Creating a blurred Background

dowheim

dowheim

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Richard
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Hi All,

I have only been doing Wildlife Photography for about a week now but I have taken a week a week off of work to do nothing but.

I am having problems with creating a blurred background on my images. Are there any other factors aside from Aperture number that effect the background?

I have a Fuji S8000FD which is an "SLR Type" camera without interchangable lenses. If you completely zoom out you can have an aperture down to 2.8, if you zoom in the best you can get is 4.5.

Out of all the shots ive taken so far I have only got one that has a background that has blurred out any where near the level that im looking for. What baffles me is this particular photo (Of a robin from about 8-9 Feet) was taken with a 6.3 aperture and a 1/320 exposure time. I thought the lower the aperture number the better the background blur? I took some photos of Deer in a National Trust park yesterday, using a 4.5 Aperture and 1/800 - 1/1000 exposure times and the backgrounds are completely in focus which has ruined all of the photos I took that day.

Are there any other factors I should be considering when looking for a blurred background?

Is there something Im doing wrong or need to be doing differently?

My photos are on Flickr at the moment so feel free to have a look if you would like to see some examples. I am only actually happy with about 2 photos on there which is a shame!

http://www.flickr.com/photos/richarddowlingwildlifephotography/
 
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The distance from your subject to the background also makes a massive difference as well which may be your problem.

But, being honest the only real way to do this is to buy an SLR. You're right in that the aperture is the biggest thing affecting this, but the sensor size of the camera also has a massive affect, basically the bigger the sensor the more blurred the background for a given aperture (everything else being equal) so the larger sensor sizes in SLRs really come into play here
 
Get the subject as close to you as possible.
Get the background as far away as possible.
Use the longest focal length you can.
Use the widest aperture you can.

You can see the distances that will be in sharp focus using the tables at
http://www.dofmaster.com/doftable.html. This doesn't really tell you how out of focus something will be but it should give you an idea.

Basically, get in close but using a long lens wide open with a good bit of space between the subject and background.
 
Three things (primarily) control the depth of field (smaller DoF will give you more background blur):

1. Aperture - Larger aperture will give you a shorter DoF
2. Distance to subject - The closer you are to the subject, shorter will be the DoF
3. Focal length - Longer focal length will give you smaller DoF

A fourth factor is the sensor size. Larger sensors in DLSRs will give you a shallower DoF. A full frame sensor (5D/1D/D700/D3) will give you the maximum b/g blur compared to smaller APS-H or APS-C sensors, assuming all other factors (FL, distance and Av) are equal.

On your camera, probably the easiest way to maximise background blur is to use longer focal lengths - so make sure you are fully zoomed in (18x or as high as you can go) whenever possible and get as close to the subject as possible.

If you have a choice between using a higher FL or getting closer to the subject and using a shorter zoom setting, choose the former - I suspect you might get a shorter DoF that way. Best to try it out yourself :thumbs:
 
I'm probably being pedantic but the sensor doesn't of itself affect the blurriness. A 50mm lens is a 50mm lens whatever camera you attach it to.
The effect of the sensor is that whereas on a crop sensor camera you might use a 50mm lens to shoot a person and get a whole body shot, if you have a full frame camera you might be able to get the same shot with an 80mm lens which will have a reduced depth of field.
 
hoohaaa said:
I'm probably being pedantic but the sensor doesn't of itself affect the blurriness. A 50mm lens is a 50mm lens whatever camera you attach it to.
The effect of the sensor is that whereas on a crop sensor camera you might use a 50mm lens to shoot a person and get a whole body shot, if you have a full frame camera you might be able to get the same shot with an 80mm lens which will have a reduced depth of field.
Click to expand...

Errr, oh yes it does! I get a shallower DOF if I attach my 50mm lens to my 5D ("Full Frame") than I do if I attach the same lens to my 40D (1.6 crop).
 
hoohaaa said:
I'm probably being pedantic but the sensor doesn't of itself affect the blurriness. A 50mm lens is a 50mm lens whatever camera you attach it to.
The effect of the sensor is that whereas on a crop sensor camera you might use a 50mm lens to shoot a person and get a whole body shot, if you have a full frame camera you might be able to get the same shot with an 80mm lens which will have a reduced depth of field.
Click to expand...

