Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and our Privacy Policy.
OK
Index  •   • New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Guest
New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Register to forums    Log in

 
FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras 
Thread started 10 Feb 2013 (Sunday) 16:55
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

Why does FF yield shallower DOF?

 
pxl8
Goldmember
Avatar
1,104 posts
Gallery: 1 photo
Likes: 59
Joined Jul 2005
Location: Somerset, UK
     
Feb 11, 2013 13:22 |  #61

DoF is defined by two things. Aperture and magnification.

Now magnification can be defined by distance and/or focal length but it still comes down to magnification. A larger sensor means more magnification means less DoF, simple as that.


-- PXL8
1DmkIV, 5DmkIII + 135mm f/2L, 24-70mm f/2.8L, Sigma 35mm f/1.4

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)
RDKirk
Adorama says I'm "packed."
Avatar
12,987 posts
Gallery: 2 photos
Likes: 534
Joined May 2004
Location: USA
     
Feb 11, 2013 13:26 |  #62

sandpiper wrote in post #15598574 (external link)
It's not a matter of "the full frame crowd", it works the same way for everybody.

Of course, if you keep all the variables the same (including viewing a smaller print from a crop camera to keep enlargement the same) then the DOF will stay the same. Nobody that I have seen is disagreeing with that. What people are disagreeing with is the fact that that is the situation in the real world.

In the real world, photographers are going to stand where they need to, and use the focal length they need, according to the FoV that their camera gives them. Have you ever worked out the position that gives you the perspective you want, and the focal length that gives you the framing you want, for your camera, then thought "hmmm, if I was using a camera with a different FoV I would be standing over there, or using a different focal length, so I'll do that instead"? People just don't work that way. You compose your shot by standing where you need to be for your perspective, and choose the focal length to fill the frame with your subject, without a load of wasted space around the edge.

To get the same composition and perspective you have to change the variables. It is true that a FF sensor does not in itself give you shallower D0F, but the need to use a longer lens from the same position (or move closer with the same lens, but that alters the image) will reduce the DOF. Therefore, to capture the image you want, the FF camera will have shallower DoF than a crop camera.

It is correct to say that a FF sensor does not alter DoF. However, it is not correct to say that "using a FF camera, or a crop camera" does not alter DoF, because you have to use them differently, and that difference alters your DoF.

I'm going to agree with this and be done with the topic.




  
  LOG IN TO REPLY
TSchrief
Goldmember
Avatar
2,099 posts
Joined Aug 2012
Location: Bourbon, Indiana
     
Feb 11, 2013 13:29 |  #63
bannedPermanent ban

msowsun wrote in post #15597368 (external link)
Sensor size WILL determine your shooting distance, or focal length used, so to say it has no effect on DOF just adds confusion to this already confusing subject.

Mike, that is probably the best way to look at this matter. As most of us already know, focal length (and aperture) are the prime determinants of DOF. Sensor size DOES play a large role in lens (FL) choice. It is only part of the choice if the shooter has bodies two different size sensors.

OP: Seems you are getting about as many different answers as respondents. This one does it every time. I hope you are able to make some sense of all this. Perhaps the best way is to just shoot various apertures and focal lengths, on different sensors if you can, and determine for yourself what difference sensor size makes to you.

EDIT: I just read through this entire thread. Yep, lots of different perspectives. Mostly correct, but approaching the problem from different angles. Some just plain wrong. Let me try to take this down a USEFUL path.

I shoot P&S, APS-c, full frame digital and 35mm film. What I am after here is a sense of how often sensor size, as it relates to DOF, makes a difference in the shooter's choice of equipment, or setting up a shot. For me, that is absolutely NEVER. I am not claiming no difference between FF and APS-c, only stating that sensor size does NOT enter the thought process of what equipment I am going to use. Keep in mind that I am a casual, hobby shooter. But I shoot the equipment in my hands. If I take out my 5D and 28-135 or 60D and 15-85, I shoot what I have. If I mount the 100-400L I treat it the same on either body, film included. It is generally at f/5.6, unless I can see I need more DOF. If so, I stop down no matter which format I am shooting. If I have a fast prime mounted I double check to make sure I am using narrow enough aperture to get all the DOF I need. Again, sensor size is irrelevant. I adjust to the equipment at hand.

