Why don't you just step back a bit for a crop body? compared to a FF.

Started Apr 26, 2010 | Discussions
NYPD1985 Regular Member • Posts: 130
Why don't you just step back a bit for a crop body? compared to a FF.

Okay can someone please enlighten me. For a 1.6 crop body like the Canon Rebels why don't you just take the shot with a few steps backward to get the result of a full frame? Maybe I am wrong so someone need to enlighten me. So for a full frame you take the picture and you can see a lot more than a 1.6 crop body. Okay now, so for a crop body like the 7D or rebel, why don't people just step back more in order to get everything in to the picture? For example if you take a picture from a full frame at 10 feet, wouldn't you get the same stuff in the picture with a rebel taken at 15 feet? Please tell me what am I missing, THANKS!

Sadja Herzog Senior Member • Posts: 1,752
Re: Why don't you just step back a bit for a crop body? compared to a FF.
1

The 1st thing that's different is the DOF, and the 2nd is pixel density (assuming the same # of pixels, those on the FF sensor will be more spread out and thus result in less noise at a given ISO).

If you shoot architectural interiors, sometimes there's no way to step back.
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Ross Murphy Senior Member • Posts: 1,968
Re: Why don't you just step back a bit for a crop body? compared to a FF.

that may change your field of view to what a FF would have been, but like the other poster said, its still a different sensor
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Will Rushmore Regular Member • Posts: 467
Re: Why don't you just step back a bit for a crop body? compared to a FF.
3

NYPD1985 wrote:

Okay can someone please enlighten me. For a 1.6 crop body like the Canon Rebels why don't you just take the shot with a few steps backward to get the result of a full frame?

Because you wouldn't get the result of a full frame. Changing your position changes the perspective. Angular field of view and framing are very different things. This really is the kind of thing that should be in the beginner's forum, not in the 1Ds forum.

Do you have a zoom lens? Try this:

Set the lens to its widest end (let's say 17mm).
Frame something, making sure there's pleny of space behind you.
Take a photo.

Set the lens to its tele end (let's say 55 mm)
Walk back until you are seeing approximately the same you were seeing at 17mm.
Take another photo.

Compare the photos.

To get the same result as a FF camera using a cropped-sensor camera, you'd need to stay exactly in the same place and use a wider-angle lens. Which can be impossible to get if your first lens was very wide to begin with. Also, a FF sensor will capture more light and therefore have comparatively less noise.

Jim Cassatt Veteran Member • Posts: 4,890
Re: Why don't you just step back a bit for a crop body? compared to a FF.

As qwas pointed out, sometimes you just can't with architectural photography.

I do a lot of shooting in DC of buildings using a 5D with 24 mm TS-E. Stepping back means going across the street and contending with cars, street lights, signs, etc.

Of course, now you can just invest in the 17 mm TS-E to do the same thing.

also, many of the best lens are less useful in a crop frame camera. When I was shooting with my 300D, I found that the 70-200 f4L was often ajust a bit too long to be generally useful. On a 5D the zoom range is much more useful for the kind of photography I do.
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kb2zuz Veteran Member • Posts: 3,202
You're missing a couple things
2
  1. Perspective: You know how when you're a distance from someone you can cover their entire head with your thumb or holding up a quarter. Now if you left that same quarter where it can cover someone's head and backed up 5 feet, the quarter would no longer appear larger than the person's head. Backing up will compress the background more, if you wanted to have foreground objects stand out more, you'd want to get closer. Backing up changes the perspective, changing to a wider or more telephoto generally only changes the field of view or how much of the scene is captured.

  2. Sometimes you can't back up. Say you're in a small room and you'd use a 35mm lens on a 35mm film body or "full frame" dSLR to get a group of people in a shot. So now you use the same 35mm lens on an APS-C dSLR (1.6x crop) and you can't fit everyone in, so you try to back up but there's a wall behind you.

  3. Depth of Field. Depth of field increases with distance, the further out you focus the deeper your depth of field will be, if you want a shallow depth of field, backing up will reduce it. However using a wider angle lens will also increase depth of field a bit as well. This is one of the reasons people who want shallow DOF prefer "full frame" cameras.

Now if you're only photographing 2D objects none of this matters, and sure you can back up no problem. But unless you're photographing paintings, backing up will change the appearance of the image.

