focus issue when recording in bright sun light

[Mark Rosen]

Hi all,
I have a Canon XH A1 and am shooting in 60i mode. I take video of my son's sporting events and I use the instant AF mode. Some times the surroundings are perfect, not to sunny and all my footage looks very sharp. When I take video on more sunny bright days I have noticed my footage is not as sharply focused. I use the same amount of in camera sharpening and a tripod everytime.

I read on page 36 of the Canon manual......

"When recording in bright conditions, the camcorder sets a small aperture value, and the picture may appear blurred. Turn the ND filter on/off according to the screen display"

I always thought having a smaller aperture will keep things in better focus as your depth of field is increased.

Is my camera instant AF simply having a hard time focusing on sunny days?

How does the ND filter help get sharper images?

Also, would it be better to shoot in manual focus mode for shooting sports?

I just thought shooting in instant AF would be better for me because my subject is always moving toward and away from my camera which might make it difficult to manually focus.

Many thanks,

Mark

[Mats Frendahl]

Originally Posted by Mark Rosen

I read on page 36 of the Canon manual......

"When recording in bright conditions, the camcorder sets a small aperture value, and the picture may appear blurred. Turn the ND filter on/off according to the screen display"

I always thought having a smaller aperture will keep things in better focus as your depth of field is increased.

Small f-value = small DOF
Large f-value = larger DOF

ND allows to have smaller f-value on a sunny day - not something you want that to maintain a larger DOF.

(Canon) lenses are known to have pretty lousy sharpness at small f-values. Get the SLR lense 50/1.4 and use it at f1.4 - pretty useless. Most lenses really shine at f4-9. Even the L-graded Canon lenses are pretty bad at 2.8. I haven't tested the 300/2.8L that is reported to be the very best lense Canon make - but on the other hand - it will not fit on the A1 ;) ... And, it's the price of about 1.5x the A1...

I would not go below f3.7 or so unless situtation really demanded it (bad footage is better than none...).

Also note that most zooms cannot hold a constant f-value from wide to tele.

[Richard Vaughan]

I think the original post referred to small aperture not small f-value. The larger the f-value the smaller the aperture, as "f" stands for focal length and the aperture is f/"f value". So f/16 is smaller than f/8 just as one-sixteenth of an inch is smaller than one-eighth of an inch.

On a sunny day the camera will try to set a small aperture, i.e. a large f-value. This can lead to lack of sharpness because of diffraction of the light passing through a small opening. The ND filter will allow the iris to be open a bit wider eliminating the diffraction effect. But this will also decrease the depth of field. So the persons or objects being focused on will be sharper than without the ND filter but the foreground and background will be less sharp.

The question of how sharp a lens is wide open, such as at f/2.8, etc., is not really related to how sharp it is when stopped down, as in response to bright conditions.

[Mats Frendahl]

Originally Posted by Richard Vaughan

I think the original post referred to small aperture not small f-value.

Once we have settled a terminology... a "small aperture value" is not the same as "smaller aperture" as given in the original post.

Originally Posted by Richard Vaughan

On a sunny day the camera will try to set a small aperture, i.e. a large f-value. This can lead to lack of sharpness because of diffraction of the light passing through a small opening.

From my experience with L lenses they are acutally worse at lower f-value than higher (unless you go to 32...). As stated before, they are at the best at 4-9, possibly 11 for some lenses.

Originally Posted by Richard Vaughan

The question of how sharp a lens is wide open, such as at f/2.8, etc., is not really related to how sharp it is when stopped down, as in response to bright conditions.

Exactly, but they do charge for that "2.8" label...

[Peter Ralph]

first a background that is brighter than the subject may cause the AF to focus on the background

second - shooting into the sun will reduce contrast dramatically - a french flag or similar can help with this.

[Mark Rosen]

Thanks for the responses everyone.

I have the Canon 50mm prime f1.4. A great lens but I was a bit dissapointed with how soft my images are at the larger apeture settings.

Now that I think about it I always shoot in tv mode. I might have used a couple a different shutter settings. I used 1/250 and 1/500. For my purposes I need to have as little motion blurr for each frame possible. On sunny days at 1/250 the apeture must be the size of a pin hole. I did not know about the light defraction issue, thanks Richard for that info.

When I shoot with a shutter speed of 1/500 I output this footage to a quicktime file and do not notice anything different about how the video plays as compared to a shutter speed of 1/250. As I said I also like the less blur factor. And at 1/500 the camera will open up the aperture a bit and that is probably why some of my footage looks extra sharp.

Is there anything wrong with using a higher shutter speed to correct my focus issue or is there some advantage of using the ND filter?

Also, when I shoot in TV mode the camera info display does not show what aperture value the camera has selected. Can I get this info in some way?


Mark

[Bill Busby]

Originally Posted by Mark Rosen

Also, when I shoot in TV mode the camera info display does not show what aperture value the camera has selected. Can I get this info in some way?

1st you have to dig into the Customize/Custom Display menu to make that info available. Then use exposure lock (EXP LOCK) mode & the f stop will be displayed.

Bill

[Richard Hunter]

Originally Posted by Mark Rosen

Thanks for the responses everyone.

I have the Canon 50mm prime f1.4. A great lens but I was a bit dissapointed with how soft my images are at the larger apeture settings.

Now that I think about it I always shoot in tv mode. I might have used a couple a different shutter settings. I used 1/250 and 1/500. For my purposes I need to have as little motion blurr for each frame possible. On sunny days at 1/250 the apeture must be the size of a pin hole. I did not know about the light defraction issue, thanks Richard for that info.

When I shoot with a shutter speed of 1/500 I output this footage to a quicktime file and do not notice anything different about how the video plays as compared to a shutter speed of 1/250. As I said I also like the less blur factor. And at 1/500 the camera will open up the aperture a bit and that is probably why some of my footage looks extra sharp.

Is there anything wrong with using a higher shutter speed to correct my focus issue or is there some advantage of using the ND filter?

Also, when I shoot in TV mode the camera info display does not show what aperture value the camera has selected. Can I get this info in some way?


Mark

Hi Mark. It's not really useful to compare lenses and settings between a 35mm camera and an HDV videocam. The size of the sensor makes all the difference.

For still photography, it is normal to expect sharper pictures at small apertures due to the increase in depth of field. For HDV with 1/3" (or smaller) sensors, diffraction of the light causes softening of the image when you close down much beyond f5.6. Therefore it is very important to use the ND filter in bright conditions to avoid having to close the lens down. it seems counter-intuitive if you come from a 35mm photgraphy background, but you willl get sharper pictures by keeping the lens nearer to the fully open setting.

Also, it is not really a good idea to use the shutter speed to adjust the exposure, as different speeds make moving video have a different appearance. In general, slower speeds have more motion blur, higher speeds have more strobing. Normally for 60i shooting, you would just choose 1/60s (or for 24p, choose 1/48s) and you would only change this if you wanted a particular effect, or maybe if you wanted to extract sharper stills from fast moving subjects.

Richard

[Mark Rosen]

Thanks,

I went into my custom menu and the aperture info was already enabled. So pressing the exp. lock button brings up the aperture setting. I just have to remember to unlock. Thanks for that Bill. Supposed to be sunny today, can't wait to go back and shoot under the same conditons to find out what the aperture setting has been all this time. As you said Richard it is probably over f5.6. I will experiment with the ND filter settings.

I am doing analysis of my son's swing and when I shoot slower than 1/250 I start to miss key movements in his swing due to Blur. I am a little unclear just what is strobing at high shutter speeds. When I use shutter speeds as high as 1/500 the video does not seem to exhibit any problem issues that I can see.

Speaking of shutter settings.

Why is it that there are less options for shutter speeds such as 1/120 in TV mode but in M mode it appears?

Do I have to change yet another custom setting to get more shutter speed options in TV mode?

Mark

[Mats Frendahl]

Originally Posted by Richard Hunter

Hi Mark. It's not really useful to compare lenses and settings between a 35mm camera and an HDV videocam. The size of the sensor makes all the difference.

Yes, true, but the lense is still crusial. As Mark points out the 50/1.4 is disappointing at 1.4 - not that that matters for the lense on the A1. In general people are very concerned and amazed to get the high priced 2.8L lenses from Canon (and pay a lot for them) only to find out that they do not meet expectations. I have tested several and they all went back to Canon, that did not complained - prob. a well known "routine" at Canon - many posts on forums also tells the same story.

Originally Posted by Richard Hunter

For still photography, it is normal to expect sharper pictures at small apertures due to the increase in depth of field.

No, not necessarily true. Macro lenses often show perfect sharpness at low f-values

Originally Posted by Richard Hunter

For HDV with 1/3" (or smaller) sensors, diffraction of the light causes softening of the image when you close down much beyond f5.6.

Is this due to sensor size? With the small sensors in Canons non-pro SLRs you get excellent images at 6.3 and above.

Originally Posted by Richard Hunter

but you willl get sharper pictures by keeping the lens nearer to the fully open setting.

I haven't made test but my experience with Canon lenses tells me otherwise, that they are pretty useless at low f-values. And I speak of the L-graded lenses, the same as on the A1.

Originally Posted by Richard Hunter

Normally for 60i shooting, you would just choose 1/60s (or for 24p, choose 1/48s) and you would only change this if you wanted a particular effect, or maybe if you wanted to extract sharper stills from fast moving subjects.
Richard

Yes, 1/50 (PAL Land) is recommended. The other speeds I guess they added for the use of the A1 as an "SLR".

[Mats Frendahl]

Originally Posted by Mark Rosen

I am doing analysis of my son's swing and when I shoot slower than 1/250 I start to miss key movements in his swing due to Blur. I am a little unclear just what is strobing at high shutter speeds. When I use shutter speeds as high as 1/500 the video does not seem to exhibit any problem issues that I can see.

The high speeds in the A1 is prob. there for stills. With "strobing at high shutter speeds" I think RIchard means that you get a jagged movement - often seen at clubs using stroboscope lights on the dance floor. When you have a fairly low fps like 25 fps or 30 fps it is not always best to have crystal clear images, a small amount of motion blur for fast moving objects will get a smooth movement across the 30 (or 25) frames during a second.

[Richard Hunter]

Originally Posted by Mats Frendahl

No, not necessarily true. Macro lenses often show perfect sharpness at low f-values

Yes but only for the parts that are in focus which is what I'm talking about here. If the macro subject has any depth then most of it will be out of focus.

Is this due to sensor size? With the small sensors in Canons non-pro SLRs you get excellent images at 6.3 and above.

It's because of the tiny CCD elements and their very close spacing. Diffraction in the lens due to the small aperture bends the light until small details are smeared across multiple elements. With larger sensors this effect is much reduced and usually unnoticeable.

I haven't made test but my experience with Canon lenses tells me otherwise, that they are pretty useless at low f-values. And I speak of the L-graded lenses, the same as on the A1.

Please go and make your tests! The A1 (also other HDV cams with similar sensors) is definitely not good when you stop it down.

Yes, 1/50 (PAL Land) is recommended. The other speeds I guess they added for the use of the A1 as an "SLR".

I'm not really sure. The XL2 has similar settings, and it does not take still pictures at all. I suppose the other speeds just meet different requirements, like Mark's need to get sharp images with fast action. What I don't get is the Av mode, because with video you would not want the shutter speed to vary uncontrolled while you are shooting, or even from shot to shot. It's possible Canon have just ported their still camera user interface over to video without thinking too much about it.

Richard

[Josh Laronge]

Originally Posted by Mats Frendahl

I haven't made test but my experience with Canon lenses tells me otherwise, that they are pretty useless at low f-values. And I speak of the L-graded lenses, the same as on the A1.

Mats,
No offense but you should make your tests before you speak. There is nothing wrong with L Series lenses including the lens on the A1. I have 8 L series lenses and they are all sharp wide open. Every lens (and this goes for every lens of every brand and type not just Canon L) has it's own sweet spot (usually around the middle of the aperture range) that is it's sharpest point and while that point is sharper than wide open at wide open I still get excellent results.

For you to make the statement in this forum (or anywhere on the net), "In general people are very concerned and amazed to get the high priced 2.8L lenses from Canon (and pay a lot for them) only to find out that they do not meet expectations." is downright irresponsible besides being inaccurate.

If your statement were true then why do the majority of photojournalists use Canon L lenses?

If your statement were true then why aren't there so many posts on this site about how poor the quality of the glass is on Canon camcorders?

Mark came to a place for advice that happens to have a very large community of users of Canon camcorders (if not the largest). His question was one of how-to technique and the answer is not your lens is crappy.

Mark,
One thing to consider if you're shooting outside, is unless the weather is changing a lot (i.e. sun going in an out of clouds) it is very easy to shoot in manual mode. Before the event starts you should be able to set your exposure and forget about it because it won't change. Then with that out of your thoughts you can try manual focusing. As you said that your subject is always moving toward or away from you this should be pretty easy to focus. With some practice, you find it will become second nature to follow focus by just turning your wrist. You could also try one of follow focus adapters that are out there.

--JL

[Jack Walker]

Originally Posted by Mark Rosen

I am doing analysis of my son's swing and when I shoot slower than 1/250 I start to miss key movements in his swing due to Blur. I am a little unclear just what is strobing at high shutter speeds. When I use shutter speeds as high as 1/500 the video does not seem to exhibit any problem issues that I can see.

Speaking of shutter settings.

Why is it that there are less options for shutter speeds such as 1/120 in TV mode but in M mode it appears?

Do I have to change yet another custom setting to get more shutter speed options in TV mode?

Mark

I think the the shutter setting in the Tv mode are the shutter speeds that are good for video, including the slower and faster speeds.

That is, 1/48 is for 24f, 1/60 is for 30f and 60i, 1/100 is for NTSC video shot in a country with 50hz electricity, and the slower speeds are for special effects, as are the faster speeds. I am guessing that the other shutter speeds don't show up to prevent mistakes in general when shooting video.

However, in manual mode, everything goes, one is more likely experimenting or doing some kind of advanced setup, so all the shutter speeds programmed into the camera will be available.

A very high shutter speed, such as 1/5000 can be used to catch very fast action then slow it way down in the NLE. I saw once example of this of a model rocket taking off. Full speed the rocket lit up and was out of the frame in a tiny fraction of a section, never really seen. However, when shot at a very high shutter speed then slowed down on the editor, there was a perfect and clear several second video of the rocket igniting, lifting off and clearing the frame.

If you are are analyzing a swings motion, try some faster shutter speeds and slow the video down in the NLE. I'm pretty sure there will be an optimum shutter speed for the kind of action you are capturing to give you quality slow motion and stop frames.

[Mats Frendahl]

Originally Posted by Richard Hunter

[On shutter speeds] I'm not really sure. The XL2 has similar settings, and it does not take still pictures at all. I suppose the other speeds just meet different requirements, like Mark's need to get sharp images with fast action. What I don't get is the Av mode, because with video you would not want the shutter speed to vary uncontrolled while you are shooting, or even from shot to shot. It's possible Canon have just ported their still camera user interface over to video without thinking too much about it.

Probably. I manage to freeze the pellets load from a shotgun on a skeet range with my SLR at 1/2000 minimum and having the 1/15000(?, IIRC) on the A1 would not give me anything - I wonder if any of the 25 fps will catch the load. During 1/25th the load travels 15 meters about and might be missed entirely - naturally IF caught the 1/50 will make the load a long black line across the frame. Anyhow, when played back the eye would never caught it anyhow - If one really has need of speeds of 1/10000 and below one is prob. shooting some very specific stuff that really cals for quite another setup than what the A1 can supply. Perhaps Canon thought anyone be using the A1 as a high power motor-camera as the 1D can "only" deliver 10 fps... :) Then there would be "use" of the high shutter speeds, but lack of the resolution given by the 1D(s) - well, one cannot ask too much I guess.