Canon 6D vs Canon 70D vs Canon 7D

[lalaknight]

Hi,
I'm new to photography and I love it. I'm having a hard time choosing between the 6D, 7D, and 70D. What's the significant differences between these 3? I want to start doing family portraits in natural light, mostly outside in natural surroundings. I also have a 8 month old who's moving all over the place and I want to get LOTS of photo's of her. I'm interested in photo's that have a high depth of field. I work at alot of music festival's (day and night, indoor and outdoor) and I really want to shoot at those. So basically I need a camera for
Natural light
Family Portraits
Baby/Infant
Concerts
Festivals
Action
Outdoor
Headshots

I'm just so confuse as to what to pick. I can't afford a Mark III. These are the only ones in my budget. Thanks so much for all the help and advice in advance.

[lalaknight]

Thank you so much. I made up my mind to go with the Rebel t5i! I was just about to get the f/1.4 lens but I really want a zoom lense. Do you think the f/2.8 will be okay in catching quick snaps of my daughter. She's a fast mover and I don't want to miss a thing.

[pdqgp]

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@lalaknight wrote:
Hi,
I'm new to photography and I love it. I'm having a hard time choosing between the 6D, 7D, and 70D. What's the significant differences between these 3? I want to start doing family portraits in natural light, mostly outside in natural surroundings. I also have a 8 month old who's moving all over the place and I want to get LOTS of photo's of her. I'm interested in photo's that have a high depth of field. I work at alot of music festival's (day and night, indoor and outdoor) and I really want to shoot at those. So basically I need a camera for
Natural light
Family Portraits
Baby/Infant
Concerts
Festivals
Action
Outdoor
Headshots

I'm just so confuse as to what to pick. I can't afford a Mark III. These are the only ones in my budget. Thanks so much for all the help and advice in advance.

---

The differences start with Full Frame vs a Crop Body sensor.   Full frame with grant you better low light image quality, & greater Depth of Field.  Those two key areas match several of the types of shooting you list.    That said, crop body cameras will give you more reach and outside the true professonal bodies, more robust autofocus systems and sports capability.   The latter leaves the 7D and 70D a better fit.

The 6D is a great starting point for full frame.   Today, the 70D is the better starting point.   That said, the noise level on a 70D is so very low that it won't really matter for what you've listed.   I have ISO shots in the 12,800 range that are great and unless you're printing posters side by side, you wouldn't notice the difference.

As Canon's motto goes, it starts with the glass, so don't overbuy on the body and not leave yourself room for good glass.  Especially for low light or shooting kids.  You'll need the speed of good glass.

[RobertTheFat]

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@pdqgp wrote:

---

@lalaknight wrote:
Hi,
I'm new to photography and I love it. I'm having a hard time choosing between the 6D, 7D, and 70D. What's the significant differences between these 3? I want to start doing family portraits in natural light, mostly outside in natural surroundings. I also have a 8 month old who's moving all over the place and I want to get LOTS of photo's of her. I'm interested in photo's that have a high depth of field. I work at alot of music festival's (day and night, indoor and outdoor) and I really want to shoot at those. So basically I need a camera for
Natural light
Family Portraits
Baby/Infant
Concerts
Festivals
Action
Outdoor
Headshots

I'm just so confuse as to what to pick. I can't afford a Mark III. These are the only ones in my budget. Thanks so much for all the help and advice in advance.

---

The differences start with Full Frame vs a Crop Body sensor.   Full frame with grant you better low light image quality, & greater Depth of Field.

Really? I've always understood that depth of field varies inversely with the focal length of the lens. For what's generally accepted as "normal" magnification, a FF camera uses a longer lens (~50 mm) than that of a crop-frame camera (~31 mm). So I guess I'd have expected the crop-frame camera to give you greater depth of field. If that's wrong, I'd be interested to hear why it is.

Those two key areas match several of the types of shooting you list.    That said, crop body cameras will give you more reach and outside the true professonal bodies, more robust autofocus systems and sports capability.   The latter leaves the 7D and 70D a better fit.

