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With Canon the 1.6X crop factor does apply to an EFS Lens also and all other EF style lens. I would also assume that this is true of 3rd party lens also.
Here's a qoute from a lens review:
Equivalent to a 16-35mm zoom on a 1.6x field of view crop factor camera, the Canon EF-S 10-22mm f/3.5-4.5 USM Lens fills a gap in Canon's ultra wide angle lens lineup.
Posted 69 months ago.
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The lens angle is unaffected by the crop factor of the camera.
A 10mm lens is a 10mm lens is a 10mm lens irrespective of what crop factor your camera may impose.
With several different sized sensors on the market it would be very confusing for lens manufacturers to scale their lenses accordingly. If that is what your friend is implying he is mistaken.
However he's partly right - you are shooting at 10mm, but the lens isn't scaling at all.
The multiplication factor is merely a convenient way of expressing the field of view you will achieve with the reduced sensor size.
Can anyone else explain this better than I can?
Posted 69 months ago.
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I agree with your statement fully that the lens is the size that it is.and that's very clear. The image you get with the camera isn't 10mm but a cropped version based on sensor size unless you have a full sized sensor that's the size of a 35mm film image.
I do wildlife photography and I love the 1.6x crop factor. It makes a 300mm f4 lens produce images like it was a 480mm f4. It also eliminates the corner resolution fall off on most lens.
Art
Posted 69 months ago.
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As usual, Nikon users not having a clue :-)
Posted 69 months ago.
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Right. Compact cameras often state (erroneously, but they're dealing with a less informed market sector) that they have e.g. a 35-350mm zoom lens (like my Fuji, which really has a 5.7-57mm zoom lens, when they should be stating "in 35mm equivalent terms" but Joe Average p'n's user wouldn't have a clue about the maths so they usually don't bother in ads).
SLR lenses always, without exception, state their true focal length. A 10-22mm EF-S lens, if you could even use it on a full frame camera, would be a fisheye-wide zoom. It's not. It's just a superwide-moderately wide zoom.
Posted 69 months ago.
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You have a 10mm lens, but with anything under a 5D you're shooting at 16mm.
In other words, your widest landscape on the camera you're using with a 1.6x conversion would be approx 1/3 wider with a full-frame sensor. That extra picture just falls off to the side of your current camera's sensor.
Posted 69 months ago.
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You are shooting at 10mm.
BUT with a 35mm (or FF dSLR), you would need to shoot at 16mm to get the same shot at the same position.
Posted 69 months ago.
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So the short answer:
No.
Posted 69 months ago.
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Leaving the technicalities aside Mormegil summarises it best... the lens is set to 10mm (as it shows) but because of the size of the sensor the whole field of view is not visible, hence the crop factor, and if you were try to get the same shot with a 35mm camera you would need a 16mm lens.
I find it easier to think in 35mm equivalent lengths, especially for hand-held shutter speed checking, so I always consider the shot including the crop factor, so in this case I would refer to it as shot at 16mm.
Posted 69 months ago.
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alright then...
why did canon call their ef-s kit lens 18-55, when really its a 28-90?
Posted 69 months ago.
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i was under the impression that ef-s were actually the focal lengths advetised (as they were made for the smaller sensors). just the rest of the ef lenses are victim to the crop factor.
but...i may be wrong.
Posted 69 months ago.
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Biggy Fries: Your impression is incorrect, but read on. :)
puja: The 18-55 is just that, a zoom lens that adjusts from a focal length of 18mm to 55mm. Just as your 28-90 zooms from 28mm to 90mm.
The point that you may be missing is that the sensor for a 1.6x crop factor camera is like a stenciled rectangle on the traditional film-size rectangle of a negative or slide. Your 50mm lens "projects" an image onto the back part of your camera that would cover an area as large as a film negative or the full-frame sensor of a 5D, but the "cropped sensor" is smaller and only uses the middle 62.5% of the projection. (Using rough math here regarding the percentages.)
Picture your film camera (or Canon 5D) capturing an image of the front of a school, from building edge to building edge. It doesn't matter what lens we use for the shot or the focal length.
Now picture a smaller rectangle drawn on that image that is about 38% smaller than the field of view captured by the film camera shot. It would exclude the the ends of the school building, some of the sky and some of the foreground, just like we were using a longer lens – just like a lens that was 1.6 times longer in focal length. That's the view that we would record with an XT, 20D or 30D.
