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Messages - Marsu42

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1816
A tip for you on focusing on 'naked' horses - I am presuming you are shooting wild ones without any head collars or tack on - try using Servo AF with the centre points expanded, and unless very close have all AF points activated. I know this sounds contrary to 'single shot AF' and centre  point being more accurate, but I have found that when trying to focus an an animal with very flat fur such as a horse, the aformentioned method is much more successful with the 5DII and 6D.

Alas, the 6d has no af pt expansion, so it's "center" or "all" or "single outer" (non-cross). The problem with outer pts has been described in length, I hope the rocket blower did the trick and there's at least some improvement. "Center" results in a big loss of resolution since I have to crop a lot.

Least and least "all" is extremely unreliable with my 70-300L, the 6d simply cannot decide where to af and keeps shunting around the place once 1-2 outer pts are not on the object. I often feel a real pity for my 6d baby, it's not the camera's fault Canon did such a botch job on the fw and the poor thing has to struggle like this. If I manage to have all pts on the object, the 6d in my experience still doesn't focus on the front, but somewhere else in a totally unpredictable manner - though I didn't try all af options with "all".

1817
I've never heard of anyone cleaning the AF sensor, dust on it does not show in the images, and is very unlikely to affect exposure, so the risk versus improvement ratio is pretty high.  Same for the sub mirror.

I've recently heard that non-cross sensors might have bad performance when dust particles are on the af sensor, and as my 6d's outer points are abysmal I think I should try to remove dust if there's any. Alas, I have absolutely no idea how the af sensor is built physically and how to clean it.

Btw for the sensor, I use the lensrentals method though w/o the expensive butterfly, works fine and is a dry method:

DSLR Sensor Cleaning (The LensRentals.com Method)

1818
@ 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.

Ah, right, that might be another reason why I find it that hard to work with the 6d af system while a lot of people seem to find everything's peachy for their holiday shots :-o

+1, if you want to track subjects coming towards you at speed successfully I suggest a trip down to your local professional camera  shop with a thick wad of cash  :(

Unfortunately way over my budget, and currently I find it much more rewarding to invest into lighting gear (tipods, softboxes, reflectors, flashes, ...) than into a camera that will be outdated again in no time.

Actually I also really like my good ol' 60d, did some great frog macros the other day @iso800, the 6d is really for thin dof and shooting in cloudy weather, the autumn and evenings. I admit I still have problems that a €1600 camera isn't "allround" capable but has (imho) deliberate design problems, other than horses running towards me it's mostly ok... but it worries me that I cannot trust the af system in critical circumstances.

Edit: If you really want to laugh from pain or sarcasm, try the 6d's top point on a *dog* speeding towards you - zero shots in focus :-p

1819
I took nearly 300 shots of the kids at a theme park last weekend with my 6D and only 4 or 5 were out of focus.  Roughly 1/3 of the shots were focused using the outer points.

Ok, that's a reference, I'll try to clean it and then get it serviced (I've got the free European CPS) if it still struggles. Btw the shot above was of course absolutely worst case, but often the outer points hunt a bit and then lock - by then the scene is gone or the focus isn't spot on @100% crop.

I also have to experiment with focus priority when doing tracking with the topmost point in portrait mode, no way around it really when tracking a horse running towards you... my problem might be a combination of dirty af array, non-cross point and bad 6d tracking behavior. Good to hear from some people without super powers, now I've much more to go on than before :-)

1820
Technical Support / How (not) to clean the phase af array & vf screen?
« on: April 23, 2014, 03:36:58 PM »
I'm shooting outdoors a lot and my 6d has gotten quite dirty - as I just learned this might be the reason why the outer points have such a mediocre performance. I clean my sensor all the time, but have never have done this with the af array and vf screen (shows a lot of dust specs).

My first idea would be the rocket blower, but if that doesn't help is there anything I should *not* do to clean these? I faintly remember someone writing the matte vf screen is very sensitive and improper cleaning can ruin it...

1821
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.

Not to be misunderstood: it's great you took the sample shots, so I know for average shooting with a fast lens the 6d outer points should be ok. I admit that very thin dof I'm still skeptical though :-p

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.

Thanks, good point, maybe that's really the reason why my 6d has such a mediocre performance with the outer points! I never use them a lot, so if they have collected dust I haven't much of a comparison and my 60d is all cross points.... general spec'ed precision/accuracy of the 6d is not worth anything if doesn't lock on first try and hunts and this is the horse picture my 6d's outer point thinks is in focus:

1822
Technical Support / Re: Canon 6D battery issue (?)
« on: April 23, 2014, 02:39:16 PM »
I am getting less than 400 shots on a charge.

The ff sensor draws a lot of power, no comparison to my very efficient crop 60d. Live view & reviewing pictures and the IS of the lens also uses power, so 400 shots is not great, but not completely unusual... simply get a 2nd battery. Btw surprisingly gps draws very little power, no reason not to use it.

1823
Since bokeh is the correlation of sensor size, aperture and distance to subject- we should know all these things based on the sensor readout.

Nope, there's your problem - the camera only knows the distance to the focused object from the af system, everything else is 2d. To any fancy calculations based on distance like bokeh, you'd need to know real 3d information and generate a depth map - probably then you'd be able to simulate different aperture sizes in post, most likely in the small->large direction.

1824
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).

You have to look for the problem a bit which might explain the "I just got my 6d and the af is fine!!!" posts. But if taking non-repeatable shots in a hurry and the focus hunts or you have narrow dof and they eyes are just a bit out of focus the consequence is better to use focus & recompose, at least that's what I ended up with.

