Long lens technique

divamum · July 20, 2009

So here I am with this wonderful new-to-me 200mmL 2.8. Thrilled to have it.

My frustration is that I am really struggling to get consistently sharp shots with it, and can't tell if it's the lens or, more likely, my approach to shooting with that long a focal length.

- I do handhold, but I'm trying to the shutter at 1/300 or greater.
- I do indeed like to shoot wide open a lot, but I'm using a single focus point and aim it where I want.

What's frustrating is that some of them are scary sharp while others aren't, and I just can't figure out why. I'd have said the lens might be soft wide open (despite its reputation), but then it will give me one that's killer sharp at 2.8, which blows that theory out of the water. It seldom hunts to lock on to focus, so my impression while shooting is that I've nailed it.... until I upload them and look at them larger.

I still have a couple of days before my 14 day return is up (I purchased from KEH), so.... time to exclude user error and get my Long Lens Technique figured out. Bring it on

These crops from shots are all SOOC, and have not been adjusted in any way except to crop; the X marks where Canon's software showed me the active focus point was located.

Sharp - f 3.5, 1/400 ISO400

Very NOT sharp - f 2.8 1/500 ISO200

For comparison, a better shot at f2.8 1/500, iso200 (focus point info not so helpful on this one, since on the center focus point, which will mean I focused and then recomposed)

kdog · July 20, 2009

The first one looks like it front-focused on her hair which looks sharp. Also, the tip of her nose looks sharp which is on the same plane as the hair. I'm not sure whether we're looking at crop or not, so can't tell your distance. But if you're close, your DOF is paper thin. For example at 5' away, you DOF with your setup is 1/4". So that's 1/8" toward the front, and 1/8" toward the back. Needless to say if you're not focused exactly where you think you are, you will get a bad shot. To compound the problem, the focus point in your camera is sensitive to a much larger area than the little red squares on your screen. It's entirely plausible that you focused on her hair. There is that one strand of hair passing right near her eye. The other possibility is that either you or she moved away slightly in between when you acquired focus and when you activated the shutter. There are so many things that can go wrong at close range with a fast lens wide-open like that.

What you really need to do is put it on a tripod and do a comprehensive lens test. Even shooting a dollar bill taped to the wall will tell you plenty. The best way is with a vertical target, next to a slanted rule. Some people just aim at a line on a slanted rule, but I personally don't like that. Much better to have a nice big vertical target on the same plane as your sensor to focus on. Then have a slanted rule next to the target so that you can see if the lens is front or rear focusing. If you get repeatable results with a fixed test target using a tripod, then the problem ain't with the gear.

Cheers,
-joel

divamum · July 20, 2009

Thanks so much - really appreciate the response.

In fact, the first one is the sharp example, posted to show that it can nail it; the 2nd one is the really sucky one :cry

Those are crops - here's the original of the first one (again, these were shot raw and have had nothing at all done to them except conversion and "x marks the spot")

If I get chance tonight or tomorrow I'll try to do the dollar bill test. Can you point me to the setup somewhere so I can see how to site the ruler? (I'll google, of course, but if you happen to know where there is one to save me trawling that'd be great too!

) As I said, I suspect that this is user error rather than a lens problem, but it can't hurt to check.

I didn't realise that the focus points were in reality outside their "boxes" so that would explain a lot - thanks for pointing that out.

kdog wrote:

The first one looks like it front-focused on her hair which looks sharp. Also, the tip of her nose looks sharp which is on the same plane as the hair. I'm not sure whether we're looking at crop or not, so can't tell your distance. But if you're close, your DOF is paper thin. For example at 5' away, you DOF with your setup is 1/4". So that's 1/8" toward the front, and 1/8" toward the back. Needless to say if you're not focused exactly where you think you are, you will get a bad shot. To compound the problem, the focus point in your camera is sensitive to a much larger area than the little red squares on your screen. It's entirely plausible that you focused on her hair. There is that one strand of hair passing right near her eye. The other possibility is that either you or she moved away slightly in between when you acquired focus and when you activated the shutter. There are so many things that can go wrong at close range with a fast lens wide-open like that.

