Avoid blurry background

I got Sony A6100 with Sigma 30mm 1.4 lens. Whatever mode I switch on (Aperture priority, Manual...) I always get either very focused object close to camera, and very blurry background, or vice versa - when I focus background, I get very blurry front object. I'm trying to increase F from 1.4 to 10 and more, and it helps somewhat with a less blurry background, but everything gets grainy and darker, it's just not usable. I wonder what I'm doing wrong. Yes, I'm aware bokeh is aesthetic quality for many purposes, but in this instance, I want to completely avoid it.

Now, I'm interested to solve this both with photos and videos. My aim is to do video cover for example of a guitar playing, with guitar in front, and some nice background that I don't want to be blurred. Basically, I want everything in focus. For reference, check this music videos -
If I tried that with my camera, guitar would be in focus, and everything in behind just a big green mess, while here it's almost whole scene in focus, not just a guitar. Thanks for all the suggestions!

You never know, but maybe if you post some photos (straight from the cmera, no processing) it might just help some here o suggest what setting to use instead.

You'll want to study the subjects of exposure and depth of field.

Exposure:
When you narrow the aperture, you must increase the exposure time or add more light to the scene to get the same exposure.

Depth of field:
A narrower aperture will offer more depth of field for the same focal length and subject distance. A shorter focal length will offer more depth of field for the same relative aperture and subject distance. A shorter subject distance will offer more depth of field for the same focal length and aperture.

There are free DoF calculator apps for your phone, get one and play with it.

If the DoF you want can't be achieved any other way, there's the option of focus stacking. Look it up.

Good luck and good light.

It is about Depth of Field (DoF). You might find more from wiki below:


DoF is governed by 3 major factors. There are many easy and good DoF calculators online or Apps for your phone. Might not be very accurate but can give you some idea on under what conditions you would expect certain DoF.


For a quick reference, the 3 major factors are:

• Aperture: smaller the aperture (size) deeper the DoF, i.e. f/8 > f/4 > f/2.8 etc...
• Focal length: the shorter the focal length the deeper the DoF, i.e. 28mm > 50mm > 100mm etc.
• Shooting Distance: the further away shooting distance from your aimed target the deeper the DoF, i.e. 15m > 10m > 5m.

But please note one most important thing of photography: capturing light. If you use too smaller aperture, to maintain the brightness of the output we might use higher ISO prematurely. This could see more noise (grainy) output. Please search for Noise vs Exposure & ISO here on this forum for detail.

As f/10 is a small aperture, so when you can get the DoF you needed, you might have a grainy output. Therefore, you might better use a larger aperture, say f/8 depending on the lighting condition, and change the focal length (for zoom lens) or change your shooting distance. It is a game we have to play with.

It is a fact of life (or physics/optics).

I understand that you do not get the background as sharp as you want it when you close the aperture to f/10 or so, but there is something wrong if you are getting darker images when you do it. If you have automatic exposure with auto ISO, I would guess the pictures will get blurry from camera shake and grainy from ISO setting too high, but not dark.

My guess is that you are trying to use a long lens, large separation between subject and background, short exposure, low ISO and low light all at the same time.

You will need to check each of these parameters before taking the photo. If the camera is set to full auto, then figure out why the camera set the parameters that it did. If one of the parameters is out of range, like too long exposure or too high an ISO, then you have to decide creatively what's gonna give.

If you have a whole lot of light, like full blown sunlight, then you may get what you are looking for. Even then, don't expect to get a tightly cropped face and sharp faraway background in the same photo.

As already mentioned, you can get much better help if you provide some examples.

A longer subject distance will offer more depth of field for the same focal length and aperture.

Klaus dk said:

A shorter subject distance will offer more depth of field for the same focal length and aperture.

Click to expand...

No, that is not correct.

A longer, not shorter, subject distance will give more depth of field for the same focal length and aperture.

Bob A L said:

A longer subject distance will offer more depth of field for the same focal length and aperture.

Click to expand...

