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d7100 crop mode
- Thread starter alcaher
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Jan Grijs
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I have crop mode assigned to a switch and I regularly use it when walking in the fields, trying to catch birds and critters with my Tamron 70-300 VC. When the subject is a bit further away, or small, the crop mode helps to get an image that is a bit sharper because the D7100 tries to lower exposure time when it’s activated.
Of course you could get the same effect when using full manual, but when walking around you don’t always have the time to get the settings just right. I use fixed aperture (the Tamron performs best at F9) and let the camera sort out the rest. At which the D7100 does a much better job than my old D5100, I might add.
So yes, I think it’s a useful feature!
Of course you could get the same effect when using full manual, but when walking around you don’t always have the time to get the settings just right. I use fixed aperture (the Tamron performs best at F9) and let the camera sort out the rest. At which the D7100 does a much better job than my old D5100, I might add.
So yes, I think it’s a useful feature!
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Depth of field refers to the range of distance that appears acceptably sharp
Remember, "appears acceptably sharp"
Extreme example:
Say in your example the picture is 15" tall and in the picture the ruler fills the picture but it's a 15" ruler. Still the same 12" inches though appears acceptably sharp so the DOF is still 12 when you look at it on the wall from 2 feet away. Only slightly blurred at the ends. Now re-print the pic to 2" tall and hang it on the wall and ask folks if the whole ruler looks acceptably sharp. They will likely say yes... So now the DoF is 15, and the only thing that changed was output size.
Now go back to that pic on the wall that's 15" tall and when viewed from 2 feet away, it's obvious that the DoF is 12. Then walk back and look at it again from 100 feet away and ask yourself.."how much of the ruler appears acceptably sharp?". DoF becomes 15
and only viewing distance changedStill true though that if all you change is crop mode vs no crop mode with d7100...as in original context...DoF does not change.
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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
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This is I think what I'm having problems with - the definition of DoF.Depth of field refers to the range of distance that appears acceptably sharp
Remember, "appears acceptably sharp"
Extreme example:
Say in your example the picture is 15" tall and in the picture the ruler fills the picture but it's a 15" ruler. Still the same 12" inches though appears acceptably sharp so the DOF is still 12 when you look at it on the wall from 2 feet away. Only slightly blurred at the ends. Now re-print the pic to 2" tall and hang it on the wall and ask folks if the whole ruler looks acceptably sharp. They will likely say yes... So now the DoF is 15, and the only thing that changed was output size.
Now go back to that pic on the wall that's 15" tall and when viewed from 2 feet away, it's obvious that the DoF is 12. Then walk back and look at it again from 100 feet away and ask yourself.."how much of the ruler appears acceptably sharp?". DoF becomes 15
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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
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Actually a very complicated concept with subject elements. For example: A blind man can say DoF is constant and never changes...and be technically correctThis is I think what I'm having problems with - the definition of DoF.Depth of field refers to the range of distance that appears acceptably sharp
Remember, "appears acceptably sharp"
Extreme example:
Say in your example the picture is 15" tall and in the picture the ruler fills the picture but it's a 15" ruler. Still the same 12" inches though appears acceptably sharp so the DOF is still 12 when you look at it on the wall from 2 feet away. Only slightly blurred at the ends. Now re-print the pic to 2" tall and hang it on the wall and ask folks if the whole ruler looks acceptably sharp. They will likely say yes... So now the DoF is 15, and the only thing that changed was output size.
Now go back to that pic on the wall that's 15" tall and when viewed from 2 feet away, it's obvious that the DoF is 12. Then walk back and look at it again from 100 feet away and ask yourself.."how much of the ruler appears acceptably sharp?". DoF becomes 15
--
My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
--
My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
Last edited:
Yes then it all becomes a bit subjective.Actually a very complicated concept with subject elements. For example: A blind man can say DoF is constant and never changes...and be technically correctThis is I think what I'm having problems with - the definition of DoF.Depth of field refers to the range of distance that appears acceptably sharp
Remember, "appears acceptably sharp"
Extreme example:
Say in your example the picture is 15" tall and in the picture the ruler fills the picture but it's a 15" ruler. Still the same 12" inches though appears acceptably sharp so the DOF is still 12 when you look at it on the wall from 2 feet away. Only slightly blurred at the ends. Now re-print the pic to 2" tall and hang it on the wall and ask folks if the whole ruler looks acceptably sharp. They will likely say yes... So now the DoF is 15, and the only thing that changed was output size.
