Questions About Nature Photography? I'm Here to Help!

[Tim]

Hi Everyone! I'm Tim, a senior technician here at Canon. I'm going to be here on the Canon Forum, live later today, from 3:30-4:00pm EST to kick off a community discussion on Nature Photography! I'll be here to answer your questions, provide tips and bounce ideas around, so drop on by and join in on our conversation!

I'm a long time photographer with over fifteen years of technical and photographic experience with Canon and the imaging industry. I particularly enjoy working with full-frame cameras and Canon's Cinema EOS gear, and take every opportunity I can to capture the beauty of the Atlantic Ocean near my home.

[clars]

Regarding full-frame and crop sensors for shooting wildlife, do the crop sensors actually get you 1.6x closer? I know the sensor is larger on the full-frame, but how come the smaller crop sensors get you closer ot the subject or is it just appearing that way because of the tighter cropped image?

[Tim]

Hello Clars,

With regards to full frame cameras versus APS-C, there is a physical attribute of magnification with APS-C cameras (like the EOS Digital Rebel series).  So, for example, if you were to use an EF 70-200mm f/2.8L IS II USM lens on an APS-C camera, the focal length becomes an effective 112-320mm, but only on APS-C.  The reason being the difference in sensor size.  Canon's EF standard was originally developed for the 35mm film size.  So using an EF lens with full frame, focal lengths do not change.  The APS-C sensor, being smaller, imparts a slight magnification ratio which, as you know, is 1.6 times. 

So, for shooting wildlife, one benefit of using EF (over EF-S) on APS-C sensor cameras is the longer reach, you get more telephoto than originally bargained for, so to speak.  The one downside is that you lose wide angle in this equation.

If you are interested in a camera that would both remain true to marked focal lengths on your EF series lens and deliver outstanding image capture ability, then a full frame camera like our EOS 5D Mark III, would be appropriate.  This of course is not the only benefit of shooting full frame, but since your inquiry was lens oriented I've focused on that aspect specifically.   

I hope this helps answer your question, and should you need further clarification or additional help - I trust you will let me know! 

[clars]

Cheers Tim, it does help a ton. Had recently upgraded two 60D's to 6D's and was suprised. A pleasant suprise for how much more image I could get with the 6D, really help showed the natural habitat of the wild animals, but confused on why the subject seemed that much further away. To clarify the 1.6x magnification is a true zoom and not something I could achieve in post processing by increasing image 1.6 times?

[hsbn]

It's not a true zoom. It's still a crop. For example, your 60D is an 18Mpx camera. So if I have a 45Mpx full frame camera, I take the photo and crop it in post processing i will get the exactly same as your 60D. But there is no Canon 45Mpx camera.

[Tim]

Hello HSBN, and thanks for joining our chat! 

The zooming effect incurred on APS-C cameras when an EF series lens is used is an optical phenomenon due to the image circle being designed around larger sensor [or film plane] coverage.  Since the EF lens series were originally designed to be 35mm film lenses [which subsequently influenced full frame digital] their coverage is more than what is needed for the smaller APS-C sensor, the end result of which is a ratio of 1.6x.  But it is in fact a physical effect and not one of the cameras’ cropping the image to gain more zoom. 

This is not an effect limited to 35mm cameras either; a normal lens on 35mm is about 50mm- on a medium format camera a normal lens, e.g. one with a similar angle of view, is more like 90mm and one step larger to the 4 x 5 large format, a "normal" lens is in the range of 150mm.  Focal length as a marked value is always relative to the format the lens is designed to cover versus a fixed value.

[ebiggs1]

Tim,

This may just be semantics but the focal length of a lens is fixed at manufacture and can not be changed afterward.

No matter what body, APS-C, FF or 4x5, etc. it is used on.

A 75-300mm lens is still a 75-300mm lens, whether it’s attached to a cropped-sensor camera or a full-frame.

What is changed is the “angle of view”. This refers to how much of a scene the lens covers. Fisheye lenses, the widest available, can capture 180-degrees. As you zoom in or change lenses to increase the focal length, the field of view narrows sometimes to just a few degrees. You can isolate small portions of the scene without moving closer to the subject.

Lens focal lengths are based on the physical characteristics of the lens so they are absolute values.

[Skirball]

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@Tim wrote:

The zooming effect incurred on APS-C cameras when an EF series lens is used is an optical phenomenon due to the image circle being designed around larger sensor [or film plane] coverage.  Since the EF lens series were originally designed to be 35mm film lenses [which subsequently influenced full frame digital] their coverage is more than what is needed for the smaller APS-C sensor, the end result of which is a ratio of 1.6x.  But it is in fact a physical effect and not one of the cameras’ cropping the image to gain more zoom. 

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You're being very selective in your words.  What you say is technically true, but misleading. 

If you use an EF lens, a lens that will work on both full frame and APS-C cameras, there is no physical effect. It simply crops out the outer boarders.  Yes, APS-C cameras allow use of different optics (i.e. smaller optics), but if anything that advantage lies in being able to offer cheaper lenses to do the equivilent of a FF option. 

I disagree that the zooming is an optical effect, that implies (at least to me) that it's due to the optics. You're simply viewing a crop of the original image (35mm equiv) at a larger magnification.  This applies to both the image you see in the viewfinder, and the image displayed on the computer monitor afterwards.  It wouldn't be considered a zoom at all if it wasn't for the fact that you pack more pixels on the smaller chip.  As noted above, if you made a FF sensor with the same pixel density you could crop out that inner section and get the identical "zoom effect".

[ebiggs1]

Nothing changes about the lens; it's simply the amount of the image that is used from the back of the lens. Canon's EF Lenses still focus the image on the same plane as before, but sensors are smaller than 35mm sensors and do not capture the entire image. They don't actually “crop” the image, it simply is not there to begin with.

All lenses produce a round image not a square one so even FF sensors discard some of what the lens sees. And this is not  technically a crop. It simply is not used. Ignored.

The most accurate definition for this is angle of acceptance or field of view. Whichever you prefer.

I realize the terminology of “crop sensor” has entered the photographic jargon but it is somewhat misleading. The bottom line is all DSLR's are full frame cameras since you get what you see in the viewfinder. More or less, that is, and the rest is just numbers printed on the outside of the lens to indicate what the lens is.

[Skirball]

I’m well aware of the physics behind the lens; nowhere did I claim it changes the lens. The rest of your stance is purely semantics.  I don’t find the term misleading at all, the image captured by an APS-C sensor is indeed a crop of what would have been captured by a 35mm “full frame” sensor using the same lens.  Most people don’t have that much difficulty understanding this concept, or utilization of the term.  Some may misunderstand it, but such is the case any time you simplify something.  It’s easier to say crop sensor than reference “the angle of acceptance afforded by an APC-S sensor relative to a 35mm sensor”.  I’m going to stick with calling it a crop sensor, and know that most everyone I talk to knows what I mean, and the effect it has on the field of view.