What you really need to do is put it on a tripod and do a comprehensive lens test. Even shooting a dollar bill taped to the wall will tell you plenty. The best way is with a vertical target, next to a slanted rule. Some people just aim at a line on a slanted rule, but I personally don't like that. Much better to have a nice big vertical target on the same plane as your sensor to focus on. Then have a slanted rule next to the target so that you can see if the lens is front or rear focusing. If you get repeatable results with a fixed test target using a tripod, then the problem ain't with the gear.

Cheers,
-joel

kdog · July 20, 2009

Darling shots.

On the first, I thought you were complaining about the eyebrow and maybe entire eye not being sharp. Looks a little soft. Yeah, the second is a basket case. Again that's a crop, but is there any portion of the shot that's in focus? Could be motion blur too, especially if you say sneezed while you were taking it.

I made my own focus test device that's a bit elaborate but you can readily see the concept. RAWWorkflow.com has a commercial version of it (I swear they stole my design.

) Scott Quier has a post somewhere where he used a ruler a pen sitting next to each other quite effectively. If you think about the mechanics, there are endless things you can do to test front/back focusing. For examples, arrange three kid's blocks on a table corner-to-corner so they they're all square to the camera, but at different distances from you. Shoot the middle one and see if that's the block that's sharpest.

Here's what my test setup looked like.

BTW, the dollar bill test is easy. No ruler necessary. Just shoot the dollar and see if it's sharp.

That's the test jig I built in the center with a vertical target and slanted rules for reading out the error. I also played with kids blocks, but those are spaced way too far apart for most purposes. And of course there's a tape measure running the length of the table too. I did determine I had some misbehaving equipment and sent it off to Canon who straightened it out.

ziggy53 · July 20, 2009

The Canon EF 200mm, f2.8L USM has a minimum focus distance (MFD) of 4.9' (1.5m). Is it possible that the troublesome shots are either shorter than this distance or at this distance?

I always test lenses for prime focus at at least twice MFD. I often have to manually focus lenses within that distance of twice MFD though MFD. My EF 135mm, f2L USM was particularly problematic about this.

divamum · July 20, 2009

Thanks Joel.

No, that second shot was pretty much a wash all round -no point of focus anywhere. Which I guess leads us to camera shake but... at 1/500? Weird. I know I didn't sneeze...

I'll do some dollar-bill testing tomorrow and see what's going on. Thanks again for the advice and examples - I'll post again in the morning!

divamum · July 20, 2009

ziggy53 wrote:

The Canon EF 200mm, f2.8L USM has a minimum focus distance (MFD) of 4.9' (1.5m). Is it possible that the troublesome shots are either shorter than this distance or at this distance?

I always test lenses for prime focus at at least twice MFD. I often have to manually focus lenses within that distance of twice MFD though MFD. My EF 135mm, f2L USM was particularly problematic about this.

Nope - I was definitely further away than that, probably about 10ft. And I definitely had the focus limiter switched to the correct setting since I had only just discovered it this afternoon (whoops) - in fact, those shots were taken BECAUSE I had just switched it to the closer min foc.distance and wanted to test it. It didn't make a significant difference to the number of keepers, alas, although it did mean I didn't need to walk to the next state to take the shot

angevin1 · July 20, 2009

1/500 may surprise you about its ability to be 0ut 0f focus with camera Shake. The longer the lens, the easier it is to make it 00F~

So take that one out of the equation and do tripod only test with it. Mirror lock-up and timer as well. Crank that DOF via aperture up a bit too and then walk it around from say 9 backing down to 2.8 and see what you get. I am certain it is much more fun to shoot that darling child of yours, but for this test you need very static subjects.

divamum · July 20, 2009

I'm going to try to set it up with a ruler marker of some sort domani, but in the meantime, here are side-by-sides.

Tripod, ~10 feet away, remote release, 430ex on camera. The flash may be a bit of a red herring I suppose, but was really the only lighting option at 11pm; synched at 1/200. ISO100. Centre focus point focused pretty much on GW's chin.

On the left is f8; on the right, f2.8. SOOC raw except to crop and convert to jpg (with no processing adjustments).

