Technique - AF and camera shake. Getting random quality shots

[Piffdog]

Hi everyone, new to the forum and enjoying the insight so many of you have shared.

I am a reasonably competent amateur and have been playing around trying to photograph our pets. I have been using my 6d and an old 400d on a 70-200 f4 IS and seem to be getting mixed results in terms of sharpness.

I have been using on a tripod, at around f8, with IS turned off and the centre af point and consistently (on both bodies) getting pretty poor results when i expect them to be really crisp.

In addition, i have also been taking photos handheld (with IS on) in aperture mode and boosting the iso so i can shoot at 1/1000 or even faster. Im still getting crummy looking shots which look like theyre blurry but that doesnt make sense as i still get that outcome veven if i boost right to 1/4000!

Im happy to post some examples (im sure that will help) once i read the instr Ctions on how to do that. In the meantime, can anyone tell me if its probably that i am still getting handshake at 1/4000? (I dont have parkinsons...)

thanks

[Tannin]

G'dat Piffdog and welcome.

I suspect that your problem is not camera movement. (As you have assumed, we need to see the shots to be sure.)

At 1/1000, let alone 1/4000th, you have to do something really drastic to get camera shake problems at 200mm.

Unless the 70-200/4 IS is a really old model (designed last century) you can happily use IS whether you are hand-holding or using a tripod. From memory, there were only ever about three or four Canon IS lenses that don't work with tripods. My ancient old 100-400 Mark 1 (a 1999 design) was not supposed to like tripods and IS, but I ignored that for a decade without any problem at all. And even 15 years ago, Canon IS was very effective, worth a comfortable couple of shots.

So it's not camera shake, and it's not going to be faulty cameras either - not with both of them acting the same.

I reckon there are two obvious possibilities:

(1) Focus problems. If this is the answer, then it must be your lens that is at fault. (Or possibly a technique thing, but I doubt that. Modern auto-focus is pretty good nearly all the time.)

(2) A cheap protective clear filter on your lens. If you have a clear or skylight or UV or indeed any kind of filter on the front of your lens, your image quality is degraded. By just a little with a good ($100-200) filter, possibly not even enough to notice, and by a lot with a cheap and nasty one. A crook filter can do truly awful things to your pictures. Filter problems are easily fixed with a simple three step system: (1) dig a deep hole, (2) throw the filter into it, (3) fill in the hole before the damn thing escapes again.

Oh, another possibility. If your lens has focus switches, make certain they are set to auto focus ON and distance to auto. (Some lenses allow you to set, say, 2m to 10m, or 10m to infinity, or auto for the full range.)

Depending on the light and the subject, you could probably come back to f/5.6 or even f/4 if you are careful with your selection of a focus point.

Looking forward to seeing the pictures.

[farmmax]

It may not be you moving, but your pets moving in and out of your dof. Erratically moving animals can be a problem. Your lens also needs to be able to focus fast enough to keep up. If you are shooting in conditions with plenty of light, have you tried pushing your aperture out to f12 and beyond to see if that helps?

Are you having problems if your pets are sitting still, or is it mainly when they are active?

I'm no professional, but photographing animals is probably what I get the most practise doing. I seem to spend more time watching them and figuring out how they move, than actually taking photos. That way I have some way of predicting where they may be when I press the shutter. Photographing skipping goat kids and lambs is still hit and miss. Dogs are only a little more predictable. Horses are easy after goats and lambs! Animals moving directly towards you are the worst.

Tripods are not my things, so I never use one taking animals. Tripods restrict my movements too much, and normally I have to fit in with the animals, not them with me.

It would be great to see some photos of your pets. If they are cute enough, I won't even notice any blurriness :D

[Tannin]

Good points Farmmax. A Canon 70-200L focuses fast enough to keep with anything much bigger than a rabbit. I don't recall any non-L Canon 70-200/4s, and all the longer L Series Canons are renowned for rapid USM focus. (Rule of thumb: some of the black L Series lenses sacrifice speed for other qualities - the 85/1.2 for example is quite slow - but the telephoto ones are a delight to use.

That said, I was assuming that the animals are more-or-less static. If they are moving around then, unless you have developed a high degree of skill and can place the centre-point exactly where you want it, it is generally better to use multiple focus points. Modern cameras are extremely good at this sort of task. Even old clunkers like the 400D can manage if you are gentle with them. Not sure where the 6D fits in. The 5D and the 5D II (both made before the 6D) were lousy at it, the subsequent 5D III was excellent.

[ameerat42]

Since all but the posting of pictures has been comprehensively covered, this is about how to
display images on AP.

1) If you want to upload images from your computer directly into posts here on AP, have a look at
this guide (http://www.ausphotography.net.au/forum/showthread.php?156515-Attaching-Images-To-Posts-On-AP). It might look --:eek:--, but after a go or two you should be swimming.

2) If you have another hosting site, such as Flickr, copy the BB code for a reasonably-sized version
of your image and paste it in the body of the post text.

You can ask for help if you have problems.

