Re: Kempton Tit pics topic

[htcdude]

OK so a few weeks I posted here:

Kempton Tit pics


Some people kindly suggested trying Shutter Priority mode. I was playing around with this a bit the other day, however if I set my shutter to it's fastest (1/4000) the picture would just be a black square, the more I slowed down the shutter speed the brighter it got, except when I got it to the correct brightness, I was back to my old shutter speed that didn't see fast enough

What can I do??

Thanks,

Nige

[Jonners]

If you are setting your camera's shutter speed to 1/4000, but don't have sufficient light OR don't adjust the ISO much higher, then the image will be very dark, as you have discovered. If your camera automatically sets the shutter speed to 1/125 at f4 (for example), then as the shutter speed increases, the aperture will need to be wider and vice versa. If you've set the shutter speed too fast for the available light, the camera should flash the aperture setting in the viewfinder to let you know that it's as wide as it can go, but the settings are not OK.The only other adjustable factor will be the ISO, as discussed in your other posting. In order to photograph at 1/4000 you would need very good light or a high ISO setting. In poor light you could try using a tripod to minimise any camera shake, (unsupported camera and lens generally will need a shutter speed at least equal to the focal length of the lens, e.g. 400mm lens = 1/400) although even that won't stop nippy little birds like blue tits from moving . Or you could experiment with the ISO levels and see where acceptabilty begins to disappear. Or you wait for the sun to shine . Or see if there is anywhere that is "brighter", even on a dull day. Have a play, even indoors, so that you can see what different settings will work and the effect of changing shutter speeds, apertures, ISO etc. Then you'll might have a better idea of what will be more likely to work when you're out next.

[Lancashire Lad]

On the original thread, you said that you had a shutter speed of 1/125th second, that you had ISO set at 400, and that your camera was in aperture priority mode.
You didn’t say what aperture you had set, so it is difficult to tailor this reply to your specific settings.

However, if you look at the shutter/ISO/aperture info given below, you should see the relationship between each element, and be able to work out what you need to be doing to get sharp photos.

You need to be aware that if you double the shutter speed, (i.e making stay open for half as long), you need to either open up by one stop (for example use f4 instead of f5.6), or double the ISO.

Likewise, if you stop down by one stop (for example using f16 instead of f11) then you would need to halve the shutter speed, (making it stay open twice as long), or double the ISO.

Alternatively, if you double an ISO setting (say from 400 to 800) then you would need to double the shutter speed, (making it stay open half as long), or stop down the aperture by one stop, (for example using f16 instead of f11).

Initially, we need to make an assumption of what aperture you had originally used, so, for the purposes of this, let’s say that you obtained correct exposure, (but not free from blur), with the first row of settings.

All the subsequent settings would give you exactly the same exposure, but would have varying effects regarding subject blur, depth of field, digital noise, etc. etc. on the final image.

Eg: - (Shutter Speed / ISO Setting / Aperture)

1/125 400 f8 = Correct Exposure

1/125 800 f11 = Correct Exposure
1/250 400 f5.6 = Correct Exposure
1/250 800 f8 = Correct Exposure
1/500 400 f4 = Correct Exposure
1/500 800 f5.6 = Correct Exposure
1/1000 800 f4 = Correct Exposure
1/1000 1600 f5.6 = Correct Exposure
1/2000 1600 f4 = Correct Exposure

Hopefully, you can see the sort of options available to you, and how these relationships will hold good when compared with any given “correct exposure” combination.

If you can’t manage to get the shutter speed fast enough by altering the aperture and/or ISO, then unfortunately, there simply isn’t enough light available at the time you are taking the shot.

Regards,
Mike.

[glsammy]

Just to muddy the water a bit. As well as those figures given above you've also got the possibility of exposure compensation you can apply. It's difficult to say as and when but often the camera can be fooled into offer too slow a shutter speed for the given light. Take this shot of mine for example:



Now the shutter speed offered by the camera wasn't that good, because the background to the birds was quite dark. I could see that the bird was being lit by the sun so I applied 2.2/3rds exposure compensation to raise the shutter speed significantly. The initial shot looked too dark, but came back nicely in editing.
The main point is that the only way you'll get all this is to go out in all sorts of conditions and try different settings to see what effects they have. Really there's no right or wrong way.

[htcdude]

Thanks for the replies guys, and thanks for the shutter/aperture/exposure table Lancashire Lad.