This is how a crop factor sensor "sees" the scene. It's a smaller sensor than the film (or full-frame sensor like the 5D) and so the rest of the view is just sort of splashed off of the sensor edges. (Not really splashed off, but for our purposes here). It's sort of like having a projection screen set up in your house, but the projector is set so that 38% of the projected image is cast outside of the screen boundaries. We don't see or enjoy the details outside of the dimensions of the projection screen.
For our lenses, we're using the same focal lengths but the smaller sensor is recording only the middle 62.5% of the projected image. (Over simplified, but mostly correct.)
The EF-S lenses make no adjustment to the focal length of the lens. EF-S refers to the mount and that's all. An EF-S lens will only mount to an EF-S compatible body. This way, Canon can make lenses which are sharp in the middle 62.5% and not worry about the edge sharpness that would be in the area of view outside of the sensor area. This is great for crop-sensor users because the lenses can be sharp to the edge of the field captured without the expense of true edge-to-edge sharpness. We can't see what we don't capture on the sensor. This is also why many lenses make great images on a cropped-sensor body where soft edges are hidden from our view (because we only use the middle 62.5% of the lens's field of view).
Originally posted 69 months ago.
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Dale Allyn (a group admin) edited this topic 69 months ago.
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why did canon call their ef-s kit lens 18-55, when really its a 28-90?
Maybe I didn't answer this part very well in my above post.
If we digest and accept my above post, then we can look at it like this:
When we take a photograph with a crop sensor body using our lens at 18mm, the sensor is recording the middle 62.5% of the area that the lens can see. This is taken into account in the view finder by the size of the mirror and masking in the view finder. That 62.5% middle area is the same area that we see on our film camera or full-frame sensor DSLR with a 28mm lens – or 1.6x the focal length of 18mm which equals 28.8mm.
That means that when we look through our crop-sensor XT using an 18mm lens we see the same view that we see when we look through our film SLR or full-frame DSLR while using a 28mm lens.
We must always be aware that focal lengths and crop factors are approximate numbers, so our math is going to vary a little. For example, a 24mm lens is rarely truly 24mm exactly when measured optically. The numbers are approximate and we should expect some discrepancies.
HTH
Originally posted 69 months ago.
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Dale Allyn (a group admin) edited this topic 69 months ago.
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Although this is more a analysis of depth of field, it also has some concise information on how sensor size affects the resultant image and lens angles of view.
Happy reading, even for Nikon users :-)
Posted 69 months ago.
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For another look at sensor size and how it affects image crop, here's a link that some may find interesting. It provides a visual plus some details about pixel density and other factors which contribute to image qualities.
Posted 69 months ago.
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geniuses amongst us.
my bad. haha
Posted 69 months ago.
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Great explanations chaps... especially Dale's in-depth one (I had to gulp some coffee before I could get my brain cells in sync with his though ..). I found, oddly enough, that handling a full-frame DSLR made the point click home for me (although I know that's not very logical).
Originally posted 69 months ago.
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curlsdiva edited this topic 69 months ago.
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why did canon call their ef-s kit lens 18-55, when really its a 28-90?
.... because it ISN'T a 28-90mm it's an 18-55mm lens. It makes no difference how big your sensor is, the focal length of the lens is what it is!
I have a medium format camera with a 75mm lens which is the equivalent of a 50mm lens on a 35mm camera. In other words, a 75mm in medium format is a "standard" lens. This camera takes 120 roll film but with the right accessories, I can use 35mm film too. But if I use 35mm film, the lens is STILL a 75mm lens. It makes no difference what film I use or if I take pictures without film in the camera, the lens is always going to be a 75mm lens.
Posted 69 months ago.
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Is all of this the same for the Sigma 30mm f/1.4? The description Sigma has on their own site makes me think it's a 30mm for x1.6.
This large aperture 30mm F1.4 EX DC HSM lens is designed to match the APS-C size image sensors of digital SLR cameras
If my interpretation is true, then the Sigma 30mm really delivers 30mm on a x1.6 crop factor camera, and not 30x1.6=48 mm equivalent. Am I right with this?