It does indeed. Have a read here:

http://www.josephjamesphotography.com/equivalence/index.htm

Cheers
 
hoohaaa said:
I'm probably being pedantic but the sensor doesn't of itself affect the blurriness. A 50mm lens is a 50mm lens whatever camera you attach it to.
The effect of the sensor is that whereas on a crop sensor camera you might use a 50mm lens to shoot a person and get a whole body shot, if you have a full frame camera you might be able to get the same shot with an 80mm lens which will have a reduced depth of field.
Click to expand...

Surely, If focus length does indeed affect DOF, i.e. using a longer focal length and filling the frame with a person's face for example, the background would be more out of focus? Then a crop sensor would indeed affect the way a lens behaves, regarding Bokeh, as well? A 50mm lens for example would be longer on a crop sensor than on a full frame sensor ? I'm sure as hell convinced that my D3s gives me a shallower DOF compared to my D300s, using like for like lenses, and settings. I think i have put that in plain enough English?LOL!!!
 
highpriest said:
Three things (primarily) control the depth of field (smaller DoF will give you more background blur):

1. Aperture - Larger aperture will give you a shorter DoF
2. Distance to subject - The closer you are to the subject, shorter will be the DoF
3. Focal length - Longer focal length will give you smaller DoF

Snip.......
Click to expand...

Add to that the distance between subject & background.

To the OP, your biggest problem is that you have a small sensor, which is making the problem worse. The larger your sensor the smaller the DoF will be.

So, if you are going to shoot birds (not the easiest of subjects - more later) you need to make sure that the background is some distance from their perch, you have zoomed in as much as possible, and your lens is a wide open as it will go.

Birds are not a brilliant subject to start with, whilst they are plentiful, they are small, tend to be easily frightened, and move quite quickly. My bird table is 10 metres from my window and I struggle to fill the frame at 200mm.

Try shooting duck at your local lake/pond to get some practice and sharpen your skills first.

Steve
 
highpriest said:
http://www.josephjamesphotography.com/equivalence/index.htm
Cheers
Click to expand...

That is a very long page and I may have missed the important bit but I don't think so. I've also read some of the other linked pages but I still maintain that my initial assertion was correct. A 50mm lens is a 50mm lens whatever camera it's on. The reason full frame appears to give more DOF is that you can shoot the same image using an 80mm lens which does have less DOF.
 
hoohaaa said:
That is a very long page and I may have missed the important bit but I don't think so. I've also read some of the other linked pages but I still maintain that my initial assertion was correct. A 50mm lens is a 50mm lens whatever camera it's on. The reason full frame appears to give more DOF is that you can shoot the same image using an 80mm lens which does have less DOF.
Click to expand...

you are wrong. (Being a pedant). You're missing that circle of confusion has an affect on DoF and that's affected by sensor size. Between crop and full frame DSLR it actually makes only a little difference and your description of what happens is pretty much correct. (That why I'm being a pedant) However on the small sensor size on P & S and Bridge cameras it makes a massive difference
 
boyfalldown said:
You're missing that circle of confusion has an affect on DoF and that's affected by sensor size.
Click to expand...

Had a quick look at CoC stuff and you might be right about that but for the life of me I can't really see why.

If I build a back box with a hole it and attach a 50mm lens to it fixed at f2.8. I then alternately place in the box (at the same distance from the lens) a full frame sensor, a 1.6 crop sensor, a tiny phone camera sensor and just a piece of card. I think I will get the same image projected onto all of them. The difference is just that with the smaller sensors I'll only be able capture the very center of the image. But with all of them the DOF will be the same. Can anyone explain why this isn't the case.
 
hoohaaa said:
Had a quick look at CoC stuff and you might be right about that but for the life of me I can't really see why.