Personally, I found the 5DII's outer points to be ok in good light, but with close subjects and fast lenses they'd miss critical focus with noticeable frequency.  If I took 2-3 shots of the same subject, if be reasonably sure if getting a keeper.

+1, that's about it, and one problem of this method is that I burn through my shutter in no time as for potential keepers it's about 3 shots (at least) for peace of mind.

1825
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.

Interesting, though my experience is different. Btw your shots are too downsized and compressed to make an assessment, note that if I say "in focus" this means it nailed the eye and you can see the eyelashes @100% crop. I'm usually taking pictures of wild horses with my 17-40L and 70-300L in good to bad light:

* With a standing, i.e. barely moving horse in good light the outer points work ok-ish (wild guess: 8/10) though I'm getting the occasional hunt around close to infinity. You have to be careful to focus on a contrast part though. Works for repeatable shots but is not "good enough" for me to use on non-repeatable keeper shots, the horses don't pose for me. In bad light the performance degrades noticeably and more hunting occurs which is to be expected as they only work up to +0.5LV at all.

* With a moving horse to the side it works sometimes, sometimes not (maybe 5/10). I'm using "Tracking sensitivity = responsive" as which immediately results in hunting if an outer point loses focus - but "locked on" doesn't work with thin dof on erratic horse movement. As you've written, the movement towards the 6d camera is a complete joke, it's  maybe 3/10 with outer and 6/10 with center point - *if* you're lucky, I've had much worse.

I find the real issue with the outer points is not the precision, but the non-cross characteristic which make them too unreliable for me in any important situation, so I revert to focus & recompose. I have to say I didn't try my f2.8 100L much with the outer points because the specs say they're not precise enough, maybe the a larger max. aperture does improve the performance?

1826
Yeah, the 6D doesn't handle subjects moving towards or away well at all, especially towards, probably more noticeable due to the shallower DOF.  Side to side is OK.

Did you try all af options? "Release priority" is the certain way to doom, and in my experience "Tracking sensitivity" responsive is better for side movement while "locked on" does better for forwards/away movement.

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

Thanks for the sample, I'll keep that in mind - though in my current experience the non-cross hunting of the outer points is enough reason not to use them on anything that moves or is low-contrast.

No doubt. There are thousands of great images taken with 5D2 AF, or older, or manual focus cameras. The 1Dx / D4 AF capabilities are nice-to-haves, not need-to-haves. They no doubt improve hit rate, but aren't strictly necessary.

Nearly nothing is strictly necessary, but when having the opportunity to take one non-repeatable keeper shot (i.e. hit rate either 100% or 0%) and your af fails that's frustrating on a camera in this price category - esp. since if the 6d af happens to hit you get a taste what could be done.

If you go into the 6D's custom settings (Magic Lantern not required)

Not quite, w/o ML you cannot use the SET button to quickly switch back to the center point (like on 60d for example) - I consider this to be essential in a 1pt af camera with some outer gimmicks. Also the ML version doesn't need you to select the af point and then focus, but instantly focuses once you selected the point  - though the latter is a matter of preference.

1827
Missing out the outer points altogether ? In the vast majority of static situations they work perfectly well when required for ultra shallow and close distance shots; ie. when 'focus and recompose' would give back focus.

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.

There are much more annoying things about the AF of the 6D than the points themselves; having to use the 'rebel' interface of first having to press an activation button before you can press the point moving button is much more of an issue.

Fyi: You can use Magic Lantern to fix that, the first thing I personally added to ML after I got the 6d was the option to switch af points w/o meta key but directly with the cursor keys :-p ... alas, I'm using them a lot less as the hunting of the non-cross points is so annoying.

1828
Are there really two threads going on about this camera's AF pushing 20 pages now?

In fact, you just made the thread one post longer :-)

Why can't people just agree to disagree, and accept the fact the 6D is a great camera for what it is - an entry level FF body with great IQ but with simplified AF.

In general, if people would  just agree upon your opinion and call it a day things would be much simpler indeed :-p

Sometimes one tool is better than another based on needs/wants.

Which would be the point with the 6d: Is it better at anything, or is it really just a cheap version of the 5d3? It does have gps and wifi, that's obvious. As for the -3LV center point af, if and when this is useful is not a simple matter - imho this is mostly a Canon marketing stunt to add a unique selling point, though it's certainly "nice to have".

As for the af system, this has basically become a troll thread: To the amazement of (almost) everyone else, one particular person claims the 6d has a capable af system and if you don't get what you want you're probably not using it properly or are not a good enough photog. Imho putting this af system in a 2012 €1600 camera is a disgrace and not meant as an "entry level" system but crippled to protect the 5d3, they should have left out the outer af points in the first place :-o as the 6d basically is a 1-pt af system. Ymmv if you have super powers :-p

1829
Can someone please explain dumb me what does focus at "-3ev" actually mean? Thanking in advance.

Note that phase af always works with open aperture, i.e. your camera will need more LV with a slow f5.6 lens than with a fast f1.4 one to still be able to focus... one reason to get a f2.8 zoom even if you seldom actually take pictures @f2.8 and are ok to carry the bulk/weight + pay for it.

http://www.kenrockwell.com/tech/ev.htm

1830
As I stated, the majority of situations which people call "low light" really offer plenty of light for the AF systems of even low-end dSLRs.  The extra one stop of sensitivity that the 6D has is an advantage only in very rare situations, so rare that many 6D users probably have not ever experienced them.

Having shot with the 6d and my 70-300L I changed my opinion and would disagree here:

The 6d still af's in dim light @f5.6 aperture just fine w/o af assist, and the exposure was taken care of with some flashes and iso 6400. For the big boys with constant f2.8 zooms pr even faster primes that might not matter that much, but for the cheap rest of us 1 more stop of af capability can come in handy

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