Beginner Do I need a larger DoF?

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#1
Hi. I am fairly new to DSLR photography and still getting to grips with the settings. I've tried to learn a bit about f numbers. To make this duckling in focus from its beak to the end of its tail, would I need to increase the f number? It was taken with f/8, exposure 1/4000. I set the f number but I think the camera did the rest. It was on Aperture priority. Yellow Duckling.jpg
 
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Simon
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#3
As the shutter speed was fast at 1/4000, you could comfortably go 2 stops slower to 1/1000, which would have allowed an aperture of f16.

When you're using a telephoto lens close to the subject, the depth of field is quite slim.

Have a look using

http://www.dofmaster.com/dofjs.html
 

kestral

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#4
Your ISO was too high. F8 should have been OK.The ISO will have been at about 800 you should have used 200 ISO at F8 -1000th sec.
 
OP
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#5
Thank you for your help. I know I set the aperture myself but I don't think I controlled the iso or shutter speed. Maybe I did though. I think I would be better doing a factory reset and starting again! There's so much to learn. Just as I think I've got something sussed there's something else I don't understand!
 

big soft moose

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Pete
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#6
Your ISO was too high. F8 should have been OK.The ISO will have been at about 800 you should have used 200 ISO at F8 -1000th sec.
I'm sorry but thats utter rubbish , the iso has no bearing on the depth of feild - having a high iso has meant that he had a faster shutter speed for a given apperture but hasn't influenced the Dof at all - and if he wanted more Dof (ie a smaller apperture) for a given shutter speed he would have to increase the iso not decrease it

For the OP, simon had the right of it - you could quite comfortably have had f16 with a shutter speed of 1000/sec , the issue here being that because the duck isnt parallel to the plane of focus - and was presumably travelling across the frame on a diagonal you needed more DoF than you would if it had been parallel to your sensor
 
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Craig
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#7
Good advice from Pete. You are on the right track with your thinking re aperture. Keep your camera on aperture priority for now while you get used to all the varying depths of field. Don't worry about iso for now, leave it on auto. The camera will take care of the shutter speed while you are in Aperture Priority mode which leaves you free to concentrate on depth of field. Good luck.
 
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#8
I'm sorry but thats utter rubbish , the iso has no bearing on the depth of feild - having a high iso has meant that he had a faster shutter speed for a given apperture but hasn't influenced the Dof at all - and if he wanted more Dof (ie a smaller apperture) for a given shutter speed he would have to increase the iso not decrease it

For the OP, simon had the right of it - you could quite comfortably have had f16 with a shutter speed of 1000/sec , the issue here being that because the duck isnt parallel to the plane of focus - and was presumably travelling across the frame on a diagonal you needed more DoF than you would if it had been parallel to your sensor
Well, ISO does have a bearing in that it would allow a smaller aperture for better DoF whilst retaining a high enough shutter speed to freeze motion and expose it correctly...!

To the OP, leave iso on auto for now, and just play with aperture priority. Smaller aperture (higher F no) let's in less light but increases DoF, so the camera will increase exposure time to compensate. Bear in mind that too slow a shutter speed can get blurry - unless you're using a huge telephoto then anything over 1/500th will be fine for a moving duck and you can probably get away with a lot lower, too! As with all animals, make sure the eyes are sharp!
 

big soft moose

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#9
Well, ISO does have a bearing in that it would allow a smaller aperture for better DoF whilst retaining a high enough shutter speed to freeze motion and expose it correctly...!
!
Well yeah - but my point was that the advice Kestral gave was bobbins , lowering the iso to 200 while retaining the F8 apperture and having a slower shutter speed wouldn't have given him any different a dof from the shot he took.

as he had a a shutter of 1/4000, he could comfortably have had a smaller apperture for increased dof without needing to increase his ISO (and decreasing it would definitely not have the way forward)

ie that is in simple terms for a beginner neither the ISO or the shutter speed have a direct bearing on the depth of feild , which is controled by the Apperture (and by lens choice - a shorter lens generally has more dof for a given f stop- but you probably don't need to worry about that here).

However because the speed / iso / aperture triangle controls the exposure, the only way you can have a narrower apperture (and thus greater Dof) thus letting in less light , is to either decrease the shutter speed (giving the light more time to enter) or incrrease the iso - which increases the sensitivity of the sensor meaning that you get the same exposure for less light
 
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Richard
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#10
Thank you for your help. I know I set the aperture myself but I don't think I controlled the iso or shutter speed. Maybe I did though. I think I would be better doing a factory reset and starting again! There's so much to learn. Just as I think I've got something sussed there's something else I don't understand!
Yes, you never stop learning, though the keys to success are not hard to acquire - then it's just practise, read some more, practise, ask questions and read some more, practise etc.

At the heart of it is the Exposure Triangle (lens f/number, shutter speed, ISO) and that needs to be understood and applied to every picture you take. And it's usually a compromise, depending on the subject, the light, the lens you have and the effect you want. The trick is to get the right shot with the best compromise settings on the day. This is a good tutorial by our Pookeyhead http://www.talkphotography.co.uk/th...ure-theory-but-were-afraid-to-ask-101.440126/

On your duckling, sure if you want the whole bird in sharp focus, then you need more depth of field with a higher f/number, and that in turn will mean shutter speed and/or ISO will have to be changed accordingly - that's where the best compromise bit comes in. On the other hand, another way of looking at all the options is to know that the important thing with people/animals/birds is to always get the eyes sharp. That's the key area of interest and you've got that. Furthermore, using shallow depth of field is a good technique for emphasising the main subject, making it stand out from the background, so there's a creative decision to be made there and from that point of view the shot is arguably better as it stands :)
 

kestral

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#11
I'm sorry but thats utter rubbish , the iso has no bearing on the depth of feild - having a high iso has meant that he had a faster shutter speed for a given apperture but hasn't influenced the Dof at all - and if he wanted more Dof (ie a smaller apperture) for a given shutter speed he would have to increase the iso not decrease it

For the OP, simon had the right of it - you could quite comfortably have had f16 with a shutter speed of 1000/sec , the issue here being that because the duck isnt parallel to the plane of focus - and was presumably travelling across the frame on a diagonal you needed more DoF than you would if it had been parallel to your sensor

Staff Edit: Your childish behaviour has been deleted, again
 
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#12
That's just what I've been looking for, cheers (y)

I was having trouble getting greater dof with one of mi images for the TP52. It turned out I was too close to the subject, (@overbez many thanks ) about 12 inches at 55mm. Looking at the link, the difference in dof was only 5mm between f5.6 - f11 at that focal length and distance from the subject........I just couldn't get mi head round why at the time :oops: :$

Cheers
 
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Mike
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#13
Pookeyheads tutorial as mentioned is excellent as a beginner trying to get my head round all the numbers, I strongly suggest you read it!
 
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Paul
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#14
The other option, given you need a wider DOF is to zoom out (either with a zoom to a wider angle or with your feet). If you double your distance to focal point you quadruple the DO (I think!) Only downside is the duck will be half the size in your picture...
 
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