View Full Version : Focusing question


Hans Sandstrom
December 2nd, 2011, 03:59 PM
I'm struggling with my 600D trying to learn to handle it. After three years with Canon HV30 I miss the autofocus...
My question is more about how autofocus works — does it measure the average distance to what I see in the viewfinder or...? If so, it must mean that everything is out of focus, more or less.

Please share your wisdom

Hans S

Murray Christian
December 2nd, 2011, 04:33 PM
The 60d (and most dslrs I think) uses phase detection for focus, which judges the image on the sensor in clever ways against a copy from a slightly different angle.
Autofocus - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Auto_focus#Phase_detection)
So when two points in the given ..er focus point match, that is in focus. You could probably triangulate distance from this system, vaguely, but I don't think it does (since it wouldn't be very accurate, depending on the lens and so forth) . Hence you can get that hunting of autofocus in low light or low contrast situations.

The HV30 has an infrared rangefinder, like a lot of video cameras, and may use a hybrid of the two (I can't find my manual right at the minute).

Hans Sandstrom
December 2nd, 2011, 05:38 PM
Thanks, this is more complicated than I expected and, according to the link, very close to rocket science.

My main problem with manual focusing is the short distance between focus and unfocus — feels like a fraction of a millemeter. Does a follow-focus use a "gear-box" to handle this?

Jon Fairhurst
December 2nd, 2011, 06:56 PM
The best way to get sharp focus in Live View is to zoom in by 10x before recording and set your focus point. If the actor will move to a second location, do this twice and mark the two positions on the lens or follow focus. Then, when you do the take, you can really nail the focus. Focus on the eyes.

For live work, use a loupe or monitor and stop down the lens to f/4 or tighter. This will increase the depth of field and make it easier to hit focus.

Another method is to go with a fast, wide-open lens and embrace the feeling of being in and out of focus. Rather than focus with the lens, you can focus handheld shots by moving your feet.

Murray Christian
December 3rd, 2011, 11:03 AM
Thanks, this is more complicated than I expected and, according to the link, very close to rocket science.

My main problem with manual focusing is the short distance between focus and unfocus — feels like a fraction of a millemeter. Does a follow-focus use a "gear-box" to handle this?

How fine that is depends on the usual stuff; brand and model of lens, focal length, aperture. But you can end up with very fine adjustments necessary in a lot of situations. Some are better than others, but it's also that using photography equipment for video isn't always the neatest fit in terms of usability (eg: if you went to "video school" like me you might have been taught that a good way to focus is to zoom in on the subject, focus and zoom back out to the frame you want. What they didn't mention was that this is a design feature, not an intrinsic property of optics, and a lot of cheaper photography gear doesn't keep focus very well when zooming in and out --- edit: I should make clear this has nothing to do with Jon's advice, merely my schooling not including a certain breadth of information). But it's all about the picture and if you've got to stand on your head to get the best resolution and operate focus with your teeth we probably will.

Anyway, can't say I've ever seen a gearbox sort of system (and I shudder to think what it'd cost. Better off making it yourself out of Technic Lego, I'd say). Mostly you swap to a different ratio'd drive wheel though, I think.
Just the difference in changing the axis of movement helps a lot in fine adjustments though. Also if focus is so critical it becomes impossible to keep the subject in for any length of time, generally people just change the shot. So it depends what you're doing.

Hans Sandstrom
December 3rd, 2011, 11:07 AM
Thank you both — I suddenly realize how much I have to learn before actually using my DSLR.
Or I can switch to my iPhone again...

vimeo.com/29743254

Hans

David Knaggs
December 3rd, 2011, 04:53 PM
I suddenly realize how much I have to learn before actually using my DSLR.


Hi Hans.
I don't know if you're a member of Lynda.com or not but, if you are, they've got a brand new set of tutorials called "Shooting with the Canon Rebel T3i (600D and Kiss X5)" and he covers some good points about using the autofocus.

I come from a 100% video background (I was never interested in taking still pictures, only motion pictures) and have always focused by turning on the peaking, zooming all the way in, setting focus and then zooming back out to my desired framing. Like Murray, I'm unsure whether the cheaper stock lens can really hold the same focus while zooming in and out and so I studied the autofocus tutorials (on Lynda.com) with great interest last week.

