5D mark II versus 7D spot focus

[PeterJ]

I bought a 7D a while back over a 5D II and my main reasons at the time were the more advanced autofocus system plus higher fps. I'm an amateur but now I'm finding myself more confident I rarely take the camera out of manual, tend to meter based on a point of interest and for focus just about always use spot towards the center of the frame and recompose.

I've seen some complaints about the 5D autofocus but I'm guessing they are mainly about the lower number of focus points and less cross-type. Anyway I guess my question in general is from anyone that's used both would spot AF be noticeably different on either body? All my lenses are f/2.8 or faster, but sometimes I do take some photos in low-light conditions without AF assist where the 7D does hunt a while.

[awinphoto]

In low light, the 5d Mark II will allow in more light to the focus sensor and will get quicker focus in those situations, however there are 5d Mark II owners that complain it STILL isn't fast enough, especially compared to some competition.  The 7d will shine in better lit condition over the 5d mark II but it really is designed and geared for different audiences than the 5d mark II so take that for what it is.  If you cannot use an AF lamp, could you use perhaps an external flash to get some help from the flash infrared lamp?  Also if you couldn't use the larger spot focus or the spot plus 4 surrounding sensors?  Relying on 1 focus mode in extreme situations can be tough but using larger or surrounding sensors (not to be confused with full zone focus or the 9 point focus modes).  Lastly try using live mode with exposure compensation... assuming your exposure is set correctly, you should see the image decently on screen, set your focus point, you can either manual focus or use the live view focus, and shoot away...

[tobiasg@gmail.com]

I too have used both most recently for video work and the rate of focus in good light between the 5DM2 and the 7D is VERY noticeable.  I often use the Quick Focus setting to setup my video shot with live view on.  Quick Focus is where it flips the mirror down, focuses and flips it back up to give you back live view.  In Good light with the 7D this is a very quick process - It grabs the focus almost instantly and you are back to live view.   On the 5DM2 it hunts, I found that I need to be more careful and give it a bit more of a contrasty spot to let it get focus.    On both cameras I was using the same copy of the 24-70.  In lower light it is a bit less noticeable but I VERY rarely feel like the 5DM2 grabs focus as quickly as the 7D. 

[Meh]

In low light, the 5d Mark II will allow in more light to the focus sensor

What do you mean by this and why do you think that?

[awinphoto]

In low light, the 5d Mark II will allow in more light to the focus sensor

What do you mean by this and why do you think that?

Almost every review comparison, by nature of a crop sensor collect x ammount of light and the full frame allowing in more ammount of light because of the bigger sensor, everything from the viewfinder will be slightly brighter, and more light will hit the autofocus sensor... In low light, by all means the 5d is not perfect and will also hunt, but can, in some instances, get focus a tad quicker than the 7D in extreme low light situations...

[bchernicoff]

In low light, the 5d Mark II will allow in more light to the focus sensor

What do you mean by this and why do you think that?

Almost every review comparison, by nature of a crop sensor collect x ammount of light and the full frame allowing in more ammount of light because of the bigger sensor, everything from the viewfinder will be slightly brighter, and more light will hit the autofocus sensor... In low light, by all means the 5d is not perfect and will also hunt, but can, in some instances, get focus a tad quicker than the 7D in extreme low light situations...

The autofocus sensor is completely separate from the image sensor, so your answer makes no sense. 7D has more advanced AF across the board.

[awinphoto]

If i may, the autofocus sensor receives light from the mirror so the more light hitting the mirror, the more light gets sent to the autofocus sensor... they are 2 separate sensors... the 7d DOES have a more advanced sensor, but light being light, if it doesn't receive as much light as the 5d does, it can only do so much...  In good lighting, the 7D kicks the 5d's butt every which way, but in low light, lighting becomes even more important. 

If you will, here's what I mean... the crop sensor is 1.6 smaller than a full frame sensor... a little more than half the size than a full frame sensor... Take 2 softboxes... both pumping out the same quality and strength of light... If 1 is on and the other is off, that's basically what a crop sensor is getting in light... a full frame camera would be like turning on the second softbox of light... you're not increasing any intensity of light but it's a bigger source overall 1 vs 2 and so it's more light and in terms of exposure, that's around 1 stop difference.  The full frame mirror will receive 2x the light gathered from the lens (all the light the lens can send it) and that light bounces into the AF motor.  The crop sensor still gets all that light but the mirror is smaller, sensor is smaller, and a lot of light is then wasted and not used...

[bchernicoff]

I bought a 7D a while back over a 5D II and my main reasons at the time were the more advanced autofocus system plus higher fps. I'm an amateur but now I'm finding myself more confident I rarely take the camera out of manual, tend to meter based on a point of interest and for focus just about always use spot towards the center of the frame and recompose.

