April 23, 2014, 04:39:52 PM

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Messages - Sporgon

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1
@ Marsu42; thanks for your comments. Incidentally don't think that you are alone in struggling with focus on horses. Animal fur is notoriously difficult to focus on, and with horses in particular I have always had trouble focusing with every camera I have used.


2
I am CONVINCED it is 7D2 with a 1d style body with 2 stops ISO improvement, 12 fps and 1dx focus. Larger LCD as well.

You may well know something that I don't, but I'm convinced it won't be. Canon have left a gap in the aps line above the xxD in terms of ergonomics, and price that can still come in slightly below the entry FF level.

Clearly, sanj forgot something in his post.  This:

<SARCASM>

I know this, because I'm almost always guilty of the same transgression...

 ;D  Oh yes, I see it now, sanj's delivery is just so deadpan !

3
So far I haven't had anything like the unpleasant experience that the OP reported. I suspect I'd try and make sure that my actions were unlikely to be misinterpreted and, if they were, I'd go for a conciliatory approach.

This is a fascinating discussion that has raised a number of issues and thrown up a number of questions.  Without wishing to hijack the thread, I would be grateful for an answer to one specific one.

I'm in the UK. We have, at least, two different legal systems in operation here (English/Welsh and Scottish - I haven't a clue how things work in Northern Ireland). We don't have a written constitution and formal rights arising from it. The English/Welsh system is based on Common Law, a mishmash of legal precedents and common sense.

People over here got very jumpy about public space photography after the bombings in London in July 2005. It certainly wouldn't have been wise to spend a lot of time trying to photograph a railway station or an airport, say, in the immediate aftermath of that. In February 2009 Section 76 of the Counter Terrorism Act came into force and appeared to open the door to making it an offence to take pictures of members of the police. The BBC covered this at the time and the police in London tried to enforce this interpretation on at least one well reported occasion, despite earlier assurances in Parliament that this wouldn't happen. References have been made to US First Amendment Rights and EU rulings in follow up debates but neither apply directly.

http://news.bbc.co.uk/1/hi/uk/7888301.stm

http://www.theguardian.com/politics/2009/jul/21/police-search-mobile-phone-court

http://www.urban75.org/photos/photographers-rights-photographing-police.html

http://www.theguardian.com/law/2011/aug/31/do-we-have-right-to-film-police

Does anyone on this forum know what the current state of play is in the UK when it comes to photographing the police in a public place?


I am from the UK, and I am pretty sure that in the letter of the Law it is not against the law to photograph a police officer in a public place. However, the police detest being photographed, let alone filmed. There have been any number of instances of gross police misconduct, not just in the UK, where a mobile phone video has turned up, often first posted on the web, which shows the police's version of the events to be completely false.

Unfortunately now the growing number of Terrorism Acts that are being passed and amended are interpreted by much of the police in the UK in such a way as to be to their advantage in any number of cases which clearly, from the outset, had nothing at all to do with terrorism.

Believe it or not a heckler at one of the Labour Party conferences, an old man in fact, was arrested under  the Terrorism Act and removed. The police were publicly ridiculed by the press, but then of course it is a free press that keeps a country free, and having a good line on suppressing of photography is definitely a worrying move in the wrong direction.

4
I am CONVINCED it is 7D2 with a 1d style body with 2 stops ISO improvement, 12 fps and 1dx focus. Larger LCD as well.

You may well know something that I don't, but I'm convinced it won't be. Canon have left a gap in the aps line above the xxD in terms of ergonomics, and price that can still come in slightly below the entry FF level.

6
Canon EF Zoom Lenses / Re: Canon EF 70-300 f/4-5.6L IS USM
« on: Today at 04:14:55 AM »
Taken long after the sun had gone down, the mist rising from the river and meadows was filling the Stour Valley. The river can just be seen in the left of the picture, and the steeple of Dedham church is just right of centre.
Shot with the 6D and 70-300L @125 mil, ISO 1600, f5.6, 1/50th. A six frame hand held panoramic.

Lovely color palettes.  I find the color rendering out of the 70-300L to be excellent!

+1  I love panoramic shots and this is a brilliant piece of craftsmanship.

Thanks Peter & Dustin. I really like this one and it was good to capture such a serene, quiet part of the day.