Basically, the camera has a number of automatic focus points spread around its field of view. By default, it automatically tries to identify which one of those points is sitting on your subject. There is a way to override that automatic mechanism, in case the camera has chosen the wrong point, by manually choosing the focus point yourself.

I chose the center focus point when I did some executive portraits last week (stills) and the auto-focus worked great. I took shots of each person in front of two different backgrounds (each with its own lighting set-up). I took portraits of 30 people in about 3 hours (I'll spare you the long backstory of how this circumstance came about). With the two different set-ups, that meant I had to focus 60 times during that period and achieved a good focus every single time.

The simple method I used was to slide the button on the lens barrel to AF, frame my subject, tilt slightly to get my centre point in the subject's face, half-press the shutter button until focus was achieved, slide the button to MF (manual focus), re-tilt to my proper frame and then take my shots.

This was with a Rebel T3i (the same model as your 600D) and this focusing method worked so well (and fast!) for stills that I'm pondering using it with the video mode on the T3i.

But bear in mind that I am probably the least experienced person on this board when it comes to DSLRs. Those portraits were the first time I'd tried to use a DSLR for stills, so you can take what I say with a large grain of salt, if you wish.

Hans Sandstrom
December 4th, 2011, 07:05 AM
Hi David,

First I have to correct you — I am the least experienced person in this forum when it comes to DSLRs :-)

Thanks for your tutorial. I used the same way as you when shooting in manual mode on my HV30 trying to get a more shallow DOF.
A question — why did you leave AF-mode when taking those stills? Couldn't this be done staying in AF all the way?

Hans Sandstrom
December 4th, 2011, 07:42 AM
Sorry, I ment MF.

R Geoff Baker
December 4th, 2011, 09:18 AM
This is not an answer to your question Hans, but a comment on the video you linked:

Your iPhone video demonstrates an often overlooked fact -- skill trumps equipment most any day of the week.

I hope you get comfortable with the expanded options the DSLR will give you, and I look forward to watching more of your work.

Cheers,
GB

David Knaggs
December 5th, 2011, 03:40 PM
Hi Hans.

We may have to call it a draw on being "least knowledgeable" concerning DSLRs. Although, coming from a purely video background, I didn't even know what "ISO" meant until two weeks ago!!!

And that was a big reason why I got the T3i (besides its video capabilities). This new breed of larger-sensor cameras around the $10,000 to $15,000 range (F3, C300, Scarlet) really demand a very solid grounding in the principles of stills photography, I think. Especially when it comes to the selection and purchase of lenses. So I've probably been using the T3i more for stills than video at this point, while studying the various Lynda.com tutorials (they've also got some great tutorials by Douglas Kirkland, the noted celebrity portrait photographer) and an excellent textbook recommended to me by a veteran DP.

As to your question, which I take to mean, "Why did you leave MF-mode when taking those stills? Couldn't this be done staying in MF all the way?"

Two reasons: 1) The large volume of people to photograph in such a short time left me with only 2 or 3 minutes to get the shots in each set-up. So focusing had to be really quick and certain. But I would always slide it back to MF immediately after focus was achieved, so that I could then take the actual shots smoothly and quickly.
2) I'm only using the stock lens on the T3i and so I'm not entirely sure whether it holds the same focus when you zoom in and out (I'm not quite sure if that's what's meant by the term "breathing"). I trust my fixed lens (to maintain focus after zooming back out) on the PMW-EX1R when I'm shooting video. Not so sure, until I get more knowledgeable, with the T3i stock lens.

But the good news is that the AF works great, so long as you manually select a single focus point for the AF to use beforehand.

Hans Sandstrom
December 5th, 2011, 04:29 PM
Hi David,

Ha, so you know what ISO means - I don't have a clue...

Besides the stock lens, 18-55, I only have one lens - Tamron 10-24. Today I went to try the Tamron for the first time but, when arriving to my location, I had forgotten to bring it with me. So I ended up recording some 200 people with torches (it was a demonstration) downtown Stockholm using the stock lens. This was at 3 pm meaning that it was dark outside.