Posted 69 months ago.
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When We talk about lens, whether it is Canon EFS/ EF lens or lens from any other manufacturer, the focal lenth is mesured and told in terms of the convention we normally use to scale. The amount of pixels required to give a proper full frame (in terms of 35mm film format) is not there in any DSLR other than canon 5D and the 1Ds. So on these SLR's, the size of the sensor is equivalent to 35mm film format and that's how we have a 1:1 ratio and no crop factor. But for any other DSLR we have a difference in the ratio of the sensor compared to a 35mm film and hence the crop factor of 1.6/1.3 or 1.5 for Nikon cameras. Now EFS lens have a property that they get close to the sensor and hence the reduction of focal length is possible with out increasing the optics required (Kudos to Canon inventors). Using a short focal length lens (say 10-22mm at 10mm), you are actually shooting at 10mm as per focal length terms. For the DSLR you are using, which has a cropped or APS-C sensor, the rest of the light just falls off the sensor and is not recorded and hence you get a cropped image. This doesnt mean that you are shooting at say 16mm when your focal lenth meter shows 10mm. In picture terms you have to use a 16mm lens to shoot the same picture on a full frame or a 35mm SLR to get the same image as you did in 10mm on an APS-C sensor camera. like 300D, 350D, 20D, 30D etc.
Originally posted 69 months ago.
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ubi4 edited this topic 69 months ago.
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Jose-Miguel: No - it's a 30mm focal length lens, so on a crop body it delivers a field of view roughly equivalent to a 48mm lens on a "Full frame" body. What Sigma's description is saying is that the lens is designed to be a "normal" lens in the traditional sense of focal length being roughly the same as the diagonal of the sensor.
For a full frame body that dimension is about 43mm but because of various historical reasons the usual choice of a normal lens is 50mm.
For a 1.6 crop factor it is almost exactly 30mm. For a medium format film camera a "normal" lens would have a focal length of 80mm.
Wikipedia on normal lenses.
Posted 69 months ago.
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I was really confused about this too when I started out and the detailed explanations did not help. It took a while to get used to the concepts. So, this is my explanation to people who are confused. It does not matter whether EF, or EFS or DC or whatever else. If you have a camera with a cropped sensor, you have to multiply the focal length with 1.6 to know the effective field of view in your camera. Ofcourse many of you know that I am not entirely correct, but close enough for a good number of people.
Posted 69 months ago.
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*Partha* yes exactly. So a 30mm Sigma used on a cropped sensor would effectively give you the same image as a 48mm lens used on a full frame DSLR or film camera. But it's still a 30mm lens.
Posted 69 months ago.
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I should add, for a bit more accuracy to my remarks, that the EF-S lenses do differ from non-EF-S by more than just the mount. I didn't mention it in the above post in hopes of avoiding a bit of confusion in that very long post. As ubi4 mentions in his post, the EF-S lenses are constructed differently optically as well. Canon has changed the placement of the rear element, moving it backwards, closer to the sensor, allowing them to design these lenses for the smaller sensors. This is part of why the EF-S lenses won't work on the full-frame (or film) camera bodies.
Originally posted 69 months ago.
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Dale Allyn (a group admin) edited this topic 69 months ago.
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@Skink74: Thanks for the clarification. I was starting to get really confused.
Wikipedia link is also very helpful.
Originally posted 69 months ago.
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Jose+Euge edited this topic 69 months ago.
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Such a long technical thread about "crop". Good.
Posted 58 months ago.
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We so need a crop sensors FAQ the amount of time this comes up!
Posted 58 months ago.
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Compact cameras have so many different sensor sizes that it is almost useless to talk about the real focus length. Even I as the owner of the camera only approximately know what kind of lens the 8.6mm of my most popular flickr photo is. On my Pansonic DMC-FZ3 this is probably a light tele. For me it would be more useful if it was recorded as an 80mm equivalent or whatever its real equivalent lens is. I just calculated the equivalent and it turned about to be about 65mm - more normal then tele.
The DSLR 1.5 and 1.6 crop sensors are the only ones where there are enough photos and lenses that people have a real idea what a 10 17 28 or 50mm looks like on a cropped sensor. What I find irritating is that people keep speaking of an 28mm lens on cropped sensor as wide angle. After cropping it is a normal lens.
