Digital Zoom?

[tich007mt]

Please excuse my inexperience but I'm trying my best to come to terms with the frightening array of technical terms associated with digital photography.
I have read in sales literature that my camera body - Canon 400D - with a Canon 70-300mm IS lens should actually give equivalent to 400mm or so. I have studied the handbook that comes with the camera but cannot find any reference to digital zoom. Is it just an automatic feature or is there a setting on the camera that gives this extra zoom?

Cheers

Tich

[galanthus]

Originally Posted by tich007mt

Please excuse my inexperience but I'm trying my best to come to terms with the frightening array of technical terms associated with digital photography.
I have read in sales literature that my camera body - Canon 400D - with a Canon 70-300mm IS lens should actually give equivalent to 400mm or so. I have studied the handbook that comes with the camera but cannot find any reference to digital zoom. Is it just an automatic feature or is there a setting on the camera that gives this extra zoom?

Cheers

Tich

this is indeed true and is due to the 1.6 crop factor. I have one and the same lens you speak of, a great combination. However, I don't think I could explain the maths as well as some peeps on here so I'll leave it with them.

[DavyG]

When dealing with DSLR's there is no digital zoom.

A 70-300mm lens is a 70-300mm lens, however DSLR's still relate to 35mm full frame cameras.

The Canon 400D has a 1.6 crop factor in relation to a full frame camera.

Therefore a 70-300 lens on a 400d would be the equivalent of a 112-480 lens on a full frame camera.

You can find a far better explanation here:

Crop Factor Explained

I hope this helps, (and that my explanation is clear)

Dave

[pressld2]

Hi Tich

It sounds like you're talking about the crop factor of your sensor. This comes about because the sensor in many DSLRs is smaller than a traditional 35mm film frame. Photographers are used to the size of image, or the amount of magnification, a particular focal length lens would give when using 35mm film. But the sensor only records a smaller area in the centre of the image that the lens resolves - i.e. it crops the image and this gives a greater magnification as if you were using a longer lens. I believe that the crop factor for Canons is 1.6 so your 300mm lens will give you the same result as a 480mm lens would on a 35mm film camera. For most Nikons the crop factor is 1.5 so 300mm looks like 450mm. Both Canon and Nikon make top-end professional cameras with full frame sensors where you don't get this effect.

I haven't heard of any DSLR having a digital zoom but would steer well clear of it anyway. All it does is blow the pixels up bigger and the results are pretty poor.

Dave P.

[tich007mt]

Thanks fellas - I hadn't realised that the comparison was against old technology - film cameras. I do understand what you are saying about the crop factor now and that it is automatically applied on my DSLR camera. I'll strive to keep learning!!!

Tich