I shot everything in full automatic mode (with Quick focus mode) and am very impressed by the result. But so far I have only seen the footage in the viewer of the 600D.

When focusing I only used the center point of the nine available and then framed the scene as I wanted it. This seems to me to be the quickest way of focusing as you don't have to change focus point for every clip.

Jon Fairhurst
December 5th, 2011, 05:33 PM
I recommend avoiding auto mode for a number of reasons, such as avoiding stuttering video, avoiding mid-scene exposure changes, and in getting the intended colors. Also, when filming similar scenes, you don't want inconsistency on different takes.

The settings you want are:
* Shutter: 1/50 (almost always. The exception is when you want a stutter effect.)
* ISO: 100 or 160 in the day; 640 or 1250 when the light is low
* Aperture: set as needed to get the right exposure. (If you want shallow depth of field when it's bright, you will need to use an ND filter. A 0.9 provides three stops and is good for bright days.)
* White Balance: Simply select sunny, cloudy, tungsten or fluorescent as needed. (For instance, choose sunny or cloudy for sunsets; otherwise, auto will remove the red from the sky!)
* Picture Style: Choose Normal. Set the contrast and sharpness at minimum. Put the saturation at one tick below mid-position.

Regarding setting the exposure, in manual mode, there are two methods. The quick and easy way is to center the exposure indicator. The more accurate way is to look at the histogram and make sure that nothing (or nothing important) is clipping.

You can print this out or make yourself a cheat-sheet for making these settings. Within a couple of days, it will become second nature. It seems daunting when it's all new. Like anything, it's simple after you know it. :)

Hans Sandstrom
December 5th, 2011, 06:32 PM
Are you joking? If I had done that all the torches had burned out before I was ready to shoot...

But you are probably right — I have to be more familiar with the settings so I'll check the Lynda course.

Thanks for the list. I'll try it tomorrow even if I, so far, is quite happy with the quality i've got from the auto mode.

Hans

Greg Fiske
December 6th, 2011, 10:17 AM
Hans,
Depending on your ambitions there are tools that are available to aid with focusing. You can install magic lanter (a camera hack) that provides focus peaking features. What it does is outlines in yellow the areas that are in focus. More expensive options include bigger monitors. The stock monitor on the camera is too small to accurately focus. With a bigger screen you can more reliable rack focus, and the monitors have focus peaking features to assist with focusing. And it just takes practice.

Bruce Foreman
December 6th, 2011, 01:04 PM
Thanks, this is more complicated than I expected and, according to the link, very close to rocket science.

My main problem with manual focusing is the short distance between focus and unfocus — feels like a fraction of a millemeter. Does a follow-focus use a "gear-box" to handle this?

Enough practice handles this. While the focusing ring on most budget EOS lenses doesn't have the same "silky" feel many older lenses used to have, I've had no problem manual focusing with these. It's a matter of doing it enough until you have your "eye" tuned to what you see in the viewfinder or on the LCD.

For still work, in the viewfinder you have two focusing aids, the autofocus "points" light up as you hit "focus" and the big green dot in the lower right of the viewfinder appears when you hit "point of focus". Don't "stare" looking for these things but study the sharpness or lack of on the focusing screen in the viewfinder and just be alert for when those two things "pop".

For video work, pretty much forget autofocus for now. The contrast detection autofocus used in video or live focus mode can be inaccurate or way to slow to "lock" focus.

You can do it much better.

Get an LCD viewfinder loupe with 3x eyepiece so you see a magnified view. In good to fair light you may be able to see "focus" well enough to "just do it". For anything critical use the 5x magnification to "hit it". The 10x function gives you more magnification but 5x may look clearer.

My advice: Quit worrying about how much more complex this has turned out to be. PICK UP THE CAMERA AND PLAY WITH IT at every opportunity. Focus on things around the room, take it out in the backyard and "play" with focus on things near and far.

Take stills to see how you're doing and build your confidence. Keep the ones you like and delete the rest from the computer. then FORMAT THE MEDIA CARD IN THE CAMERA. Keep at it and you'll master it and have fun at the same time.

Many of us had to learn focus this way DECADES before autofocus came along.