Thank you, you are right. This is so embarrassing. One is trying to help and instead making things worse. If anything, it may be a consolation for the OP that getting it right isn't easy.

mxr12 said:

I got Sony A6100 with Sigma 30mm 1.4 lens. Whatever mode I switch on (Aperture priority, Manual...) I always get either very focused object close to camera, and very blurry background, or vice versa - when I focus background, I get very blurry front object. I'm trying to increase F from 1.4 to 10 and more, and it helps somewhat with a less blurry background, but everything gets grainy and darker, it's just not usable. I wonder what I'm doing wrong.

Click to expand...

It seems to me what you are doing "wrong" is because you haven't yet got a good grasp of the concepts of exposure, image lightness and DOF (Depth of Field).

Exposure is the amount of light that strikes the sensor per unit area during a shutter actuation.

• Scene luminance (light coming from the scene)
• Aperture
• Shutter speed

are the 3 things that affect the exposure directly.

Image lightness is simply how light or dark an image looks.

For a given scene there is a reciprocal relationship between any two of aperture, shutter speed and ISO in order to maintain a constant image lightness, not always a constant exposure.

For example: for a given scene -

f/8, 1/200s, ISO 400 and f/8, 1/100s , ISO 200 will result in the same image lightness but the ISO 400 shot will have had only half the exposure because only half the amount of light struck the sensor resulting in a noisier image.

DOF (Depth of Field) is how much of the scene after and before the focal plane is acceptably sharp. Only the scene at the focal plane is actually in focus.

• For a given aperture and focus length, the larger the subject distance the larger will be the DOF.
• For a given aperture and subject distance, the longer the focal length the smaller will be the DOF.
• For a given subject distance and focal length, the larger the aperture ( smaller f-number) the smaller will be the DOF.

After you get a good grasp of these three concepts then it will become much more straight forward to balance the DOF you want with the image lightness you want.

If we will speak strictly only about your apsc setup with 30mm lens, the big influence on background blur aside of aperture have focus distance. You can play with it a little bit to achieve desired effect.

In general, if you want to avoid background blur, use wider lenses. If you switch to eg. Sigma 16mm f1.4 and use it at f5.6-f11, not much blur will be visible.

Stopping the lens aperture down from f/1.4 to f/10 (or something thereabouts) is indeed how to get more depth of field. However, you must compensate for less light coming through the lens (since you now have a smaller opening) by either increasing exposure (longer shutter speed) or increasing the ISO.

Increased ISO can reduce image quality somewhat (more noise and lower dynamic range) and longer shutter speed can cause blurriness with subject movement or camera shake.

A camera or lens with image stabilization can help with camera shake, as can a tripod. Proper exposure will maximize image quality, even if you must use high ISO settings in low light.

steve_z said:

...

DOF (Depth of Field) is how much of the scene after and before the focal plane is acceptably sharp. Only the scene at the focal plane is actually in focus.

Click to expand...

It is focus plane or the plane of focus.

steve_z said:

• For a given aperture and focus length, the larger the subject distance the larger will be the DOF.

Click to expand...

It is focal length. You've got the two the wrong way round. "Focal" is inside the lens and "focus" is on the subject.

Having the background blurred helps isolate your subject and prevent it from getting lost in all the background noise.

For example: in this photo, the figure I am working on is standing infront of his ride. While the tank in the background is not in sharp focus, I think the tanker got lost in the photo.







Where as in the photo below, the blurred out tank puts the tanker as the focus point of the image.





In this photo of me working remotely while on vacation, I get a little lost in al the background information. but truth be told, the background was the real subject in this photo.



This photo of a cat on the lake (same vacation) the blurred background puts the viewer's attention on the cat.



While I understand what you are trying to do and the others are telling you how to accomplish that, I would like you to consider if you should. Experiment with the different ways to take your photo and think carefully which is better. Is the guitarist your subject or is the background?

Aloha,

Val

Dem Bell said:

steve_z said:

...

DOF (Depth of Field) is how much of the scene after and before the focal plane is acceptably sharp. Only the scene at the focal plane is actually in focus.

Click to expand...

It is focus plane or the plane of focus.

Dem Bell said:

• For a given aperture and focus length, the larger the subject distance the larger will be the DOF.

Click to expand...

It is focal length. You've got the two the wrong way round. "Focal" is inside the lens and "focus" is on the subject.

Click to expand...

It doesn't matter because the meaning in context is still very clear.