Newbie question - how do you convert the mm of a lens into a magnification factor?

[Adey Baker]

Originally Posted by kennygee

Adey

Its an interesting point you raise about the impact of the viewfinder in magnification issues. I must admit I'd never considered it.

Most DSLRs with a 'cropfactor' seem to have smaller viewfinders than full frame models but I've got a Canon EOS50E film camera plus Olympus OM1 which are both 35mm full-frame cameras but the OM1's viewfinder image is noticeably bigger (and brighter).

Incidentally, if you've got something like the OM1 which has a range of interchangeable focus screens you can fit a 'clear' type and see just how bright your lenses really are - it comes as quite a shock to see how much light the normal screens soak up in order to give you a focussed image across the frame (you have to use the microprism in the middle of the clear screen to accurately determine correct focus).

[kennygee]

I used to like the microprism/split screen focussing methods. As my eyes get worse - I'm very short sighted - these methods would be much better.

If it wasn't for autofocus, I'd be lost.

[LSB]

Ok Cheers
Its a Fuji S5500 and an Olympus Tcon 17 conertor..Does this help?

[robski]

The actual lens on the S5500 is 5.7 - 57mm.

With the crop factor taken into account the 35mm Focal Length Equivalent is 37 - 370mm.

Now if you add the Olympus Tcon 17 TC to it (x1.7 ) it converts this to 62.9 - 629mm

[LSB]

Cheers Rob
I thought it was only around the 500mm mark..Im surprised.
Thanks

[Craftysnapper]

It's actually a crop factor and not a multiply

[Terry O'Nolley]

Thank you all for this information! I was totally confused because printed on my lens is a red "1:4" and I had no idea what that meant since the lens is fixed focal length.

[Terry O'Nolley]

Originally Posted by Adey Baker

Again, if you're using the camera as a sort of ad hoc binocular you need to consider the viewfinder magnification (or reduction, rather!).

No, I use my binoculars for viewing. WHen I look through my D-50's viewfinder, it looks very tiny and I am lucky when I can see the bird at all. Unless I am very close to the subject, I can't even tell if the bird is in focus or not - I just guess and take a range of photos moving the focus a tiny bit each time. Autofocus never works because there is always brush and branches in the way.

[robski]

I do miss the view finder on a full frame camera, as you say the view on the smaller formats is tiny. Many a time I have missed something in the background I did not want in the photo. For example a for sale sign appearing above somebodys head. You get it on the PC monitor and it is plain as day. Dam and blast and a few other bad words are expleated.

[1st round robin]

You might try looking up the specs for your lens and camera to find that information. For example the following link will give that info for Canon lenses.

http://www.the-digital-picture.com/C...ion-Value.aspx