Canon EOS 1Ds DOF

Alex, sorry I misread your previous post.

What calculator are you using? What Coc values does the calculator use for the different formats you're comparing, and what focal lengths?

As Jon mentioned, if you compare different camera formats at the same focal length, you'll get greater DOF with the larger format. But it's a useless comparison since it won't generate the same field of view.

asylumxl wrote in post #4112545
http://www.outbackphot​o.com …hnique/essay07/​essay.html
this page illustrates the difference in depth of field between a nikon 1.5x crop and a 1ds sensor.

I've been out of this discussion today, but now let me chime in.

The problem with the above posted link, and with all the discussion about how sensor sizes affect DOF, is that you are trying either to shrink a full-frame image and compare it with a non-shrunken cropped image, giving the same affect as viewing the image from a distance, making things appear sharper, which to me is not a valid comparison, or, even worse, the link above used a longer focal length to replicate the cropped image, which we know will affect the DOF, making the DOF on the full-frame camera shallower in actuality.

My premise is that, if you view two images with every thing but the sensor size being equal, you should view them at an equivalent viewing magnification, not viewing size. The image captured by the full frame sensor is larger; well so it is. View both images at 50%, 66%, 100%, whatever floats your boat, but if you shrink one down to the others' viewing size you are altering the perceived DOP and there is no comparison.

I actually spent time testing this stuff out today because I wanted to be damn sure of what I was talking about. Using my 5D and 30D and my 100mm f/2.8 macro and my 50mm f/1.8 lenses, I took a number of shots to compare.

If you are curious, want to learn, or think I'm wrong, or even if you think I'm correct, check it out on the PBase link below. I won't post all the pictures here, but here's the link:

http://www.pbase.com …ong/dof_and__se​nsor__size

I illustrate how shrinking an image will affect perceived DOF and how changing the focal length changes the actual pixel-level DOF, and, here goes, how viewing a cropped-sensor image with a full-frame sensor image cropped to contain just the image from the cropped sensor gives you, well, equivalent DOF!!!

Hope this stirs up the pot a bit! Maybe if those who are in this debate can check out my pics, we might get on the same page about a few things, and the newbies might get some helpful info instead of just sqabbling.

BTW, if you want to see pics from a recent day trip to Mount St. Helens, an active volcano in Washington State, with a 5D, click here
Tony
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Several Canon cameras, too many lenses and stuff to list
Tony Long Photos on PBase

Well, here's a teaser:

Before checking for EXIF data, try to guess: which pic came from the 5D? Which from the 30D? Which has more DOF?

For more, check my previous post for the link.

I haven't gotten any responses of my demontration of depth of field yesterday -- did anyone check out my results? Comments?

Tony

---------------

Several Canon cameras, too many lenses and stuff to list

If you want to see pics from a recent day trip to Mount St. Helens, an active volcano in Washington State, with a 5D, click here

Tony Long Photos on PBase

tonylong wrote in post #4143573
I've been out of this discussion today, but now let me chime in.

The problem with the above posted link, and with all the discussion about how sensor sizes affect DOF, is that you are trying either to shrink a full-frame image and compare it with a non-shrunken cropped image, giving the same affect as viewing the image from a distance, making things appear sharper, which to me is not a valid comparison, or, even worse, the link above used a longer focal length to replicate the cropped image, which we know will affect the DOF, making the DOF on the full-frame camera shallower in actuality.

My premise is that, if you view two images with every thing but the sensor size being equal, you should view them at an equivalent viewing magnification, not viewing size. The image captured by the full frame sensor is larger; well so it is. View both images at 50%, 66%, 100%, whatever floats your boat, but if you shrink one down to the others' viewing size you are altering the perceived DOP and there is no comparison.

I actually spent time testing this stuff out today because I wanted to be damn sure of what I was talking about. Using my 5D and 30D and my 100mm f/2.8 macro and my 50mm f/1.8 lenses, I took a number of shots to compare.

