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Registered: ‎07-21-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

[ Edited ]

Thank you to you both for the responses and input! Very much appreciate the time folks are taking to help me figure this out Smiley Wink and learn a lot along the way!

 

Since my daugher is usually just sitting somewhere and fidgity or acting out minor scense with her toys (vs acuatlly moving - ie walking, running playing socker or playing hockey etc) i use Single Shot.  But i know definately understand the other modes better - thanks for the detail!

 

The part that i'm hung up on is that she moves ... but when i say that i mean she looks at me, i'm using Single Shot, press the shutter down half way, camera locks focus and then she moves before i press it all the way... she moves maybe 1/2 an inch...by turning her head slightly or smilling more or less etc... i would have thought that since the DOF allows for an inch or less (roughly 60mm, 3 feet way, using a f/2.8 or 4 - based on a calculator i found online) - her eye that i had focused on should still be in focus??? No??  i guess i'm confusing DOF and focus???

 

If she is only moving an inch or less would you consider using AI Servo or AI Focus? would it still work well with and f/2.8-3.2 and give me that nice sharp image with lots of bokeh in the back (if i'm shooting from 3-4 feet from her and using maybe something like 50-60mm zoom, and 1/250)?

 

Also, sounds like a child moving around is different than a bird in flight Smiley Wink and bird in flight might fit better with the 70D and the fidgitty child the 6D??? is that a good representation?  or would you still consider the 70D over the 6D for the 'fidgity' child? is the 6D more than capable of that sort of movement?

 

 

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Body: Canon 6D, Canon T1i, Canon Elan II,
Glass: Canon 24-70mm f/2.8L II USM, Canon 70-200 f/4 IS II, Canon 16-35 f/4, Canon 100 f/2.8 macro.
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Respected Contributor
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Registered: ‎02-06-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

Maria,

When I take portraits the way you describe, I don't use AI Servo or the other in between mode because I don't think it's accurate enough, especially if using  f/1.8.  Having said that I haven't tried so I wouldn't know. You may still get much better results not using the single shot mode for a fidgeting child.  You might want to experiment and compare.

 

Once you set the Tv to a high enough value to eliminate movement blurs, you just need to focus and take the shot quickly before your daughter moves - and take many to get a few keepers.  Sometimes the kind of precise focus that you are looking for is not appropriate for a fidgeting child...when she's fidgeting, set Av to f/5.6 instead of 2.8 or 1.8.

 

The reason I mentioned the 70D may have an edge for Birds in Flight (BIF) is that it has more focus points so it can better track the moving birds (moving several yards across from you) in AI Servo mode.  For a fidgeting child that moves several inches, I can't see if either camera will have any advantage, focus-wise.  In this scenario, the 6D has an edge because of the sensor size (full-frame) so theoretically at least, your image will have less noise and better Depth of Field (see TCampbell's post).

 

Also in your focusing method (which is the default), I can see another possibility for blurred pictures...the default method of re-focusing every time you press the shutter button can throw focus off as I think you already have observed.  Say you had the left eye in focus then she moved half an inch as you press the shutter button, the camera would refocus , now the focus was on her nose or worse on the couch behind her.  There are three ways I know of combating this.  One is the focus lock button (you can program either the * or the Focus button to do this).  So you press the button and lock the focus.  Two you keep the shutter half-depressed the whole time so it doesn't refocus.  Three you program the camera not to focus when the shutter is depressed.  You use the focus button to focus instead.  I chose option 3 so once I focus, it doesn't change until I command it to change by pressing the focus button.

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Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

Small movements aren't an issue unless you are close distances using a very low focal ratio (low f-stop value).

 

When you focus the camera, it turns out there is actually a "range" of distances at which your subjects will appear to be acceptably focused.  That zone or range of distances at which things will appear to be acceptably focused is referred to as the "Depth of Field".  We sometimes abbreviate it as DoF when talking about it online.

 

For example... if you are using a full-frame camera body such as the 6D and you are using a 50mm lens at f/4 (I'm just picking these as an example) and your subject is 10 feet away, THEN you have a "DoF" of about 3'.  

 

Specifically in that example, everything from 8' 9" to 11' 8" will appear to have acceptably sharp focus.  Anything closer will be appear to be just slightly blurry... anything a lot closer will appear to be very blurry.  The same is true going farther way... something 12 or 13' away will appear to be slightly blurry... something perhaps 20' away will appear to be very blurry.  