[John King]

A good rule of thumb is do not use IS if shooting at or faster than the reciprocal rule.

For a 200mm lens on your 6D, that's 1/200th. For your 400D, it is 1/(FL X crop factor), 1/(200x1.6) = 1/320th.

IS can cause blur or funny artifacts with shutter speeds that are very much higher than the reciprocal rule suggests.

Some types of ILIS, IBIS or combinations of them can cause problems if used on stable tripods.

[Tannin]

Chhers John, but where on earth did you hear that? My first impression was that it is complete nonsense. On thinking it over, perhaps it is something peculiar to sensor-shift IS or even the Olympus implementation of it. Or possibly it's just a myth. I have certainly never heard of such a thing applying to optical IS (as used by both Nikon and Canon, and also by Tamron, Sigma and Tokina).

Further, I have successfully used IS with high shutter speed (up to 1/8000th) for many, many thousands of shots with a wide variety of lenses, including the Canon 70-300L, 100-400 Marks I and II, 500/4 Mark I and 600/4 II. Nowhere in the Canon literature is it recommended to turn off IS for high shutter speeds, and Canon are generally very good about providing that kind of advice. A Nikon person might be able to confirm my assumption that the same applies to Nikon's VR.

Canon has not released a lens which requires IS to be switched off when using a tripod since some time last century, and similar remarks apply to Nikon's VR lenses. I'm not sure when Sigma, Tamron and Tokina IS implementations became tripod-safe, but I rather suspect that they always were insofar as none of the third-party makers had an IS product at all until well after Canon (and probably Nikon too) had dealt with the tripod compatibility problem. It was only ever an issue with a handful of very early IS lenses, all of them long since discontinued, and few of them likely to be still in daily use after all these years.

Of my long-lens shots (these are the one where I am most likely to be using high shutter speeds), I handhold about a third, take another third or perhaps a quarter using the car windowsill as a rest, and the remainder with a tripod. I never turn the IS off except for flight shots, and often not even then. Here is what happens when you use a Canon IS lens with a tripod at 1/8000th. (In this case, it was a Canon 500/4.)

http://tannin.net.au/upload/17/170802_121331-cf.jpg

That's not a fluke shot. That sort of clarity is what one can expect as routine, given (a) nice light, and (b) no silly mistakes by the photographer.

(Why did I use 1/8000th and a high ISO? I was set up for flight shots and this little chap decided to sit still.)


http://tannin.net.au/upload/17/171007_102440-4_1s.jpg

Here is another one: 1/4000th, tripod, Canon 600/4 II.

Years ago, some people used to recommend switching IS off at higher shutter speeds, not for any direct image quality reason, but because IS systems used to slow down auto-focus. Not by much, but enough to make a difference. And it does (this is why I turn it off for flight shots), or rather, it used to. On my old 500/4 Mark I, for example, it can make a slight but visible difference. With newer IS lenses, AF in the preferred IS Mode 3 is lightning fast. (I should be careful here not to exaggerate: AF on the older IS L Series lenses is still very quick indeed. We are not talking chalk and cheese differences in AF speed with IS on or off, just a moderate effect which is usually worth tolerating in exchange for the extra sharpness of a stabilised image.)

[ameerat42]

...

Canon has not released a lens which requires IS to be switched off when using a tripod since some time last century, and similar remarks apply to Nikon's VR lenses. I'm not sure when Sigma, Tamron and Tokina IS implementations became tripod-safe, but I rather suspect that they always were insofar as none of the third-party makers had an IS product at all until well after Canon (and probably Nikon too) had dealt with the tripod compatibility problem. It was only ever an issue with a handful of very early IS lenses, all of them long since discontinued, and few of them likely to be still in daily use after all these years. ...

(Certainly on another forum:eek::eek:) ---:umm: Oh, hang on! Here too a couple of times --- it was the evangel to "switch off IS when using a tripod:eek:"
So at first I did, using the Σ50-500. - Nope! - I got camera shake. Anyway, I quietly and heretically left it on... Anyway, I can routinely hand-hold it
at f=500mm to about 1/200sec. - Because of the IS, not my bi- and triceptal prowess:o

PS: About that rule-of-thumb: be careful when using a hammer:p:p:D

[Mark L]

Welcome to the forum Piffdog.
If the subject is moving I'd simply try using more AF points than just the center one. And try Al Servo as your AF Mode.

[swifty]

A Nikon person might be able to confirm my assumption that the same applies to Nikon's VR.


Have a quick look at this guide.
http://www.bythom.com/nikon-vr.htm
First two paragraphs already addresses the issue of when to/not to use VR. Article is 8 years old but I'm not aware of anything that has changed unfortunately.
I think it's not so much VR (or IS) can't work above a certain shutter speed, only that it can introduce artifacts.

[Tannin]

Thom is usually very good, but frankly a lot of that is nonsense, and much of the remainder is so far out of date as to be useless. (Unless, perhaps, Nikon VR technology is many years behind Canon's, which I very much doubt. Sure, Canon invented IS and remain the market leader in it to this day, but neither company tends to lag the other in any significant respect for more than a year or two. They simply can't afford to, and they spend whatever it takes to remain competitive.)