I didn't realise I didn't give the aperture before! It was f5.6


I'll have a play around and see what happens.

Thanks again for the tips guys.

Nige

[Lancashire Lad]

Originally Posted by htcdude

....I didn't realise I didn't give the aperture before! It was f5.6....

Ok - using these settings 1/125th 400-ISO f5.6, we can use the same principles as in my post above, to work out what options would have been available to you.

I am assuming that your lens will not open up beyond f5.6 at the 300mm end, but I will add the equivalent settings for f4, just in case.

Note also, that hand holding at 300mm will almost always result in a degree of subject blur with any shutter speed which is longer than 1/250th second.
This is because you simply won't be able to hold the lens steady enough for slower shutter speeds. (Many people say they can, but in truth, if they did comparison tests hand held v. tripod mounted, most of them would see that they are only kidding themselves).

1/125th. 400-ISO f5.6 = Correct exposure (but showing signs of subject movement)

1/250th. 400-ISO f.4 = Correct exposure (but better for reducing subject movement - if your lens can open up to f4 at the 300mm end. Note though, that depth of field will be reduced due to wider aperture)

1/250th. 800-ISO f.5.6 = Correct exposure (also better for reducing subject movement, and probably won't show any noticable digital noise on image).

1/500th. 1600-ISO f5.6 = Correct exposure (better still for reducing subject movement, but probably the highest ISO that you would be wanting to use before digital noise might become evident on large(ish) blow ups of your image).

1/1000th. 3200-ISO f5.6 = Correct exposure (better again for reducing subject movement, but at these sorts of ISO settings, with many DSLR's, digital noise can become a factor on the resulting images - but, if it's that or no image at all, still well worth while trying, as you might just get some good results).

Note that if your lens is at its fastest at f5.6 (at 300mm), the results will be noticably softer than for example when it is used at f8/f11. (But you need better lighting conditions on the day to make the most of this). This is true for most if not all such lenses, and just has to be lived with.

Also, it is a fact of digital photography life, that digital images are to varying degrees, soft, straight out of the camera. Every digital image worth its while, should be tweaked for sharpness (and other factors) by using post camera image editing software such as PaintShopPro, Photoshop, etc. etc.

Most DSLR cameras have in-built sharpening options, which will do a servicable job, but you will have far greater control by setting the in-built sharpness to zero, and doing any necessary sharpening & tweaking once you have the images on computer.

Hope that helps.

Regards,
Mike.

[htcdude]

Thanks Mike,

You assume right, my 75-300mm only goes to f5.6.

I can also only go to ISO1600, I'll try these when I get a chance to get out next.

So if I was to change from f5.6 to say f20, what I then need to modify the ISO/exposure again?

Thanks for your patience with me ,

Nige

[Lancashire Lad]

Originally Posted by htcdude

....So if I was to change from f5.6 to say f20, what I then need to modify the ISO/exposure again?....

Hi, yes you would need to alter the shutter speed and ISO settings accordingly.

However, you are unlikely to be able to use anything like f20, (assuming that you need shutter speeds in excess of 1/250th second and ISO settings of 800 or less) unless the lighting conditions are extremely bright.

Have a look at this interactive online exposure equivalent calculator - The instructions are nigh on useless, but once you get the hang of it you can see every available option at the click of a mouse button. (Don't take any notice of the written lists below the calculator, as they aren't relevant for what we're doing here).

What you need to do is input the three variables ISO / Shutter Speed / f-stop, which you know give a correct exposure.

Depending on what values you have used, the table might now be saying over or under exposed at this stage.

Just keep clicking on different letters in the first column, until the table says "Good Exposure"

At this point you have your baseline from which you can see the effect of altering any one of the ISO / Shutter Speed / f-stop variables.

All you need to do now is adjust each of the three variables up or down, one at a time, to find whatever equivalents to your original three values would still give a good exposure.

If you feel so inclined, you could even create a paper table of all the various options, that you could then carry with you.

Extended Range Exposure Guide

Good luck.

Regards,
Mike.

[Lancashire Lad]

Afterthought: -

If you had selected 1/125th, 400 ISO, and f5.6, you would need to click on letter G to get the table to indicate the baseline "Good Exposure".

Regards,
Mike.

[htcdude]

Thanks again Mike! I'll give that a go and will probably end up printing it out, my memory's not brill

Nige