 

The size of the field where subjects are nicely focused depends on three things:

 

1)  The focal length of the lens -- short focal lengths (wide angle lenses) have a VERY generous depth of field.  I have a Canon EF 14mm f/2.8L II.  The depth of field at a 14mm focal length is so generous -- that lens practically doesn't need a focus ring (of course it has one... but if I focus it for about 3 to 4' away, the whole world will appear to be acceptably focused.)

 

2)  The focal ratio (f-stop) value being used.  Very low numbers create a shallow depth of field.  Very high numbers create a very broad and generous depth of field.  Of course those high numbers also allow less light through the lens so the exposure time gets longer.

 

3)  The distance to the subject.  At very close focusing distances, the depth of field becomes narrow.  In fact when I use a macro lens, the depth of field is so thin that it's just a few millimeters thick.  This is a case where just a tiny bit of movement would put something out of focus.  But when subjects are farther away, the depth of field naturally grows to a very generous size.

 

If you combine all those factors... to the "narrow" extreme, then a "long" focal length lens with a very low focal ratio at very close focusing distances (such as what happens when I use my 100mm "macro" lens at it's lowest focal ratio and closest focusing distance) you end up with a "paper thin" depth of field.    But if you go the other way... to the "broad" extreme, then a wide angle lens with a high focal ratio and distant objects is so very generous with the depth of field that you practically don't need to focus the camera at all.

 

You can read articles and watch videos to learn more about how depth of field works.  Here's a link to one such site:  http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

 

Suppose you have Canon's EF 50mm f/1.2L lens (which is a fairly expensive high-end lens... but an f/1.2 focal ratio is VERY low) and you were taking a portrait of your child specifically at f/1.2.  Suppose the child is 3'6" away.  At that distance, using that focal length and f-stop, the depth of field is literally just 1/10th of a foot.  Barely over an inch wide.  At such distances your childs eye's might be in focus, but their nose and ears would most certainly be quite blurred.  If you back away by merely 6" but change no other settings, the depth of field grows to just about 2".  At 5' it grows to about 3".  So you can see how increased distance improves the depth of field.    If you back off the f-stop to f/4 it will grow to about 8".  

 

I'm giving some examples to show that with some settings, a small amount of movement on the part of your child will not affect the focused result... but other settings will be very sensitive to a relatively small amount of movement.  

 

Once upon a time, lenses had marks on the focus ring which showed the depth of field at various focal ratios.  Some prime lenses still have these marks on them.  Most modern zoom lenses do not have the depth of field marks (push-pull zooms sometimes do -- but few modern lenses use push-pull zooms.)

 

Tim Campbell
5D III, 5D IV, 60Da
Frequent Contributor
Posts: 84
Registered: ‎07-21-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

THANK YOU both again! Smiley Wink  really appreciate the information!

 

Re Camera: Today is the last to decide about the camera (need to return one of the two tonight or tomorrow morning at the latest).  From your comments (unless i'm missunderstanding) doesn't sound like i will go wrong with the 6D.  That for my purpsose (fidgiting child, usually sitting or walking, in my living room) the 6D is the better choice. BUT if i start taking more shots outside or in better light the 70D may be a better idea .... does that sum it up correcty?

 

Re Lenses/DOF/Focus: I primarily am using my Canon 24-70 f/2.8L II for all the shots - when not i've been testing out the 24-105 f/4L that came as the kit lens with the 6D.  Even though i use the Single Shot and center focus point (i always push the shutter down half way to lock focus then recompose and don't lift my finger until i have taken the shot - so as far as i know it should be refocusing) i have been trying to 'expand' by using one of the other focus points (the one closest to where the eye is) to avoid changes in distance that will imapact the focus at close distances.  I've found that when using the 24-70 at about 60mm at 1/125 and f/3.2 if i use any of focus points other than the center one on the 6D the shot is not as sharp as the 70D.  ;(  I've read the 70D has 'better' focus points (center one still suggested to be better on the 6D).. so how do i find that balance of when to use center one vs the others?  ....