Originally posted 58 months ago.
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Andreas Helke edited this topic 58 months ago.
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 We so need a crop sensors FAQ the amount of time this comes up!
This thread is nearly a year old. I have no idea why Sakthivel Thirupur has 'bumped' it.
Posted 58 months ago.
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Couple of things on which I'd like to add my $0.02:
Cropped sensor cameras having a sensor smaller than 35mm also have a mirror smaller than 35mm. When the mirror flips out of the way (the key element of it being Single Lens Reflex) in a cropped camera there is more clearance to the lens. An EF-S lens sits deeper into the camera body, using up that clearance. If you put an EF-S lens on a 35mm camera the bigger mirror will crash into the back of the lens when you try to capture an image. An EF lens will work on either cropped or full frame, simply having more clearance on the cropped camera.
Also, while many believe their cropped sensor is giving them an advantage in the long zoom range (my 300 works like a 480), that's not the case. The optical magnification is no larger. A 300mm lens will bring the object just as close on a cropped sensor as on film. The smaller sensor won't take in the whole scene, thus the object covers more of your view, but optical magnification is no greater. Visualize this in your mind by thinking of a 300mm lens on a film camera and then putting on a lens cap with a small hole cut in the center. The object doesn't look closer, only not as much to see. I say this, but I haven't actually done empirical testing. If someone wants to buy me a 5D, I'll do the testing. :) I'm not sure how the digital fall-out effects the image, could be that the cropped sensor allows better enlarging, but I guess that would depend on pixel density, which I'm not sure is any better on cropped? Someone here will know.
Posted 58 months ago.
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@ harveycat:
cuz we're all still learning and some of us weren't flickrites 11 months ago! :)
Posted 58 months ago.
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It seems that this topic gets dscussed fairly regularly and often devolves into an argument. Maybe I was too readily sceptical, but that's why I wondered about the reason for the 'bump'.
Posted 58 months ago.
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@vfrjeremy Your are right that the lenses project the same image regardless of sensor size. But the cropped sensor cameras tend to have higher resolution sensors than full size cameras. Even the 8MP cameras have a slightly higher sensor resolution than the 16MP 1Ds MK II. So you still end up with a cropped sensor advantage for tele photography.
And a 12.4 MP Nikon D2X has a lot higher resolution than anything Canon currently has to offer.
Originally posted 58 months ago.
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Andreas Helke edited this topic 58 months ago.
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And a 12.4 MP Nikon D2X has a lot higher resolution than anything Canon currently has to offer.
Have you ever used one? I have. My 1D mk II produces a higher quality image with less noise, is easier to use, better built, shoots faster and is cheaper. And if you compare it to a 1Ds mk II it is not even on the same planet.
Ever seen a Pro who has to pay for his own kit (rather than those issued with stuff by a rich employer) using a Nikon? Not for a few years now.
Posted 58 months ago.
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Andreas, before you touch off another Nikon/Canon debate, please review the Canon product literature. The 1Ds Mk. II is a 16.7MP full frame sensor camera, safely giving much higher resolution with much lower noise (bigger pixels = lower noise) than the competing product. That camera is so good, it approaches medium format quality (though purists will never agree to that...).
Posted 58 months ago.
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That camera is so good, it approaches medium format quality (though purists will never agree to that...).
Don't know if I qualify as a purist, (but I like to think of myself as a reactionary old sod) but for colour images I would rate the 1 Ds as better than medium format film (B&W film still has a slight edge on digital in its dynamic range) and a lot better to use than the MF digital backs. Used with the Canon range of TSE lenses it can actually replace large format in nearly every situation, which is demonstrated by the many top architectural photographers now using them.
If Canon can ever build lenses that can actually deal with its resolving power then will take over (Nikon lenses are sometimes a little better, but they need to be beacuse Nikon uses such "high resolution" meaning small pixals, sensors and the Auto focus is so slow). I think the only reason that some stick with their M/F cameras is that they already have the lenses and it is easier to focus with the larger view. However the fact that one camera can do so many different tasks and that it is a small camera at that (relatively speaking). When the III comes out with the same 14 bit sensor as the 1DmkIII then I think the last of the reactionaries will no longer be able to complain about quality.
Posted 58 months ago.