If you are curious, want to learn, or think I'm wrong, or even if you think I'm correct, check it out on the PBase link below. I won't post all the pictures here, but here's the link:

http://www.pbase.com …ong/dof_and__se​nsor__size

I illustrate how shrinking an image will affect perceived DOF and how changing the focal length changes the actual pixel-level DOF, and, here goes, how viewing a cropped-sensor image with a full-frame sensor image cropped to contain just the image from the cropped sensor gives you, well, equivalent DOF!!!

Hope this stirs up the pot a bit! Maybe if those who are in this debate can check out my pics, we might get on the same page about a few things, and the newbies might get some helpful info instead of just sqabbling.

BTW, if you want to see pics from a recent day trip to Mount St. Helens, an active volcano in Washington State, with a 5D, click here
Tony
---------------
Several Canon cameras, too many lenses and stuff to list
Tony Long Photos on PBase

The problem with your premise is that we don't make 8x, or 13x enlargements from all our images. We make 5x7", or 8x10" enlargements. To get an 8x10 you need to enlarge a 30D image more than a 5D image. So we need to compare the final print size even if it means we're comparing different enlargements.

tonylong wrote in post #4151751
I haven't gotten any responses of my demontration of depth of field yesterday -- did anyone check out my results? Comments?

It's kinda pointless.

DOF is not a way to quantify the blurriness of the background.

In order to calculate the DOF of a small crop being viewed on a screen, you need to know the size of the crop in terms of its original sensor area, pixel density of the viewing screen, viewing distance, and maybe a few other things.

When comparing DOF from different camera formats, the overall size of the film/sensor is important as it relates to the required focal length for a given field of view and the magnification required to produce a print of a given size. As soon as you start cropping images you immediately change important parameters that are part of the equation.

Jon wrote in post #4142137
Are you changing just the camera, i.e. the sensor? If you are, you aren't getting the same picture with the two cameras until you crop the FF picture to match the crop camera's picture. But then, the 8x10 crop camera picture will be getting compared to a 5x6" print from the FF body. If you want to start with both the cameras taking the same picture, edge to edge, from the exact same spot (so perspective is the same), you'll find the FF camera has a shallower DoF when you compare the two 8x10 prints, because you'll need to use an 80 mm lens on the FF camera to match the FoV of a 50 on the crop.

Sorry to resurrect this thread again, but that's exactly what I was missing. Thank you .

tonylong wrote in post #4143573
the link above used a longer focal length to replicate the cropped image,

That's the whole point, isn't it. That's why people use a 10-20mm zoom on a 1.6 crop, and a 17-40 on a full frame: To get a certain FoV.

If you want to take a picture from a certain point, you choose a focal lenght to get the FoV you want.

Think about this. I have a Canon Powershot S3is which has a tiny sensor compared to the EOS400D. My Canon S3is can open up to f/2.8 at 50mm but produce images with a very large DOF, most things in focus. My EOS400D at 50mm f/2.8 is a completely different story, so yes sensor size WILL affect DOF!

svpworld wrote in post #4171019
Think about this. I have a Canon Powershot S3is which has a tiny sensor compared to the EOS400D. My Canon S3is can open up to f/2.8 at 50mm but produce images with a very large DOF, most things in focus. My EOS400D at 50mm f/2.8 is a completely different story, so yes sensor size WILL affect DOF!

You're talking about a completely different optical system: the lense on a fixed zoom focuses the image onto the tiny sensor, so of course there is a compressed depth of field! Another reflection of this is the fact that, as you implied, an aperture opening in a compact camera is not equivalent to an aperture opening in a DSLR system. They are two different beasts! Apples and oranges! The zooms, like the S3, are pretty cool, though -- the S3's 72 mm zoom actually gets about the same field of view as a 300mm tele on my 30D (cropped). But the cropped DSLR system is based on the 35mm optical system:

A cropped sensor is in fact a cropped version of a full frame sensor, using a lens that projects an image over a full frame field. So an image captured by the cropped sensor is in fact the center portion of the image that would be captured by a full frame sensor (pixel densities aside). There's no way you can get that comparison with a compact.

Take a full-frame shot. Use the same lens, distance, and aperture and take a cropped-frame shot. Crop the full-frame to the same field of view as the cropped frame. Print them at the same size or view them side-by-side at the same size and they will have the same appearance depth-of-field wise.

