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Messages - THX723

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1
Software & Accessories / Re: Screw-on ND filter for 16-35 II
« on: December 10, 2013, 05:19:00 PM »
I don't have any vignetting problems with my B+W 10-stop filters... No problems with the 82mm filter on my 24-70 or 16-35 lenses, or the 77mm filter with my 24-105 lens & a full frame 5d3... Now I do have big-time issues with the color cast of the B+W's! Color correcting the indego-blue of my Lee Big Stopper is a breeze compared to dealing with the peculiar orangey-magentaish brown tint of the B+W's, and they're not cheap filters! I may have to look into the Haida filters for when I don't want to hassle with the whole Lee filter kit...


@ Dustin

I would love to find a screw-in 10-stop ND filter who's color cast is easy to deal with! Those Haida filters of yours look very interesting... A quick Google of "Haida filters" found me this site where the reviewer does what appears to be a very careful & thorough comparison of the Haida filters with the B+W's: http://text.flowtographyberlin.de/neutral-density-filters-are-haida-nd-filters-as-good-as-bw/2/ Are your observations regarding the Haida filters similar to his? Particularly with regards to the color cast? His sample images comparing the color casts of the B+W's, the Haida Pro II MC (multi-coated), and the Haida non-coated are particularly interesting. In item #7 of the review, he points out that the color cast of the multi-coated Haida filters are quite similar to that of the B+W's. He appears to show that it is only the non-coated Haidas which exhibit a "slightly cool cast to it which is rather neutral and easy to fix." Has this been your experience also?

Lastly, where in the world do you buy the Haidas? A quick check with the usual suspects came up empty...


Agreed. It was due to the quirky color cast that I prefer Hoya over B+W, when it comes to circular ND filters. For everything else other than ND filters, I do in fact prefer B+W.

Here's a shameless plug of my search for the elusive Hoya ND X400 in 82mm a year ago ...
http://www.canonrumors.com/forum/index.php/topic,11564.msg206728.html#msg206728

A year later, I've given up the quest for the above ND X400 filter. Alas I did eventually find some, but they were incredibly expensive (price gouging?); not worth it.

But wait, there's better news ... Hoya has just launched a whole new line of ND filters -- The PRO-ND series with no color cast!?! (I would love to verify this myself) 8)

Even better that it comes in 82mm (Hooray for 16-35 II & 24-70 II peeps!), up to 10 stops (previously 9 for ND X series), and reasonably priced. It's win, win, win. The search is over folks!

http://www.hoyafilter.com/news/press/N0000026/

B&H has them in stock btw. :)

2
The focusing screen stacks over the transmissive LCD screen, so you would still have all the AF/grid elements in place and you certainly still need battery power for that. The question is if the added screen affects exposure metering in anyway.

3
Very cool. I'm looking into doing something similar eventually, so thank you for the review!

Btw, it's www.focusingscreen.com (without the 's').  ;D

4
Actually what I'd really like now is a FW800 SD Card reader.
Now you're just being unreasonable!  :P

5
Hallelujah! Thank you both for the valuable feedback.
I shall get me one of those soon enough. Also very glad it's working well with Mountain Lion. Woot! :)

6
Belkin is finally shipping their Thunderbolt Express Dock, so USB3 is now an option.

http://www.belkin.com/us/F4U055/p/P-F4U055

I prefer FW800 and got a used SanDisk CF reader from LensRentals used side when it pop'ed up for $26.

Sadly, my Macbook Pro is pre-Thunderbolt too!
I know. An upgrade is definitely on plan; in a holding pattern for when the new model based on Haswell is announced.

7
It's a real pity my current Macbook Pro doesn't have USB 3.0.  :'(
I see there's a used Lexar reader in the local CL listed for $100. Darn that supply & demand.  :-\

8
http://www.ebay.com/itm/NEW-Gold-Flash-FireWire-800-FW800-CF-UDMA-Compact-Flash-Card-Reader-IEEE-1394-/230758761847?

Firewire CF card reader has been a dying breed, so it was a bit of a surprise when I came across the above.

This being an eBay dealer has my Spidey senses on guard, but still optimistic. The little LEGO dude and the beat-up Hot Wheels pickup truck, though admittedly cute, wasn't exactly calming.  ;D

I'm unaware of the brand, Gold Flash, who appears to be Japanese or intended for the Japanese market. It doesn't appear to be a one-off, as the dealer indicated there are many still avail for sale and are "new in box". Also claimed to have tested okay on OS X Lion (Mountain Lion compatibility unknown).

Has anyone had any experience with this reader and the dealer?

9
Just a few minutes.

10
Canon Digital Learning Center (DLC) now updated with a piece on this new HDMI/AF firmware update:

http://www.learn.usa.canon.com/resources/articles/2012/5d3_clean_hdmi_out.shtml

11
Lenses / Re: 5D3 + 50 F1.2 L
« on: February 27, 2013, 01:20:19 AM »
Folks, the 50L focal plane isn't curved or anymore curved than the average lens.

Apologize. I shouldn't have said focal plane. I'm not a techie. I guess I was referring to the field curvature. I just know that if you lock focus with the center point and recompose you will more than likely end up with an image that is at least slightly out of focus.
No apology. Field Curvature and Focal Plane Curvature are of the same btw. See my response above.

12
Lenses / Re: 5D3 + 50 F1.2 L
« on: February 27, 2013, 01:18:52 AM »
I disagree. True, SA, CA, and coma all constitute aberrations, yes...but what the lay-person refers to as "curved focal plane" while not technically or semantically precise, is nonetheless not an imagined phenomenon. Petzval field curvature does exist.