I've seen some complaints about the 5D autofocus but I'm guessing they are mainly about the lower number of focus points and less cross-type. Anyway I guess my question in general is from anyone that's used both would spot AF be noticeably different on either body? All my lenses are f/2.8 or faster, but sometimes I do take some photos in low-light conditions without AF assist where the 7D does hunt a while.

I own both and here is the breakdown. The 7D's autofocus is much more advanced. Does this matter for portraits and landscapes (non-moving subjects)...probably not very much. With both bodies, I have set them so AF doesn't engage with a shutter press, but with the AF On button. On the 5D, I almost always have set to the center point only, and press the AF On button 2 or 3 times when shooting in a situation that makes good AF difficult. For my taste the center point is too large, which brings me to the one real advantage of the 7D when talking about non-moving subjects...enabling the smaller, precise center point that is disabled by default. It offers a true pinpoint for focusing on small subjects that may be behind something larger (squirrel face looking out from behind a fork in a tree branch). In this case, the 5D or the default center point on the 7D will want to focus on the foreground object.

When it comes to sports or moving subjects, setting the 7D to use the 9 center points and AI-Servo, will blow away the 5D on AI-Servo. The 5D is still not bad in this area, but it is much harder to keep the focus on the moving subject...you really have to concentrate. For sports, you should definitely set the AF to start with shutter press.

The Too Long Didn't Read of all this is: 7D has better AF than 5D Mk II, but the 5D Mk II's AF is plenty good. For me, the image quality of 5D is more important than the slightly better AF of the 7D. UNLESS, I am shooting sports, then I grab my 7D every single time and set it to 8fps, 9 center AF points, and AI_Servo.

[bchernicoff]

If i may, the autofocus sensor receives light from the mirror so the more light hitting the mirror, the more light gets sent to the autofocus sensor... they are 2 separate sensors... the 7d DOES have a more advanced sensor, but light being light, if it doesn't receive as much light as the 5d does, it can only do so much...  In good lighting, the 7D kicks the 5d's butt every which way, but in low light, lighting becomes even more important. 

If you will, here's what I mean... the crop sensor is 1.6 smaller than a full frame sensor... a little more than half the size than a full frame sensor... Take 2 softboxes... both pumping out the same quality and strength of light... If 1 is on and the other is off, that's basically what a crop sensor is getting in light... a full frame camera would be like turning on the second softbox of light... you're not increasing any intensity of light but it's a bigger source overall 1 vs 2 and so it's more light and in terms of exposure, that's around 1 stop difference.  The full frame mirror will receive 2x the light gathered from the lens (all the light the lens can send it) and that light bounces into the AF motor.  The crop sensor still gets all that light but the mirror is smaller, sensor is smaller, and a lot of light is then wasted and not used...

You have to remember that each AF point only sees a very small amount of the total reflected light. The smaller mirror means that less total light is reflected, but this in no way diminishes the intensity of each point of light reflected up to each AF point. Using your 2x figure, the full-frame mirror reflects 2 times as many points of light as the crop mirror, but each of those points of light are the same intensity. If the AF points on the sensor are the same size between the bodies, each AF point receives the same amount of light. I do not know if they are the same size and if you have experimentally determined that in identically conditions with the only variable being the body, that the 5D has better AF performance, than this argues that each AF point is larger or more sensitive.

[awinphoto]

If i may, the autofocus sensor receives light from the mirror so the more light hitting the mirror, the more light gets sent to the autofocus sensor... they are 2 separate sensors... the 7d DOES have a more advanced sensor, but light being light, if it doesn't receive as much light as the 5d does, it can only do so much...  In good lighting, the 7D kicks the 5d's butt every which way, but in low light, lighting becomes even more important. 

If you will, here's what I mean... the crop sensor is 1.6 smaller than a full frame sensor... a little more than half the size than a full frame sensor... Take 2 softboxes... both pumping out the same quality and strength of light... If 1 is on and the other is off, that's basically what a crop sensor is getting in light... a full frame camera would be like turning on the second softbox of light... you're not increasing any intensity of light but it's a bigger source overall 1 vs 2 and so it's more light and in terms of exposure, that's around 1 stop difference.  The full frame mirror will receive 2x the light gathered from the lens (all the light the lens can send it) and that light bounces into the AF motor.  The crop sensor still gets all that light but the mirror is smaller, sensor is smaller, and a lot of light is then wasted and not used...

You have to remember that each AF point only sees a very small amount of the total reflected light. The smaller mirror means that less total light is reflected, but this in no way diminishes the intensity of each point of light reflected up to each AF point. Using your 2x figure, the full-frame mirror reflects 2 times as many points of light as the crop mirror, but each of those points of light are the same intensity. If the AF points on the sensor are the same size between the bodies, each AF point receives the same amount of light. I do not know if they are the same size and if you have experimentally determined that in identically conditions with the only variable being the body, that the 5D has better AF performance, than this argues that each AF point is larger or more sensitive.