If I build a back box with a hole it and attach a 50mm lens to it fixed at f2.8. I then alternately place in the box (at the same distance from the lens) a full frame sensor, a 1.6 crop sensor, a tiny phone camera sensor and just a piece of card. I think I will get the same image projected onto all of them. The difference is just that with the smaller sensors I'll only be able capture the very center of the image. But with all of them the DOF will be the same. Can anyone explain why this isn't the case.
Click to expand...

your starting to get into things that this tutorial http://www.cambridgeincolour.com/tutorials/depth-of-field.htm (the first part looks at the affect of CoC and answers just your question) explains better then I can
 
boyfalldown said:
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
Click to expand...

I don't think it contradicts me. It says:
"Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view (see the tutorial on digital camera sensor sizes for more on this topic)."​

I think this is the point, and it's the point I originally tried to make. Sensor size appears to make a difference but it doesn't actually do anything at all.
 
Wahhey Ive started an argument on my first post! ;P

Judging by your comments about getting a shorter DoF when im zoomed all the way in, I can now see that this is one of the things that made the difference now that I have gone back through my photos. The important thing is, its not me using the camera incorrectly.

Having been out to an RSPB reserve this morning Im beginning to realise that I have definitely got what I paid for. The S8000FD is not suited to wildlife Photography becuase it is extremely difficult to fill the frame unless you have got the animal sitting on the end of your nose. I think the solution is to sell the camera and get one that is a bit more suited. I was just testing the water with this camera afterall.

Thanks for your help guys, I should have a slightley better idea of what camera I need to look out for when buying again now.
 
hoohaaa said:
I don't think it contradicts me. It says:
"Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view (see the tutorial on digital camera sensor sizes for more on this topic)."​

I think this is the point, and it's the point I originally tried to make. Sensor size appears to make a difference but it doesn't actually do anything at all.
Click to expand...

But it's relative, and therefore does have an effect. At a given focal length, given aperture and subject distance, you will not get the same depth of field on different sized sensors.

Steve
 
dowheim said:
Hi All,

I have only been doing Wildlife Photography for about a week now but I have taken a week a week off of work to do nothing but.

I am having problems with creating a blurred background on my images. Are there any other factors aside from Aperture number that effect the background?
Click to expand...

Depending on your software you may have a "blur brush" which allows you to selectively blur the background.

.
 
Jelster said:
But it's relative, and therefore does have an effect. At a given focal length, given aperture and subject distance, you will not get the same depth of field on different sized sensors.

Steve
Click to expand...

I don't think so. Surely the point is that at a given focal length, given aperture and subject distance, you will get exactly the same depth of field on different sized sensors.

(The point is that you probably won't use the same focal length on different sized sensors.)
 
dowheim said:
I think the solution is to sell the camera and get one that is a bit more suited.
Click to expand...

Be prepared to spend some money on a decent lens, anything for birding is going to cost much more than you have paid so far.
 
hoohaaa said:
I don't think so. Surely the point is that at a given focal length, given aperture and subject distance, you will get exactly the same depth of field on different sized sensors.

(The point is that you probably won't use the same focal length on different sized sensors.)
Click to expand...

Nope:

F/4, 50mm, @ 10m, DoF =

Crop x 2 = 5.06m
Crop x1.6 = 6.66m
Crop x1.3 = 8.95m
Crop x 1 = 12.37m
 
DemiLion said:
Nope:

F/4, 50mm, @ 10m, DoF =

Crop x 2 = 5.06m
Crop x1.6 = 6.66m
Crop x1.3 = 8.95m
Crop x 1 = 12.37m
Click to expand...

If this is true (and it may be) explain why what I suggested earlier isn't true:

"If I build a back box with a hole it and attach a 50mm lens to it fixed at f2.8. I then alternately place in the box (at the same distance from the lens) a full frame sensor, a 1.6 crop sensor, a tiny phone camera sensor and just a piece of card. I think I will get the same image projected onto all of them. The difference is just that with the smaller sensors I'll only be able capture the very center of the image. But with all of them the DOF will be the same."​
 
You are right in a sense, but in your example, while the dof is the same the effective field of view isn't. For cropped sensors the same field of view would require a smaller FL, smaller FL lenses have greater dof - hence why your example doesn't hold true, it is the effective focal length that counts.
 