Jon Fairhurst
December 6th, 2011, 02:51 PM
Are you joking? If I had done that all the torches had burned out before I was ready to shoot...

Don't be silly. :)

You keep the Neutral picture style loaded at all times. You keep the shutter at 1/50 at all times. You set the ISO and WB ahead of time, based on the general conditions. Same with the ND. Put it on for day shots and take it off at night. The only thing left is the aperture. There's a dial for that so you can do it live without going into any menus. Controlling the aperture takes much less time than taking the camera from the bag, turning on the power, removing the lens cap, starting Live View, and hitting REC.

It only feels like a lot because it's unfamiliar. After a week or two of manual shooting, it will feel very comfortable - especially if you prepare the camera (Picture Style, Shutter) for the expected conditions (WB, ISO, ND.)

HDR timelapse? Now that's another story. I have a 35 point checklist for that. Believe me, when you're going to do hundreds of shutter clicks and sit there for an hour, you want nothing less than perfection.

But for normal video shooting, manual is only about one second slower to start than auto. No checklist needed (after a bit of practice.)

Hans Sandstrom
December 6th, 2011, 05:49 PM
Thank you guys for giving me so much of your time. You really have inspired me to leave the auto mode and try the manual settings. I already feel more comfortable with manual focus and will try the other settings according to your advices.
BTW, I now know more about ISO after watching some videos on Youtube...

Hans

Jon Fairhurst
December 6th, 2011, 08:25 PM
Regarding focusing, one thing to play with is being purposefully out of focus. Here's a video that I shot handheld with a 5D2 and an EF 85/1.8 lens (no stabilization), wide open. I would get the focus close with the lens, then move the focus by moving the camera. In this style, being out of focus is as important as being in focus. (If you try to keep sharp focus 100% of the time, missing focus once looks like a mistake. Miss it a lot and it looks intentional.)

You can get a similar look with a $99 50/1.8 lens on a crop camera. :)

"High and Dry" Radiohead Cover - by Melissa Fairy on Vimeo

Luke Gates
December 7th, 2011, 11:35 PM
My main problem with manual focusing is the short distance between focus and unfocus — feels like a fraction of a millemeter. Does a follow-focus use a "gear-box" to handle this?

Hans there are so many elements that affect focus, many of which were mentioned on here. But what I think your problem is, you need to experience a k/m/a series pentax! What will an older pentax do for you? It will turn that fraction of a millimeter into a centimeter. They have perfect "dampening" I think the word is where the focus ring is firm or solid but not too tight/sticky/etc., More importantly the focus ring has a LOT more travel if thats the right word. Basically the ratio how much the focus ring has to be turned to how much the focus moves forward or backward is drastically different, in the direction you would like. Either way its great! I'm sure there are countless other non pentax lenses with similar dampening, I just personally love the pentax lenses so I use them as an example

Hans Sandstrom
December 25th, 2011, 03:21 PM
Hi guys,
The other night I took my 600D (T3i) to shot some video downtown Stockholm. I just wanted to test how good the autosettings worked. So I used autofocus (quick-mode) and all other settings in auto. My lenses are Tamron 10-24 and 18-270 (first time I used them). All clips are shot hand-held.

My question now - is it possible to get a better result in manual mode? I can see that some clips are very grainy, others are out of focus. Maybe I'll try to do it all over again - this time in manual mode :-)

Happy for your thoughts...

Hans


Stockholm City - dan fφre dan on Vimeo

Murray Christian
December 26th, 2011, 09:48 AM
If you had everything in Auto I guess the ISO is auto as well. That's the source of your graininess. Unfortunately there's not a lot to be done about it in many of those situations. Those two lenses appear to be both f/3.5 at their widest (if my googling serves me). Probably fine lenses. But they're going to have a tough time in a lot of artificial lighting conditions. You'd want much faster options if you want to do a lot of that sort of thing. Although even the "standard" f/2.8 a lot of lens lines aim for struggles a bit.
The Canon 50mm 1.8 is nice and cheap. Limits your shot options a bit, but the light is like night and day, so to speak.

