Full Frame, please explain

[Gaffer]

i dont get this..are you saying crop is better or worse?

I was poking fun at Inquisitor. He is saying that with full frame, you can't use EF-S lenses. I'm saying that with full frame, you don't need EF-S lenses.

It is two sides of the same coin.

I think that most would agree that for the best quality, you want full frame, but you pay a significant premium for FF bodies. And the reality is that with a FF body, you'll end up spending more on glass too (because you'll end up with longer focal lenghts...)

Some of the improvements are subtle. Nicer viewfinder. Ability to get the full use of ultra wide angle L-glass. Better low light performance. Better resolution. Better bokeh. Whether they are worth a significantly higher price tag is something that only you can decide.

I have only full frame bodies and mostly L-glass...

Andrew

 

[Gaffer]

Yes, but you're capturing that part of the image at a much higher resolution.

Hmmm...

Lets look at a range of cameras.

Number of horizontal pixels per milimeter:

5D = 4368/35.8 = 122
1DIII = 3888/28.1 = 138
1DsIII = 5615/36 = 156
450D = 4272/22.2 = 192

A mixed bag...

My 1DsIII has more dense pixels than it's 1DIII stablemate.

There will be a quality tradeoff to cram all those pixels into the little 450D sensor...

Andrew

 

[Inquisitor]

Hmmm...

Lets look at a range of cameras.

Number of horizontal pixels per milimeter:

5D = 4368/35.8 = 122
1DIII = 3888/28.1 = 138
1DsIII = 5615/36 = 156
450D = 4272/22.2 = 192

A mixed bag...

My 1DsIII has more dense pixels than it's 1DIII stablemate.

There will be a quality tradeoff to cram all those pixels into the little 450D sensor...

Andrew

I said nothing about quality

You're right of course that ultimately a full frame body can do everything a crop body can do. It's just a question of whether or not you have the cash to spend on better/longer EF/FX glass where an EF-S/DX equivalent could've provided the same results on a crop body

 

[V-Spec]

I think its a bit "weird" to say whether full frame is better or worse than crop. They both have their own pros and cons, and it all comes down to what you do..

I'd like a 1DS for wildlife portrait work where ultimate length isn't required, and I don't have to worry about high ISO, as the 1DS MKIII isn't wonderful at over ISO 400. It does however produce massive warm nice files not too different from Kodachrome film. The noise isn't that much of an issue for me.

There is a subtle difference regarding bokeh (ie: getting the background out of focus)

For a given subject at a given distance, you will be using a shorter focal length with a crop frame.

This means that for the same shutter and aperture values, you will have more depth of field with the crop setup.

This means that there is a trend towards getting better bokeh from a full frame.

Subtle, eh?

Andrew

I don't normally research this kind of stuff, but I don't really understand how that works?

Surely, the lens is presenting the same image to both types of sensor, the crop one is just chopping the outside away, so ultimately the depth of field and bokeh must surely be the same, the only difference being that with a FF camera you get the full image, I don't see how a cropped or full frame sensor affects the bokeh/dof as thats all generated by the lens??

I understand that the focal length multiplier of the crop gives the *impression* that you're shooting at a longer focal length, but thats only because your looking at a zoomed in crop of exactly the same image that a full frame sensor would record..?

 

[Inquisitor]

I don't normally research this kind of stuff, but I don't really understand how that works?

Surely, the lens is presenting the same image to both types of sensor, the crop one is just chopping the outside away, so ultimately the depth of field and bokeh must surely be the same, the only difference being that with a FF camera you get the full image, I don't see how a cropped or full frame sensor affects the bokeh/dof as thats all generated by the lens??

I understand that the focal length multiplier of the crop gives the *impression* that you're shooting at a longer focal length, but thats only because your looking at a zoomed in crop of exactly the same image that a full frame sensor would record..?

I think what he means is that for a given field of view on a full frame body, you'll be using a focal length than you would be on a crop body, so this affects the DoF.

 

[D.P.]

With a cropped body, you will use a focal length 1.5 times smaller to get the same subject size in the frame. The DoF is a function of aperture, focal length, and distance to subject.