So far so good...? I really hope the earlier problems can be attributed to user error, because it's much easier (and more interesting) to teach me how to shoot better than it is to mess about with exchanges and/or repairs....

pathfinder · July 21, 2009

I think your lens looks pretty good, and that one image was probably just a flier.

As Joel mentioned, the DOF at f2.8 with near subjects is razor thin. I prefer to shoot at f4 or 5.6 to be sure I get both eyes or eyes and nose sharp, but f2.8 can look very good if carefully done.

Shutter speed helps, but so does a gentle pressure on the shutter button also.

You dollar bill test suggests the lens is adequate to me.

Tim Kamppinen · July 21, 2009

The original blurry image definitely looks like camera shake or motion blur to me. Look at the edge of her cheek. There's a thin line of ghosting clearly visible there.

divamum · July 21, 2009

Thanks PF and Tim.

pathfinder wrote:

I think your lens looks pretty good, and that one image was probably just a flier. snip Your dollar bill test suggests the lens is adequate to me.

[/quote]

It does seem from all this that it is, as I suspected, "user error" rather than a lens fault. This is good in that it's something in my control, but now I just have to learn how to work with the equipment to get the best from it. When it's good it's so VERY good; unfortunately, my keeper rate with it at the moment is scant, hence why I posted the question (and why I posed it here instead of in "Gear"

)

As Joel mentioned, the DOF at f2.8 with near subjects is razor thin. I prefer to shoot at f4 or 5.6 to be sure I get both eyes or eyes and nose sharp, but f2.8 can look very good if carefully done.

I just need to get better at it! I really love the shallow DOF look (even in portraits - I think a wide open shot melting away into the shoulders is just gorgeous when down well, emphasis on "well"

). And, of course, it's just nice to have the extra light that the wide ap offers.

Shutter speed helps, but so does a gentle pressure on the shutter button also.

I think I'm going to have to concede defeat and use my monopod with this one whenever possible. I really, REALLY prefer to handhold, but obviously I'm just not doing it well enough. Maybe I'll even try a foot-string stabilizer with this one, too... The funny thing is I have a couple of 1/125s shots that are really sharp - I guess that just comes down to how still I managed to stay

In any case, thanks all - I'm still going to see if I can do a more extensive test with text+ruler, but so far it does seem my problems are likely a combination of camera shake from the magnification combined with the shallow depth of field. Also, I can see that focus+recomp isn't successful with this lens, presumably because of the very shallow DOF.

Anybody care to share any other shooting-with-long-lens tips?

Chile Chef · July 21, 2009

divamum wrote:

Thanks Joel.

No, that second shot was pretty much a wash all round -no point of focus anywhere. Which I guess leads us to camera shake but... at 1/500? Weird. I know I didn't sneeze...

I'll do some dollar-bill testing tomorrow and see what's going on. Thanks again for the advice and examples - I'll post again in the morning!

Also try lowering your shutter speed to maybe 90-125 also you might want to pick your arp around 3.0 - 5.6 and you will "should see a lot of difference in the photo's.

Also switch to Raw if your mem stick can take that much data.

thoth · July 21, 2009

Divamum,

Coincidentally, I just picked up an 80-200 and have been reading about handholding techniques myself. I ran across this pdf yesterday. It's not super-detailed but does have a couple non-intuitive suggestions.

kdog · July 21, 2009

divamum wrote:

Anybody care to share any other shooting-with-long-lens tips?

Yeah, here's a good one for reducing motion blur. Shoot in burst mode and always rattle off two or three exposures. The theory is that second and third shots aren't subject to camera motion induced by pressing the shutter. Plus increasing the number of shots gives you better odds all the way of getting a keeper, not only because of motion blur, but subject blinking or changing expression as well. I always shoot bursts in low light for this reason.

Cheers,
-joel

kdog · July 21, 2009

Chile Chef wrote:

Also try lowering your shutter speed to maybe 90-125

Tim Kamppinen · July 21, 2009

Also pull your elbows in tight to your body and sort of roll your shoulders in to make a more stable platform.

thoth · July 21, 2009

Tim Kamppinen wrote:

Also pull your elbows in tight to your body and sort of roll your shoulders in to make a more stable platform.

