Shutter; how fast for moving objects for sharp pic?

[dsze]

Still testing my new 70-200 f4L; I shot my daughter yesterday on a rope swing and the photo is horrible. It is so blurry that it is useless. I don't think it was the lens. Here were my shot details:

shutter: 1/640
f4
ISO 100
focal length 200.

Sorry, I can't post the photo from here....but just looking at that metadata, was my shutter just too slow for a swinging child coming at me?

thanks,
daniel

[robertwgross]

Suggestion: Crank up your ISO as far as it will go, and then back off one notch. Now see what kind of exposure solution your camera will do in sports mode. The shutter speed should be significantly faster than what you were trying.

Also think about depth of field. If you are shooting your daughter on a rope swing, then either you are on the side or else in front. If you are in front, then she is swinging in and out of the optimal focus, so you have to widen the depth of field significantly (which means smaller aperture, which means slower shutter, which is not what you want). If you are shooting from the side, then she is swinging along a constant plane of focus (which means you can get by with a small aperture, which means a faster shutter, which is what you want).

On the other hand, if you are in front and she is swinging toward you, then her apparent motion blur will be behind her and not so visible, but then you are back into the quandry above.

---Bob Gross---

[boBquincy]

Isn't it true that the fastest shutter speed is actually 1/200? This is shortest time at which the first curtain is fully open before the second curtain starts to close. If so, then any 'faster' shutter speed is really only a 'window' which moves acroos the focal plane, with the window being more narrow as the shuter speed is reduced.

This might cause blurring of an object that is moving quickly towards the camera, as different parts of the image would be exposed at different times (and in varying degrees of focus).

???

boB

[robertwgross]

No, it does not cause blurring.

A focal plane shutter can go to 1/4000 on some cameras. No problem. No blur.

Don't be confused by the maximum sync speed for flash units, which is typically like 1/200. You can go faster than that, but only with a flash unit that supports high speed sync mode.

---Bob Gross---

[dsze]

Hmm? Interesting question. I don't know if the fastest actual shutter speed is 1/200. I certainly would have thought that it was actually the speed that is available.

[dsze]

Yeah, Robert, that is what I would have thought. I know the flash sync with the built in flash on the rebel won't let the shutter go faster than 1/200

[GenEOS]

A good rule of thumb for longer glass is 1/focal length to stop action.
Faster for faster subjects or to help freeze all motion.
In some situations cranking it up to 1/1000 to 1/1600 is possible.
Doing so not only stops action, but keeps camera shake from being an issue.
Depending on the usable max ISO setting of your camera, you can adjust the ISO setting faster to allow faster shutter speeds.
The fastest shutter speed comes into play when using a flash. The fastest shutter speed the flash will sync at is 1/200th. You can shoot at faster shutter speed with a flash in high speed sync mode, but usable distance is decreased for your flash.
The window theory would be true if the subject is moving towards you or away from you fast enough to move out of your focal field in the same time as the exposure. It would have to be moving extremely fast to move out of focus in say, 1/2000th of a second.

[CyberDyneSystems]

1/640th..?

That's pretty fast... but if you double the ISO you can double that shutter speed to 1/1280 or so...

With a 200mm I usually need 1/250th or so to get people in motion.. if they aren't moving to fast that is :)

[GenEOS]

Still testing my new 70-200 f4L; I shot my daughter yesterday on a rope swing and the photo is horrible. It is so blurry that it is useless. I don't think it was the lens. Here were my shot details:

shutter: 1/640
f4
ISO 100
focal length 200.

Sorry, I can't post the photo from here....but just looking at that metadata, was my shutter just too slow for a swinging child coming at me?

thanks,
daniel
I would also check where the focus point was in the shot. This could be a case of the focus point not being the child, but somewhere else in the image.

[robertwgross]

A few weeks ago, a helicopter flew overhead, and I shot a photo using a 200mm lens. At 1/400 shutter, the main rotor was blurred. At 1/4000 shutter, it seemed to be frozen perfectly. But I had to crank up the ISO high to get an exposure solution, even in bright sunlight. It was far enough away that there was no depth of field issue, so I could shoot wide open.

---Bob Gross---

[dsze]

Well, I its not an AF point problem. That is right where I intended it to be.

Is there a way to post photos on here...or do I have to provide a link to another website?

[Biko]

You need to upload pic to webspace then use insert image tags. You can use alt and p to insert them. the last one has to have a / in it.

[boBquincy]

After some further research, it appears the *actual* shutter speed is pretty close to the flash sync speed. This is the fastest speed at which both shutter curtains are fully open, & the fastest speed at which the curtains travel across the focal plane.

The *effective* shutter speed is faster when the slit is narrower, up to 1/4000 and less. At fast shutter speeds each pixel gets only the selected time for exposure, but the *total* exposure time still takes about 1/200 second.

High speed sync flashes fire a burst of rapid pulses to allow each burst to expose a different area of the sensor as the curtain slit travels across (or down in some cases) the focal plane.

I would have to agree that the object would have to be moving towards the camera pretty quickly to affect the focus so the shutter speed is probably not the cause in this case.


boB

[dsze]

not being able to upload the photo here. With the AF in the right spot, the shutter at what seems fast enough....I guess I have only to blame the new lens?

The other thought is that the DOF being set at f4 was just too shallow and she swung out of the DOF by the time I fully depressed the shutter release?

[GenEOS]

not being able to upload the photo here. With the AF in the right spot, the shutter at what seems fast enough....I guess I have only to blame the new lens?

The other thought is that the DOF being set at f4 was just too shallow and she swung out of the DOF by the time I fully depressed the shutter release?

What probably did it was the lapse of time from your brain telling your finger to shoot and the shutter lag combined. It may have appeared in focus, but the actual shot was off.
You can put a link here to were you have the image posted.

[dsze]

GenEOS, Are you trying to say that my brain is too slow? :D

In thinking about the shot more, I may have half-way depressed the button to auto-focus and then fully depressed the button later, when she was swinging closer to me and now longer in focus.

[Tom W]

not being able to upload the photo here. With the AF in the right spot, the shutter at what seems fast enough....I guess I have only to blame the new lens?

The other thought is that the DOF being set at f4 was just too shallow and she swung out of the DOF by the time I fully depressed the shutter release?

That would be my guess based on what I've read. I'm not familiar with the 300D - does it offer "A1 Servo" mode so that the auto focus can track moving objects? If so, use it.

If that isn't an option, you'll have to get a deeper DOF (using a smaller aperture) and remember to minimize the time lag between focus and shutter.

Another alternative would be to switch to manual focus and prefocus on a spot in the swing's travel - then release the trigger as she passes through that focus plane.

[GenEOS]

GenEOS, Are you trying to say that my brain is too slow? :D

Not at all!
:oops:
Have you tried the AI focus, it may help track when the sbject is moving like that..

[scottbergerphoto]

The f/4 is most likely causing the blur, not the shutter speed. That lens at f/4 has a very small dof. If you were standing 10 feet away, the dof would have been about 3 inches. As already mentioned, kick up your ISO. I use ISO 400 and AI Servo in good lighting to track small radio controlled planes. I usually get shutter speeds of 1/1000-1/2000 sec.
Scott

[robertwgross]

I use ISO 400 and AI Servo in good lighting to track small radio controlled planes.


You probably have a ruler mounted on the bottom of one of those, to improve your focus.

---Bob Gross---

[blackviolet]

i s'pose it's sorta off dsze's original topic... anyway, there are 2 components to a mechanical shutter
- mirror movement + iris 'constricting'. this is the mechanical 'slap/click' bit that is felt when you depress the shutter release. it's also why mirror lockup is useful - to prevent magnified vibrations. on some of my older slr's, the mechanical action took as long as 1/60th of a second (or longer on some). i believe on my 10d and 300d, it's around 1/200th or so. remember the old pinhole/box cameras where the photographer would take off the lenscap, and then walk back and put it back on a few seconds later. oops - major digression....


- curtains moving over film/sensor to obscure light from entering the exposed sensitive area. it's kinda like the lightbar on a copy machine when it goes over a document. only instead, it's a little window that slides across to let light in very quickly. on the 10d, i can set the shutter to 1/4000. this means as the curtains travel across, any one area of the sensor receives only 1/4000 sec of light. if you were taking a photo of a very fast object, it could move between the time one side of the sensor was exposed and the other - leaving not a blurry image, but an askew one.

there are also electronic shutters which electronically cut off the signal after 1/x second (well... cutoff processing the signal), but we won't go into that.


i don't, however think this was dsze's problem. i'm guessing it may have had to do with area of focus and the object (girl on swing) leaving the area of focus. we'd have to see a photo, though.

[scottbergerphoto]

I use ISO 400 and AI Servo in good lighting to track small radio controlled planes.


You probably have a ruler mounted on the bottom of one of those, to improve your focus.

---Bob Gross---
Not a bad idea Bob!. I'll see if the owners will give it a go. Copies to Measurebaters Anonymous.
Scott

[Phil Hall]

I had a similar problem with my grand daughters a couple of years ago. Your speed is ok. The problem is the focus time, if the swing is moving towards or away from you. You can shoot from the side or use manual focus and select a point in the swing to take the picture.

[Mike H]

Phil has the answer, I think.

Try this: focus where she is at the highest point of motion, either when she gets all the way back, or when she is all the way forward. At each of those points there will be a momentary halt to her motion, and that's where your best chance to catch her is, both from the standpoint of your reaction time and how fast the required shutter speed will be.

Your depth-of-field will be very shallow, so this is going to be tough. Try is several times. Also, remember to switch the lens to manual focus when you are focused on the right point so it won't hunt when you try to fire.

I would try a slower shutter speed (say 1/350th) and higher ISO to minimize your aperture setting (and thereby maximize your zone of focus).

Just so you don't get discouraged, and so you know how good this lens is, turn the ISO and shutter speed down for a few shots, and take a portrait with the lens wide open of her sitting on the swing motionless. The background will be blurred, and if you make the shot nice and tight, you'll get a portrait that will make you less unhappy about not getting the action shot you want. This will especially work well if you shoot late in the afternoon when the light is softer and warmer.

I hope this helps. Good luck.

Mike

[LEC_D30]

http://www.pbase.com/lec_d30/galleries

Click on the picture when you get to the site...

All with a 300D and a lot cheaper lens than the 70-200 F4L

Regards,


lec_EOS

[RichardtheSane]

Just as an example, I have photo's of my lurcher when he's running shot at 1/640th of a second and they are sharp @ 400mm.

I would say that those who are suggessting it is a focus issue are bang on there :) because I am sure your shutter speed is quick enough :)