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OP NYPD1985 Regular Member • Posts: 130
Re: You're missing a couple things

wow you just enlightened me !! now I understand the meaning of full frame with your thumb and quarter example. Thanks !! now...to the 5D Mark II that i'm going to buy... hehehe

kb2zuz wrote:

  1. Perspective: You know how when you're a distance from someone you can cover their entire head with your thumb or holding up a quarter. Now if you left that same quarter where it can cover someone's head and backed up 5 feet, the quarter would no longer appear larger than the person's head. Backing up will compress the background more, if you wanted to have foreground objects stand out more, you'd want to get closer. Backing up changes the perspective, changing to a wider or more telephoto generally only changes the field of view or how much of the scene is captured.

  2. Sometimes you can't back up. Say you're in a small room and you'd use a 35mm lens on a 35mm film body or "full frame" dSLR to get a group of people in a shot. So now you use the same 35mm lens on an APS-C dSLR (1.6x crop) and you can't fit everyone in, so you try to back up but there's a wall behind you.

  3. Depth of Field. Depth of field increases with distance, the further out you focus the deeper your depth of field will be, if you want a shallow depth of field, backing up will reduce it. However using a wider angle lens will also increase depth of field a bit as well. This is one of the reasons people who want shallow DOF prefer "full frame" cameras.

Now if you're only photographing 2D objects none of this matters, and sure you can back up no problem. But unless you're photographing paintings, backing up will change the appearance of the image.

Dan_168 Veteran Member • Posts: 8,729
Re: Why don't you just step back a bit for a crop body? compared to a FF.

I don't want to step back too far because I don't want to fall off a cliff or fall into the river when I am out in the woods.

Crocodile Gena Senior Member • Posts: 1,017
Sometimes you can, sometimes you can't, but...
1

NYPD1985 wrote:

Okay can someone please enlighten me. For a 1.6 crop body like the Canon Rebels why don't you just take the shot with a few steps backward to get the result of a full frame? Maybe I am wrong so someone need to enlighten me. So for a full frame you take the picture and you can see a lot more than a 1.6 crop body. Okay now, so for a crop body like the 7D or rebel, why don't people just step back more in order to get everything in to the picture? For example if you take a picture from a full frame at 10 feet, wouldn't you get the same stuff in the picture with a rebel taken at 15 feet? Please tell me what am I missing, THANKS!

...when you do, a couple of things happen:

  • the perspective changes,

  • the DOF likely changes, and

  • the noise or motion blur / camera shake may increase.

The first point is somewhat obvious, since perspective, which is the relative position of objects in the frame, depends only on subject-camera distance. All the focal length does is determine which portion of the scene is recorded.

The second point is less obvious. For the same framing and relative size of the aperture diameter, the DOF will be the same. For example, the aperture diameter at 50mm f/2.8 = 50mm / 2.8 ~ 18mm, and the aperture diameter at 50mm f/1.8 = 50mm / 1.8 ~ 28mm.

If the FF camera is 10 feet from the subject at 50mm f/2.8, and the crop camera is 16 feet away from the subject at 50mm f/1.8, then the relative sizes of the apertures are the same (18mm / 28mm ~ 10 ft / 16 ft), so the DOFs will be the same. But if the FF camera is at 50mm f/1.4, then crop is SOL since it can't get an aperture 1.6x larger.

The last point is also not obvious, but very much related to the second point above. The thing is that noise is determined by three factors:

  • How much light falls on the sensor (exposure x sensor area)

  • How efficiently the sensor captures the light (QE -- quantum efficiency)

  • How efficiently the sensor processes the signal (read noise)

Since the crop camera cannot increase the sensor area, it must increase the exposure to maintain the same noise, given relatively equal sensor efficiencies. To increase the exposure, it must either use a larger aperture diameter than FF (which, if possible, would also solve the DOF issue), or a longer shutter speed (which may adversely affect motion blur and/or camera shake).

Using the same example as above, if FF were shooting the scene at 50mm f/2.8 (aperture diameter = 50mm / 2.8 ~ 18mm at 10 feet, then if we used 50mm f/1.8 (aperture diameter = 50mm / 1.8 ~ 28mm) at 16 feet with crop, then we would maintain the same DOF, and, for the same shutter speed, the same noise.