Howi said:
For cropped sensors the same field of view would require a smaller FL, smaller FL lenses have greater dof - hence why your example doesn't hold true, it is the effective focal length that counts.
Click to expand...

In my first post on the subject I wrote:

"The effect of the sensor is that whereas on a crop sensor camera you might use a 50mm lens to shoot a person and get a whole body shot, if you have a full frame camera you might be able to get the same shot with an 80mm lens which will have a reduced depth of field."​

So I obviously know that the 'effective' focal length affects DOF. My point is, and I again acknowledge that it is slightly pedantic, is that actual sensor size has no bearing on DOF.

To put it another way, when you say that 'it is effective focal length that counts' all you are really saying is that 'different' focal lengths count. This is quite clearly true.

The only reason I originally pointed this out is the OP was looking for advice about DOF and had been told by 2 people that sensor size affected it. This incorrect statement leads to a misunderstanding and confusion about the role sensor plays and I wanted to correct it. Crop sensors are nothing more than that; cropped sensors. Just sensors that are smaller than full frame sensors. The size of the sensor has no affect on DOF at all. The effect comes when you use a different focal length to achieve the same shot and focal length does affect DOF. But sensor size does not.
 
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hoohaaa said:
The only reason I originally pointed this out is the OP was looking for advice about DOF and had been told by 2 people that sensor size affected it. This incorrect statement leads to a misunderstanding and confusion about the role sensor plays and I wanted to correct it. Crop sensors are nothing more than that; cropped sensors. Just sensors that are smaller than full frame sensors. The size of the sensor has no affect on DOF at all. The effect comes when you use a different focal length to achieve the same shot and focal length does affect DOF. But sensor size does not.
Click to expand...

But the effective focal length is so important, especially when using a bridge camera with a much smaller sensor. 50mm at f1.8 is very different on his APS-H sensor compared to a standard APS-C on a typical DSLR. His issue is that he's finding it difficult to get a reduced depth of field, and it the sensor on his camera that is going to be the one thing against him that he cannot alter.

In real terms sensor size has a big influence on depth of field, especially when they're that small....

Steve

Sent from my iPad using TP Forums
 
Jelster said:
In real terms sensor size has a big influence on depth of field, especially when they're that small....
s
Click to expand...

No it doesn't. It might appear to but it doesn't.

What does have an effect is that on a crop sensor camera one will be using a wider lens to get the same shot and this will have less DOF but it is just incorrect to say that sensor size iteslf has an affect on DOF.

To anyone trying to understand exactly what is meant by a crop sensor this is not a trivial point.
 
hoohaaa said:
No it doesn't. It might appear to but it doesn't.

What does have an effect is that on a crop sensor camera one will be using a wider lens to get the same shot and this will have less DOF but it is just incorrect to say that sensor size iteslf has an affect on DOF.

To anyone trying to understand exactly what is meant by a crop sensor this is not a trivial point.
Click to expand...

It's not incorrect to say that sensor size affects DoF, it's just technically incomplete - but most folks understand what is meant as the bits that are missing are assumed as a given.

The complete answer is when a subject is framed the same, from the same viewpoint, the camera with a smaller sensor will deliver greater depth of field (at a given f/number).

What isn't explicitly stated there is that the focal length must change in order to maintain the framing, which is where I think you're coming from, but since the fundamental driver of everything is because the sensor size has been changed in the first place, then it's kind of a ligitimate shorthand to say that sensor size affects DoF. Feel free to disagree :D

Anyway, it's easy to compare DoF between formats by using the crop factor. So, if you frame the subject the same from the same viewpoint with a crop camera and a full framer side by side, then f/4 on a Canon cropper will deliver the same DoF as f/6.4 on full frame (4 x 1.6 = 6.4).

