MF to 35mm to 20D sensor crop factor.

When I use a lens on my 20D I know the angle of view is reduced by a

factor of 1.6 (so some people say there is "more" telephoto)

 

I have a 300mm F4 Pentacon lens with an adapter to M42.

 

I think it is a medium format lens, when I use it on a film camera

there is a crop factor. On my 20D there is a second crop (the already

known 1.6)

 

Does anybody know the first crop factor? I mean the medium format to

24x36 sensor angle downsizing?

 

Thanks in advance

What does it matter? It's a 300mm lens. It will be the same as any 300mm lens. It doesn't matter what format it's designed for. All 300mm lenses mounted on a 20D give exactly the same view.

 

The "crop factor" from 6x9 to 35mm is about 2.3x

Then the equivalent focal length is 300mm x 2.7 = 810mm so for hand holding the suggested exposure time is 1/1000

 

Thanks

Sorry, new math

 

Then the equivalent focal length on a 20D is 300mm x 2.3 x 1.6 = 1104mm so for hand holding the suggested exposure time sould be faster than 1/1100 of a second

 

Thanks again

No. A 300mm lens is a 300mm lens is a 300mm lens, regardless of what you put it on.<p>

The effective focal length is thus 1.6 x 300mm = 480mm. Whether or not it can or has been used on MF, LF or the Hubble Space telescope is irrelevant ;-).

Jorge - on the 20D you will get the same FOV with that 300 as you would by putting the 1100mm lens that you came out with onto the medium format camera. However, as other posters have said, it's a 300mm lens regardless of what it is attached to. All that varies between different mount 300mm lenses that may be designed for different formats is the size of the image circle and the back-focus distance (ie the distance from the mount/back element to the sensor/film plane). Then the size of the sensor determines the field of view.

If one gave a bunch of different people 300 dollars each; each would "feel" a different amount of "boost".<BR><BR> Each got 300 dollars as a gift. A billionaire might just use it as more cash in is wallet. A retired couple might use it for a chunk of medical bills. A teenager might get a flashier cell camera; clothes; and star war tickets. A poor Ukrainian retired couple might see the 300 dollars as a radically bigger slug of cash. An airline might use it to run an airliner for a minute or two. Each still only got 300 dollars. <BR><BR>One could twist the 300 dollar figure and call them "crop dollars" ; adjusting for each's different needs; standards of living; expenses. Each still only got 300 dollars.<BR><BR>

I understand english if you write it slowly but it is not easy for me to make myself understood.

 

Thanks Isaac, you explained it very well.

 

Mr. Atkins, I think it matters for minimun speed when handholding and for FOV calculation (a la Fred Parker Digital Lens Computer)

 

All of you are right, it is still black when used on diferent bodies.

 

Thanks and regards