Focal length multiplication

[Spinners]

Maybe im just an idiot, but i think i missed something in all the posts regarding focal lenght mulitpliers.

I have a canon EOS10D. I know it has a 1.6 multiplier. But what i see in my viewfinder is what i get in my pictures. If i slap on my 24-80 lense, and set it at lets say 50mm, i get what i see.

I would expect that what i saw would get cropped. Does it? cause if it does i don't notice it. And if i am correct, (your all probably thinking im an idiot, but i dont really analyze things all that much) then how do they get that to work? how does the viewfinder crop to match the sensor?

[MediaMagic]

check this thread... sums it up pretty good.

http://photography-on-the.net/forum/showthread.php?t=18880


David

[Spinners]

Okay, but... does the viewfinder show you the full 35mm view or the cropped view?

[Belmondo]

You will see the cropped image in the viewfinder, or very close to it. I seem to recall reading somewhere that the actual image recorded in the camera will be very slightly larger than what you see in the viewfinder.

Hopefully someone will verify that.

Tom

[Rob Larsen]

If my poor memory serves me, I believe the viewfinder shows you ~95% of the recorded image. You will notice that when composing tight to edge elements, you will get a little more than you planned on in the final image.

[CyberDyneSystems]

Indeed the 10D's veiwfinder was made for the 10D :D

Fotunately that means what you see is pretty much what you get! It wouyld really blow if they had left an Elan viewfinder in there!

We could easily mess up a lot of shots!

[hmhm]

spinners wrote:
I have a canon EOS10D. I know it has a 1.6 multiplier. But what i see in my viewfinder is what i get in my pictures. If i slap on my 24-80 lense, and set it at lets say 50mm, i get what i see.


Yeah. They thought of that. Your viewfinder is cropped 1.6x as well, so it matches the sensor.
-harry

[defordphoto]

Rob Larsen wrote:
If my poor memory serves me, I believe the viewfinder shows you ~95% of the recorded image. You will notice that when composing tight to edge elements, you will get a little more than you planned on in the final image.

Correct-a-mundo.

[sjprg]

Repeat after me. The 1.6 is NOT a multiplier, The 1.6 is NOT a multiplier, The 1.6 is NOT a multiplier. It is a 1.6 reduction in the field of view! :)

[defordphoto]

Canon officially calls it a multiplier. Makes it easier for Joe Consumer to relate to. Multiplier, crop, whatever...

[defordphoto]

Canon officially calls it a multiplier. Makes it easier for Joe Consumer to relate to. Multiplier, crop, whatever...

This is the best way to explain the less-than-35mm sensor our beloved cameras have:

http://www.bytephoto.com/photopost/data/500/353Crop_Factor_Illustration_jpb-med.jpg

[defordphoto]

And that brings up the question: What aren't our lenses rectangular? (Yes, I know the answer)

[Rob Larsen]

RFMSports wrote:
And that brings up the question: What aren't our lenses rectangular? (Yes, I know the answer)

As an extension to that, should sensors be produced circular to avoid the "rectangular crop" that is convenient for film? Could open up whole new markets for printers, framers, etc... :D

(please, nobody take me serious...)

[Conor]

RFMSports wrote:
Canon officially calls it a multiplier. Makes it easier for Joe Consumer to relate to. Multiplier, crop, whatever...

This is the best way to explain the less-than-35mm sensor our beloved cameras have:

http://www.bytephoto.com/photopost/data/500/353Crop_Factor_Illustration_jpb-med.jpg



VERY GOOD PIC to show the 1.6 CROP Factor......

[defordphoto]

Conor wrote:
VERY GOOD PIC to show the 1.6 CROP Factor......

I can't take credit for that. That is from Belmondo, another member (in good standing) here on the forums. I see that example being used time and time again. ;)

[Dave I]

Focal length multiplier works too.

My 100-400mm acts in all ways but DOF as a 160-640mm would on a 35mm (or 1Ds). Thus I can refer to it as a multiplication of the listed focal length by 1.6 when using the 10D.

[Belmondo]

Dave:
Call it whatever you like. It's only important that you understand that your image is the cropped equivalent of a lens that's 1.6X longer. In fact, your depth of field is unchanged --- it's your field of view that's modified.

It sure isn't a point worth arguing about; I'm not even sure it's worth debating. Just make sure you understand that when you eventually buy a camera with a full frame sensor, you won't be giving up magnification, you'll be gaining field of view. It's an important distinction.

BTW. I just got a call from my local camera store, and my 100-400 is in!! I'm going to pick it up this afternoon and hopefully be playing with it before the sun sets.

This is better than Christmas!

[Dave I]

I probably wasn't being clear on the DOF. I meant that my 100-400mm lens on my 10D acts the same as a 160-640mm lens would act on a 1Ds or 35mm camera, except the DOF would be deeper on the 100-400/10D than on the 160-640/1Ds, given the same f-stop.

This is more evident when you look at the much higher crop factor/focal-length multiplier on the typical P&S. With a P&S with a tiny little sensor, giving a focal-length multiplier/crop factor of say 5.0x, you could have the same field-of-view at 7mm as a full-frame camera would have with a 35mm lens. The DOF on the P&S would be much much deeper at a given f-stop, though.

I'm not considering the lens quality issues here, as they tend to balance out. You use the center of the image circle with a cropped camera, and that can lead to better images (lenses are worse at the outside of the image circle), but the crop factor leads to you enlarging farther for a given print size, exaggerating lens defects.

Naturally, I understand that the apparent magnification is due to the fact that I'm blowing up the cropped image farther to reach the same print size, but it's still effectively magnification from the user point of view. Actually, if you were going from a 1.6x crop factor 10D to a hypothetical full-frame camera with the same exact pixel count, the 10D would have a true magnification, I think. Something that spanned 500 pixels on the full-frame 6MP camera with a 160mm lens would span 500 pixels on the 10D with 100mm lens.

[Dave I]

Oh, and congrats on the lens :)

[Belmondo]

Dave I wrote:
Oh, and congrats on the lens :)

Thanks, Dave. I just walked in the front door and the wife has decided she wants dinner before I go outside and play.

I'M LOSING THE LIGHT!!!!

Ow well, I'll just get up real early tomorrow and --------