The 6D is a great starting point for full frame.   Today, the 70D is the better starting point.   That said, the noise level on a 70D is so very low that it won't really matter for what you've listed.   I have ISO shots in the 12,800 range that are great and unless you're printing posters side by side, you wouldn't notice the difference.

As Canon's motto goes, it starts with the glass, so don't overbuy on the body and not leave yourself room for good glass.  Especially for low light or shooting kids.  You'll need the speed of good glass.

---

"Speed" and "good glass" aren't necessarily synonymous, though. There are a lot of cheap f/2.8 lenses around.

[pdqgp]

---

@RobertTheFat wrote:

Really? I've always understood that depth of field varies inversely with the focal length of the lens. For what's generally accepted as "normal" magnification, a FF camera uses a longer lens (~50 mm) than that of a crop-frame camera (~31 mm). So I guess I'd have expected the crop-frame camera to give you greater depth of field. If that's wrong, I'd be interested to hear why it is.

---

I didn't word my point correctly... I meant more shallow DOF aka better for portraits.

[pdqgp]

---

RobertTheFat wrote

"Speed" and "good glass" aren't necessarily synonymous, though. There are a lot of cheap f/2.8 lenses around.

---

That's why I said they'll need the speed OF good glass not just speed.

[cale_kat]

---

@RobertTheFat wrote:

---

@pdqgp wrote:

---

@lalaknight wrote:
Hi,
I'm new to photography and I love it. I'm having a hard time choosing between the 6D, 7D, and 70D. What's the significant differences between these 3? I want to start doing family portraits in natural light, mostly outside in natural surroundings. I also have a 8 month old who's moving all over the place and I want to get LOTS of photo's of her. I'm interested in photo's that have a high depth of field. I work at alot of music festival's (day and night, indoor and outdoor) and I really want to shoot at those. So basically I need a camera for
Natural light
Family Portraits
Baby/Infant
Concerts
Festivals
Action
Outdoor
Headshots

I'm just so confuse as to what to pick. I can't afford a Mark III. These are the only ones in my budget. Thanks so much for all the help and advice in advance.

---

The differences start with Full Frame vs a Crop Body sensor.   Full frame with grant you better low light image quality, & greater Depth of Field.

Really? I've always understood that depth of field varies inversely with the focal length of the lens. For what's generally accepted as "normal" magnification, a FF camera uses a longer lens (~50 mm) than that of a crop-frame camera (~31 mm). So I guess I'd have expected the crop-frame camera to give you greater depth of field. If that's wrong, I'd be interested to hear why it is.

Why Full Frame Cameras offer greater control of Depth of Field than Cameras with smaller sensors

If it is a narrow band of DOF, the aperture opening plays a very big role. But the aperture opening is expressed as a relationship between the width of the opening and the length of the lens and in terms (in context) that are derived from 35mm photography. Consequently, a FF camera equipped with a 50mm lens and shooting at f/1.8 has a true aperture opening of f/1.8. In contrast, a Crop body camera equipped with a ~31mm lens will have an "effective" focal length of 50mm in 35mm terms and when used with the same aperture (f/1.8) will have an "effective" aperture of f/2.8. The sensor size matters because specifications expressed in 35mm terms must be converted before a true, or effective, comparison can be made.

The upshot of this is that for any given focal length/aperture combination, a FF camera will have greater control over DOF than a camera with a smaller sensor. (I am certain that there are about a thousand reasons why cameras differ in other ways that can influence their capacity to control DOF but as a generalization, this interpretation holds true.)

Also note, that those in search of narrowed bands of DOF should consider sensor sizes larger than 35mm. The same principle holds true and a Medium format camera (the Hasselblad 2-1/4" square size for this example) equipped with a 80mm lens will have an "effective" focal length of 52mm in 35mm terms. When this lens is used at the same aperture (f/1.8), it will have an "effective" aperture of ~f/1.2. What a win for Medium format photographers!

Those two key areas match several of the types of shooting you list.    That said, crop body cameras will give you more reach and outside the true professonal bodies, more robust autofocus systems and sports capability.   The latter leaves the 7D and 70D a better fit.

The 6D is a great starting point for full frame.   Today, the 70D is the better starting point.   That said, the noise level on a 70D is so very low that it won't really matter for what you've listed.   I have ISO shots in the 12,800 range that are great and unless you're printing posters side by side, you wouldn't notice the difference.