Taking SA as an example, imagine if the points in sharp focus can be joined in a 3D graph across the "focal 3D space" and your sensor can be magically bent to precisely pass through these points of maximal focus... It will not be a flat plane...while one could hope for a nice smooth bowl like graph, some complex optical systems, at least in theory, could generate nice central plane with concentric ripple with circular throughs and waves around this plane.

The challenge for optics designers is to address/correct SA, CA, coma and other spurious aberrations and distortions that arise in multi-element optics in a fair compromise and yet keep price and weight down...I do however agree that some SA was intentionally incorporated into the f/1.2 systems for artistic effect.

But field curvature does exist and is in fact the norm, to varying extent in both corrected and uncorrected optical systems.

So when the fanboys want corner-to-corner sharpness in the f/1.2 systems with zero CA and that melting bokeh, one has to just smile and be nice :)

Of course there will always be some however measurable curvature to the focal plane in the real world. Is the Earth truly round? Is a flat wall ever truly flat?

It was that very reason I took the time to qualified with "the 50L focal plane isn't curved or anymore curved than the average lens." For the intent and purpose, the focal plane of the 50L is not abnormally nor excessively curved. In layman's term, it’s flat or of no real concern.

Spherical Aberration is not remotely the same as Chromatic Aberration nor does it have anything to do with focal plane curvature. It does however have everything to do with the shape/curvature of the spherical lens and can be corrected by way of aspherical contouring and/or counter elements (e.g. floating element).

The phenomenon of front focusing with the peripheral AF points is an entirely different matter and surely isn't called Focal Plane Curvature. Instead what was observed is none other than misjudgment by the phase-detect AF system in the presence of excessive Spherical Aberration. Despite such flaw, each peripheral AF points are still able to arrived at a given focus plane (even if not actually in-focus), but more importantly, be uniformly out-of-focus (aka flat).

On the other hand, given a lens that does exhibit significant Focal Plane Curvature, one would be able to achieve perfect focus at any AF points (including peripherals), but the image would not be uniformly in-focus (only area near the center of focus). This phenomenon is independent of the type of focusing system used btw; AF or Manual. No amount of eye-balling MF will ever get you a flat pic. Clearly not what's going on here. We know the 50L is fully capable, especially MF'd or even Live-View contrast AF’d.

So what is it about SA that sends phase-detect AF to the funny farm?

Imagine at any given point on the actual in-focus plane, there exists a series of also in-focus points in-front and/or behind it (projected from different parts of the lens. see illustration). A typical phase-detection AF system simply doesn't have the smarts to make that judgment call. In a way, it did what it was designed to do, just didn't lock-on to the best one. This same mechanism is also the reason for Focus Shift at all AF points (even the center).

By stopping down (pinching of the aperture), you can cut down on the number of these false positives projections; less interference. For the 50L, the cut-off is somewhere around f/5.6-8.0 (DOF is large enough by then, that it’s tough to say for sure).

The bottom of the line is Canon had made a conscious decision to leave excessive (not little, but a lot) amount of SA uncorrected. Call it for the artistry or what have you, it’s there and it’s real – a real pain in the arse … until one learns to cope with it.

Through the ownership of the 50L, I have come to leverage the peripheral AF error against the center point focus shift.

AFMA wrt the center point is assumed. Focus shift at the center is some degree of back-focus when in the red-zone (within a several feet of subject, and  f/1.2  > aperture > f/5.6). Knowing that switching from center to the peripheral points would result in some degree of front-focus, it could be used to negate the back-focus (from the focus shift). Examples:

  • At wide open (f/1.2) I know I can shoot fairly reliable without thinking much.
  • Inside the red-zone, I select one of the peripheral AF points best for the given aperture (you’ll have do some test runs for yourself to determine which pairs well).
  • Outside of the red-zone, I shoot normally (any F-stop with any AF points).

13
Canon EF Prime Lenses / Re: Canon EF 100mm f/2.8L Macro IS USM
« on: February 26, 2013, 09:55:06 PM »
And the Andromeda Galaxy..... not just for things small and/or close.....
Wow! That is cool! On the iPad I can't see the Exif. I'll look at it later. Really curious about the settings. It looks very crisp.
Yeah I'm a little confused. EFIX reads ...

30 seconds, f/5.6, ISO1600 (via EOS 60D), 400mm (via 120-400mm)
... which I presume is the EF70-200 @f/2.8 + 2X TC

Surely the EXIF info is amiss. Apart from the wrong lens for the discussion, there isn't remotely enough exposure time for that outcome.  :-X

14
Lenses / Re: 5D3 + 50 F1.2 L
« on: February 26, 2013, 03:54:07 PM »
Folks, the 50L focal plane isn't curved or anymore curved than the average lens.

Imagine taking a single picture of a flat poster on a wall (for exaggeration, this could be f/1.2 at close range), do you suppose the picture is out of focus away from the center? The answer is no. That was field curvature, or the lack of, in a nutshell.

The subject of focus variance using different focus points (wrt other points) has everything to do with the excessive spherical aberration (SA) inherent to the 50L's optics. While this designed SA is great for its artistry, it is problematic for any phase-detect type auto-focusing systems. This same under-corrected SA is also responsible for the infamous focus shift.

15
Software & Accessories / Re: AFMA advice sought
« on: January 03, 2013, 09:10:47 PM »
There's also a less sophisticated (and less expensive) FoCal alternative from the maker of LensAlign, called FocusTune:

http://michaeltapesdesign.com/focustune.html

It works similar to FoCal manual mode, where the software analyzes a series of images you took at various AFMA settings then spits out a report with its best recommendation. Again it's far less elegant than FoCal, but does the trick too. Also good to know that current LensAlign owners qualify for a discount. :)


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