Beginner Shallow Depth of Field

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Ronnie
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I was out in the garden with the cat just now and I was practising shallow depth of field photos. I thought it was as simple as getting a really high f stop value and getting close to the subject, but I was really struggling to get what I wanted. The best one (below) actually had a value of f7.1 (ISO 100, 1/160, 50mm), so not what I expected. The light was constantly changing, which did not help matters and the cat kept moving, so I was trying to change my settings on the fly. I'll read some more and keep practising. Hope you enjoy this shot though :)

 
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owen
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f7.1???? you sure that's right?
when you are talking a shallow depth of field the f number should be very low 2.8 and lower etc......
I'm not sure if its just a typo or not but though I better mention it ;-)
 
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8,276
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Carl
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Shallow DOF - smaller aperture - F1.4/F1.8/F2.8 is about as wide as they get for most (though you can get F1.0 and F1.2 though distance from the subject is abysmal). You're shooting in medium DOF I would say, F7 - that will get you lots of detail on your subject but depending on how far the subject is away from the background or you are from the subject, can change the DOF surrounding the subject.

It does "feel" complicated, but the more you practice - at some point it will "click" with you.

Use the lower F-number for more blurry backgrounds - but be prepared to be nearer your subject.

F7 is good for portraits and getting lots of detail on the subject itself. But if I wanted to say - based on your cat photo, have just its eyes in focus and everything else fuzzy, I'd go as "open" as I can i.e. F1.4/F1.8/F2.8 and be a couple of feet in front of the cat. The cat lying in the garden - not much behind so thats great - and your background DOF is good - <because> you're close to the cat and the cat is far away from a background (wall/fence/hedge etc..)

Of course, the more open the aperture, the more light is being let in, so you will have to compensate with a higher shutter speed to balance out the exposure (to make it darker) depending on your lighting/sunshine as it is in your image.

Close the aperture, and you'll have to slow the shutter speed to let more light in, or up your ISO to artificially boost the light-sensitivity.

You can get great background bokeh, even at F7 (as you have) just as long as the subject is far enough away from the background.
 
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Ronnie Mutch
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Ronnie
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Argh, I still keep getting confused between a high aperture and a high number. lol.

But, yeah, seems to be 7.1 although I was changing my settings up and down as the sun came out and hid in quick succession, so it was really hard to stick to a single setting. The photo properties in Windows is reading 7.1. Is this likely to be accurate?
 
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Ronnie Mutch
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Ronnie
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Shallow DOF - smaller aperture - F1.4/F1.8/F2.8 is about as wide as they get for most (though you can get F1.0 and F1.2 though distance from the subject is abysmal). You're shooting in medium DOF I would say, F7 - that will get you lots of detail on your subject but depending on how far the subject is away from the background or you are from the subject, can change the DOF surrounding the subject.

It does "feel" complicated, but the more you practice - at some point it will "click" with you.

Use the lower F-number for more blurry backgrounds - but be prepared to be nearer your subject.

F7 is good for portraits and getting lots of detail on the subject itself. But if I wanted to say - based on your cat photo, have just its eyes in focus and everything else fuzzy, I'd go as "open" as I can i.e. F1.4/F1.8/F2.8 and be a couple of feet in front of the cat. The cat lying in the garden - not much behind so thats great - and your background DOF is good - <because> you're close to the cat and the cat is far away from a background (wall/fence/hedge etc..)

Of course, the more open the aperture, the more light is being let in, so you will have to compensate with a higher shutter speed to balance out the exposure (to make it darker) depending on your lighting/sunshine as it is in your image.

Close the aperture, and you'll have to slow the shutter speed to let more light in, or up your ISO to artificially boost the light-sensitivity.

You can get great background bokeh, even at F7 (as you have) just as long as the subject is far enough away from the background.
Thanks Carl, that's really useful. I'll try again after lunch I think and report back, although the cat's probably away to God knows where.
 
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owen
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probably :) ........ if you put the aperture down to wide open ( depends what 50mm guessing 1.8) then you will have to up the shutter quite some if it is bright light like in your photos this does have advantages with a fast moving cat... but your focal plane is much lower so try to get the cats eyes in perfect focus is my advice ;-) the main thing is practice at low aperture it can be tricky to start with but well worth it in the end
 
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Chris
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Also I'd add that the focus seems to be on the cat's back and the fur there is much sharper than the face. What focus mode did you use as you've definitely missed the area of focus you were aiming for.
 
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Ronnie Mutch
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Ronnie
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Also I'd add that the focus seems to be on the cat's back and the fur there is much sharper than the face. What focus mode did you use as you've definitely missed the area of focus you were aiming for.
Hmm. Focus modes are actually not something I've covered at all yet so gonna go have a read up on this.

Practicing on a cat is probably making your life more difficult than it needs to be, try practicing on an inanimate object first, cats are buggers for moving just to annoy lol:D
Definitely! But he's quite photogenic and nice to get a pic of him in the sun.
 
