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Focal Length/Magnification (1 Viewer)

K

kennygee

Well-known member
Am I right in calculating the magnification of my DSLR setup as follows?

EOS 300D - 'crop factor' = X 1.6
300mm Canon lens
Total focal length - 300 X 1.6 = 480mm

Does this give an overall magnification of 480/50 = 9.6, or is the correct calculation 480/35 = 13.7 (when compared to a 35mm film camera)?

I think its the 'crop factor' that is confusing me

The reason I ask is that I am considering the Panasonic FZ20 (12X zoom) as a second camera for holidays/casual use and want to compare the reach in comparison to my DSLR

Cheers

Ken
 
I just replied to your other post as you were moving this.

50mm focal length of lens = normal = x1 so any multiple of 50 for the lens magnification.

crop factor is the equivalent size of sensor to match 35mm film so the 300D sensor has to be 1.6 x bigger to cover the same area as 35mm film.

which probably makes more sense that way than my last reply.
 
Thanks Paul and Yossi for your help.

Sorry I confused things with my duplicate thread.

From your replies it looks as though the FZ20 will fit the bill with its 12X zoom compared to my DSLR's 9.6. Sounds great for a light, portable casual setup.

Cheers

Ken
 
kennygee said:
Thanks Paul and Yossi for your help.

Sorry I confused things with my duplicate thread.

From your replies it looks as though the FZ20 will fit the bill with its 12X zoom compared to my DSLR's 9.6. Sounds great for a light, portable casual setup.

Cheers

Ken
Click to expand...
No, the 12x of the FZ20 is 12x the focal length at it's minimum (wide angle) position...which is 36mm, so 12x 36mm = 432mm.
regards,
Andy
 
kennygee said:
Andy

Does that mean that the Panasonic is 436/50 = X8.72?

Cheers

Ken
Click to expand...
Yes. Like I say forget about the 10x, 12x figures given with a camera (it's just 10/12x whatever the min focal length is, and that varies on cameras)... it's the 35mm equivilant focal length at maximum zoom that counts, then divide this by 50 (which isn't really a true 1:1 but just an accepted standard).

regards,
Andy
 
kennygee said:
I think its the 'crop factor' that is confusing me
Click to expand...

I think the 'crop factor' causes a lot of confusion! It is literally just a crop compared to 35mm 'full-frame' - you could achieve just the same effect by doing a 1.6x crop from a 35mm film but there wouldn't be any claims of the lens suddenly turning from a 300mm into a 480mm as often happens (not on BF, I hasten to add!)
 
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