Hans Sandstrom
December 26th, 2011, 12:40 PM
Murray,

Yes, ISO was set to automatic (I should have checked all values but I didn't).
I checked the Canon 50 mm and it is very cheap (best price on Amazon). Maybe I'll buy one when going to Hongkong in February.

So my next mission is to go out again and shoot in manual mode and use the skill I have achieved after following your advices. This time I'll take notes on all settings...

I'll keep you informed.

Hans

Murray Christian
December 26th, 2011, 01:06 PM
Good luck. I think you'll do fine. Just keep in mind it is actually as tough as it seems, it's not just you ;)

There are easier lenses to operate than that one too. I usually start at the bottom thanks to people I talk to often being tired of hearing "Want to do XYZ? Get more lenses."

Reuben Miller
December 28th, 2011, 02:34 PM
Hans you need to experience a k/m/a series pentax! What will an older pentax do for you? It will turn that fraction of a millimeter into a centimeter. They have perfect "dampening" I think the word is where the focus ring is firm or solid but not too tight/sticky/etc., More importantly the focus ring has a LOT more travel if thats the right word. Basically the ratio how much the focus ring has to be turned to how much the focus moves forward or backward is drastically different, in the direction you would like. Either way its great! I'm sure there are countless other non pentax lenses with similar dampening, I just personally love the pentax lenses so I use them as an example

In my short experience with DSLR to date - I could not agree more! I discovered this after purchasing an adapter just for the heck of it - to see if I could use my late father -in-law's Vivitar 20mm that has a Pentax M mount.

My wife was showing me some of the images he made with that lens from back in the day, and I thought what the heck, If I can make it work I'll have a Trifecta!

• Wife will be ecstatic...
• I'll have a 20mm that is as sharp as a freeking pin...
• Investment will be $14.00 (usd) to bring a fine piece of glass back to life in a new era.

The ratio and feel on the focus ring, is like driving a Lexus vs. a Forklift!

Hans Sandstrom
December 28th, 2011, 04:13 PM
So I went out again to shoot in manual mode. The good thing was that the temperature was around 15 degrees (centigrade) warmer than normal this time of the year. The bad thing was the outcome of the video...

When shooting in auto mode the camera most often uses a very slow shutter speed (down to 8, which can't be done in manual mode, or...?). The clips are always over-exposed compared to when shooting in manual mode.

So my conclusion is that shooting in manual mode is the way to go if you want to have your clips as close to reality as possible. And, after trying a lot, I'm getting more and more familiar with the camera. Just as you guys have tried to explain to me.

This is the video (not very scientific, though...). The password is DVINFO

This is a password protected video on Vimeo

Edward Mendoza
December 30th, 2011, 02:56 PM
Hey Hans...Murray's right. I noticed you're shooting a lot of night shots; you'll definitely need lenses with wider apertures (F/2.0, F/1.8, F/1.4, etc.) to better deal with low light situations. You could continue cranking up your ISO but you'll get granier shots as a result (anything above 1600 and grain will become more evident). And your shutter, for the most part, should always stay the same (unless you were going for some cool moving effect). Shutter should be double your frame rate (24 fps with 1/48 shutter; 30fps with 1/60 shutter; etc.)

Go out and purchase the 50mm F/1.8 II (you can find it now for under $100). Great, cheap starter lens to prove the point. You'll be amazed at the difference! Input your settings manually. Don't let the camera choose for you 'cause it's gonna constantly be adjusting itself to changing settings. The only drawback to the faster lens ironically goes back to your original point about focus issues. The wider your aperture, the narrower your field of focus is. Anytime your subject moves back and forth, they will be out of focus.

Oh, the drawbacks!! But with A LOT of practice, you can overcome that issue, like many on this forum have done. You can also tweak your aperture and ISO to better compensate: don't shoot AS wide open with your aperture and crank up your ISO just a bit to let in some more light, therefore your field of focus won't be SO narrow.

Hope this all makes sense. If not, here's a small home video to demonstrate (Canon 60D, 50mm F/1.8, 24fps, ISO 1600 (I believe), shutter 1/50; F/1.8, dimly-lit living room)

50mm 1 8 Test - YouTube (http://www.youtube.com/watch?v=7rzcebj3nlo)

Good luck...