Using that same formula shows the OP's problem. Fuji S8000fd has a small sensor even for a compact, with a crop factor of 5.8x relative to full frame. In other words, with the Fuji at 84mm f/4.5, it is delivering framing and DoF equivalent to shooting on a full frame DSLR with a 486mm lens at f/26. And it's pretty much impossible to get anything like shallow DoF with that.
 
I always fing that on bridge/ps shoot type cameras to forget about the normal things you would to get a blurred background and whack the camera in Macro mode if it has one
 
HoppyUK said:
The complete answer is when a subject is framed the same, from the same viewpoint, the camera with a smaller sensor will deliver greater depth of field (at a given f/number).
Click to expand...

I know that. I've already stated as much. The point I'm making is that what you say is only true because you are now using a different focal length to achieve the same field of view. It is focal length that affects DOF and not sensor size. Sensor size itself is irrelevant.
 
hoohaaa said:
I know that. I've already stated as much. The point I'm making is that what you say is only true because you are now using a different focal length to achieve the same field of view. It is focal length that affects DOF and not sensor size. Sensor size itself is irrelevant.
Click to expand...

I still say that at a fixed focal length and aperture the size of the sensor comes in to play (big time in this particular case) but I'll agree to disagree and put this to bed.

However, as Hoppy explained, the OP is up against it trying to get a shallow depth of field on his particular camera when shooting a longer range. It just ain't gonna happen.

Steve
 
Gary Coyle said:
it will if its got a macro mode
Click to expand...

But he's shooting birds, not exactly a macro subject.

Sent from my iPad using TP Forums
 
Jelster said:
I still say that at a fixed focal length and aperture the size of the sensor comes in to play (big time in this particular case) but I'll agree to disagree and put this to bed.
Click to expand...

That's a bit like saying "I'm still right and would like the last word but you should stop arguing". :lol: Which is OK as it is getting repetative but I'd just like to point out that as yet nobody has actually explained why sensor size has an affect on DOF, they have just asserted that it does (even though it doesn't).
 
boyfalldown said:
Hoppy did a pretty good job of explaining to you ;)
Click to expand...

No he absolutely didn't. What he said was:

"The complete answer is when a subject is framed the same, from the same viewpoint, the camera with a smaller sensor will deliver greater depth of field (at a given f/number).

What isn't explicitly stated there is that the focal length must change in order to maintain the framing, which is where I think you're coming from, but since the fundamental driver of everything is because the sensor size has been changed in the first place, then it's kind of a ligitimate shorthand to say that sensor size affects DoF."​

What he says is that it appears that smaller sensors give you less DOF because you use wider lenses for the same image. What he quite definitely doesn't say is that sensor size itself has an affect. The reason he didn't say it is that he appears to know what he's talking about and knows that sensor size itself is irrelevant. It is the change in focal length that affects DOF not the sensor size.
 
hoohaaa said:
No he absolutely didn't. What he said was:

"The complete answer is when a subject is framed the same, from the same viewpoint, the camera with a smaller sensor will deliver greater depth of field (at a given f/number).

What isn't explicitly stated there is that the focal length must change in order to maintain the framing, which is where I think you're coming from, but since the fundamental driver of everything is because the sensor size has been changed in the first place, then it's kind of a ligitimate shorthand to say that sensor size affects DoF."​

What he says is that it appears that smaller sensors give you less DOF because you use wider lenses for the same image. What he quite definitely doesn't say is that sensor size itself has an affect. The reason he didn't say it is that he appears to know what he's talking about and knows that sensor size itself is irrelevant. It is the change in focal length that affects DOF not the sensor size.
Click to expand...

Both his explanation and the link I gave to you explained it perfectly well but you're just latching onto things to support your argument. As stated, while saying sensor size affect DoF is absolutely correct there is a more complete explanation as well. You seem for some reason to be having difficulty seperating the two.