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John
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instead of 'chasing settings'.....do you have an 'aperture priority' mode on your camera..? <<<which is..?

set it at f2.8
and let the camera change the speeds up/down as the sun goes bright/dim
and the ISO setting to 'Auto'
this should enable you to see the effects of a shallow DoF......then change to say f1.8 and see the results there too

some people practice with 5 match boxes in a row

for 'action', select 'shutter priority' and choose say 1/250
the camera will then select the aperture
if your lens is not 'fast' enough say f1.8 it will bump up the ISO for the shot

dont be wary of higher ISO values on todays Digital compared to the ISO values of 400 on a high-speed film...:)
 
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Ronnie Mutch
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Ronnie
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instead of 'chasing settings'.....do you have an 'aperture priority' mode on your camera..? <<<which is..?

set it at f2.8
and let the camera change the speeds up/down as the sun goes bright/dim
and the ISO setting to 'Auto'
this should enable you to see the effects of a shallow DoF......then change to say f1.8 and see the results there too

some people practice with 5 match boxes in a row

for 'action', select 'shutter priority' and choose say 1/250
the camera will then select the aperture
if your lens is not 'fast' enough say f1.8 it will bump up the ISO for the shot

dont be wary of higher ISO values on todays Digital compared to the ISO values of 400 on a high-speed film...:)
That's a good idea. Thanks.
 
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Chris
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instead of 'chasing settings'.....do you have an 'aperture priority' mode on your camera..? <<<which is..?

set it at f2.8
and let the camera change the speeds up/down as the sun goes bright/dim
and the ISO setting to 'Auto'
this should enable you to see the effects of a shallow DoF......then change to say f1.8 and see the results there too

some people practice with 5 match boxes in a row

for 'action', select 'shutter priority' and choose say 1/250
the camera will then select the aperture
if your lens is not 'fast' enough say f1.8 it will bump up the ISO for the shot

dont be wary of higher ISO values on todays Digital compared to the ISO values of 400 on a high-speed film...:)
We don't even know what lens he has yet ;) Or have I missed that? @Ronnie Mutch which do you have?
 
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RJ
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Shallow DOF - smaller aperture - F1.4/F1.8/F2.8 is about as wide as they get for most (though you can get F1.0 and F1.2 though distance from the subject is abysmal).
I don't want to be pedantic, but as the thread concerns a beginner trying to understand depth of field and apertures, I think it's important to be clear that f/1.4 constitutes a larger aperture than f/1.8 or f/2.8. In other words, the diameter of the entrance pupil (the aperture) where light enters is physically larger at f/1.4 than at f/2, f/2.8 and so on.
 
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Phil
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That video is a nice illustration, but it'll be dependent on focal length / distance as well won't it? e.g. shooting that scene at f/2.8 on a 10mm lens will give deeper depth of field than shooting it at f/2.8 with a 200mm lens from much further away.
Actually focal length doesn't enter the equation, it takes some 'getting your head round' but it's all about subject distance
 
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Phil
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Ah. I'll have to try and read up on that and do some tests to see how it works and get a feel for it. Do you happen to know any decent sources of info? Cheers.
It's been shown on here before, I don't have anything to hand.

But you can try this tomorrow just with a std zoom in your garden.

Take a picture at the long end at the widest aperture, don't move, but zoom to the widest and take a 2ndshot at the same aperture.

At your PC, crop the wide image to match the long one, and you'll find the images are identical.

What we think of as 'telephoto compression' is all about the different way we use our lenses.
 
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23,183
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Richard
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It's been shown on here before, I don't have anything to hand.

But you can try this tomorrow just with a std zoom in your garden.

Take a picture at the long end at the widest aperture, don't move, but zoom to the widest and take a 2ndshot at the same aperture.

At your PC, crop the wide image to match the long one, and you'll find the images are identical.

What we think of as 'telephoto compression' is all about the different way we use our lenses.
Erm...?

This thread is about depth of field, not perspective ;) In that comparison, depth of field will change a lot between the two images, though perspective will stay the same.

But (if the OP isn't confused enough already) if you frame the subject the same size in two images - one at the wide end of the zoom and then a second at the tele end after moving back to keep the main subject the same size, depth of field will be the same and perspective will change.
 
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Jamie
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It's been shown on here before, I don't have anything to hand.

But you can try this tomorrow just with a std zoom in your garden.

Take a picture at the long end at the widest aperture, don't move, but zoom to the widest and take a 2ndshot at the same aperture.

At your PC, crop the wide image to match the long one, and you'll find the images are identical.

What we think of as 'telephoto compression' is all about the different way we use our lenses.
Are you sure that focal length doesn't factor into depth of field? that's contrary to my experience (i'm far from an expert though). I just tested it myself to be sure, using a 35mm prime at f1.8 and a 85mm prime at f1.8, shot from a tripod to ensure the same distance, cropped to the same size the 85mm prime give a much much shallower depth of field. We're not talking about a small difference, its night and day. It may be true with a zoom as you're using the same glass, i'm not so sure its true when comparing primes.
 