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LOL @ reactionary old sod! I'm VERY interested to see what the (insert speculative sigh here) maybe-they'll-make-it-maybe-they-won't 1Ds Mark III's images would look like with the 14 bit sensor. Since that camera is full frame, we're way off topic here... but I can still smile, right?
Posted 58 months ago.
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I'll just call it really-really-really-wide, thank you. :->
Posted 58 months ago.
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BoldPuppy, the last rumours on the web I saw hinted they were having problems with the Auto Focus. Didn't really understand why this should be. It will have a 22mps"Foveon" (not sure what that really means) sensor.
Of course this is all rumour, but hopefully they may have some ready for the great (and free) Pro days they run in spring for CPS members. I always enjoy playing with somebody else's gear. Last year I had a go with the600mm lens and a 2X converter...now that is what I call a telephoto. Unfortunately it costs more than my car.
Originally posted 58 months ago.
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ambient troutmask edited this topic 58 months ago.
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I was talking about sensor resolution not about image quality. Here some numbers for Canon cameras.
350D 8.0 MP 22.2x14.8mm sensor 328 mm2 24390 pixel/mm2 156 pixel/mm
400D 10.1MP 22.2*14.8mm sensor 328 mm2 30792 pixel /mm2 175 pixel/mm
5D 12.8 MP 35.8x23.9mm sensor 855 mm2 14970 pixel/mm2 122/mm
1Ds MK2 16.8 MP 35.8x23.8mm sensor 852 mm2 19482 pixels/mm2 139 pixel/mm
The 5D sensor only has 70% of the 400D sensor resolution. This lower resolution allows the superior low light performance of the 5D
Posted 58 months ago.
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Too much tech talk. What matters is application. We are artists, not engineers.
Somewhere up the stream a comment was made, "I do wildlife photography and I love the 1.6x crop factor. It makes a 300mm f4 lens produce images like it was a 480mm f4."
Uh no way. You set a 5dii up with a 300 f4, 200 ISO and get a shutter of, say, 1/250. Now put that 300mm lens on your 7d and set to 200 ISO and 1/250. Your image will be underexposed and your depth of field will be deeper. You will need to compensate. It is not like a 480mm f4. It is very much like a 480 5.6. or more.
I own this setup. I've done the test. And people constantly tell me I'm wrong. Please advise.
Posted 29 months ago.
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I'm interested in this too Gibbygoo.
My thinking is that it should be the same exposure regardless of sensor size*. However I want to make sure that the reason you might see a difference in exposure is not down to performance difference between the camera models...
*but with a wider angle you're collecting surrounding light sources which could tip the balance. It would be interesting to try this on a uniform subject with uniform lighting instead of for example on a football field surrounded by floodlights.
Originally posted 29 months ago.
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Dave Wilson Cumbria edited this topic 29 months ago.
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Your comparison is not the right one.
Take your 5DII with a 480mm f/4.0 and shoot something 1/250 ISO 200 (Hard I know since this lens does not exists...)
Then take a 7D with a 300mm f/4.0 1/250 ISO 200 and shoot the same thing with the same light.
Now you're comparing the two like they said above...
The field of view will be almost the same, if not the same. The exposure should be the same.
The DOF would be better on the 5D because of the sensor size. but apart from that, the resulting photos would be the same at first glance
Posted 29 months ago.
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If you take a properly exposed 5dII image and crop it, does it become underexposed? Of course not. This is precisely what happens when you compare full frame vs. crop sensor. Exposure does not change.
The light coming out of the rear of the lens is the same no matter what it's attached to.
Posted 29 months ago.
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Exposure depends on ISO, shutter speed and aperture. End of story.
Posted 29 months ago.
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+1. Cropping doesn't change anything related to exposure. It's simply ISO, shutter speed and aperture. Nothing else.
Posted 29 months ago.
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To be brutally honest, you're completely wrong.
If you noticed an exposure difference it is likely either that your light changed or the fact that ISO200 on one camera is not ISO200 on another camera. I don't have a 5Dii on hand to repeat your test but I have noticed smallish exposure differences among the crop sensor cameras in my stable. Sensor size cannot cause exposure differences as the same number of photons are entering the lens regardless of whether or not there is even a camera attached. The photon density is also even across the image circle (well it does drop of near the corners due to diffraction or mechanical vignetting) and I notice photons have no special affinity for any specific portion of the lens. Thus, the same density of photons is hitting a crop sensor or a full frame sensor and while the FF sensor does collect more photons overall (b/c it is bigger) this doesn't change the exposure as they key is photon density.