With longer focal lengths you get less DoF for a given aperture - hence at a real 14mm focal length and f/5.6 you would still have a large DoF useful for landscape, while at 500mm f/5.6 the DoF is small, isolating your subject on nice out-of-focus background.

hence with full frame you will use a focal length 1.5 times that of the cropped sensor counterpart, decreasing the DoF.



the DoF itself doesn't change between sensor sizes, if the focal length was constant. But since the FL changes, the DoF changes.



It should also be stated that this can be a negative - with FX sensors you need more focal length to capture the same scene but if you need sufficient DoF to keep everything in focus this is harder to do because you will need to decrease the aperture to gain the DoF.

this is apparent in macro Work where usually you want the biggest possible DoF to keep the whole of your Bug/flower in focus etc. And also in Macro work it is often good to get the free 1.5x tele extender. The downside of course is that Macro work is one area where especially detailed and sharp images are desired (hence Macro lenses are the sharpest around). And Macro work often requires the use of a tripod because one is zoomed in so much and so close to the subject and the fact that to get you large DoF you will push to smaller apertures loosing light. a tripod is not great outside. The Ability of the Nikon D3 to push to such high noise levels maywell exceed the disadvantage of decreased DoF.

 

[Gaffer]

Surely, the lens is presenting the same image to both types of sensor, the crop one is just chopping the outside away, so ultimately the depth of field and bokeh must surely be the same

Absolutely correct.

But you just lost a big chunk of the image because it is cropped. So, all else being equal, you need to change to a shorter lens... And there goes your bokeh.

It is sort-of artificial comparision but it does also reflect the reality you are likely to select a shorter focal lenth lens for a crop camera than on a full frame and that this in turn has an influence on the depth of field that you are able to achieve.

Of course, whether you consider one or the other to be an advantage is entirely up to you

Andrew

 

[V-Spec]

Absolutely correct.

But you just lost a big chunk of the image because it is cropped. So, all else being equal, you need to change to a shorter lens... And there goes your bokeh.

It is sort-of artificial comparision but it does also reflect the reality you are likely to select a shorter focal lenth lens for a crop camera than on a full frame and that this in turn has an influence on the depth of field that you are able to achieve.

Of course, whether you consider one or the other to be an advantage is entirely up to you

Andrew

Gotchya,

 

[BUFF]

This could simply be that the A700 sharpens the image more than the Nikon, or processes the images in other ways (e.g. boosting contrast).

Well, he's a pro (yes, some do use Minolta/Sony or Pentax or Olympus etc. ) & shooting in RAW so I'm assuming that he's talking about a level playing field.
As I said he reckons that it's down to Nikon's choice of aa filter for the sensor.

 

[Gaffer]

Gotchya,

Thankyou.

I feel that I understand it better, now that I have sat and thought of a decent explanation...

Andrew

 

[aztechnology]

Absolutely correct.

But you just lost a big chunk of the image because it is cropped. So, all else being equal, you need to change to a shorter lens... And there goes your bokeh.

It is sort-of artificial comparision but it does also reflect the reality you are likely to select a shorter focal lenth lens for a crop camera than on a full frame and that this in turn has an influence on the depth of field that you are able to achieve.

Of course, whether you consider one or the other to be an advantage is entirely up to you

Andrew

I'm pretty sure we both know what your are referring to, but Bokeh, isn't quite the term for it as far as I am aware.

Bokeh is a Japanese derived term for the subjective quality of the out of focus parts of an image. Two different lenses of the same focal length and the same maximum aperture, can give results that are more or less attractive than each other. It's a function of the lens design, type of glass, and the type (and design) of aperture mechanism used.

I think you are referring to Depth of Field. Which is independent of Focal Length, if you end up with the same final image size*. See Here

I think this is the link I found useful when trying to work out the DoF issues of crop sensors.


* - apart from near Hyperfocal distance issues.

 

[V-Spec]

I think what Gaffer is saying is that the Bokeh would be better on a full frame camera than it would a crop camera.
This is because to get the same image on a full frame camera you need to be closer to the subject, which will give a better bokeh, as a shorter piece of glass will be slightly higher quality, and you'll have a much larger image containing that bokeh, so the end result will be better.

With a crop camera you won't need to be as close, as the crop zooms things in a bit, but because you're further away from the subject, the lens is longer and thus the perspective compression is greater, and because you're further away the dof will be increased slightly, and not as blown out. (I think )