DSLR Lens matched in max

[Sketchrender]

Good morning

I have a canon 350D with a 18-55mm lens.

Apparently there is a difference in the the lenses between DSLR and SLR, as 35mm SLR is not a 35mm DSLR.

 

Can anybody help me with this.

 

thank you

 

phil

[Jeff Mottle]

This difference does not have to do with the lens but the size of the sensor that captures the image. Film uses 35mm typically so the area available to light is 36mm x 24mm. Most Digital SLRs do not have full frame sensors, which means their sensors are not the same size as their film counterparts. They are smaller. Being smaller this effectively crops the image. As a result you have to multiply your lens focal length by what is called a crop factor, field of view crop or the focal length multiplier. For many Nikon DSLRs for example that crop factor is 1.5 because their sensor size is 23.7 x 15.5 mm.

 

More and more DSLRs are coming onto the market with FF sensors, but they are for now targetted at professionals and have prices to match.

 

With a crop factor taken into consideration (1.5) A 28mm prime lens acts like a 42mm lens, and a 105mm lens acts like a 158mm lens. Crop factor is great when it comes to distance work as you don't have to pay as much to get the same effective distance, but becomes problematic with architecural work becuase for very wide angle photography you have to sometimes use a very wide (= expensive) lens to get a normal wide angle.

 

Here are some links that explain some of this in more detail.

 

http://www.bobatkins.com/photography/digital/size_matters.html

http://www.dpreview.com/learn/?/key=focal+length+multiplier

http://www.lonestardigital.com/multipler.htm

http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml