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Messages - neuroanatomist

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7981
Lenses / Re: How to reduce the nd filter warm color cast?
« on: February 15, 2013, 11:51:52 AM »
Buy LEE or schnider optic.
If you're talking about schnEider :-> optics (B+W) - they are just releasing their 82mm nd filters, they much more expensive than Heliopan (probably early adopter's premium) and one of the above posts also states that b+w also has a color cast - so I went for the cheaper Heliopan w/o coating (it's not supposed to let through light after all).
Schneider has had an 82mm 10-stop ND for a while (in fact, when I bought it in 2011 they were the only game in town for an 82mm ND3.0 screw-in).  It does have a warming effect, you can see an example I posted in this thread.

7982
Canon General / Re: Bag question
« on: February 15, 2013, 11:46:00 AM »
I personally don't like photo backpacks.

Regardless of my personal feelings, when carrying a 15 lb (or more) load, my back really likes two shoulder straps and a hip belt, vs. just one shoulder strap...

7983
EOS Bodies - For Stills / Re: New MFA method
« on: February 15, 2013, 11:41:48 AM »
I checked the method again today with the 300 f/2.8 series II plus extenders using a high contrast black cross on white in good light. In all cases, the dot method was way out. Recalibration using the same target and sloping ruler was within 1 unit of previous.

Thanks for the update (despite the bad new for DotTune® fans  ;) ).

7984
Canon General / Re: Bag question
« on: February 15, 2013, 08:51:06 AM »
Sorry forgot to post the budget, ideally somewhere around US $150. This looks really promising: http://www.bhphotovideo.com/c/product/577361-REG/Lowepro_LP35271_PEU_Flipside_400AW_Backpack_Black.html

I have and really like the Flipside 400 AW.  It's comfortable to wear with a load, and will hold the gear you list. I like the Flipside design, you can access your gear withour setting your bag on the ground.  I also have the Flipside 300 for carrying less (and I can see a Flipside 500 AW in my future if I need to travel with my 600mm lens).

7985
Software & Accessories / Re: Gloves for Photography
« on: February 15, 2013, 08:48:06 AM »
Fingerless with the mitten cover is good if it's not too cold.  But 0 °C with some wind chill on top of that, exposed fingertips get uncomfortable pretty quickly.  I use a thin pair of all-weather gloves (in my case, I have capacitive fingertips so I can use my iPhone too), and over those I put the windblock fleece fingerless gloves with the mitten covers.

7986
Lenses / Re: Focusing Problem with 600mm f/4.0L IS II with 1.4X Extender
« on: February 14, 2013, 06:38:28 PM »
Once the target is set up, taking the 83 shots takes 10-12 min, so a prime takes me <25 min and a zoom usually <1 hr. Manual analysis in FoCal takes just a few minutes per image set.

7987
EOS Bodies / Re: What if the rumored 5Dx is actually a 4D?
« on: February 14, 2013, 06:32:30 PM »

And as you said elsewhere on this site, without high fps, you can't take good photos :P

Obviously the mods removing your previous remark and susequent rebuttals to the same effect wasn't sufficient to prevent you from having another go at the expired horse....

Thank you for your insightful comment. Now would you like to comment on the topic of the 5Dx/4D?

...and thank you for flagrantly misrepresenting what I said.  Now would you like to provide a link to where I stated, "Without high fps, you can't take good photos," or, perhaps you'd like to suggest that the 5Dx/4D will actually be a lens, and not a camera?

7988
EOS Bodies / Re: Big Megapixel Camera in 2014
« on: February 14, 2013, 05:41:06 PM »
1D body

46 Megapixels

5 FPS

61-Point AF

16-bit processing - 14+ stops of DR

7499$

Bring it canon.  8)

And a 135mm f/1.8L IS to go with it, right?  :P

7989
Lenses / Re: Focusing Problem with 600mm f/4.0L IS II with 1.4X Extender
« on: February 14, 2013, 05:37:05 PM »
FoCall is still using sharpness to quantify the images (I'm running the latest Mac beta).  Where their 'modeling' comes in is to reduce the number of data points this software requires to make a call on the AFMA value.  This is pretty evident when I load in >80 data points and look at the curve fit.  Sometimes the fit is 'fair' or even 'poor' when the same data loaded into a bona fide data analysis program yields a much better fit, and a resulting value which matches what I see from visual inspection of the plotted data, but is sometimes off by 1-2 units from FoCal's selected value. Basically, I think FoCal tries to fit a few data points to a pre-specified curve, rather than fitting a curve to the data.

RE what the data points actually are, I have done what FoCal does (measure sharpness and peak contrast) with a MATLAB script and gotten the same rank-ordering of image sets. FoCal is just easier to use, as I don't need to batch-convert to TIFs, etc. 

I guess the key point is that there are LOTS of wrong ways to do an AFMA, and a few right ways.  As long as you find a right way that works for you, and gives you sharp images, you're fine.

7990
Lenses / Re: Focusing Problem with 600mm f/4.0L IS II with 1.4X Extender
« on: February 14, 2013, 03:02:24 PM »
The best way is to just do it manually.  You can start by taping a newspaper to a wall and running through AFMA adjustments until you get the best image.  Then go out and shoot a duck on the water to dial in the adjustment. 

Makes sense...and that's pretty much what I do, although still using FoCal.  Basically, I trust an image analysis program to determine which is the 'best image' more than I trust my own eyes (and I should point out that my day job for many years was analysis of microscopic images, both 'by eye' and with digital image analysis algorithms). 

When I do a FoCal calibration, I use lots of light (my 600 II tests were in the EV 14-15 range) and a solid support (RRS TVC-33) on a stable surface (concrete or asphalt).  I don't tether the camera and let FoCal do the iterative adjustments...rather, I take 83 shots per 'test' - 2 shots at even-numbered AFMA values from |20| to |12| with one starting focused at ∞ and the other starting at the MFD, then three shots at every AFMA value from +10 to -10 (inclusive), one from ∞, one from the MFD, and then one without moving the focus ring.  I load the 83 images into FoCal in manual mode, and there are ample data to drive a curve fit.  I run a test at 25x focal length and 50x focal length, and for zoom lenses, at each end and 1-3 intermediate focal lengths.

I then take the value(s) from FoCal and do real-world testing with the lens with AFMA applied, to make sure I'm getting sharp images.

7991
Lenses / Re: Using two Canon EF 1.4X entenders
« on: February 14, 2013, 12:17:05 PM »
Neuro - you said you've tried your 100-400 with a 2x TC:
When you say focusing was difficult, do you mean manual focusing was difficult, or AF was difficult?

Phase AF is not supported.  I meant that manual AF was difficult - through the VF it was very dark (f/11 will do that), and in Live View, although the display was bright with exposure simulation, the vibration resuting from moving the focus ring with an 800mm lens on APS-C was significant.

7992
EOS Bodies / Re: What if the rumored 5Dx is actually a 4D?
« on: February 14, 2013, 12:00:56 PM »
Either way, high MP will mean low fps.

Which is not really a bad thing for a camera that is mainly used for Portrait/Landscape/Architecture as long as they keep it reasonable (around 3fps) ... I only hope they will keep a good AF system and not go back to the stone age AF of the 5d MkII, in that regard the 5d MK III is really two steps forward ...

No, I think it's perfectly reasonable.  The 1Ds wasn't known for it's high frame rate...  Still, if they give it dual Digic 5+, 18 MP at 12 fps could mean 45 MP at 4.8 fps, and that's not too bad (and right in line with the 1DsIII).

I suspect the decision on AF will come down to the body type.  If it's a high MP sensor in a 1-series body, it'll get the 1D X/5DIII AF system (and likely the 1D X metering).  If it's in a 5-series body, it'll get the 'old' 63-zone iFCL metering and a lesser AF system than the 5DIII.  That would effectively force a choice between a true 'action' camera (1D X), a true 'studio/landscape' camera (high MP), and a 'jack-of-all-trades' (5DIII) - or, as Canon's internal marketing presentations may pitch, result in people buying at least two bodies to get their needs met.

Low FPS but high MP and great DR - Perfect trade off! :)

High MP - Canon have certainly demonstrated a willingness and ability to go there.  Good DR they have.  Great DR?  That remains to be seen - Canon's sensor development efforts to date appear to not have been focused in that area.

7993
EOS Bodies - For Stills / Re: New MFA method
« on: February 14, 2013, 10:17:55 AM »
1 AFMA is 1/8 of the depth of field.

Point of clarification...  1 unit of AFMA is 1/8 the depth of focus, not depth of field.  The AF system doesn't know subject distance (that's estimated by the lens after focus is achieved).  Depth of focus is measured at the AF sensor itself (micron distances).  The practical consequence is that a unit of AFMA has more impact on depth of field the closer the subject is to the camera.

7994
70D is Coming, The Future of Pro APS-C Will Change! I read and re read the interview with Masaya Maeda and wonder why I am the only one who sees No 7Dll in the Future because the Future is Full Frame.

I am hoping for 5Dlll like camera with a $1,500.00 to $2,000.00 price tag.   

So…you're hoping for Canon to release a 5D Mark III-like camera at a price point that is cheaper than the 6D?  That seems pretty unlikely.  "Future" is a long way off in this scenario, IMO.

7995
Lenses / Re: Using two Canon EF 1.4X entenders
« on: February 14, 2013, 07:20:51 AM »
Does anyone here use two 1.4X extenders? If so, can you tape one set of pins and say focus at f8 on a canon ef 400 L f5.6? 

Right now I use a 5d mk iii and I find it quite capable with the extender taped .  I guess I am thinking, when the new firmware comes in the spring, can I feasibly have a 800 f8(f11 reality)?

I've used the 2xII with a 100-400L for 800mm f/11, on a 7D and 5DII.  Focusing was difficult even on a tripod.  Optical quality was not great, contrast was very low.  Stacked 1.4x TCs would be worse.

I've used the 1.4xIII with the 100-400 on the 1D X, AF worked, and optically the results were quite decent.

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