Canon EFS?? Does Crop Exist???

[Stevedevil]

WOW whats happenin

 

[ksmattfish]

Every lens projects a certain amount of coverage. Coverage is how big the image circle is at the film/sensor plane. Your photo is a rectangle taken out of that circle. Obviously the circle needs to be big enough to contain the rectangle.

Many large format lenses have a circle of coverage over 6" in diameter, while lenses for 35mm cameras probably have a diameter of coverage of maybe 2 inches. APS-C sized sensor DSLRs can get away with even less coverage, because the sensor is a rectangle smaller than a 35mm film frame.

If you put an EF-S lens, with it's smaller coverage, on a 35mm SLR, the rectangle that makes up your photo may be larger than the circle of coverage. Your photo would come out with dark corners and edges in a circular shape.

If you put an EF lens, with it's larger coverage, on an APS-C DSLR, it just means there is more lens coverage than required by the smaller format.

The "crop factor" is how the angle of view of a smaller format DSLR compares to the angle of view on the same focal length 35mm camera lens.

A 50mm lens gives you an angle of view (diagonal across the frame) of approx 47 degrees using the 35mm format. On an APS-C DSLR a 50mm lens gives you an angle of view of approx 30 degrees. 47 divided by 1.6 = approx 30.

Or you can divide the 35mm format focal length by 1.6 to get the focal length that would give the approx the same angle view on an APS-C format camera. 50mm divided by 1.6 = 31mm. A focal length of 31mm gives an angle of view of approx 47 degrees with the APS-C format.

 

[Big Mike]

my question still stands, does an EFS 18mm come close to a 10mm EF,

NO...no...no :roll:

18mm is 18mm...it does not matter if it's EF-S, EF or XYZ.

 

[Stevedevil]

Can we go private ALEX B

 

[shingfan]

I read about quality in your forum, and yes a wider f stop ( lower number ) is important, my question still stands, does an EFS 18mm come close to a 10mm EF, with obvious implications or usage ( bluring from behind ) where a higher ISO met with good lighting can achieve same results

EFS should reduce crop factor in this sense....and a EFS 18mm would behavior wider compare to a EF 18mm technically speaking

 

[Alex_B]

we have to find some webpage or good images which explain it ....

 

[Big Mike]

and a EFS 18mm would behavior wider compare to a EF 18mm technically speaking

No, No, No.

 

[Alex_B]

stevedevil ... i have to leave ... not fleeing conversation... but PM me and i will respond later ...

 

[Stevedevil]

AN EF lense will spot an image that on Digi is cropped, an EFS makes a longer focal Length, so wont work on norm Canon, Yes ???

 

[Stevedevil]

WOW its gettin pretty hard here, As I said an 18mm would compare wider, but are the only probs f stops, thanx Big Mike

 

[Alex_B]

no. EF and EF-s make no diff in focal length or crop!

i am off now.. but if you cannot get this sorted tonight, pm me.. i will think of some way to explain it then .. don't despair ... this happens to many!

 

[Stevedevil]

Cheers all

 

[lostprophet]

there is NO 10mm EF lens!
The Widest corrected EF lens is the 14mm F2.8 (costs over £1000.00)
there is of course the Canon EF 15mm fisheye

the Canon 10-20mm is EFS ( i have sold many )

 

[Steph]

Have a look at this. It might help.

 

[tempra]

an 18mm EF-S lens gives exactly the same view as an 18mm EF lens, there is no difference on an EF-S compatible body.

F-stops are whatever the lens has, as a general rule, the lower the f number, the more you pay.