As for DOF... while it is an ultimately subjective measure, the key parameters are subject magnification and sensor resolution. In theory, if you crop your 5Dii image down to match the framing on a crop camera, the DOF should be equal, provided that lens/sensor resolution was equal as well (which of course never occurs in the real world). Due to this discrepancy, while there are going to be DOF difference, it is difficult to say in which direction they will occur.
Now of course, if you can creep closer with your 5dii and get the same framing, the DOF will be shallower... but that wasn't the point you were making. Besides, for a lot of long lens work, greater DOF is better, especially for video applications.
Originally posted 29 months ago.
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Meddaugh Photography edited this topic 29 months ago.
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.. is it?
So if a spotlight, or say the sun, is at the side of a frame that is captured in a FF but not in a crop, are you saying that average metering see the same. I say no. You have a greater field of view so if there is a significant change in lighting in the edges of a Full Frame the metering will pick this up, a crop would not. Clearly if you used the centre weighted metering this would not have an effect.
But in most cases (nearly all I would say) I doubt there would be any real difference - but it is possible.
Originally posted 29 months ago.
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Ian H's edited this topic 29 months ago.
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We are artists, not engineers.
I'm both. :P
Exposure depends on ISO, shutter speed and aperture
I would rephrase that. Shutter speed and aperture are calculated based on ISO and the EV reading.
Posted 29 months ago.
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Thanks for the corrective points.
I just had a tough time wrapping my brain around the idea that a given lens, say an $1,100 135 f2, would in effect function as a $6000 200 f2. Or that a $6000 200 f2 on a crop body would function as nonexistent fantasy optic like a 320 f2.
I thought it would be the same as if you put a (hypothetical) 1.6x teleconverter on a lens--sure it gives you extra reach but you "lose" a stop or so. Looks like with a crop body, the end effect is the same, but without the same type of light loss. Correct?
Posted 29 months ago.
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Because it's light *density*, there is no light loss when going to a crop, assuming the same field of view, metering, and elements in the frame.
Posted 29 months ago.
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Yes, gibbygoo. Using a crop sensor is exactly the same as using a 5D MkII and cropping it. In fact, if you have a 350D the pixel density is virtually identical too.
If you're seeing a stop of difference between the cameras then either you're doing something wrong or one of the cameras is broken. There will be slight differences, but it shouldn't be this much. The crop factor doesn't effect exposure.
Posted 29 months ago.
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One thing to keep in mind in regards to crop factor however is that it actually has an effect on the shutter speed. Many seem to forget this:
If you shoot at 100mm on a full frame camera, the rule of thumb says that you'd need a shutter speed of a minimum of 1/100 sec (not taking the effects of IS into account). But using the same 100mm EF lens on a cropped sensor makes it the equvalent of 160mm, which also means you'd need a shutter speed of 1/160 sec.
This is only a rule of thumb to get a good handheld sharpness. But I've been asked about this a lot lately, so I just thought I'd throw that in there :-)
Back on subject, the "mm" stated on the lenses is a real physical and measurable distance inside the lens, so therefore it won't take the crop factor into account. That is also the reason why the small compact cameras have such small numbers i.e. starting at somewhere around 4mm which might be equivalent to 24mm on a 35mm sensor.
For more on this subject I can recommend the book: "Langford's advanced photography" - a good read if you dig the technical aspects of photography (like me, I'm also an engineer).
Posted 29 months ago.
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Tamron has a nice demonstration of what they mean "designed to fit APS-C"
www.tamron.com/B005special/lineup/b005/di2.html
Posted 29 months ago.
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There are some disadvantages to crop sensors in terms of ultimate resolution and ISO sensitivity. A 200f/2 on a FF will be superior to a 135/2 on a crop. However, as you noted you would be paying quite a bit more for the advantage.
Posted 29 months ago.
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+1. Cropping doesn't change anything related to exposure. It's simply ISO, shutter speed and aperture. Nothing else.
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