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Messages - neuroanatomist

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6136
It's classed one up because its a FF body ...

And therein lies the conundrum ... for if the size of the sensor is the criterion, then the 6D with its 20.2MP sensor trumps the 1DX with its 18.1MP sensor ... on paper.

There is no conundrum. Size as in physical dimensions, not MP count.  The 6D, 5DIII, and 1D X all have the same size sensor, and it's the ability of that physically larger sensor to collect more total light than an APS-C sensor that leads to the better high ISO performance. 

6137
Lighting / Re: Recommendations for flash for telephotos and birds
« on: April 21, 2013, 06:58:45 AM »
580 or 600 flashes (and there's no advantage to the 600, since the higher guide number is only due to the greater head zoom, and with a Better Beamer you'll manually set your zoom between 35-80mm).  I recommend the more powerful flash because even though you'd dial back the power with a Beamer (-2 FEC if using E-TTL), with birds you'll want a fast shutter, and faster than Xsync means using the power-robbing HSS.

Also, it helps to get the flash off-axis to avoid steel-eye (red-eye effect).  I use a RRS B91-QR bracket (attached to the lens foot) and an FA-QREX2 extender, along with an OC-E3 cord to get the flash elevated.

6138
Speedlites, Printers, Accessories / Re: Ring Flash for Macro Work
« on: April 20, 2013, 07:50:26 PM »
What sort of subjects?  A ring flash is generally  best suited to documentary images (medical/dental, stamp collection, etc.), because they produce a 'flat' light.  Even the better ones like the Canon MR-14EX, which have two tubes that can be set to different power, don't give much dimensionality. If you're shooting creatively, I'd consider other options.

A better solution to consider is a regular Speedlite with a long flash bracket (I like the Manfrotto 233B for this), an off-camera cord, and a small softbox (Lumiquest, etc., ~8x8") positioned over the front of the lens.

Another excellent option (budget permitting) is the MT-24EX Twin Lite.  Ideally, rather than the little ring at the front of the lens, mount the heads on a separate brackets for complete flexibility in positioning.  I use a pair of Wimberley F-2 macro brackets for that.

Hope that helps...

6139
I think the situation may be a bit more complex than that.  One observation I made when doing manual AFMA (LensAlign Pro) with the 85L II (a lens with AF slow enough that one can actually observe the focusing with the focus distance window) was that the 7D seemed to lock on faster (or at least in a different manner, I didn't time it) than the 5DII.  Specifically, when focusing from infinity or MFD, the 7D would move the focusing group in one direction then stop, whereas the 5DII would consistently overshoot by a little bit, then move slightly in the opposite direction.

6140
EOS Bodies / Re: Safe to leave lens on camera?
« on: April 20, 2013, 02:45:07 PM »
I have my 70-200 f4L USM on my 7D and it got me wondering, with the weight of this lens (and other lenses), is it safe to leave the lens on the body at all times? If so, should the body be facing up with the weight of the lens pushing on the body? Or maybe should the camera be hanging down so the lens is pulling on the body?

Or should the lens be removed and a body cap used?

I store the body with a lens mounted, on its left side.

6141
Read the article I linked. According to Roger, all of Canon's newer lenses, dating as far back as the 70-200 f/2.8 L II I think, have rotation detectors.

Oh, I've read it - including the part where you seem to have missed the 10 year difference between when you suggest rotation detectors were incorporated, vs. when Roger does, or maybe that's a typo on Roger's part...but it makes me wonder what was going on for those 10 years...

Quote from: Roger Cicala
If this is the case, then the newer Canon lenses should definitely have a rotation detector built into them. We know there are rotation detectors in many lenses released after 2000, but if they are  in older lenses we can’t identify them, so this fits too. (As an aside, I am particularly skilled in finding them because usually if you touch them with your fingers the lens won’t focus anymore and the unit has to be replaced.)



A Phase Detect System for all manufacturers operates as a limited closed loop, but that only assures that the lens tells the camera that it has moved where it was told to go.

This was my point earlier - the closed loop is 'look-move-confirm' but not 'look-move-confirm-look'.

6142
Canon cameras contain information about all the EF lenses and the commands to send to them.  Third party lenses tell the camera that they are a Canon lens and then translate the command they receive to their lens.  This can cause even another step that adds to inaccuracy, but it can be adjusted by AFMA as well.
 
Its a lot more complex that a person might think.

Again, all of that would be solved by closing the loop. Then all you'd need is a correction for sensor/vs AF array, which would be body specific and programmed by Canon at the factory.

It is sounding like the whole phase detect AF system is fully open loop, which really surprised me. Is Nikon like this too? Do they also have an AFMA type feature on their bodies?

