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Messages - neuroanatomist

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EOS Bodies / Re: Canon EOS 7D Mark II Spec List [CR2]
« on: February 19, 2013, 06:48:09 PM »
I've never used AI Focus... I've also never really understood what that third focus option was, or how it worked. Would it be better for non-tracking servo-type AF work?

AI Focus is supposed to behave like One Shot, and if the camera thinks the subject has begun to move, it automatically switches to AI Servo.  Sounds nice, in theory. How well does it work?  Well...AI Focus is not an option on 1-series bodies, so you can probably draw some conclusions based on that.

EOS Bodies / Re: 2013 Predictions for Canon EOS Products
« on: February 19, 2013, 06:11:28 PM »
Anyone know what Canon camera is in this below linked picture?  Never seen one with the red piece by the hotshoe.   


Update:Even more suspicious is the Canon logo has been removed, this has a pop-up flash and looks to be in new condition.  Can't place the lens either the more I look at this - size wise looks like the 85mm 1.2 but the bulge appears different by the camera mount from the current 85,1.2???

Lens is the 50L. Camera looks like a 7D.  If it was a new body, it would have the locking mode dial. The 7D has a separate piece of plastic where that red piece is, would be one click with the PS magic wand and a color change.

EOS Bodies / Re: 2013 Predictions for Canon EOS Products
« on: February 19, 2013, 05:59:33 PM »
The 3D will have eye-controlled focus and a blink-activated shutter. You heard it here first.   :P

Canon non-EF Lenses (TS-E, FD, etc.) / Re: Canon TS-E 24mm f/3.5L II
« on: February 19, 2013, 03:08:38 PM »
Palace of Fine Arts, San Francisco, CA

EOS 1D X, TS-E 24mm f/3.5L II, 13 s, f/8, ISO 100

Lenses / Re: Recommendations for Selling Expensive Telephoto
« on: February 19, 2013, 11:07:21 AM »
FWIW, looking at my local CL today there's a 300/2.8L IS (MkI) for $4200 and an 800/5.6L IS for $11K (overpriced, IMO).

Lenses / Re: lens question for the math geniouses
« on: February 19, 2013, 10:36:06 AM »
Now I use for example the EF 135L at F:2.0 I can mount it to my 5D and or 60D and I get the same AE of 200/1 Second at 2.0. So the crop does not cost me any light while extending my lens to  216mm. ...Putting the lens on a crop camera extends its effective length to 216 but does not change it's front element so we have now a 1:3.456 lens (which fits to my observation with the DOF on the 5D either by rule or incident)

Putting a lens on a corp body does nothing to the lens.  A smaller sensor doesn't cahnge the focal length, that's an intrinsic property of the lens.  A smaller sensor merely samples a smaller area of the image circle of the lens, meaning you get a narrower AoV from the same focal length lens.

Now to my question: How can the crop change the F number in regards to DOF but not in regards to the speed of the lens?  And applied to the rest of the universe does this mean I need not only to convert the mm up but also the DOF capabilities down by 1.6 on all EF-S lenses?

Exposure (shutter speed for a given aperture) is determined by light per unit area of sensor, so a smaller sensor does not change exposure.  Under the same lighting conditions, a f/2 lens on FF will give the same exposure as an f/2 lens on a PowerShot with a 4.6x crop sensor. 

Practically, you multiply the aperture by 1.6x to get the equivalent DoF of a lens on a FF sensor.  The underlying principle as that to get the same framing with FF, you are closer to the subject than with APS-C, and clsoer means shallower DoF.  If you take a shot with the same focal length lens at the same aperture and distance on APS-C vs. FF, the DoF will actually be shallower with APS-C (because of the different circle of confusion), but of course the framing will be radically different.

The example I often use relates to people who shoot an EF-S 17-55mm f/2.8 IS on APS-C and claim they won't go FF because there's no FF equivalent to that lens.  In fact, the FF equivalent to the 17-55mm is a hypothetical 27-88mm f/4.5 lens (in terms of DoF for the same framing), so the 24-105mm f/4L IS is wider, longer, gives shallower DoF, and has IS.  The larger area of the FF sensor translates to 1.3-stops lower noise, which more than makes up for the stop of aperture lost in terms of shutter speed.

EOS Bodies / Re: Canon EOS 7D Mark II Spec List [CR2]
« on: February 19, 2013, 10:21:11 AM »
ISO Performance to get close to the 5D3

The rest of the spec list looks pretty darn good, but I'll believe the line about ISO performance when I see RAW files.  But then again, in marketing speak 'close to the 5D3' might mean simply that the native range is 100-12800 (which is 'close to' the 100-25600 native range of the 5DIII and a 1-stop improvement on the 7D spec).  Many times, Canon's statements about ISO performance improvements refer to JPG images or ISO range, not noise levels at a given ISO setting.