The reason the noise would be the same is because since the crop camera is 1.6x further away than the FF camera for the same framing (but different perspectives), the light reaching the lens will be 2.56x (1.6^2) times less intense. Thus, it needs an aperture with 2.56x the area (1.6x the diameter) to collect the same amount of light for a given shutter speed.

And, once again, if the FF camera is at 50mm f/1.4, the crop camera is once again SOL because it cannot get an aperture large enough to make up for the greater distance.

So, if we don't care about DOF or noise, or shoot under circumstances when crop can use a corresponding larger aperture, then the "only" issues are if there is enough room to back up, if perspective is an issue, if the crop camera's sensor will oversaturate with the larger aperture, and how sharp the image will be at the wider aperture.

Some might argue that it's best just to get a FF DSLR. Until you become focal length limited, that is.

s majesk Contributing Member • Posts: 587
It's too late foran April Fools joke?

Are we kidding here?
1.6 Crop vs Full Frame
step back a few?
Come on Guys, it virtually makes no difference,
exept for accuracy of viewfinder!
And the viewfinder not pedicated on whether the camera is
1.6, 2/3, Full Frame whatever

Anastigmat Forum Pro • Posts: 12,664
Re: Why don't you just step back a bit for a crop body? compared to a FF.

NYPD1985 wrote:

Okay can someone please enlighten me. For a 1.6 crop body like the Canon Rebels why don't you just take the shot with a few steps backward to get the result of a full frame?

You can do that in most cases, but sometimes it is not possible. If you are standing at the edge of a cliff then obviously you cannot step back. If you are standing with your back against the wall, literally, then you cannot step back. You would have to tear down the wall to get everything in your frame. Besides, full frame can do more than just give wider angles. It can deliver better high ISO performance. Canon simply cannot deliver the same low noise performance with a crop body that a camera like the 5D or Nikon D3 can. Neither can Nikon of course. That is why Canon and Nikon can get away with charging a premium for a full frame model.

There are other advantages to a full frame, including more resolution at small apertures, better dynamic range and shallower depth of field. The size of the sensor therefore affects much more than angle of view.

Roy Helge Rasmussen Regular Member • Posts: 212
Well said! (NT)

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CutterUK Senior Member • Posts: 1,306
Re: Why don't you just step back a bit for a crop body? compared to a FF.

and who needs long tele lenses, simply walk closer to the subject...

and who really needs wide angles anyway, just take the shot with a normal lens and tell the viewer to imagine the missing bits

right off to play golf with a baseball bat

NYPD1985 wrote:

Okay can someone please enlighten me. For a 1.6 crop body like the Canon Rebels why don't you just take the shot with a few steps backward to get the result of a full frame? Maybe I am wrong so someone need to enlighten me. So for a full frame you take the picture and you can see a lot more than a 1.6 crop body. Okay now, so for a crop body like the 7D or rebel, why don't people just step back more in order to get everything in to the picture? For example if you take a picture from a full frame at 10 feet, wouldn't you get the same stuff in the picture with a rebel taken at 15 feet? Please tell me what am I missing, THANKS!

Skip M Veteran Member • Posts: 7,174
Think about your question...

NYPD1985 wrote:

Okay can someone please enlighten me. For a 1.6 crop body like the Canon Rebels why don't you just take the shot with a few steps backward to get the result of a full frame? Maybe I am wrong so someone need to enlighten me. So for a full frame you take the picture and you can see a lot more than a 1.6 crop body. Okay now, so for a crop body like the 7D or rebel, why don't people just step back more in order to get everything in to the picture? For example if you take a picture from a full frame at 10 feet, wouldn't you get the same stuff in the picture with a rebel taken at 15 feet? Please tell me what am I missing, THANKS!

Sometimes you can't step back. Sometimes you're in a confined space, but need to shoot the entire width. You need the FOV of a 14mm or 16mm lens, but can't move because of a wall, fence, drop off, etc.

When you move back, your angle of view changes, so your perspective changes. Try this with a fixed focal length lens; take a shot, then step back to get more in the frame. Now you'll have to stand on a step stool to get the same angle of view that you had before. If you do that with a zoom, you don't have to move, or get taller.

Sometimes, there's not a lens available that will give you the same effect on crop that you can get on a full frame. An 8mm fisheye on a crop looks very close to what a 15mm fish looks like on a full frame, you miss some of the circular effect.