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Richard
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Are you sure that focal length doesn't factor into depth of field? that's contrary to my experience (i'm far from an expert though). I just tested it myself to be sure, using a 35mm prime at f1.8 and a 85mm prime at f1.8, shot from a tripod to ensure the same distance, cropped to the same size the 85mm prime give a much much shallower depth of field. We're not talking about a small difference, its night and day. It may be true with a zoom as you're using the same glass, i'm not so sure its true when comparing primes.
See my post above yours. I think Phil has just got this DoF thread mixed up with perspective :)

ps And welcome to TP!
 
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Simon
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Ronnie you'll have to take account your lenses f values minimums at 16 and 50 mm
At 16mm f/3.5 is the largest and at 50mm f/5.6 is the largest.
Meaning if you start at 16mm with f/3.5 and without adjusting you f value but still zooming to 50mm you'll find the camera has set f/5.6 without you re-setting it.
This is because the lens can't go to f/3.5 unless it's at 16mm and as you zoom out to say 35mm it will be f/4.0 for example and finally 50mm at f/5.6
The reason I mention this is others have said about low f/1.8 etc and the lens you have won't go there.
There is this E mount lens https://www.parkcameras.com/p/72405...0mm-f18-oss??gclid=CLTG-K2298sCFRHhGwodwpYD4A
£50 off RRP at the moment.
Search for the E 50mm F/1.8 OSS Sony RRP is £250
 
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Phil
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See my post above yours. I think Phil has just got this DoF thread mixed up with perspective :)

ps And welcome to TP!
Phil had a brain fart last night.

Normal service will hopefully be resumed shortly
 
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Nikolay
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With 1,8 or F2 you will have shallow DOF but pictures will be less sharp.
It is good idea to try F number around 2.8 but subject to be at good distance from baground.
And also to use telephoto lenses 70-200 mm and full the frame at aprox 90-100 mm for portraits.
 
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Mark
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Actually focal length doesn't enter the equation, it takes some 'getting your head round' but it's all about subject distance
It does and it doesn't. From the same viewpoint and aperture, a longer focal length will give less dof. For the same subject size, then you are right, dof is the same, because you have to get further away with a long focal length and dof increases with increasing subject distance.
 
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Phil
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It does and it doesn't. From the same viewpoint and aperture, a longer focal length will give less dof. For the same subject size, then you are right, dof is the same, because you have to get further away with a long focal length and dof increases with increasing subject distance.
You missed this bit...
Phil had a brain fart last night.y

Normal service will hopefully be resumed shortly
 
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I don't want to be pedantic, but as the thread concerns a beginner trying to understand depth of field and apertures, I think it's important to be clear that f/1.4 constitutes a larger aperture than f/1.8 or f/2.8. In other words, the diameter of the entrance pupil (the aperture) where light enters is physically larger at f/1.4 than at f/2, f/2.8 and so on.
I don't meant to be pedantic either but this isn't strictly true either :p An f2 200mm lens will have a significantly larger physical aperture/entrance pupil than an f1.4 50mm lens.

200mm/2 = 100mm diameter aperture
50mm/1.4 = 35.7mm diameter aperture

The f number is a relative number and only really tells you how 'bright' a lens is, not how large the aperture is.


OP to keep it simple a wide aperture (small f number), long focal length and small camera to subject distance will all help to give a shallow depth of field. You don't have to have all of these to get a shallow DOF though.

For example, this was shot at a relatively high f number (f8) but due to having a large-ish focal length and close subject distance (approx 6ft I'd guess) the background is almost completely blurred and the DOF is about the size of the swan's head.

DSC_8171
by TDG-77, on Flickr

This is an even higher f-number (f16) and shorter focal length (105mm) but because it was taken from about 30cm away DOF is tiny and less than the size of a damselfly's head, so around 2mm, and the background is completely blurred.

DSC_8759
by TDG-77, on Flickr

Then we have one here that's at a fairly fast f2.8 relatively long 200mm yet because of the much larger camera to subject distance the DOF is much greater.

DSC_0938
by TDG-77, on Flickr


I hope this isn't too confusing for you, but am just trying to show that you can't just use a small f-number and expect shallow DOF, subject distance and focal length matter too.

Finally, if you want a blurred/out of focus background there has to be a good separation/distance of the subject from the background too.
 
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RJ
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I don't meant to be pedantic either but this isn't strictly true either :p An f2 200mm lens will have a significantly larger physical aperture/entrance pupil than an f1.4 50mm lens.

200mm/2 = 100mm diameter aperture
50mm/1.4 = 35.7mm diameter aperture
Yes, that is very true. While my example was based on using the same focal length, not comparing across focal lengths, I didn't make that clear in my post looking back on it now, so this is worth noting.
 
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