Not if you think about terms of exposure... 2x the light means 1 stop difference... 1 stop difference means more overall intensity of light overall... The light source intensity hasn't increased but adding that extra bit of light makes a world of difference on exposure and in this example, light hitting each AF point. 

[K-amps]

If i may, the autofocus sensor receives light from the mirror so the more light hitting the mirror, the more light gets sent to the autofocus sensor... they are 2 separate sensors... the 7d DOES have a more advanced sensor, but light being light, if it doesn't receive as much light as the 5d does, it can only do so much...  In good lighting, the 7D kicks the 5d's butt every which way, but in low light, lighting becomes even more important. 

If you will, here's what I mean... the crop sensor is 1.6 smaller than a full frame sensor... a little more than half the size than a full frame sensor... Take 2 softboxes... both pumping out the same quality and strength of light... If 1 is on and the other is off, that's basically what a crop sensor is getting in light... a full frame camera would be like turning on the second softbox of light... you're not increasing any intensity of light but it's a bigger source overall 1 vs 2 and so it's more light and in terms of exposure, that's around 1 stop difference.  The full frame mirror will receive 2x the light gathered from the lens (all the light the lens can send it) and that light bounces into the AF motor.  The crop sensor still gets all that light but the mirror is smaller, sensor is smaller, and a lot of light is then wasted and not used...

The image sensor as you say is not the same as the focus sensor... are you saying the 7D has a crop (1.6x) focus sensor too?? 

[awinphoto]

If i may, the autofocus sensor receives light from the mirror so the more light hitting the mirror, the more light gets sent to the autofocus sensor... they are 2 separate sensors... the 7d DOES have a more advanced sensor, but light being light, if it doesn't receive as much light as the 5d does, it can only do so much...  In good lighting, the 7D kicks the 5d's butt every which way, but in low light, lighting becomes even more important. 

If you will, here's what I mean... the crop sensor is 1.6 smaller than a full frame sensor... a little more than half the size than a full frame sensor... Take 2 softboxes... both pumping out the same quality and strength of light... If 1 is on and the other is off, that's basically what a crop sensor is getting in light... a full frame camera would be like turning on the second softbox of light... you're not increasing any intensity of light but it's a bigger source overall 1 vs 2 and so it's more light and in terms of exposure, that's around 1 stop difference.  The full frame mirror will receive 2x the light gathered from the lens (all the light the lens can send it) and that light bounces into the AF motor.  The crop sensor still gets all that light but the mirror is smaller, sensor is smaller, and a lot of light is then wasted and not used...

The image sensor as you say is not the same as the focus sensor... are you saying the 7D has a crop (1.6x) focus sensor too?? 

The focus sensor isn't smaller but the light allowed through to the mirror to the AF sensor is proportional by the diminished light.... Canon isn't going to waste money putting a full frame size mirror into a crop body when it doesn't need it.  Plus by doing so, you would see image you wouldn't be getting anyways...  When you read reviews about the 5D's viewfinder, you read adjectives such as Big, bright, pictureframe... when you do the math, it makes perfect sense...

[awinphoto]

Dont get me wrong, I have the 7D and shoot regularly with 7D... I shoot almost 90% of my shots with that great camera... but it does have it's limitations and when the new 5d's are released... can you imagine what the 7D AF with the more light input of the 5D can pump out?  When that camera comes, if it has the same AF as the 7D, i'm dumping my 7D's in favor of the 5d's...

[sb]

PeterJ, I have both cameras. It is my subjective opinion that 5D does better in low light/contrast situations, but there is no question that 7D's system is noticeably better overall. That being said, Mk2's system is as good as I ever need it to be for what I do. If I were shooting sports, I'd definitely favor the 7D, hands down.

Simply put - these 2 cameras complement each other. One has better IQ (Mk2), one is faster (7D) so it boils down to what you shoot.

[Mt Spokane Photography]

I have both as well as having had a 1D MK III for the last two years.  For focus accuracy and low light focus, my 5D MK II beats the others.  For tracking moving objects, the 7d and 1D MK III are much better.

Speed of AF is largely a function of the lens used, but my 1D MK III was noticibly faster to AF, and in some cases, so is the 7d.

If you are one of those trying to focus on very fast moving objects or track them as they move from side to side, the 7D and 1D MK III will obviously be better.

If you have a wide aperture lens like a 35mmL, the 5D MK II will focus more accurately (using the center point), and the larger viewfinder of the 5D MK II and 1D MK III makes manual focusing much easier.