SLR Lens Question

[whit]

Wanted to see if I could clarify a question regarding SLR lenses.

[Zach Matthews]

DSLRs work just like old film cameras.  You change the lenses as the situation requires.  They do not stack together, however (at least the two you named don’t).

Here’s a primer:

First off, most traditional SLR camera makers agreed that the human eye sees approximately a 50mm field of view.  So think of 50mm as a baseline.

An older traditional SLR commonly came with a 28-80mm zoom lens, which would take the perspective from about twice as wide as the human eye can see to a little short of twice as zoomed.  As the field of vision narrows when you zoom a lens, the image, because it is still displayed or perceived by a “picture box” that is the same size, gets larger.  Stated another way, zooming in magnifies what you are seeing.

So far that works the same as an X-count (which started out in binoculars, by the way, since all binoculars zoom more than 100%, or 2x).

All you need to do is adjust your frame of reference for a given image size (and again 50mm is a good place to start), and you’ll soon get the hang of the different nomenclature.

Now, some other things to keep in mind.  *Digital*SLRs have a smaller “picture box” than old school traditional film cameras.  Film was, you guessed it, 35mm across on a diagonal, measured like a TV screen.  Almost all modern digital SLR cameras have a sensor that is 23.5mm across, on the diagonal, which happens to be about the same size as a failed film standard called APS, so DSLRs are commonly said to have APS-sized “digital film.”

Now, DLSRs can mount lenses that are made both for traditional cameras and specifically for digital ones.  Because of that smaller film size, the rule of thumb is that to get an equivalent field of view, you multiple the number on the barrel of your lens on a FILM camera (e.g. 50mm) by 1.5X or 150% to get the same look on a digital SLR.

[whit]

Zach,

Thank you VERY Much for the reply.

[Steve K.]

Whit,

Can you pass along a link to the D50 kit you’re looking at?

Drifter

[whit]

There are TONS of places to go…

Try here: http://www.bhphotovideo.com/

Also, go to http://www.pricegrabber.com and do a search..

I actually bought mine at BestBuy here in town (I had a Gift Card to use, and they also had a 4 year extended warranty for $99).

[Author]

Posts