I am NOT claiming that sensor size does NOT affect which aperture I choose; it most certainly does. What I am claiming is that for me, sensor size is NOT something I can adjust in the moment, so I don't waste time pondering it. I adjust the equipment in my hands to meet the needs of what I am shooting. Does anyone else do it differently? I don't believe so. Formal portrait shooters most likely are using FF bodies, exclusively. They work with what they have. Ditto pro sports shooter and APS-C or APS-H. Most casual hobby shooters only have one body. That makes the sensor size debate completely irrelevant to them, also.

Please, continue the discussion.


Gear List

  
  LOG IN TO REPLY
JohnB57
Goldmember
1,507 posts
Likes: 20
Joined Jul 2010
Location: Holmfirth, Yorkshire, England
     
Feb 11, 2013 13:42 |  #64

marsaz wrote in post #15598505 (external link)
Is it not an opinion?

Let's say an image is a result of many variables like sensor, focal lenght, aperture, distance, etc.

DOF is one part of the result and if you just change the sensor you do get a different result but not a different DOF. The bigger sensor allows you to change other variables like longer focal lenght or close distance - variables that change DOF.

If you keep the same framing on FF as you had on the crop sensor then YES, DOF will be more shallow but it's not the sensor that changes it. It got shallower because you changed other things. So technically speaking sensor alone does not change DOF but it allows you to change other variables that go in to the picture to extract a shallower depth of field than a smaller sensor allows you to.

We're getting to the point that there are no other combinations of words but no, it's not opinion, yes it is fact.

I've been careful to say that field of view and enlargement from a smaller image - or virtual image - is where sensor size comes in to play. To fill the whole of the sensor frame requires a wider FoV lens. In our comparison the wider lens has a factor of 1.6x1.6 the DoF at a given aperture. Enlarging the smaller sensor image by an extra 1.6x reduces the overall gain in DoF to 1.6x (1.6 squared, divided by 1.6 = 1.6) or one and a third stops.

I'm sure you know all this already.




  
  LOG IN TO REPLY
SkipD
Cream of the Crop
Avatar
20,476 posts
Likes: 154
Joined Dec 2002
Location: Southeastern WI, USA
     
Feb 11, 2013 14:52 |  #65

JohnB57 wrote in post #15598444 (external link)
Depth of field comparison between formats always assumes the same perspective, which means identical distance to subject and implies a change of focal length/FoV to maintain that. It does not - and cannot - mean using the same lens.

Your final sentence is wrong. Assuming same aperture and subject distance, DoF is a characteristic of both focal length and format size - format size because you have to take into account final image size, which with viewing distance also has to be a constant.

This is not a matter of opinion, it's a statement of fact.

I agree 100% with the above....


Skip Douglas
A few cameras and over 50 years behind them .....
..... but still learning all the time.

  
  LOG IN TO REPLY
Andrushka
"all warm and fuzzy"
Avatar
3,735 posts
Likes: 8
Joined Oct 2007
Location: OC, CA
     
Feb 11, 2013 16:28 |  #66

So what we can take away from this is size matters... hahahaha


http://www.paradigmpho​tographyoc.com (external link)

  
  LOG IN TO REPLY
JohnB57
Goldmember
1,507 posts
Likes: 20
Joined Jul 2010
Location: Holmfirth, Yorkshire, England
     
Feb 11, 2013 16:41 |  #67

Andrushka wrote in post #15599284 (external link)
So what we can take away from this is size matters... hahahaha

Of course - if you want the best quality end result.




  
  LOG IN TO REPLY
Andrushka
"all warm and fuzzy"
Avatar
3,735 posts
Likes: 8
Joined Oct 2007
Location: OC, CA
     
Feb 11, 2013 16:46 |  #68

JohnB57 wrote in post #15599323 (external link)
Of course - if you want the best quality end result.

:lol:


http://www.paradigmpho​tographyoc.com (external link)

  
  LOG IN TO REPLY
khwaja
Senior Member
894 posts
Gallery: 4 photos
Likes: 118
Joined Aug 2012
     
Feb 11, 2013 16:47 |  #69

For given FOV and DOF, are exposure values same for both the formats?


Canon 6D Mark 2, 50mm STM

  
  LOG IN TO REPLY
sandpiper
Cream of the Crop
Avatar
7,171 posts
Gallery: 1 photo
Likes: 50
Joined Aug 2006
Location: Merseyside, England
     
Feb 11, 2013 16:59 |  #70

khwaja wrote in post #15599344 (external link)
For given FOV and DOF, are exposure values same for both the formats?