In simple terms, if I take a photograph at 85mm with an FX camera I will be able to get a shallower depth of field then I would using a crop sensor (assuming everything else is the same)

Its perfectly legitimate to say thats down to sensor size (indeed DoF calculations us, in part CoC which is governed from sensor size.) What you seem to be after is an explanation of why, which comes down to framing etc etc and amongst other factors sensor size has a large infulence on that.

Maybe to keep us all happy you could find a DoF formula that doesn;'t count CoC or sensor size as part of it
 
boyfalldown said:
In simple terms, if I take a photograph at 85mm with an FX camera I will be able to get a shallower depth of field then I would using a crop sensor (assuming everything else is the same)
Click to expand...

No you won't. Try it.

Just what exactly do you think is happening? What do you think is so special about a crop sensor that causes it to affect the DOF. All it is is a smaller sensor. It is the lens and it's aperture that control the DOF. Do you think the lens can magically tell how much of the focal plane is being covered by the sensor, whether the sensor is full frame or or a piddly little phone sensor? Of course it can't. The light from the lens falls on the focal plane and the DOF is dependant on the focal length and the aperture. That's it.

Suppose there isn't a sensor there at all, suppose there is just a translucent sheet so you can see the image directly from behind. How much DOF will the image have? None? An infinite amount?

I think you don't know what's really going but you are so certain you are right that you haven't really stopped to think about it.

Just to make things clear. I accept that small sensors appear to have more DOF but only because you have to use a shorter focal length to get the same image. But the sensor size itself has no bearing at all on DOF.
 
hoohaaa said:
No you won't. Try it.

Just what exactly do you think is happening? What do you think is so special about a crop sensor that causes it to affect the DOF. All it is is a smaller sensor. It is the lens and it's aperture that control the DOF. Do you think the lens can magically tell how much of the focal plane is being covered by the sensor, whether the sensor is full frame or or a piddly little phone sensor? Of course it can't. The light from the lens falls on the focal plane and the DOF is dependant on the focal length and the aperture. That's it.

Suppose there isn't a sensor there at all, suppose there is just a translucent sheet so you can see the image directly from behind. How much DOF will the image have? None? An infinite amount?

I think you don't know what's really going but you are so certain you are right that you haven't really stopped to think about it.

Just to make things clear. I accept that small sensors appear to have more DOF but only because you have to use a shorter focal length to get the same image. But the sensor size itself has no bearing at all on DOF.
Click to expand...

I haven't got a DX sensor camera I'm afraid so I can't. Maybe you'd demonstrate.

Show me a depth of field calculation without CoC in it please. I understand that ultimately its the framing that makes the difference. Are you saying sensor size doesn't affect this? Please stop being so patronising. I'd explained and agreed that sensor size was a very abbreviated explanation, but you seem so determined that someone agrees with you that you'll bang on and on. Jeez do something more interesting ;)
 
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hoohaaa said:
No you won't. Try it.

Just what exactly do you think is happening? What do you think is so special about a crop sensor that causes it to affect the DOF. All it is is a smaller sensor. It is the lens and it's aperture that control the DOF. Do you think the lens can magically tell how much of the focal plane is being covered by the sensor, whether the sensor is full frame or or a piddly little phone sensor? Of course it can't. The light from the lens falls on the focal plane and the DOF is dependant on the focal length and the aperture. That's it.

Suppose there isn't a sensor there at all, suppose there is just a translucent sheet so you can see the image directly from behind. How much DOF will the image have? None? An infinite amount?

I think you don't know what's really going but you are so certain you are right that you haven't really stopped to think about it.

Just to make things clear. I accept that small sensors appear to have more DOF but only because you have to use a shorter focal length to get the same image. But the sensor size itself has no bearing at all on DOF.
Click to expand...

I think this argument is going nowhere fast, Hoohaa is absolutely right, sensor size (in itself) CANNOT affect depth of field, what DOES come into play when you CHANGE sensor size is the effect on FL to get the same FOV.
We all know that smaller sensor cameras exhibit a larger DOF, but it is not the sensor size, but the changes to the lens needed to maintain FOV due to the sensor size that produces the longer DOF.
It is a rather moot point, but nevertheless a very important one to understand.
 
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