I think, if you had given full consideration to your question, you could have answered it without help...
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Skip M Veteran Member • Posts: 7,174
Re: It's too late foran April Fools joke?

s majesk wrote:

Are we kidding here?
1.6 Crop vs Full Frame
step back a few?
Come on Guys, it virtually makes no difference,
exept for accuracy of viewfinder!
And the viewfinder not pedicated on whether the camera is
1.6, 2/3, Full Frame whatever

Really? Have you fully thought this answer out? Read the responses, and try them out. Then get back to us.
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ossme Contributing Member • Posts: 828
You don't need to step back
1

I didn't really get the question about stepping back. Because most of the time you won't need to step back at all. cropped sensors have a different lens selection than FF.

Instead of a 24-70mm F2.8 lens you could use a 16-50mm F2.8 lens and you get almost the same field of view.

For wide angle, you have the 10-20mm which equals the 16mm on a Full frame. I never shot with anything wider, in fact I rearly use anything wider than 24mm. But you can still get wider with crop sensors using lenses like Sigma's 8-16mm.

So, It is not the issue of taking few steps back when you shoot with an APS-C sensors. FF is far more important than just that. Here are some of my thoughts:
1- You get a bigger and brighter view finder.
2- you get a better DOF. (provided that both images are framed equaliy).
3- You get a better high ISO performance as a result of the bigger pixels.
4- you get a higher dynamic range with deeper colors.

All of the above translates into a better image quality.

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Skip M Veteran Member • Posts: 7,174
Yes, but...

ossme wrote:

I didn't really get the question about stepping back. Because most of the time you won't need to step back at all. cropped sensors have a different lens selection than FF.

Instead of a 24-70mm F2.8 lens you could use a 16-50mm F2.8 lens and you get almost the same field of view.

For wide angle, you have the 10-20mm which equals the 16mm on a Full frame. I never shot with anything wider, in fact I rearly use anything wider than 24mm. But you can still get wider with crop sensors using lenses like Sigma's 8-16mm.

So, It is not the issue of taking few steps back when you shoot with an APS-C sensors. FF is far more important than just that. Here are some of my thoughts:
1- You get a bigger and brighter view finder.
2- you get a better DOF. (provided that both images are framed equaliy).
3- You get a better high ISO performance as a result of the bigger pixels.
4- you get a higher dynamic range with deeper colors.

All of the above translates into a better image quality.

What if you need more than equiv. 24mm but need f2.8? Can't get that with crop. As far as the VF, the 7D has a bigger, brighter VF than the 5D, and neither influences the image quality of either camera.
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Guv Contributing Member • Posts: 779
That's like saying...

Why do you buy a Porsche when you can just drive your Honda 100mph?

There's a bit more to it than just the FOV. I think others have covered the finer points pretty well

OP NYPD1985 Regular Member • Posts: 130
Re: That's like saying...

very good point...

Guv wrote:

Why do you buy a Porsche when you can just drive your Honda 100mph?

There's a bit more to it than just the FOV. I think others have covered the finer points pretty well

bronxbombers Forum Pro • Posts: 18,226
1. sometimes impossible, but not the point 2. what about light collection?

NYPD1985 wrote:

Okay can someone please enlighten me. For a 1.6 crop body like the Canon Rebels why don't you just take the shot with a few steps backward to get the result of a full frame? Maybe I am wrong so someone need to enlighten me. So for a full frame you take the picture and you can see a lot more than a 1.6 crop body. Okay now, so for a crop body like the 7D or rebel, why don't people just step back more in order to get everything in to the picture? For example if you take a picture from a full frame at 10 feet, wouldn't you get the same stuff in the picture with a rebel taken at 15 feet? Please tell me what am I missing, THANKS!

for starters:

it's not really an issue since on APS-C you'd have purchased a different lens set and there you go

but if you used the same lens there are still problems:

how do you step back and frame that amazing landscape shot when there is no place back to step?

how do you step back from a tall building to fit it in frame without being able to walk through the ground or other buildings and shoot through that?

granted sometimes you can and it doesn't change things too much and it's sort of like living with a prime instead of a zoom

and more starters:

how does stepping anywhere let the APS-C sensor suddenly collect 2.5x as much light for better performance?

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