7
I've made them fit the page but have included a magnification in each one where you can see that the very narrow dof has been achieved over the focus point.

Are the corner pips really 100% crops? If so, the dof is indeed to wide to test the outer pt. performance. I don't doubt the outer af points focus *somewhere*, but they either tend to hunt (mostly on my 17-40L for some reason or another) or miss critical focus (indeed as speculated 70-300L @200-300mm, focus on the eyes).

What I was trying to show was that the AF accuracy at f1.6 was way more than f5.6. To this end the 2m dof was 'very narrow' compared with the 12m dof that f5.6 would have given.

The examples were in reply to the comments you made about this, and could be demonstrated by attaching the very small, but fast loading files.

The page has had around 1000 views overnight ( UK time) so hopefully some people have found it interesting, despite the ridicule of Mr Skirball.

The smallest dof that I can achieve with my gear is 6mm. This is with the 50mm at minimum focusing distance at f1.4. Please note: the 50mm f1.4 at minimum focus distance and f1.4 and off centre is crap.  I took three consecutive frames using the 2 o'clock outer point using the bottom of the eye as a target in low light; EV 3 to be precise. Each time, as before, I turned away focus manually so the camera had to re focus each time.

You will see that in each consecutive frame the camera has produced focus within the 6mm depth of field. There is perhaps a 1 or 2 mm variation, but the end result is the same: it's in focus. ( In fact at this distance this lens/body combo is back focusing a touch).

Now I would argue that for the vast majority of 6D owners ( and 5DII for that matter) this performance is absolutely acceptable.

The last frame is me attempting to manually focus using live view, but as you can see I have not succeeded; the manual focus on the 50 '1.4 just isn't good enough. I also tried live view contrast focusing but the focus zone is too big. 

I am not saying the 6D/5D AF is anything like the 1 series and 5DIII, but I am saying that people who state the outer points are 'useless', 'pointless' etc are talking out of their collective behinds.

The crops are 100% of full resolution. As I said, don't expect it to be razor with that lens at that aperture at that part of the frame.

There is one other thing to consider though: dust. I find that the single orientation points are highly susceptible to contamination by dust / pollen etc, and if you are struggling with your outer points on these cameras try using a rocket blower or even blower brush to get the dust off your AF module.




8
Consider that we are imaging three-dimensional space, and compare the XY dimension (FoV) to the Z dimension (DoF).  When magnification is low, the DoF is relatively large compared to the FoV.  For example, with a 50mm lens and 8 m distance, Z/X is ~0.4.  At higher mag, e.g., a close up of the dog with the 50mm lens at <2 m, Z/X is <0.1. 

Basically, misfocus is less obvious with a lower magnification.

Interesting, this explains why with longer lenses AF accuracy can be problematic even though there is a relatively large dof.

All I have tried to show is that the outer points on the 6D give infinitely more accuracy than an f5.6 dof - because there has been confusion in this thread about the meaning of an 'f5.6 precision' AF point, and that the outer points are perfectly useable in many circumstances whether near or far.

9
I've made them fit the page but have included a magnification in each one where you can see that the very narrow dof has been achieved over the focus point.

Not to be argumentative, but that isn't a particularly narrow dof. How far away is the dog?

Narrow to me means if you hit eyelashes, the retina is OOF.

+1

@ Sporgon, your 'very narrow DoF' looks to be over 2 m deep, distant subjects aren't as taxing for an AF system.

Even as a 6D owner I can laugh at the (unintended) sarcasm of posting pictures of “very narrow DoF” on the order of 2 meters.  See, the 6D can do f/1.6 as well!

If you look at the pictures of the bear at the top of the page you'll see a dof of 10mm with an outer point and it's accurate every time. ( The bear's nose is about 40mm long ). Some of the points being raised in this thread are based upon the accuracy of the 6D's outer point during movement and low light. Just how much movement and low light is anyone going to shoot with a depth of field of a few mm ?

Shooting at some distance with wide apertures requires AF accuarcy, despite the fact that real dof is much greater. Try shooting a moving target with the 135L at f2 at a distance of around fifteen metres with cameras that are not in the league of the 1D and see how you get on with a dof of 1.5m.

10
I've made them fit the page but have included a magnification in each one where you can see that the very narrow dof has been achieved over the focus point.

Not to be argumentative, but that isn't a particularly narrow dof. How far away is the dog?

Narrow to me means if you hit eyelashes, the retina is OOF.

Narrow depth of field is relative to the distance. If you are taking a picture of a football field and have the centre line in focus with a depth of field of two metres; that's narrow.

These pictures are intended to show that even at f1.6-8 on a 50mm focal length the focusing is accurate enough to drop the depth of field over the correct point of focus.

Where the two dogs are moving I was about two metres away, so dof would be about 18 cm. Where the individual ones are further away I would say eight metres, so a dof of 2.5m. However remember that at f5.6 you would have a dof of 12 metres with the 50mm lens, so 2.5 is 'narrow' in comparison with 12. 


11
I've made them fit the page but have included a magnification in each one where you can see that the very narrow dof has been achieved over the focus point.

12
This whole subject of the 6D outer points has piqued my interest now. This afternoon I tried shooting moving and static subjects in both 'one shot' and 'servo' using just various of the outer points. Light was reasonable, EV 7 to  8, so not dark but not really bright either.

I put together a few shots, and you can see that the camera hits focus using a 50mm 1.4 at f1.6 - 1.8 very accurately with the outer points. I don't know what the engineering and physics are of the 'f5.6 sensitive points', but I can show you that these points nail focus on an appropriate target. "Appropriate' being the key word because you do have to be aware of the orientation you are using.

I would say one shot = 10/10 in reasonable light and appropriate target.  Servo on static subject = about 9/10. Servo on subject moving across your view = about 7/10. Remember this is f1.6 on a 50 mil. Servo on subject coming towards you fast = forget it.   

My point here is to show: A, that the outer points are quite useable in a number of situations, and:B, they are accurate to f1.6 on a 50mm focal length.

13
Lenses / Re: Will Sigma 50/1.4 Art push Canon to release a 50/1.2L II?
« on: April 21, 2014, 09:00:08 AM »
I don't think it will have much influence on the 50L as that lens is specifically bokeh before sharpness. The replacement for the 50 1.4 - well that's a different thing altogether. I wonder if the development of the 50 Art is what has delayed the Canon 50 IS ? Canon must have been aware of what Sigma were up to. I don't think Canon will reply with a mainstream retrofocal 50 design, but their own new 50 is going to have to compete. I think Canon will 'cheat' as they did with the 35 IS and produce a slightly slower traditional 50 design that has IS and is also really sharp at whatever aperture it is. I'm guessing f2, possibly f1.8/7, but almost certainly not 1.4 IMO.

14
If you go into the 6D's custom settings (Magic Lantern not required), you can set it up so you don't have to press the AF-point selection activation button (or whatever it's called - I assume you mean the button near the top right corner of the camera when you have you eye to the viewfinder) to select an AF point.  You can set it so you simply press the 8 way switch/dial to move the AF-point around.  It's still a very sad second best to having a joystick (like on a 7D/5D series/etc), but it's an awful lot better than having to press the AF-point selection button first every time you want to move an AF point.

Aaargh ! Why was this hidden in the 'Custom Button' function and not 'Custom AF' !?

Thanks jd7, that's a big improvement. I might have time to start complaining about the outer points now  ;)

As someone said' "CR is the manual" !

15
This really improves af w/ fast lenses? I don't have lenses faster than f2.8, but reading the specs the outer points only have f5.6 precision and are so near the f2.8 center point that my guess was that focus and recompose still is better than using the outer points? This is the reason I wouldn't buy a fast prime for the 6d with the intent to af, but I'm happy to stand corrected.

Yes indeed. I think f5.6 precision is misleading - it's requiring f5.6 to function. It will then not be as accurate ( in theory) as the f2.8 'precision' sensor.

Here are four consecutive shots taken with the 85 f1.8 at 1.8, three of which using some of the outer points. The contrast and lighting is good but it has got it bang on each time. As a comparison the last frame is with live view. These are 50% enlargement of a medium jpeg.

When using the single orientation outer points you must consider the detail orientation of the target. If this is done then I find the outer points very good in suitable conditions.

Don't let the outer points of the 6D stop you from getting a faster lens !

Just an addition: the distance here was 1 metre, so at f1.8 the dof was 10mm. At f5.6 the dof would have been 40mm, and f2.8 would have given 20mm. So you can see that this is concrete proof that the '5.6 precision' points give much greater precision than f5.6.

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