I enjoyed this thread.. made me think.... I think I now fully understand DOF .. maybe not the maths .. LOL!
Does Depth Of Field Change Between FX And DX Lenses?
(62 posts) (19 voices)-
Posted 2 years ago #
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spraynpray said:
Bottom line:If you took a picture of a butterfly which filled the sensor at 1 metre using a 100mm lens at f16 on a DX then transferred the lens onto an FX camera using the same settings and distance, the butterfly would remain the same size and the DoF the same depth but the FoV would be bigger (so you would see more 'other stuff' round the outside of the butterfly). To then get the butterfly the same size on the FX (i.e. filling the sensor), you would have to use a 50% longer lens so the DoF would be shallower.
....I'll bring this one up top again.
You got it spot on with the exception of the last statement regarding the 50% longer lens and shallower DOF thereof which is a bit to generic and will likely be misconstrued as longer focal length equals shallower DOF wich is not true but also not false depending on the circumstances :)Instead of the longer lens lets say we maintain the same 100mm lens on the FX and now attempt to get the same butterfly size on sensor as on a DX and in order to do that we have to get closer --> closer to subject means shallower DOF.
Now we take a 150mm lens and do the same size butterfly on DX and FX sensors again and we again have to be closer to the butterfly with FX thus will have a shallower DOF but the DOF of the DX with 100mm and DX with 150mm will be identical as well as the DOF on the FX with 100mm and the FX with 150mm because in order to maintain on sensor subject size we have to be further away with the 150mm than with the 100mm ;)
The focal length in on itself does not change the overall DOF as long as the on sensor subject size is maintained and you are at a close distance to the subject (below Hyperfocal).Posted 2 years ago # -
Depth of field between FX and DX cameras is actually of very great importance whether or not you are willing or able to wrap your head around it. This is a GREAT thread. Being a photo pro using 35mm gear and considerably larger formats (both medium and large formats) details like angle of view and even lens shifting to increase (or decrease depth of filed were practical considerations to be made with almost every shot. I have always been a big fan of larger film or sensor sizes in field applications as well as using the right camera and lens for the specific photo assignment. If you really wanted to do digital photography right you would want access to a variety of gear. Yet due to physical and financial constraints we rarely have the option of selecting the optimum image capture gear for the intended photo. If Hollywood made movies that way many studios would be out of business. Nikon Rumors Forum members are serious amateurs or pros without unlimited budgets. My budgets are smaller than they used to be. My willingness to carry heavy gear in the field is FAR LESS than I used to be willing to accept. Yet Nikon DSLR available today is right up there with as professional gear as a photographer has ever had available to them. I for one DO NOT EVER MISS THE FILM DAYS! Yet depth of field considerations with your Nikon DSLRs is critical. If you are shooting large buildings that are presented pretty much as human eyes would see them you will require shift lens or after photo correction. I use DX DSLR Nikons most of the time.
I do think I need to use FX more. Yet I would WANT to KNOW what impact DX compared to FX has in terms of depth of field BEFORE I took critical photos.Posted 2 years ago # -
Panamon_Creel said:
You got it spot on with the exception of the last statement regarding the 50% longer lens and shallower DOF thereof which is a bit to generic and will likely be misconstrued as longer focal length equals shallower DOF wich is not true but also not false depending on the circumstances :)
Instead of the longer lens lets say we maintain the same 100mm lens on the FX and now attempt to get the same butterfly size on sensor as on a DX and in order to do that we have to get closer --> closer to subject means shallower DOF.
Now we take a 150mm lens and do the same size butterfly on DX and FX sensors again and we again have to be closer to the butterfly with FX thus will have a shallower DOF but the DOF of the DX with 100mm and DX with 150mm will be identical as well as the DOF on the FX with 100mm and the FX with 150mm because in order to maintain on sensor subject size we have to be further away with the 150mm than with the 100mm ;)The focal length in on itself does not change the overall DOF as long as the on sensor subject size is maintained and you are at a close distance to the subject (below Hyperfocal).
I think you may just be as bad at explaining this as I am! ;-) I'll say the important bit again for us to focus on:
"To then get the butterfly the same size on the FX (i.e. filling the sensor), you would have to use a 50% longer lens so the DoF would be shallower."
If the distance and aperture are the same, the DoF will only be affected by the focal length of the lens (whatever it is) and the focal length would have to be 50% longer on the FX to get the butterfly the same size on the (larger) sensor so the DoF will be shallower.
Agreed?
