effects of using ef lens on rebel xti

CWA_JGEISINGER

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I was at the local camera shop today looking at lenses
the lens I was looking at was the cannon 50mm 1.8f

but the woman told me by using that lens on my xti that I would not be getting the full 1.8f it would end up more like 2.8f and that the focal would be more like 85mm
due to the magnification in the camera


anybody have any truth or explanation for this?
and is there truley any effects of using an ef lens on the rebel xti 400D?
 
it WOULD act like an 85mm(still is 50mm away from the sensor, and needs a shutter speed of 1/60 or faster to handhold but the sensor, being smaller than film, gets covered by the light entering through the center of the lens so it appears bigger) it however WOULD still be 1.8 and act as such.

On a side not: that lady should be fired. She is one of the reasons misconceptions spread making even harder for people to understand photography.
 
I didnt really think there was much truth to what she was saying

Just thought id ask around because I really didnt understand what she was trying to get across
 
The difference comes from the size of the sensor in the camera...it's smaller than a frame of 35mm film...and EF lenses are designed for 35mm film or 'full frame sensors'.

Think about it this way...the lens is like a projector, projecting the image into the camera. The camera in question, has a smaller sensor...which would be like having a smaller projection screen for the image to show on. The part of the projected image, that is outside of the screen/sensor is simply not recorded as part of the image...it is 'cropped' off.

That is why we have the 'crop factor'. Basically, it means that your camera see less with a lens than a 35mm film camera would. It make it 'feel' like a longer lens.

It's isn't anything to really worry about.
 
as said before, the only effect would be the crop factor, so the magnification you see, would be similar to an 85mm lens on a 35mm. The aperture would still be f1.8 max. I have no idea why she would tell you otherwise about the aperture.
 
perhaps she was getting confused about that depth of field thing....
 
Even though everyone else explained it correctly, let me put it another way.

Your 1.8 lens, is still a 1.8 lens, no matter what camera you put it on.

A 50mm lens is always a 50mm lens, no matter what camera you put it on.

What you are getting is a field of view that compares to an 80mm lens, nothing else. The crop factor is one of the most misunderstood concepts, that I've ever seen. People keep saying it's going to make your 50mm into an 80mm lens, because of the 1.6 crop factor. Which gives the impression that you'll get that magnification. You don't. :D

IT'S STILL a 50mm LENS! You are only getting 62% of the image it projects, because the sensor is smaller than film.

By the way, nice all around lens and usually a good value.
 
All DSLRs have a 1.6x or 1.5x focal length (mm) conversion factor. So She is right in the fact that yes, it WOULD be the equivelent of an 85mm lens. But on the aperture note, she has no idea what she was talkin about. There is no conversion factor for aperture, it remains the same. BUY THE LENS! I have never found a better deal in photography ever. In fact, I own that ense myself. And use it quite often. You won't be dissapointed.
 
It is a VERY good lens.... I have the f1.4 and a friend of mine loved it ,but didn't have the cash. So he bought the f1.8. In almost all departments it is almost impossible to tell the difference. And at 1/4 the price for 1/2 a stop... it must be worth it.
he gets some really good images from it. And as we all know that I am a far better photographer than he could ever be. It MUST be that he has a good lens ! ! ! .... :lmao:(Sorry Keith):hail::blushing::er:
 

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