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Lenses / Acceptable AFMA difference for zoom between W and T ends?
« on: December 25, 2013, 02:03:56 PM »
I've got two new copies of the 24-70mm f/2.8 II (playing the zoom-tick lottery).  I'm wondering, what would be an acceptable AFMA difference between the Wide and Telephoto ends?

1st copy: -1 at 24mm and +1 at 70mm (so a difference of 2). 
2nd copy: +2 at 24mm and +7 at 70mm (so a difference of 5).

I'm pretty happy with the first copy, but I'm not sure about the second copy.  Practically, I will input the two AFMA values into my 5DM3 and it will interpolate the AFMA for focal lengths between the two extremes.  My question is more general, which is "what is an acceptable difference before you should consider returning the lens to the store?"

The main reason I'm asking this question is because I read Roger Ciala's old article about how to test a lens, and he suggested that +/-3 between the two ranges for a 4x zoom is acceptable.  Since my second copy has a difference of 5, I was wondering if I should be concerned.  I'm also curious what you guys think the biggest difference is before you'd return a lens back to the store.

http://www.lensrentals.com/blog/2010/11/how-to-test-a-lens
Quote
My absolute requirements for an acceptable lens are:
...
3.  Front / backfocus is similar throughout zoom range and at near and far focusing. How similar is a judgement call, but if it changes less than +/- 3 for a 4x zoom and +/- 5 for a 10x zoom throughout the zoom range, then I’m pretty happy.


P.S.  I'm not certain about the meaning of his terminology of "4x zoom" and "10x zoom", but I'm assuming that it means it's the longer focal length divided by the shorter focal length?  So  24-70mm and a 70-200 would be <4x zoom, and a 18-200mm would be >10x zoom.  Please correct me if I'm wrong.

2
I've been doing AFMA tests using Spot AF.  I recently read through Focal's documentation (I haven't bought a license but am considering it) and it says that specifically for Canon bodies that testers should be using 1-Point AF and not Spot AF.  I've always used Spot AF before because I somehow thought that the more precise focus area would be more appropriate for AFMA tests, but Focal's directions make me wonder if I've been doing it wrong this whole time.  For example, if I use the LensAlign ruler, should I be shooting the target in 1-Point and not Spot?

If it's the case that using one is "correct" and using the other is "incorrect", I would greatly appreciate if someone could clarify me how the incorrect might might skew or even corrupt AFMA/focus tests.

As a related question, in the 5DM3 manual, the section titled "Manual Focusing" (p. 112), it says "with 61-point automatic selection, when the center AF point achieves focus, the focus light [dot] will light up."  I'm a little confused as to what they are saying.  When a lens is set on Manual focusing mode, Spot vs 1-Point vs Area vs etc. is irrelevant right?  Perhaps I'm reading the sentence wrong but I'm wondering why they are mentioning "automatic selection" at all when talking about Manual focusing.  Perhaps someone could clarify.

Thanks!

3
Lighting / Is YN622C's Test Fire button a remote shutter release?
« on: December 04, 2013, 12:26:09 PM »
Does the Test Fire button on the Yongnuo YN622C act as a standard wireless shutter release?

1) Can you half-press the button to make the camera Auto-Focus, and then full-press the button to take the shot? 

2) If you hold down the button, can you shoot in continuous burst? (assuming no speedlight mounted, so no power cycling cooldown)

Basically I'm trying to figure out if the button on the YN622C acts exactly like the camera's shutter button.

Note:
I made a similar thread regarding the Canon 600EX-RT at http://www.canonrumors.com/forum/index.php?topic=18425d
A poster replied that the 600EX-RT's release button has neither of the two functions I asked above.

The problem I'm trying to solve is that many standard wireless shutter releases (e.g. Satech WRT-A, Vellos Wireless Shutterboss) require a receiver brick to cold-mount onto the hot-shoe, which means I can't mount a speedlight onto the hotshoe.  I am trying to find a wireless shutter release solution that allows me to have a remote release button that acts exactly like the camera's shutter button yet allows me to have a speedlight on the hotshoe at the same time, should I have need to.

Thanks!

4
Lighting / 600EX-RT: Viability as a remote shutter release?
« on: December 04, 2013, 03:49:56 AM »
I know that with two 600EX-RTs or one 600EX-RT + ST-E3-RT, that the off-camera flash unit has a button that can act as a remote shutter release.

My questions are:
1) Can you half-press the button to make the camera Auto-Focus, and then full-press the button to take the shot? 

2) If you hold down the button, can you shoot in continuous burst?

Basically I'm trying to figure out if the button on the 600EX-RT acts exactly like the camera's shutter button.

Thanks!

5
EOS Bodies / 5D Mk III - Anything better than RC-6 remote?
« on: December 03, 2013, 05:17:37 PM »
I'm looking for a wireless remote for the 5D Mk III. I looked at the default option, which is the Canon RC-6. It's relatively cheap ($20) and has the Canon brand, but after looking at many reviews on Amazon and B&H, it seems to have a few problems:

A) It uses the IR receiver on the 5D's front, which anytime you shoot from behind, you have to annoyingly and awkwardly angle your arm around the front of the camera if you want the signal to go through.

B) You can't trigger the AF by half-pressing the remote button; all you can do is press it the full way and take a shot.

C) You can only use the remote in conjunction with the 2-sec delay and 10-sec delay modes. 


With all these problems, I'm looking for an alternative to the RC-6.
My questions:
1) I know an IR remote will probably always encounter Problem (A).  But can anyone recommend a well-reviewed IR remote that doesn't have Problem (C) and especially Problem (B)? 
2) If I want to bypass Problem (A) I'm guessing I need to buy a remote that requires a wireless transceiver module attached to the 5D.  All the ones I've seen are big, bulky bricks that mount to the hotshoe and require me to run an annoying wire between it and the camera.  My buddies who have Nikon D800 all seem to use the RFN-4s, which is a tiny receiver that doesn't need to take up the hotshoe and doesn't require the wire. 
http://www.amazon.com/gp/product/B005PCDSBQ/ref=wms_ohs_product?ie=UTF8&psc=1

I've tried to find if there's a version of the RFN-4s that works for the 5D but haven't found one.  Does anybody have any recommendations?

Thanks!

6
I've been using a RRS L-bracket to mount my camera on my tripod.  If I buy a new camera, I have to buy a new bracket to fit it.  I can sell my old camera on eBay, but I'm curious what do people usually do with their old brackets.  Does anybody know?

When I search through eBay for RRS brackets for Canon 5D MK III and Nikon D800, I see nearly none being sold.  When looking at entries for the camera bodies themselves, many sellers include batteries and other accessories as bonuses to attract buyers, but I never see brackets being included.

So my question is, what are people doing with their old brackets when they move to a new camera?  I mean these things are not cheap ($140 new from RRS).  I'm pretty sure RRS doesn't have a trade-in program (please correct me if I'm wrong), so where are people selling their old brackets?

Thanks!

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