The actual EV doesn't change, exposure needs to be the same regardless of sensor size. However if you are standing in the same place and wanting the same image (so a given FOV) then you would need to stop down the aperture on the FF camera, relative to the crop camera to give the same DOF. If you were using f/5.6 on the FF you would probably find that around f/3.2 on the crop would give you the same DOF. You would also need to adjust the shutter speed or ISO accordingly of course.




  
  LOG IN TO REPLY
mikeassk
Goldmember
Avatar
2,329 posts
Likes: 3
Joined Aug 2006
Location: San Diego/ San Fran/ Berkeley
     
Feb 11, 2013 17:01 |  #71

n1as wrote in post #15595460 (external link)
To get the same field of view, the crop-sensor camera needs to shoot with a shorter lens(ALSO KNOWN AS WIDER OR LONGER). The shorter lens yield wider(ALSO KNOWN AS SHALLOWER OR DEEPER) DOF. Is that why the crop-sensor gives more DOF?


If you shoot with the same lens on both cameras (same scene, same shooting position, same f/stop) and then crop the FF image to equal the FoV of the 1.6 crop-factor sensor will you have the same DOF?

So in question 1)

A 5D with a 50mm lens and a 7D with a 50mm lens will not change the depth of field for the real estate covered by both sensors from the center outward, however the 5D will have more image area to record as it is much larger. This is simple. So in that scenario, where the only thing changed is the camera, you will have much more image and more importantly a much different image and so the comparison is trite to me.

If a 5D with a 85mm and a 7D with a 50mm were used you may have a similar Field of view as you said, but a host of variables makes the 2 images anything but exactly the same other than that. The specifics of why are as simple as you need them to be, but in a reality never did much to progress my photography. I took it as fact and that was that.

So in question 2)

If you use the same lens on both formats and
stay in the same location then the identical real estate recorded will be of the same DOF.

If you use the same lens on both formats and
move around to achieve a similar FOV you have once again opened up a host of variables that not only change the DOF but also the perspective which can be one of your most valuable composition points.


Stuff

  
  LOG IN TO REPLY
JohnB57
Goldmember
1,507 posts
Likes: 20
Joined Jul 2010
Location: Holmfirth, Yorkshire, England
     
Feb 11, 2013 17:06 |  #72

khwaja wrote in post #15599344 (external link)
For given FOV and DOF, are exposure values same for both the formats?

Exposure value is the same regardless of format. However, to achieve the same DoF, a 35mm format sensor requires an f number 1.6x that of a 1.6x crop - approximately one and one third stops smaller in aperture.




  
  LOG IN TO REPLY
SkipD
Cream of the Crop
Avatar
20,476 posts
Likes: 154
Joined Dec 2002
Location: Southeastern WI, USA
     
Feb 11, 2013 17:24 |  #73

mikeassk wrote in post #15599391 (external link)
A 5D with a 50mm lens and a 7D with a 50mm lens will not change the depth of field for the real estate covered by both sensors from the center outward, however the 5D will have more image area to record as it is much larger. This is simple. So in that scenario, where the only thing changed is the camera, you will have much more image and more importantly a much different image and so the comparison is trite to me.

The depth of field WILL change when using different format cameras when both have the same focal length lens, same camera-subject distance, and same aperture settings. The reason is a point that most folks checking into this thread (and most similar threads) are totally missing is that depth of field is not analyzed at the film/sensor plane inside the camera.

ALL depth of field analysis is done with a standard-sized print which is viewed at a standard distance (the size and distance are defined by the person creating the formula for the calculation). Thus, the different sized in-camera images from different format cameras (format refers to the size of the film frame or sensor in a camera) must be enlarged (magnified) by different amounts to fill the same standard print. If two different format cameras were used to make test shots with the same subject distance, same focal length, and same aperture, the IN-CAMERA blurs for out-of-focus points would be the same. After printing the images, though, the same blurs would be larger from the smaller format camera as compared to the ones from the larger format camera. There is a difference.


Skip Douglas
A few cameras and over 50 years behind them .....
..... but still learning all the time.

  
  LOG IN TO REPLY
TSchrief
Goldmember
Avatar
2,099 posts
Joined Aug 2012
Location: Bourbon, Indiana
     
Feb 11, 2013 17:40 |  #74
bannedPermanent ban

JohnB57 wrote in post #15599410 (external link)
Exposure value is the same regardless of format. However, to achieve the same DoF, a 35mm format sensor requires an f number 1.6x that of a 1.6x crop - approximately one and one third stops smaller in aperture.

