 06, 2012, 11:20:08 AM »
I've read somewhere, that the most often reason for damaging computer memory modules was cosmic radiation.

I once received a box of Kodak BioMax MS (ultrasensitive autoradiography film), a sealed package of 100 sheets, and after developing the first one (following a 5 day exposure to a radioactive sample), I noticed a ~6mm diameter black spot on the film that didn't come from my sample, and could not be attributed to a light leak in the film cassette.  I pulled a few more sheets from the pack and developed them immediately, they had the same spot - stacking the whole pack together after developing showed that the spots formed a complete column passing through the stack at a slight angle, and I suspect the pack was hit by a cosmic ray during shipping. 

RE the green RAW wedding photo, I suggest you contact all the guests and a random sample of individuals nearby the locale but not present at the event.  Check your watch, the watches of the guests, and the watches of the people not actually at the event.  I suspect you'll find a small temporal difference between those there and those not there, indicating that the entire wedding party and all the guests, and you, were abducted by aliens.  Your shot was taken just as the matter transmitter beam was collecting you all for transport, and while the aliens eliminated most other traces of their presence, they missed your 5DIII.  I would not report this to Canon, but to the National Enquirer, instead.   :P

7818
Actually, it seems like a case of automated/formulaic calculations without the benefit of a human eye looking at the data.  The D3100 read noise plot has no data point at ISO 3200, which was treated as 0.0 instead of being properly flagged as n.d.  There's also a missing data point for ISO 3200 DR, which was assigned a DR of 25 stops in the table, another clear impossibility.

I have respect for most of DxO's methods (generally, and with the caveat that you have to understand what they measure, what they don't measure, and where the black boxes are so you can ignore meaningless values like the 'sensor score').  I also have respect for people who re-analyze others' published data.  But I lack respect for those who report data that have obviously not been QC'd, which is immediately apparent from the read noise = 0.0 and the DR = 25 stops. 

Since DxOMark does have data for the D3100 at ISO 3200 for both ISO Sensitivity and Full SNR curves, which Sensorgen draws upon for their source data, it seems that the problem is with Sensorgen's reanalysis, and not the original DxO data.

It is not necessary to attempt to reproduce someone else's results to invalidate those results in cases where the results are clearly not credible - and 0.0 noise with 25 stops of DR is simply not credible, any more than pennies and bowling balls defying gravity.

7819
His chart claims that a D3100 has 0.0 read noise! 
That should give a clue as to accuracy / credability.

Why, you have your own data from doing the same measurement with a D3100 sensor that contradicts it?
Or you have another source that you can cite to show that it is wrong?

No, I didn't think so.

Is one necessary? If I told you that I dropped a penny and a bowling ball off the Leaning Tower of Pisa, and both of them flew straight up into the stratosphere, would you need a source to prove I was wrong?  0.0 read noise is an electronic impossibility (if it had stated below the LLOQ, or something similar, fine, but not zero).

7820
EOS Bodies / Re: 1DX lock up?
« on: August 05, 2012, 11:12:00 PM »
4.  Using the Mode Dial, change from Auto to Creative Zone modes and back testing each, to shoot and note if the issue persists.

Good luck with that one on a 1-series body...   :o

7821
Lenses / Re: Special serial number codes?
« on: August 05, 2012, 08:11:31 PM »
Yeah, but that's Zeiss. When I order a new $150K research microscope (just a 'basic' one, not confocal or multiphoton), it takes 8-10 weeks to ship.  I assume that's because some guy named Hans who wears horn-rimmed glasses is painstakingly grinding glass and assembling optics somewhere in the Black Forest (or the factory in Jena, as the case may be)...   :P

7822
it can´t be so bad... i don´t have exact numbers but my guess is... 1 out of 80 of my customers complain about a dirty sensor

How many set f/22 and shoot the sky or a white wall to check?

7823
Could be that's a 'feature' of the transmissive LCD? 

7824
EOS Bodies / Re: Understanding AF on the new 650d
« on: August 05, 2012, 02:31:50 PM »
You only get the benefit of a specific AF point if it's selected, either manually or automatically (via expansion, zone, or full auto selection).  The only exception is that all the points work together for extreme defocus detection, but that just gets you in the ballpark when needed.

7825
Rich, in the custom controls screen, do you have the multicontroller set to direct AF point selection?  That eliminates the need to press the AF point selection button first.

7826
EOS Bodies / Re: Understanding AF on the new 650d
« on: August 05, 2012, 01:42:17 PM »
Yes, the 650D is a decent step up from the 500D/550D/600D in terms of AF for stills.  The previous recent xxxD bodies have 9 points, only the center is a cross-type, and it's a single 'hybrid' cross, with one f/5.6 line and one f/2.8 line in a '+' shape, while the outer points are f/5.6 lines.  The 650D inherits the 60D's phase AF - still 9 points, but the center point is a dual cross, an f/5.6 '+' with an f/2.8 'x' superimposed, and the outer points are all f/5.6 crosses.  The f/2.8 lines are more accurate, because they have a wider baseline.

However, I should point out that the better AF itself may not solve the problem for your f/1.4 primes, for two reasons.    First, the xxxD bodies don't offer AF microadjustment (neither does the 60D, although the 50D does, else it's 7D and up). AFMA is especially important for fast primes, where the DoF is thin. Without AFMA, the only option for a front- or backfocusing lens is to send lens(es), and possibly body, to Canon.  Second, even with a perfectly calibrated lens, shooting a fast lens wide open using focus-recompose basically guarantees you a backfocused shot, due to geometry. So, if a new 650D plays nice with your lenses (or you're willing to send to Canon), and if you use those outer cross-type points to AF, instead of focus-recompose from the center, then you should see sharp focus (as sharp as possible, at any rate - do keep in mind that lenses aren't at their sharpest wide open).

Hope that helps...

7827
EOS Bodies - For Stills / Re: Problem with 5D III?
« on: August 05, 2012, 11:38:48 AM »
Makes sense. As Mt. Spokane stated, 3rd party lenses 'spoof' the camera by using Canon lens codes - this has caused other issues in the past, and it isn't Canon's job to fix them.

7828
Lenses / Re: Special serial number codes?
« on: August 05, 2012, 10:36:21 AM »
So...Canon has two production lines for each lens...one for higher quality, and one for just so-so copies?  Or maybe they individually QC every single lens that comes off the line (which, for the 24-105, means millions of copies), and then engrave serial numbers on them based on quality?

Both of those possibilities sound pretty ludicrous to me...

7829
Software & Accessories / Re: FoCal Pro version 1.5 and the 5D Mark III
« on: August 05, 2012, 10:14:39 AM »
Neuro,

The Focal manual (p14) says that Canon recommends 50x the focal length and you mentioned you use 25x and 50x - what is the rationale behind the shorter test? Are you trying to get an average over you most used focal distances?

The manual does go on to say:
"In practice, the distance you calibrate at is the distance that the selected AF microadjustment value will be correct for. So you should try to pick a distance that is around the “most used” distance for your particular shooting style."

That's the main rationale, yes.  Plus, more data points are better (within reason), and 25x is the distance LensAlign recommends.

7830
EOS Bodies / Re: Need help from All 5D markiii user
« on: August 05, 2012, 09:14:20 AM »
I can't speak for the 5DIII, but I find the 1D X gives me about two full stops over the 5DII in RAW high ISO shots.  A little more than 1 stop directly, the rest due to better quality of noise that's more amenable to NR.  So...I was ok with 3200 in the 5DII, and I'm ok with 12800 on the 1D X.

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