Wish there were a Canon engineer I could speak to this about, would be a fascinating discussion!

You should read Roger Cicala's LensRentals blog. He does extensive testing with lenses, and in his assessment, modern AF systems, including Canon's, ARE closed loop! Here's a good read:

http://www.lensrentals.com/blog/2012/08/autofocus-reality-part-3b-canon-cameras

And to quote, from Canon's own patent:

Quote
In order to achieve this objective, this invention provides a camera system comprising: a first focus detection unit, a second focus detection unit, a stepping motor that drives a focusing lens, . . . or a rotation detector, which detects the rotation . . . of the motor. . . The control circuit performs closed-loop control, based on the output of the rotation detector to control the motor.

Yes, Canon patented that. But...did they actually implement it, and if so, in which lenses and bodies?

6143
Speedlites, Printers, Accessories / Re: Where is this new flash?
« on: April 20, 2013, 07:41:02 AM »
The only way I see canon getting around that is making this hypothetical flash only capable of being a radio slave, which I have a hard time seeing happen. Thoughts?

I have no problem thinking that's exactly what will happen.  The 430EX II is only capable of being an optical slave (and since an optical master transmits the signal with the main flash tube, there's no hardware limitation on the 430 being an optical master).

6144
Lenses / Re: Canon L Glass costs over $1200 / pound
« on: April 20, 2013, 07:35:54 AM »
All we need now is a plot of photographer income per pound of body weight, and we can start to put this all together...   ;)

6145
It's easy.  You do need a stable tripod, and lots of light in the target (sun or tungsten/halogen, not fluorescent or LED).

6146
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: April 19, 2013, 08:47:12 PM »
You are misunderstanding my argument. I know exactly why Canon has poor low ISO DR. I am not talking about low ISO, I'm talking about high ISO.

I think we've pretty well established that there are some people (e.g., Mikael/ankorwatt) and organizations (e.g., DxO) who believe that DR at ISO 100 is the only thing that's relevant.  In my case, it might even be relevant....for the 17% of my shots that are at ISO 100.  ::)

6147
Lenses / Re: 24-105 &/or 24-70
« on: April 19, 2013, 08:27:27 PM »
Let get ready to sell that 35L too, once mrk II arrived ;D   

Maybe. But the wide angle + thin DoF with a close subject is something you can't get with the 24-70/2.8 II.

6148
Lenses / Re: 600mm lens - tripod
« on: April 19, 2013, 08:06:25 PM »
It looks like I also need a quick release plate of some type to mount the lens to the Whimberly?

Yes, the Wimberley P-50 plate, or the RRS LCF-53 replacement foot. I went with the latter, for the reasons listed here.

I use the same thing for my 500 f/4 II and 400 f/2.8 II. Works great, reliable and has yet to even consider failing me. I honestly use the PG-02 more then my ballhead these days for about everything I shoot.

I still use the BH-55 quite a bit.  But with an L-bracket on the camera, you can mount it to the PG-02 LLR, and by adding a nodal slide (I use the MPR-CL II), it's a full multirow pano setup.

Random, unsolicited tip for the PG-02 LLR - I initially bought the dedicated LensCoat neoprene pouch/bag.  It's well-constructed, but big and not easy to carry. I found that the disassembled head, along with the nodal slide, fits in a Lowepro Lens Exchange 200 AW.  Half the cost of the LensCoat pouch, Sliplock attachment to connect to my backpacks, and the inner flaps separate the parts and keep it quiet.  Pics here.

6149
Lenses / Re: 600mm lens - tripod
« on: April 19, 2013, 06:58:10 PM »
The 4 section one I believe is a little smaller for portability.  That was the only reason but I may have to rethink.

I considered that, in looking at the RRS TVC-33 vs. the -34L.  While the 4-section is 1.5" shorter, I decided that 1.5" wasn't enough - 25.5" (TVC-34L + leveling base) was still too long to be 'portable'.  I did get a RRS TQC-14 + BH-30 as a travel tripod (it can still hold my 600 II), with the head on it's 20.5" long and when in its quiver bag, the whole thing still fits inside my Pelican Storm im2500 carry-on hard case - that's my definition of 'portable'.  The TVC-33S would still not be quite short enough, and would have me hunching over during use (I'm 5'7"), whereas the -33 gives me a few inches extra for use on a slope.

6150
Lenses / Re: 24-105 &/or 24-70
« on: April 19, 2013, 02:08:46 PM »
Interesting, Ive always heard it sucked at 24.
Has a lot of distortion at 24, but it gets softer at the long end. Different kinds of flaws.

Yep...and while you can correct for distortion at the cost of some loss of corner sharpness, you can't correct for lost detail.

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