Actually, the link I posted recommends not pulling your elbows into your body. According to the article, pulling your arms in with a long lens will accentuate motion problems by adding your breathing as a cause of motion. He recommends holding a long lens, with your non-shutter hand, near the end and holding the camera securely to your forehead.

I played with his suggestions last night and did find that I had more trouble with motion blur with my arms tucked in versus out. Your mileage may vary but it's certainly worth consideration.

Qarik · July 21, 2009

Well I would observe one thing..at 200mm your DOF is going to be very shallow wide open...ESPECIALLY if you are so close to the subject. The dollar bill shots look okay..so perhaps you are not using the lens as you might be using it in real world situations. For example if I were doing torso shot at 200mm I would be very reluctant to do it wide open because I know my DOF is razor thin at that point. I guess this is a part of getting to know your lens. For example there might have been a slight delay between the focus and the shutter actutation..if you or your subject was moving at that time and your dof wide open is 1/4 inch then in all likely hood you will get blur. By simply increasing your aperture you can get the dof to be few inches and your issue is no longer an issue.

Tosser · July 21, 2009

Also, if you are shooting at 2.8 from 10' or so and your body moves some (even a half inch or so), your focus will not be spot on even if you hold it still and your subject is still. No one can stand perfectly still.

kdog · July 21, 2009

thoth wrote:

Actually, the link I posted recommends not pulling your elbows into your body. According to the article, pulling your arms in with a long lens will accentuate motion problems by adding your breathing as a cause of motion.

Odd. Doesn't everybody know that you take a half-breath and hold it before pressing the shutter?

I'm a firm believer of arms-tucked-in for long lenses. Stabilizing the camera against your face is also a good idea.

EDIT: Wait a second. I just read the PDF you linked. Step 1 is to SIT ON A STOOL.

The rest of the article appears predicated on that. When you look at the picture of the old crufty dude who wrote the article, you can see why. :rutt

WingsOfLovePhoto · July 21, 2009

As always...cute girl you got there Diva! What I have learned lately especially with my 70-200 is that when at 200mm I usually use f4 though occasionally f2.8 and put up the iso so I can hand hold with shutter at about 250. (my lens is a vr) Focus point on one eye or between eyes.... Much higher it seems to loose something....because you are taking away so much ambient light. I always shoot in shade so I want to have some ambient. With the Nikon iso 800 is most of the time not noisy as long as properly exposed. Don't know about the Canon.... I also often shoot from the ground alot squatting and using my elbow on my knee as a tripod....with all the babies I do anyway! and as you know...practice makes perfect!:D

thoth · July 21, 2009

kdog wrote:

Odd. Doesn't everybody know that you take a half-breath and hold it for a split-second before pressing the shutter?

I'm sure there are many things that everybody knows, such as how to spot an insulting reply, but I doubt breathing techniques are on the mind of every amateur photographer.

Besides, holding your breath for a split second will not necessarily be a benefit unless your lens was relatively motionless at the point in which you took the breath. If the lens was bouncing up and down, due to breathing, prior to pausing then it will continue to be bouncing for a split second afterward. Your split second pause, just was with rifle shooting, stops additional movement caused by breathing. I does not, however, stop movement that's already there.

thoth · July 21, 2009

kdog wrote:

EDIT: Wait a second. I just read the PDF you linked. Step 1 is to SIT ON A STOOL. The rest of the article appears predicated on that. When you look at the picture of the old crufty dude who wrote the article, you can see why. :rutt

...

I'm sure you're right. Sitting on a stool could, in no way, provide a more stable platform than standing. So much for alternative views... bring on the leg irons.

kdog · July 21, 2009

thoth wrote:

...

I'm sure you're right. Sitting on a stool could, in no way, provide a more stable platform than standing. So much for alternative views... bring on the leg irons.

I merely pointed out that the suggestion in your PDF about not pinning your arms to your body is predicated on sitting on a stool, and not standing up. You did not say that when you made the suggestion. And yes, sitting on a stool could very well provide greater stability, as could lying on the ground, or better yet, using a tripod. But we weren't talking about any of those.