If, however, you shrink the entire FF image to the same viewing size as the cropped-frame image, you are changing the viewing relationship, similar to if you viewed the full-frame image at a greater distance than the cropped-sensor image. Viewing from a greater distance makes the "perceived" depth-of-field seem narrower; so does shrinking a FF image to match the CF image's viewing size. The FF image is larger, and contains more data, but that just means that if you print the FF image on, say, an 8x10, then to compare its DOF with a CS image you should print the CS image proportionately smaller, then view them side-by-side at the same distance to compare "actual" depth of field (actual rendered softness/sharpness). "Perceived" depth of field is pretty much what you make of what you see, I guess, and depends on other things besides your camera and output device.

You have another situation if you increase the FF focal length to get the same field of view as the CS's, or if you move closer to the subject to do that. Both of those will make the depth of field narrower than that of the CS in actuality.

Tony

tonylong wrote in post #4179194
You're talking about a completely different optical system:

A completely different system that still obeys the same laws of physics. Calculating DOF is done the same way, and regardless of camera format you simply need an appropriate circle of confusion value to get correct results.

The commonly expressed aperture value is nothing more than the iris diameter as a fraction of the focal length. Same beast. Apples, apples, apples.

Curtis N wrote in post #4179261
A completely different system that still obeys the same laws of physics. Calculating DOF is done the same way, and regardless of camera format you simply need an appropriate circle of confusion value to get correct results. The commonly expressed aperture value is nothing more than the iris diameter as a fraction of the focal length. Same beast. Apples, apples, apples.

OK, I don't know enough about the compact camera's optical sytem to say anything more that might be wrong.

But what I have is think through the Crop and FF physical attributes in DSLRs and then test, using my FF and my Crop camera with the same fixed focal length lenses and when I compared the portion of the FF image that corresponded with the crop, the depth of field was the same. Of course, I did not shrink the FF image, as I explained above. I viewed a cropped portion of that image at the same viewing size as the crop-sensor image, and, as I suspected, DOF was the same.

I suspect there are optical dynamics with the compact cameras, such as tightly focusing more of the field of view into the sensor rather than just taking a cropped portion of the FF field of view like the crop DSLRs do, that would probably affect the DOF for that system. The crop DSLRs don't do that, and the DOF with the same portion of its image match the FF. But, like I said, I don't know much about the compact optical differences, so I won't say more about them.

Tony

tonylong wrote in post #4180338
I viewed a cropped portion of that image at the same viewing size as the crop-sensor image, and, as I suspected, DOF was the same.

With the same aperture, focal length and distance, of course it will be the same.

It doesn't matter if you use a FF camera and crop the image, or use a "crop factor" camera, if the sensor area ultimately used to make a print is the same size.

tonylong wrote in post #4180338
OK, I don't know enough about the compact camera's optical sytem to say anything more that might be wrong.

But what I have is think through the Crop and FF physical attributes in DSLRs and then test, using my FF and my Crop camera with the same fixed focal length lenses and when I compared the portion of the FF image that corresponded with the crop, the depth of field was the same. Of course, I did not shrink the FF image, as I explained above. I viewed a cropped portion of that image at the same viewing size as the crop-sensor image, and, as I suspected, DOF was the same.

I suspect there are optical dynamics with the compact cameras, such as tightly focusing more of the field of view into the sensor rather than just taking a cropped portion of the FF field of view like the crop DSLRs do, that would probably affect the DOF for that system. The crop DSLRs don't do that, and the DOF with the same portion of its image match the FF. But, like I said, I don't know much about the compact optical differences, so I won't say more about them.

Tony

And how often do you crop your FF shots to 40% areally before printing them? How often do you print your "crop" shots full size, not cropped to the same extent that you crop your FF shots? DoF takes into account the final viewing size of the image, not just the circle of confusion on the sensor. You can't divorce the final viewing size from the calculation - the more you enlarge a spot, the bigger it gets, and the blurrier it looks. And it's a basic truth that you'll need to enlarge a crop more than a 35 mm/FF more than a 4x5" view camera shot in order to get that 8x10" print for your desk or mantel.

Thanks , http://www.dofmaster.c​om/doftable.html
helped a lot .