Posted 2 years ago # -
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This conversation was started up again on the thread linked to below. I don't know a better way to merge the threads than close the other one and link to it here.
http://nikonrumors.com/forum/topic.php?id=5636Posted 1 year ago # -
^^^as I said in the above thread
DOF is a function of focal length, aperture and distance to subject. nothing else.
why does sensor size affect DOF?
Because you are 1.5 the distance to your subject when framing the same shot on an FX vs a DX camera.I hope this example makes it clear to everyone.
I used a tape measure to measure distance to subject and live view to match the composition to the alternative shot. You will notice that the framing is actually a bit tighter on the DX shots, this probably had to do with my measuring from the centre of the tripod, not the nodal point of the lens. This should actually give the DX shots slightly less DOF than if they were matched perfectly.
I removed colour in post as I felt it made the difference clearer.
SORRY, I JUST RELISED I EMBEDED THE WRONG INFO. THOSE BOTTOM TWO PICS ARE F/1.4.
Posted 1 year ago # -
From the other Thread:
Oops! Looks like I got this part wrong: “As the sensor/film format gets larger the DOF get shorter. The inverse is true as the sensor/film format gets smaller the DOF gets larger”mspman is right I got it backwards in my defense I just have to say this has been so ingrained in my head that when I would switch between my 35mm film camera with the normal lens 50mm to my medium format camera with the normal lens 80mm, I lose DOF. Yes more than one variable changing and technically I was wrong but in practice it’s how it usually works out. As others have explained.
Posted 1 year ago # -
^^^yes, as I said sensor size is irrelevant in terms of DOF, but does affect distance to subject.
It seems MANY people get confused by this. that's why I posted the pics in an effort to explain.
Posted 1 year ago # -
That's a nice set of images to illustrate, Gareth. Thanks for posting them.
Posted 1 year ago # -
Gareth is absolutely right. I study cinematography and have lots of experience shooting in both 16mm and 35mm film (different 'sensor' sizes, very similar to the FX/DX sensor size differences). This is always tough for people to wrap their head around at first but its really very simple once it clicks.
Sensor size has NOTHING to do with depth of field, it has a lot to do with FIELD OF VIEW, however. Lets say you have two cameras, one DX and on FX, and you have one FX lens. In order to frame the subject the same way with both cameras, you will need to be at different distances from the subject with both cameras because with the smaller sensor, you will have to back up in order to frame the subject the same way as you did with the FX sensor. The smaller sensor sees a smaller part of the image the lens is 'projecting' onto it, virtually 'cropping it'. Being at a different distance from the subject, the depth of field changes. Let me put it another way: The sensor size you are using can often dictate which focal length (lens) you will be using. Cameras with smaller sensors (assuming you are using FX full frame lenses, not DX lenses) require shorter focal lengths than FX sensors for the same field of view. Thus, generally you are shooting with wider lenses than you are with full fame cameras, giving you MORE depth of field (more in focus). A 50mm lens will have the same depth of field, the sensor size doesn't matter. However, your subject will appear closer up with the smaller sensor camera, so the photographer backs up, completely changing the depth of field.
I know this has been explained to death in this thread, but I thought I'd give it a go, writing it out helps as well :)
Posted 1 year ago # -
landru515 said:
Gareth is absolutely right. I study cinematography and have lots of experience shooting in both 16mm and 35mm film (different 'sensor' sizes, very similar to the FX/DX sensor size differences). This is always tough for people to wrap their head around at first but its really very simple once it clicks.Sensor size has NOTHING to do with depth of field, it has a lot to do with FIELD OF VIEW, however. Lets say you have two cameras, one DX and on FX, and you have one FX lens. In order to frame the subject the same way with both cameras, you will need to be at different distances from the subject with both cameras because with the smaller sensor, you will have to back up in order to frame the subject the same way as you did with the FX sensor. The smaller sensor sees a smaller part of the image the lens is 'projecting' onto it, virtually 'cropping it'. Being at a different distance from the subject, the depth of field changes. Let me put it another way: The sensor size you are using can often dictate which focal length (lens) you will be using. Cameras with smaller sensors (assuming you are using FX full frame lenses, not DX lenses) require shorter focal lengths than FX sensors for the same field of view. Thus, generally you are shooting with wider lenses than you are with full fame cameras, giving you MORE depth of field (more in focus). A 50mm lens will have the same depth of field, the sensor size doesn't matter. However, your subject will appear closer up with the smaller sensor camera, so the photographer backs up, completely changing the depth of field.
I know this has been explained to death in this thread, but I thought I'd give it a go, writing it out helps as well :)
Hmmm, I hope you are saying use an FX lens on both the DX and the FX camera so that you don't get vignetting as that is the only reason to do so? Other than that, your explanation is clear.
Posted 1 year ago #
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