As Canon's motto goes, it starts with the glass, so don't overbuy on the body and not leave yourself room for good glass.  Especially for low light or shooting kids.  You'll need the speed of good glass.

---

"Speed" and "good glass" aren't necessarily synonymous, though. There are a lot of cheap f/2.8 lenses around.

---

[ebiggs1]

Bob from Boston,

" If that's wrong, I'd be interested to hear why it is."

As a matter of fact like a leopard, a lens can not change it's 'spots'.  So to speak.  A 50mm f1.8 lens remains a 50mm f1.8 lens no matter what body you bolt it on. Doesn't matter if it is a crop, a medium or a FF.  It can not change the way it was born.

A larger sensor will naturally absorb more light because of size, but the lens has no idea what sensor is behind it.

There is a mathematical formula for aperture. If you have a 500mm lens with a 125mm front objective element, the f-stop will be, roughly f/4, for instance.  That can not change.  Changing the size of the sensor, crop to FF, doesn't change that fact.

Assuming the same pixel pitch, each pixel will receive the same amount of light, regardless of the size of the sensor.

A properly exposed photo at f1.8 and 1/1000 at ISO 100 from that 50mm f1.8 lens will remain properly exposed regardless of whether the sensor is a crop, FF or medium format.  It will receive the same amount of light, no matter what size the sensor is.

Now the effective or apparent focal length does appear to change, not the lenses actual  focal length (that can not change) but what is seen by the sensor.

 A  Canon Rebel crop sensor records a smaller portion of the total image that the lens is able to deliver to the sensor, when  viewed at the same print size, the image appears larger. But your lens focal length does not get longer.  It is the field of view or angle of acceptance that makes everything look like the lens has a field of view like one that is 1.6 times as long.

If it was compared to a FF sensor that is.

But in the end all of this is just numbers because you get exactly what you see in the cameras view finder.  It is better to just ignor it and shoot away!

[cale_kat]

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@ebiggs1 wrote:

Bob from Boston,

" If that's wrong, I'd be interested to hear why it is."

As a matter of fact like a leopard, a lens can not change it's 'spots'.  So to speak.  A 50mm f1.8 lens remains a 50mm f1.8 lens no matter what body you bolt it on. Doesn't matter if it is a crop, a medium or a FF.  It can not change the way it was born.

Indesputably! But it doesn't operate the way it did on the two different bodies. Think of it this way. Imagine the lens is a pipe running through a dam. The lake is filled with water which act like photons, being held back by a hatch or shutter. On the other side of the dam is an array of buckets just waiting to be filled with photons. (Obviously the array of buckets is an anology for the camera sensor.)

I actually have two arrays of buckets. The first has buckets organized side-by-side to represent the organization of sensor cells on a 35mm frame. The second has the same number of buckets organized side-by-side to represent the organization of sensor cells on a APS-C frame. Of course, these buckets are smaller in size so that they can fit within the smaller area of the APS-C frame.

If you're following me, I'll let you open the hatch and let the water, or photons, in to fill the first array.

What happened? The bigger array captured nearly all the water that came through the pipe.

Now the second array, the one representing the APS-C array, is set to capture the water from the same distance. This time the array captured fewer photons because many of the photons never fell into the smaller area of buckets.

The same pipe is used in both tests and the only variation was the area of the array. 

A larger sensor will naturally absorb more light because of size, but the lens has no idea what sensor is behind it.

There is a mathematical formula for aperture. If you have a 500mm lens with a 125mm front objective element, the f-stop will be, roughly f/4, for instance.  That can not change.  Changing the size of the sensor, crop to FF, doesn't change that fact.

Assuming the same pixel pitch, each pixel will receive the same amount of light, regardless of the size of the sensor. 

Check your math. Pixel pitch is the distance from center-to-center of the cells. If the pixel pitch of a 35mm frame is 100 (easy numbers for explanation purposes only) and has 1,000 cells horizontally then a APS-C sensor with the same pixel pitch of 100 can not contain as many cells. The original 1,000 won't fit. Only by making the pixel pitch smaller can you fit the same number in. Smaller cells can not gather as much light.

A properly exposed photo at f1.8 and 1/1000 at ISO 100 from that 50mm f1.8 lens will remain properly exposed regardless of whether the sensor is a crop, FF or medium format.  It will receive the same amount of light, no matter what size the sensor is.

It will receive the same intensity of light but certainly not the same amount. It can't receive the same amount because the array area is not as big as that found on a full frame camera. Much of the light is missed as it is projected outside the area around the smaller APS-C sensor.

Now the effective or apparent focal length does appear to change, not the lenses actual  focal length (that can not change) but what is seen by the sensor.

True but we're here to take pictures and my goal is to put the "right" photons into the buckets. I can' t put the right photons into a smaller array unless I move closer to the subject or change my focal length. I don't like waste, so unless I can't move close enough, I'll frame for only those photons I want.

 A  Canon Rebel crop sensor records a smaller portion of the total image that the lens is able to deliver to the sensor, when  viewed at the same print size, the image appears larger. But your lens focal length does not get longer.

Now this is where it gets interesting. The focal length does not change but the ability to control the depth of field changes depending on the size of the sensor behind it. Going back to the anology of the dam with a pipe sticking through it, let's add the capability to change the length of the pipe. As the length of pipe gets shorter, it allows water around the sides of its lake-side opening to rush through and spray out the other side. Lengthen the pipe and the water acts in a much more controlled fashion. We like this because our ability to select the right photons is made easier when we can adjust the length of the pipe.  Now if I can change size of the pipe, its length, and how long I keep the hatch open, I have much more flexibility to select the right photons. It doesn't matter if I am using a APS-C or full frame sensor, as long as I'm willing to move around to line-up the photons I want, I'll be okay.

But the behavior of the camera varies depending on which photons you want to capture. Let's say I want to capture the photons coming off a chapel at some distance (more than a mile). I don't want all the other surrounding photons so I pick a long pipe, err lens, and I make it narrow, stopped down to f/16, and I let the photons flood into my camera. They arrive in a nice stream of nearly parrallel photons after being organized by the nice long pipe I chose and because I didn't let too many in at a time.

This sort of behavior, the organization of distant photons into a nice nearly parallel stream, is something that most camera lenses do pretty well. The trouble occures on the other end of the specturm. When the photons I want are immediately in front of me, such as when I'm shooting a portrait. I can choose to capture them with a very wide and reasonably short pipe. Assuming that the camera lens can organize the light to create a clear image of the subject in front of me, I can capture a nearly instanteous record of the light where all the light surrounding the subject is diffused. I can do this because my camera receives a huge package of light in one cycle, organizes that which falls within its focal range, in this case the maximum aperture, and can not resolve the light coming from the surrounding areas uniformly.

When the shutter opens and I get the spray, only a large array of buckets is going to capture all the photons I want. The smaller array will receive the same spray but only capture the spray in the "middle". If only I could change something.

It turns out that there is a limit to how close I can get to my subject. And that distance is limited not by factors on the array side but on the pipe side. (Plus the camera's ability to open and close the hatch.) Making a lens that has a very wide opening in relation to its length is extremely difficult. Because of this limitation, photographers will have to rely on being able to chose the right sensor size for the job. (Full frame gear may offer greater control but that comes at a price in the form of additional size and weight. Not all jobs require the full capabilities of full frame, or beyond, and it is great to be able to shed a few pounds every now and then.)

If the limitation on a lens is f/2.8, then the FF array will capture more light than the smaller array and with greater control of that light. If manufacturers of cameras with APS-C sensors can make a lens with a very large opening in relation to its length, they might be able to catch up with the FF sensor in term of capturing the same organization of light. But this is not likely for practical reasons. The benefit of such a lens is uncertain because it would be extremely expensive, pressing the limits of optical technology and such, and that cost would be inconsistent with the lower cost of smaller sensor cameras such as those with an APS-C format sensor. These may not be entirely irreconcilable interests but only time will tell. For the time being, FF dominates the professional world of photography because of the support manufacturers provide to the full frame format and the control it allows.

 It is the field of view or angle of acceptance that makes everything look like the lens has a field of view like one that is 1.6 times as long.