Thom has far greater knowledge of Nikon lenses than I will ever have, but his understanding of physics, as laid out in this article, is lamentable. His argument amounts to the proposition that:

(i) The VR sampling frequency is 1/1000th.
(ii) Therefore the Nyquist frequency is 1/500th. (The Nyquist frequency is to motion as the pixel is to photography: it sets the ultimate limit of detail detection. This is why CD audio has a sampling frequency of 44kHz; the Nyquist frequency is thus 22kHz, which is conveniently higher than the limit of human hearing at around 20kHz.)
(iii) From this (says Thom) we can see that the fastest vibration the VR system can detect is 500Hz, so VR is useless above 1/500th of a second. (!)

Think about that for a moment.

If the fast vibrations he is concerned about actually happened in real life (they don't, at least not to any extent we need consider here) you could hear them. 500Hz is the B above middle C - that's right in the sweet spot for human hearing. If your lens is vibrating at 500Hz (or any other frequency between about 100Hz and about 10kHz) you will know about it. It will be thrumming like a power line in a hurricane. (Or indeed, like a piano string when you hit a key.)

Thom's argument is palpable nonsense.

The motions we need be concerned about occur at much lower frequencies: we are talking tens of cycles at most. For these frequencies, Nikon's sampling frequency of 1kHz is not just enough, it is verging on overkill. This is exactly what we would expect of a quality manufacturer like Nikon: their system uses a sampling frequency more than an order of magnitude greater than the expected frequency of vibration.

However, all this discussion of frequencies is a red herring. It isn't the frequency of a vibration we are concerned with here in any case. Primarily, we are concerned with the angular velocity of the end of the lens relative to the focal plane. (There are other motions as well, although these are generally much less important. The best macro lens IS systems, as an example, also compensate for changes in the distance between focal plane and subject. Obviously, given that the maximum distance is likely to be only a few millimetres even hand-held, this is only significant where the subject is very small and very close.) Because long lenses have a small angular field of view, small angular velocities at the end of the lens have a disproportionately high impact on image sharpness, even at high shutter speeds. This is why IS is so useful.





Another way of looking at this question is to simply ask the experts - the people who designed and built the lens in the first place.


Canon does not quote the sampling frequency for its Image Stabilizer mechanisms. Also, Canon does not recommend users to avoid using IS at fast shutter speeds. The visual effects of IS in captured images diminish as the shutter speed increases over 1/focal length, but the use of IS for moving subjects in these conditions can be beneficial because it presents a steadier image to the camera's AF detection mechanism.

Finally, note that the latest and best IS systems now offer Mode 3 IS, which disposes of the one remaining really good reason to consider not using it. (Presumably Nikon are doing this too by now, doubtless under a different trade name.) Mode 3 IS does not stabilise the image in the viewfinder until immediately before the shutter activates. This allows direct visual feedback, meaning that the photographer is able to see exactly how still she is holding the lens and make adjustments to steady it. The IS system thus has less work to do, and the result is a better picture. It also makes tracking of a fast-moving object (think birds in flight) much easier and more accurate. Mode 3 IS is the next best thing to magic. I am regularly amazed at the results it delivers. From memory, it was introduced with the Mark II super-teles a few years ago and seems to be making its way into various other new models progressively.

[swifty]

Thanks Tony.
I must admit I only use VR when my shutter speeds become marginal and leave it off at higher shutter speeds. This is something I picked up (possibly from Thom's article, I can't remember) and never questioned it as VR isn't something I've really looked at in great detail.
Even as I linked the above article, I only skimmed it picking up take some take home points rather than try to analyze the reasoning.

However re-reading the article, is it the frequency of vibration that he's talking about? I thought it was just the frequency at which the angular velocity VR sensors sample the motion that needs to be compensated.

Please correct me if I'm wrong but from my layman's way of thinking, there must be cycle of movement sampling followed by processing by a CPU of some sort followed by compensation of said movement. And there must be a time lag for the entire cycle to be accomplished. Is this not what is referred to as the sampling frequency of 1000Hz, ie. it will do this 1000x every second.

So if the shutter speed is much lower than this sampling rate, in the time the shutter is opened the VR unit has the chance to sample and compensate many times.
But if the shutter speed is much higher than the sampling rate, then in the time that the shutter is opened, at what point during the VR cycle did the exposure occur? It could be such that detection has occurred but not the corresponding compensation?

However does it even matter if we're talking very high shutter speeds eg. 1/8000, since exposure times could be short enough such that no movement manifests regardless of when during the VR cycle the exposure occurred.

Lastly, FWIW VR when active does produce a very quiet hum. Detectable to the extent that you know it's active even if you're not looking through the viewfinder.

[Mark L]

Welcome to the forum Piffdog.
If the subject is moving I'd simply try using more AF points than just the center one. And try Al Servo as your AF Mode.

Just in case you missed this simple advise that might help Piffdog.
Of cause you've lost interest by now.:rolleyes: