Motion blur problem

Hi i recently took some shots of my local waterfall, i used the TV setting on my Canon 450D, i used a zoom lens ( Canon EFS 75- 300mm ), as getting closer isnt an option. The problem is that although i achieved the soft silky water effect, the overall photo was well over exposed, can anyone advise on how to combat this. i have used Canons Zoombrowser program to auto adjust the image but i feel its still a little over exposed and would like to achieve the perfect result `on camera` without having to tweak in a program.

Thanks,

Paul

[chris-p]

Hi Paul, welcome to the forums

It's difficult to suggest things to do without knowing what settings you used. If you used Tv mode, what was the aperture that the camera selected? What was the ISO and what made you choose the shutter speed that you did?

If you're using Tv mode, the shot shouldn't be over exposed unless you're making the shutter speed longer and the camera can't decrease the aperture any more. If thats the case you need to either reduce your ISO or, if thats not possible, reduce the amount of light entering the lens with something like an ND filter.

Thanks Chris for the reply, i have sadly deleted the photo from my camera so the exact settings are unknown, however zoombrowser can tell me the following...

aperture value 45.0 / ISO - 100 / focal length 300mm / white balance- automatic / TV shutter speed 4

You mentioned an ND filter, am i right in guessing that's a Neutral density filter ? Could you please tell me what it does and the benefits of using it..

Thanks again Chris,

Paul

[chris-p]

Wow, f/45?! I didn't realise that lens could go that small. Sure it's 45 not f/4.5?

If you're using Tv mode and making the shutter speed longer, the camera is going to be trying to make the aperture smaller to control the amount of light. Whats happening is that the aperture can't be made any smaller (you should find that the Av number in the viewfinder or on the display screen flashes or goes yellow to indicate that it can't go any further).
The camera will also (depending on settings) try to drop the ISO as far as it can - which it has.

Once all that happens (the lens is closed down as far as it can go and the ISO is at it's lowest setting) there is nothing the camera can do to compensate for you increasing the shutter speed and your pictures will get more and more over exposed.

If you go back to try again what I would do is using manual (M) mode and set the aperture fairly small, say somewhere around f/16-f/22 (f/45 is going to give you all sorts of issues with diffraction). Then set your ISO to its lowest and adjust the shutter speed until you get a correct exposure.
If that shutter speed is long enough to give you the milky effect you're after then great. If not you've only got 2 options. 1 - get an ND (yes Neutral Density) filter, or 2 - wait for it to get darker.

Hi, thanks again Chris, having looked again, its def 45.0, however the problem may be my shutter speed, as you may have seen in `my album` the over exposure may be caused by the 4 second shutter speed i used, i had thought i would have got away with a longer exposure as the scene was a little dark, seems i need to reduce shutter speed until i get it right... One more question if you don`t mind ? Regarding ND filters, i`ve looked and i can see a few variations of ND filters ie ND / ND2 / ND4 etc etc, which one would you recommend ( and whats the difference between ND and ND 2 ?

[chris-p]

I've just had a look at the shot and you're dead right - f/45 it is.

It is quite over exposed. If you're shooting in Tv mode then it can only be the shutter speed as it's the only thing you're selecting. The camera will try to adjust the aperture and ISO to ensure a correct exposure but if you push it outside that range then there is nothing the camera can do to compensate for it.

With regards to NDs they usually come in 2 types, ND grads and solid NDs. The grads are graduated and designed to balance skies with landscapes. The solid NDs are usually screw in filters of a specific density (ND2, ND4 etc) which cut out a specific amount of light.

The numbers refer to the amount of light they block out (or let through depending on which way you look at it).

An ND2 cuts out 50% of the light (or only lets 50% through). It's a decrease of 1 stop
An ND4 cuts our 75% of the light (or only lets 25% through). It's a decrease of 2 stops
An ND8 cuts out 87.5% of the light (or only lets 12.5% through). It's a decrease of 3 stops

There is no "right" ND filter. Most people usually have a set of a 2, 4 and an 8 which means they can work with whatever they need. They can also be stacked to multiply the effect.

Thanks again for all your help Chris, much appreciated, im learning already !!!

Regards,

Paul

[chris-p]

No worries!

[ianpinion]

Hi Paul,

I've had a quick look at your shot and to me the water seems to be flowing quite fast, so in those conditions you would get the nice milky effect in it with a shutter speed of between 1 and 2 seconds. As Chris has already suggested, go back to the falls again and this time put the camera into manual and select a smallish aperture, a low ISO and then using the histogram as your guide adjust the shutter speed until the highlights are just about to be clipped on the far right of it. Now if the shutter speed shown is shorter than 1/15th of a second then you will need an ND filter to reduce the amount of light entering the lens. If it's a longer exposure that 1/15th then you should be alright.

If you take a quick look at my gallery, you will there's a few shots taken of Aysgarth Falls in the Yorkshire Dales. These were taken last November between 4pm and 4:30pm using no filters at all. I took them in full manual mode with a small aperture at ISO 100 and set my shutter speed to about 1.5 seconds, using the Histogram on my Live View as a guide and you'll see that I managed to get the effect you're looking for because the water was moving so fast.

Anyway, have another go and see how you get on this time now that you're armed with this extra knowledge.

[matt wilson]

Canonfreak......I copied your pic into adobe photoshop lightroom.I was surprised actually that there is more detail in the highlights than first appears .There's some areas that have totally blown out that will never be recovered but a fiddle in Canon's software may surprise you .

One other thing to do is shoot in raw ......it gives you far more scope to rescue pics you think have had it .Also bracket the exposures where you can.

Your pic is close to being a good one in terms of the composition just get out and practice.....it is also a good candidate for converting to black and white.