 

Tim - have read all the information you posted - and i think i understand it all Smiley Wink thank you for spending the time to explain! when i look at my 24-70 lens and i do the caluculations (online of course) to see the DOF at the distances i use (usually 3-4 feet from my daughter) i should have about an inch of room - so i would think that if i've focused on her eye even if she moves (but only less than an inch) at least part of her eye should still be within that plane and in focus? No?  i know it's not scientific and difficult to be sure how much EXACTLY she moves, left, right, up, down etc, but theoretically some part of her eye should be in focus if she did not move all of it more than an inch - correct?

 

Learning a lot!

 

But still not sure about which camera ;(  those darn focus points are worrying me...

 

____________________
Body: Canon 6D, Canon T1i, Canon Elan II,
Glass: Canon 24-70mm f/2.8L II USM, Canon 70-200 f/4 IS II, Canon 16-35 f/4, Canon 100 f/2.8 macro.
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Registered: ‎06-11-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

Years ago there was no need to do calculations for depth of field because most manual focus lenses had depth of field marks on the lens.  Today, some prime lenses still have the marks, but they are almost never seen on zoom lenses anymore (it really needs to be a lens with a push/pull zoom).  

 

I've attached a photo of my original Canon AE-1 35mm SLR (this was the first real camera that I ever owned... I think I got this in 1977 and it still works great!)

 

Hyper-Focal.jpg

 

On this camera, the f-stop / aperture ring is actually on the lens (it's the ring closest to the body.)  Noticed it's currently dialed in to "22" (f/22).  But notice just above that, there is a scale with a center mark and numbers going up both left and right of the center mark.  The outermost marks are "22".  If you look at the focus ring (just above that scale), this means everything from the "22" on the left to the "22" on the right will be in focus.  The "22" on the right is at infinity.  The 22 on the left is roughly around 6'.  This means that with this 50mm lens currently "focused" to just about 11', everything from about 6' to infinity will be in focus (btw, this lens just happens to be focused to the "hyper focal distance" -- but that's another subject.)

 

You can also see by looking at the scale that the inner-most marks (the "4"s just left and right of center line) would have a rather narrow depth of field ... that looks like it might be from about 10' to about 13'.   While this lens does go down to f/1.8, they don't bother to etch those marks -- but you can well imagine it would be extremely narrow.

 

If you give yourself a few exercises (commonly you would line up a lot of identical objects (bottles, cans, dominos, etc.) go to one end of the row, "focus" on the center object, and experiment by shooting with both very low focal ratios and very high focal ratios and compare the results.  

 

Use low focal ratios (f/2.8, f/4) when you want selective focus and want to deliberately blur the background.  You high focal ratios (f/11, f/16) when you want to maximize what you have in focus (e.g. landscape shots).  When everything is roughly the same distance from the camera, use the middle focal ratios (f/5.6, f/8) because most lenses tend to deliver their sharpest results when those middle focal ratios are used.

 

While most of my lenses offer me f/2.8 or better, I seldom shoot at f/2.8 -- usually I'm up around f/4.  Here's an example:

 

Perch

 

This image was shot using my 5D II (full-frame -- like the 6D), using the Canon EF 100mm f/2.8L IS USM Macro lens -- but the lens is at f/4 for this shot.

 

Notice the asparagus tip at the near edge of the plate...  look carefully and you'll see it's a bit out of focus (but slightly behind that everything is quite sharp.  Now notice the asparagus at the far side of the plate and you can see that's also just out of focus.   The "hero" (that's the term for the main subject in food photography -- this happens to be perch with a dill cream sauce) is sharp all the way from front to back.   Had I used f/2.8 it would not have been completely in focus all the way through.  

 

Also... I wanted the background to be blurred, but only slightly.  I wanted to make sure that the background elements in this photo were blurred... but recognizable for what they are.  They provide a nice compliment to the food.

 

While you might be tempted to crank open to to f/2.8 when photographing a subject in low light... keep that depth of field in mind.  Sometimes wide-open is not your best option.

Tim Campbell
5D III, 5D IV, 60Da
Respected Contributor
Posts: 1,117
Registered: ‎02-06-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

[ Edited ]

@Maria wrote:

THANK YOU both again! Smiley Wink  really appreciate the information!

