Dumb questin re: Magnification factors

[scowan007]

I have read that it is 1.5 or 1.6. Which is it? And is "magnification factor" the proper term?

Be gentle. I am new, and if you think think question is dumb, wait until I really get warmed up! :shock:

Thanks!

[robertwgross]

You did not refer to any particular camera. Different cameras have different factors.

Technically, magnification factor is not a good description. Crop factor works for many. Field of view crop factor works. If that gets too complicated, then just use "factor" to avoid the inevitable argument.

At the beginning, it seems a lot like magnification factor. Later on, it doesn't seem that way.

---Bob Gross---

[Belmondo]

Depending on the camera, it's 1.0 (1Ds), 1.3 (1D and 1D Mk II), or 1.6 (all the rest including Rebel, 10D, 20D, D30, & D60).

The proper name is whatever you're comfortable with. Some prefer "magnification factor," while others call it "crop factor." I think Canon calls it magnification factor, so maybe that's the pseudo-official term.

[scowan007]

Sometimes I'm not terribly detail oriented. :cry: Sorry about that.

I have a 20D.

Thanks for the info, folks.

I'm doing a little Excel spreadsheet to help me out with the conversions.

[Olegis]

Just multiply all the values that describe the lens focal length by 1.6 and everyting will be OK 8) . For example - 28-135mm lens will become 28x1.6-135x1.6 = 45-216mm lens. Or, more precisely - the 28-135mm will have a field view of 45-216mm lens on 20D.

[aam1234]

the 28-135mm will have a field view of 45-216mm lens on 20D

Now I have to ask a dumb question. Does the cropping factor affect the perspective.

[Jesper]

Please do a search. The crop factor and what it does and does not affect have been discussed so many times that it has become a boring subject... :?

[aam1234]

Thanks Jesper,

I know it doesn't, but just wanted to make sure.

[PacAce]

I have read that it is 1.5 or 1.6. Which is it? And is "magnification factor" the proper term?

Be gentle. I am new, and if you think think question is dumb, wait until I really get warmed up! :shock:

Thanks!

I'm assuming that you've had previous and more than the casual experience with 35mm cameras, correct? If not, then the magnification factor won't be of much use to you and will only serve to confuse you even more. The only reason people have to deal with the magnification factor is because they want to compare the view of field of a lens on the digital camera vs. what they would get with the lens on the 35mm camera.

[MarkH]

I don't think that it is a magnification factor. As far as I know the number is a focal length multiplier which means that it is the number that you multiply the focal length by to work out which 35mm lens you would compare it to when you want to know what angle of view you will get from a particular lens attached to the D-SLR.

For example: If I mount a 200mm lens on my Canon 10D then I would multiply 200 x 1.6 to find out that I will get the same angle of view as a 320mm lens would provide on a 35mm (or full frame) camera.

If you compare the 10D to the 1Ds MkII then you can see that the number is not a multiplier at all, just a crop factor. The 1Ds MkII produces a full frame 16MPix image, if you crop to the centre 6MPix you will get a picture nearly identical to what the 10D produces.

The biggest difference you see is on wide angle (which means a lens with a wide angle of view) because the Focal Length Multiplier is used to figure out the angle of view. A 28mm lens is a wide angle to someone using full frame, but on my 10D I get an angle of view that resembles a 45mm lens. This means that I need a lens like the 17-40 to produce a similarly wide angle of view to what a 28mm would normally give. If I need wider then I would need Sigma's 12-24 or use the new canon EF-S 10-22 lens (only works with the 300D or 20D, not the 10D or D60 (also not the pro cameras with smaller multipiers)). If you mainly shoot with telephoto then the 1.6x limitation is not usually a problem, this is because it is easier to zoom out when you are on 200mm with a 70-200 then when you are on 24mm on a 24-70.

Important:
'Focal Length Multiplier' is not a magnifier, it is a number that you multiply the Focal Length by. You use it to work out what to compare the lens to, but not for magnification purposes, only for the purpose of equivalent angle of view. It is easier for most people to use than an Angle of View Divider!

[jwhee0615]

Thank you MarkH for that explanation. As I have just moved to digital this was something that I was wondering about as well. With regard to telephoto lenses, I was under the false impression that my conventional 28-200 would now be even more telephoto at 44.8-320 on my 20D. If I understand well your explanation, this means that the field of view is lessend to equal the latter FL with the 1.6 chip. The object that I might be photographing will not have an increase in magnification, only a reduced field of view. Right?

[gcogger]

'Magnification' is a red herring when it comes to digital images. An image from a digital camera is a collection of pixels, and pixels have no inherent size. The magnification can therefore only be talked about in conjunction with a final display size (whether that's a print or a size on a monitor).

Assuming you look at the images at the same size as when you were using 35mm (e.g. a 10x8 print of the whole image), then the 28-200 lens on a 20D will give you the same print as a 44.8-320 lens on the 35mm camera. The only difference will be the depth of field.

Whether you want to call this a focal length multiplier, field of view crop, magnification factor or anything else is entirely up to you :)

[MarkH]

Thank you MarkH for that explanation. As I have just moved to digital this was something that I was wondering about as well. With regard to telephoto lenses, I was under the false impression that my conventional 28-200 would now be even more telephoto at 44.8-320 on my 20D. If I understand well your explanation, this means that the field of view is lessend to equal the latter FL with the 1.6 chip. The object that I might be photographing will not have an increase in magnification, only a reduced field of view. Right?

Well, compared to a theoretical 8MPix Full Frame D-SLR with the same noise characteristics as the 20D then there would indeed be more telephoto on the 20D, essentially capturing an image at 200mm that is near identical to what the Full Frame D-SLR would get from a 320mm. But compared to the 1Ds MkII then no, nearly no magnification. Compared to film it would depend on how well you felt the 20D image compared to a shot on film. If you are happy to say that an image from a 20D printed 20x30 could easily match a shot on 35mm printed the same size, then yes, the 20D image is comparitively magnified by the 1.6 multiplication factor.

Just remember that you have lost your wide angle ability from the 28-200 lens due to the crop.