This is getting ridiculous. NOBODY thinks like that when they are shooting. NOBODY would think to do that when a change in DOF is desired.

Shooter to self: "Let's see, now. I need switch formats for this shot. I think I'll go back home, get my other (FF/APS-c) camera, mount a different lens, then shoot from the exact same spot, which changes my composition HUGELY, then I'll do a small calculation do determine which aperture I need to get EXACTLY the same DOF out of completely different equipment, for a completely different shot."

This may or may not work. Not my point. The ridiculousness of anyone actually doing this defies the imagination. Any particular f/stop, on a set FL, whether on APS-c, full-frame, or 8x10 for that matter, will yield the same DOF when shot at the same distance. Who cares what FF aperture yields the same DOF as APS-c at a completely different distance? You will shoot what is in your hands AT THE MOMENT.

DOF is affect by:
Focal length, aperture and sensor (film) to subject difference. Note that sensor size is NOT in that list. Sensor size WILL affect your choice of lens. It does NOT directly affect DOF.

Someone please hold me to this. When I get a chance, I'll take test shots clearly showing that sensor size has NO effect on DOF. I will shoot the same subject from the same distance with the same lens and the same aperture, with a 60D and a 5D. Does anyone really think I'll get anything but EXACTLY the same DOF from these shots?

SkipD, stay tuned. You are in for a surprise.


Gear List

  
  LOG IN TO REPLY
davidc502
Goldmember
Avatar
3,459 posts
Gallery: 1 photo
Likes: 38
Joined Dec 2010
Location: Tennessee
     
Feb 11, 2013 17:44 |  #75

TSchrief wrote in post #15599539 (external link)
This is getting ridiculous. NOBODY thinks like that when they are shooting. NOBODY would think to do that when a change in DOF is desired.

Shooter to self: "Let's see, now. I need switch formats for this shot. I think I'll go back home, get my other (FF/APS-c) camera, mount a different lens, then shoot from the exact same spot, which changes my composition HUGELY, then I'll do a small calculation do determine which aperture I need to get EXACTLY the same DOF out of completely different equipment, for a completely different shot."

This may or may not work. Not my point. The ridiculousness of anyone actually doing this defies the imagination. Any particular f/stop, on a set FL, whether on APS-c, full-frame, or 8x10 for that matter, will yield the same DOF when shot at the same distance. Who cares what FF aperture yields the same DOF as APS-c at a completely different distance? You will shoot what is in your hands AT THE MOMENT.

DOF is affect by:
Focal length, aperture and sensor (film) to subject difference. Note that sensor size is NOT in that list. Sensor size WILL affect your choice of lens. It does NOT directly affect DOF.

Someone please hold me to this. When I get a chance, I'll take test shots clearly showing that sensor size has NO effect on DOF. I will shoot the same subject from the same distance with the same lens and the same aperture, with a 60D and a 5D. Does anyone really think I'll get anything but EXACTLY the same DOF from these shots?

Valid points.... Too bad no one really listens....

LOL the word "ridiculousness" <<< You've been watching to much MTV!!


_
My Gear is ---> Here

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)

10,230 views & 0 likes for this thread
Why does FF yield shallower DOF?
FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras 
AAA
x 1600
y 1600

Jump to forum...   •  Rules   •  Index   •  New posts   •  RTAT   •  'Best of'   •  Gallery   •  Gear   •  Reviews   •  Member list   •  Polls   •  Image rules   •  Search   •  Password reset

Not a member yet?
Register to forums
Registered members may log in to forums and access all the features: full search, image upload, follow forums, own gear list and ratings, likes, more forums, private messaging, thread follow, notifications, own gallery, all settings, view hosted photos, own reviews, see more and do more... and all is free. Don't be a stranger - register now and start posting!


COOKIES DISCLAIMER: This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and to our privacy policy.
Privacy policy and cookie usage info.


POWERED BY AMASS forum software 2.1forum software
version 2.1 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member was a spammer, and banned as such!
935 guests, 231 members online
Simultaneous users record so far is 15144, that happened on Nov 22, 2018

Photography-on-the.net Digital Photography Forums is the website for photographers and all who love great photos, camera and post processing techniques, gear talk, discussion and sharing. Professionals, hobbyists, newbies and those who don't even own a camera -- all are welcome regardless of skill, favourite brand, gear, gender or age. Registering and usage is free.