Now go back to that pic on the wall that's 15" tall and when viewed from 2 feet away, it's obvious that the DoF is 12. Then walk back and look at it again from 100 feet away and ask yourself.."how much of the ruler appears acceptably sharp?". DoF becomes 15
--
My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
Last edited:
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Yes, that's why it's a concept and you have to define the parameters and assumptions under which you are applying it when trying to discus/understand. Like in Jim's 2/3 stop case. You can get a 2/3 change but only in very specif scenarios and only when using the CoC criteria some (not all) of the online calculators use and their assumptions.That's the problem with this definition how literal do you take it. People with very poor eye sight could look at two picture with two different DoF's that is apparent to you and me and say the the DoF is the same - if you go by this definition then he isn't wrong.Actually a very complicated concept with subject elements. For example: A blind man can say DoF is constant and never changes...and be technically correctThis is I think what I'm having problems with - the definition of DoF.Depth of field refers to the range of distance that appears acceptably sharp
Remember, "appears acceptably sharp"
Extreme example:
Say in your example the picture is 15" tall and in the picture the ruler fills the picture but it's a 15" ruler. Still the same 12" inches though appears acceptably sharp so the DOF is still 12 when you look at it on the wall from 2 feet away. Only slightly blurred at the ends. Now re-print the pic to 2" tall and hang it on the wall and ask folks if the whole ruler looks acceptably sharp. They will likely say yes... So now the DoF is 15, and the only thing that changed was output size.
Now go back to that pic on the wall that's 15" tall and when viewed from 2 feet away, it's obvious that the DoF is 12. Then walk back and look at it again from 100 feet away and ask yourself.."how much of the ruler appears acceptably sharp?". DoF becomes 15
--
My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
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Understand, but that not what was being discussed. We were discussing your assumption that Crop mode gets you another stop of DoF vs crop mode being off...in the context of all else being equal. Sorry if I foggy.
I consistently claimed that the crop would actually have less DOF when magnified to the same size. As usual in these discussions there is a great deal of heat generated by differences in the precise framing of the situation and definition of terms.
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I complete understand what assumptions you're using and how you would come to that calculation.
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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
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What I was trying to demonstrate - just as with DX vs. FX - is that there is a broad range of equivalent shots where if you choose the right aperture and ISO you lose very little in terms of SNR, DR, etc. with the 1.3x crop. However - as again Great Bustard points out - it is in the non-equivalent shots that the larger format proves superior. In reality though it is the danger of clipping wings that keeps me from using the 1.3x crop.
BirgerH
Veteran Member
The dof changes, when you magnify the cropped images to the same viewing size as the uncropped - not just viewing them both at 100% - thats no magnifying. Print out both at same physical size (10x15 etc). then the cropped have a larger magnifying and dof is changed.
And this is actually what you are doing, when you are using the cropmode. You don't view it in a less physical size (neither on print or on screen), than the uncropped. If not, the only differenties in the pictures are the frame.
BirgerH.
wildlifr
Senior Member
You've enlarged the ruler in the DX frame by 1.25x to match the crop - and you have exactly the same DOF. This is your conceptual error (and Mako et al). You need to read the DOF off of the smaller ruler in the DX frame vs. the larger ruler in the DX crop. Even then, the difference will be subtle.
jimoyer
Senior Member
So one side of the argument is going to say that it's "unobservable", and the other side is going to comment on how "subtle" it is, yet we'll still argue about the difference for 5 pages. Only on DPR!
wildlifr
Senior Member
The test for my claim is to use a zoom at 40mm f4.5 with 1.25x crop vs. 50mm at f5.6 mm in DX. DOF should be equal - in fact if done right the pictures should be identical except for resolution. But you're looking at two identical pictures, finding them to be identical, and inferring something from that? Again, the other face of this is that the cropped picture will have less DOF than the picture from which it is cropped. But these are very different pictures: the "full frame" DX featuring a ruler which is 20% smaller. But if you magnify that ruler to line up with the one from the crop then the two pictures of the ruler will be absolutely identical.
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Jim
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Jim
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wildlifr
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