Lenses / Re: FoV difference between Tamron 70-300VC and Canon 70-300L
« on: February 19, 2013, 06:56:19 AM »
In real world use, it's probably more useful to many more photo genres than the sports / press orientated 70-200 lenses. Landscapes, travel, documentary, details, a bit of wildlife...etc

Well, they'll get my 70-200 II when they pry it from my cold, dead hands (or Canon releases a MkIII), but I might pick up a 70-300L as a travel zoom...

EOS Bodies / Re: Canon 1DX vs 5DIII Wildlife Comparison
« on: February 19, 2013, 12:04:17 AM »
You're saying that you have to get the exposure right at capture, except when using an ISO that is above the native?  I don't understand how this could be, since the file that gets stored, has less information, if it is underexposed by 4 stops.  Sure that information is stored based on a boosted sensor's output (thus you are seeing a reduced dynamic range from the sensor, with all the other unwanted artifacts)...but the file itself has more bits, does it not?

Native ISO uses analog gain, before the signal is digitized. Expanded ISOs are digital gain, applied after ADC on top of the maximum analog gain. There's no difference between shooting at H2 and shooting at max native then pushing two stops in post.

Technical Support / Re: Strange pattern in long exposure images
« on: February 18, 2013, 07:53:56 PM »
You're seeing a 'Newton's rings' artifact (let the Googling begin  ;) ), not sure of the cause but most likely a combination of the monochromatic light of the Aurora and antireflective coatings on either a filter (if you were using one), the lens itself, or the filter stack on the sensor.

Lenses / Re: FoV difference between Tamron 70-300VC and Canon 70-300L
« on: February 18, 2013, 04:05:50 PM »
I suspect that's the case.  There is something a little odd about the design about the Canon 70-300L, though.  For example, if you compare it to the Canon 70-200/2.8L IS II, both have the same specified MFD and maximum magnification (47.2" and 0.21x), but obviously the 70-300mm has a 50% longer focal length at the long end.  Canon mentioned a  The Tamron 70-300 VC, despite not being able to focus as close (55.1" MFD) achieves a higher 0.25x maximum magnification.

The 70-300 L has a 'floating' optical system (the 85L II has this, too).  Canon stated, "As mentioned above, the use of a “floating” optical system means that as the lens is progressively focused closer, other lens elements continually change position to preserve image quality throughout the focus range. (Many lenses are optimized for best quality at or near infinity, and as focused closer, there’s a drop-off in contrast and sharpness… that’s not the case with this new lens)."  It seems something had to be traded for that sharpness when focusing close, and that something translates to maximum magnification, apparent focal length, or FoV at the long end (three ways of saying the same thing, sort of).

Reviews / Re: Camera Help 7dii 5d3 or 6d
« on: February 18, 2013, 02:29:19 PM »
If the 5D3 is more than you want to pay for a new body, then consider the 6D, which works great in low-light situations.

Not sure about the AF performance of the 6D for tracking fast-moving subjects, though...

Reviews / Re: Camera Help 7dii 5d3 or 6d
« on: February 18, 2013, 02:15:20 PM »
Get the 5DIII, if it's within your budget.  You'll gain two more stops of usable ISO over the T2i and 7D, better AF than the 7D, and a faster frame rate than your current camera.  IMO, the only current camera that would be better for your needs is the 1D X.  A 7DII may come out, but barring some sort of electronic miracle, the high ISO performance of a FF sensor is still going to trump APS-C. 

I was shooting boxing over the weekend, poor lighting, fast action (the hands, at least).  I needed 1/800 s to have a chance of stopping action, shooting the 70-200/2.8L IS II in the f/2.8 to f/4 range (depending on distance and subject placement, f/2.8 can be too thin).  My ISO settings ranged from ISO 3200 (not a single shot lower than that) to ISO 12800. 

Lenses / Re: 24TS-E Version I v. Version II
« on: February 18, 2013, 02:07:41 PM »
Yeah, but Samyang lenses are all manual focus.  Oh, wait...   :P

The 24 II is a significant optical improvement over the MkI, at f/3.5 and even stopped down to f/8.  It also offers the ability to change shift and tilt orientation to one another on the fly.

But...the 85L II is an amazing lens, too.  I suppose it comes down to whether you want to improve the optical performance of your wide TS-E images, or have another great lens for portraits. 

EOS Bodies / Re: Canon 1DX vs 5DIII Wildlife Comparison
« on: February 18, 2013, 12:03:32 PM »
True on the super telephotos, my 200 (which I guess is more medium~) and 400 MK II are fast regardless of the body. Good to know lenses like the 85 benefit from the higher voltage. Is it a MK I or MK II?

I have the 85L II, which Canon claims has improved AF speed relative to the MkI ('improved' in the sense that a tortise has improved ground speed relative to a snail...).

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