 

Re Camera: Today is the last to decide about the camera (need to return one of the two tonight or tomorrow morning at the latest).  From your comments (unless i'm missunderstanding) doesn't sound like i will go wrong with the 6D.  That for my purpsose (fidgiting child, usually sitting or walking, in my living room) the 6D is the better choice. BUT if i start taking more shots outside or in better light the 70D may be a better idea .... does that sum it up correcty?

 

Maria,

Not quite what I mean to say...the 6D, with a larger sensor, should be better in all light conditions.  Not counting video, the 70D only has an edge if you do a lot of sports and BIF shooting that needs:

1. faster frame rate

2. better AI Servo type focusing

3. More reach - the cropped 70D gives you 1.6 advantage in reach than the 6D - for the same focal length, say 70mm, the 6D shows you an image at 70mm view while the 70D shows you an image magnified 1.6 times as 112mm.

 

So, imho,  70D is a better idea if you shoot sports and BIF...anything else you are better off with a 6D.

 

================================================
Diverhank's photos on Flickr
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Posts: 84
Registered: ‎07-21-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

Love that picture Tim! Makes me hungry and understand things better. My first real camera was an A-1. Sold it years ago - wish I had kept it.

One thing re the 'sport' comment - would you consider a figity, moving child in the 'sport' category?

I love the ISO range on the 6d but when using the shutter button feels soft to me - meaning I feel a tiny delay in taking the shot. Something I'm sure I can get used to but different. Also seeing the benefits of all the extra focus points on the 70d - I used to always use centre, focus and recompose but about 6 months ago started using all the other focus points.

About 4 hours left to make a decision. Now leaning towards the 70d - just wish it did better on low light . I've been avoiding using a flash but that may be silly of me.

Would love any further thoughts feedback and especially the 'sport' = child piece Smiley Wink
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Body: Canon 6D, Canon T1i, Canon Elan II,
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Registered: ‎06-11-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

I would consider a child playing outside (i.e. running around) to be in the "sport" category. Indoors, I'd probably shoot One-Shot mode and allow for a depth of field to deal with the modest changes in distance. (i.e. being basically in one place... but squirming around a lot.)

I've heard of this "mushy" shutter button. I have a friend who recently bought a 6D but I have yet to get my hands on one. I'll have to go bug him and find out what this shutter button is all about. Every other Canon DSLR I've used has a shutter button that feels about the same as all the rest -- so it surprises me that Canon would change something that's worked so well.
Tim Campbell
5D III, 5D IV, 60Da
Frequent Contributor
Posts: 84
Registered: ‎07-21-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

[ Edited ]
Thanks Tim! I keeping back and forth between the two cameras. I don't think I'll do badly with either. I just went for a walk (very grey day here) and walked around with each camera to see which felt better in my hands, talking shots etc. although I love that the 6d is full frame and has better ISO range the 70d felt better (in my smaller hands). So was set on the 6d but now think it may be the 70d. Yes I'm VERY indecisive Smiley Wink

One more thing re the child being like 'sport', would that mean I'd need to shoot on AI SERVO and continuous shots (of the moving figity child) or can I use One Shot and continuous? ie does it ever make sense to use that last combination together?
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Body: Canon 6D, Canon T1i, Canon Elan II,
Glass: Canon 24-70mm f/2.8L II USM, Canon 70-200 f/4 IS II, Canon 16-35 f/4, Canon 100 f/2.8 macro.
Flash: Canon Speedlite 430ex ii
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Posts: 84
Registered: ‎07-21-2013

Re: 70d vs. 7d - which to get? does anyone have both? which do you prefer and why?

Decision made! I am going with the 6d. Returned the 70d. I was sold in the 70d earlier today but I know I'd always regret not having the ISO range the 6d offers.... Now to learn to use it to it's full potential - and mine!

Thank you VERY much for all the input!!! I really appreciate it! It was extremely valuable and helpful!!

Now to get my daughter to 'freeze' for portrait type shots Smiley Wink I'm thinking a game of sorts may help. Then in the next couple yrs if she does get into sports or I can't get her to stop fidgeting I can always sell the 6d and get a used 70d or whatever else is out there then Smiley Wink

Again, thank you!
____________________
Body: Canon 6D, Canon T1i, Canon Elan II,
Glass: Canon 24-70mm f/2.8L II USM, Canon 70-200 f/4 IS II, Canon 16-35 f/4, Canon 100 f/2.8 macro.
Flash: Canon Speedlite 430ex ii
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