If it was compared to a FF sensor that is.

But in the end all of this is just numbers because you get exactly what you see in the cameras view finder.  It is better to just ignor it and shoot away!

---

[TCampbell]

Depth of field is controlled by only three factors:

1)  focal length of the lens

2)  distance from the subject

3)  aperture size

This means that "in theory" there is no difference between the depth of field on a full-frame vs. crop-frame camera given the three factors above are the same.  And it turns out... this is actually true.  

But in practice it'll seem like it's not true.  The reason for this is that you probably wont shoot the "same" photo using the same values above.

Suppose for example that you're shooting a simple portrait using a 50mm lens at f/4 with a distance of 10' away using a crop-frame body.

The following would then be true:

At that distance, the dimensions of the frame would be 4.5' x 3'.

The depth of field would be 1.84' (9.16' - 11' would be the focused field.)

Now suppose you switch to a full-frame body but leave eveything else the same.

The angle of view immediately becomes wider (using the same lens) BECAUSE the image circle projected into the camera by the lens was the same... but on the crop-frame camera, the sensor was smaller.  Much of the image "spilled off" the sides of the sensor.  But since the full-frame camera has a bigger sensor... it get's a bigger and wider area of that image being projected into the camera body by the lens.

The new dimensions of the frame will be about 7.25' x 4.75' (I'm rounding a bit here ... this isn't precise).

The depth of field will not change at all... but now we're getting a much wider shot of our subject and what we WANTED was to get approximately the SAME framing around our subject.  This means we'll need to change something.

We can either:

(a) stand closer to our subject, or

(b) use a lens with a narrower angle of view.

If we switch from the 50mm focal length to an 80mm focal length then the dimensional field of view at 10' will be exactly the same (4.5' x 3').

However... since we are no longer using the same focal length lens... the depth of field will become a bit shallower.  It'll be reduced to 1.125' (down from the 1.84' with the 50mm lens).  Also the intensity of the background blur will increase.

The other option we have is to stick with the 50mm lens and move in closer.

If we divide 10' by the 1.6x crop factor, we get 6.25'.  Stand at that distance and you'll get exactly the same dimensional field of view that you were getting with the crop-frame camera (4.5' x 3').  

If we do that, the depth of field changes down to 1.125' (that's the same DoF as it was with the 80mm lens without moving).  

The bottom line (yes I threw around a lot of numbers) is that two things are generaly true:

1)  If you don't change the focal length on the lens, the aperture (f-stop), or the subject distance, THEN the depth of field will remain the same.

but

2)  You PROBABLY will change your behavior when switching cameras because you're usually going after a specific subject-framing.  That means you'll either (a) stand closer, or (b) change the focal length of the lens.  Either of these two will result in a narrower depth of field and stronger background blur.

Most people do #2... and consequently would say that the full-frame cameras have a shallower depth of field and stronger backgroudn blur.  It's not the camera that causes this... it's the shooting behavior of the photographer that causes it.  But the photographer chooses the different lens focal length or subject distance because the sensor size is larger and naturally captures a wider angle of view.

Many people really love that "full frame look".

As for the ISO performance and noise...

 If you think of the sensor as being covered in tiny pixels (technically it's covered in photo-sites which get debayered into pixels but I digres), the larger the pixel, the more light will land on it and the less noise it gets.  Full frame cameras tend to have larger pixels (not always true... but usually true).  Even if they have smaller photosites, they would end up having more of them and, as we typically don't use all the pixels, the image has to be "resampled" down to the size we intend to use for image display.  That resampling results in a side-effect which decreases the noise.

I can show you images I shot with my 5D II at ISO 6400.  They "look" like they're noise-free (even at ISO 6400).  But really that's just because of the web-sized image.  If I take a 100% crop on the image, you do see the noise is there.  But it is generally true that you'll get much better overall noise performance with a full-frame camera.  You'll "feel" like you can shoot about 2 ISO stops higher with a full-frame camera than you would have shot with a crop-frame camera.  

[ebiggs1]

Very well said Tim as always.  You hit the "Post" a second or two before I did.  But a nice explanation.

People, or novice's get way too caught up in numbers than they do in just using the equipment.