Try to not to hurt yourself when you fall off that high horse of yours.

thoth · July 21, 2009

kdog wrote:

Try to not to hurt yourself when you fall off that high horse of yours.

High horse?

kdog wrote:

Odd. Doesn't everybody know that you take a half-breath and hold it for a split-second before pressing the shutter?

High horse?

kdog wrote:

Wait a second. I just read the PDF you linked. Step 1 is to SIT ON A STOOL.

High horse?

Come on now. I offered the OP an alternate viewpoint from an article I had recently read and those were your responses. I'm not derailing this thread anymore with an agrument but would be glad to discuss how completely out of line you are in a private message or with a moderator.

divamum · July 21, 2009

Thanks for all the ideas, folks - keep 'em coming!

I had a chance to use it extensively while out today - got plenty of duff shots, but I'm also starting to understand how to use it... (also why I'm noticing the motion blur problem WAY more with this lens than I have with previous telephotos: my 55-250 had is, and my 70-210 just isn't as sharp a piece of glass this one, so it just wasn't so apparent.)

Mostly, it's clear that there's just a very narrow margin of error which can be either motion blur, OR inaccurate placement of the focus point (for whatever reason, including my moving it slightly "off" when I press the shutter), so I simply have to be very mindful of those things, far more so than with my other lenses which are a bit more forgiving

And I now seriously see why people pay the big bucks for those long lenses with IS

wink

In any case, I managed to hack my acceptable-shot rate up from the 1-in- 30 of this past week to about 1 in 10 so; while there's still a considerable way to go before it reaches an acceptable hit rate (!!!), I think I'm on my way. Practice, practice, practice indeed!! (And I simply MUST get a head for my monopod sorted out - clearly this is no longer a wishlist item, but a necessity.)

In any case, I was rather pleased with this one, taken on a small, spontaneous beach-outing adventure today (and sorry for yet more pictures of my kid - I swear I really DO shoot other subjects, but she's my most available test pilot....

)

f 4.5 1/250 Focus point was just at the bottom of her left eye (at 1:1 it's dead sharp)

kdog · July 21, 2009

thoth wrote:

High horse?

High horse?

High horse?

Come on now. I offered the OP an alternate viewpoint from an article I had recently read and those were your responses.

Why are you so defensive? My comments were directed about the article, and not to you. I was absolutely serious when I said "doesn't everybody know about taking a half-breath before pushing the shutter?". That's like rule #1 in every photography book every written. You think it's out of line for me to question advice that states the exact opposite? True, I try to have some fun with my posts. But my comments were not in any way meant to be derogatory to you and I'm sorry if you misinterpreted them.

I'm not derailing this thread anymore with an agrument but would be glad to discuss how completely out of line you are in a private message or with a moderator.

kdog · July 21, 2009

divamum wrote:

f 4.5 1/250 Focus point was just at the bottom of her left eye (at 1:1 it's dead sharp)

Looks good!

But 1/250s is way too slow. Use a higher ISO and get those shutterspeeds up and I bet you increase that keeper rate significantly.

Cheers,
-joel

divamum · July 21, 2009

kdog wrote:

But 1/250s is way too slow. Use a higher ISO and get those shutterspeeds up

Yeah, I know it was slow - I was actually surprised when I looked at the exif because this one was so killer sharp. Weirdly, it was sharper than some taken at a higher shutter speed, but in those the canon software shows I didn't hit the mark focuswise. Like I say, this lens is an unforgiving beast!! But man, when it's right... yum

Wil Davis · July 21, 2009

This thread reminded me of an article published by J. Phil Arnold by way of diagnosing a focusing problem with an Olympus E10. I had a similar problem with an E20 I used to own, and so I followed his instructions and ended up with a very inexpensive way of checking out the accuracy of the focus of any camera. The setup is very important so the instructions have to be followed to the letter.

Here's the link: http://jphilarnold.com/e10focus/tests.htm

As for the resolving power of the lens; the dollar bill is a good idea, although I've always used a sheet of the New York TImes pinned on the wall - I guess I was worried about an unexpected visit from the Secret Service resulting in my camera gear being confiscated, not to mention a spell in the slammer… :cry

HTH -
- Wil

Long lens technique

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