the difference in the mm of the lens

[compro_1975]

hi all, i am lookin at http://www.tamron.com/lenses/prod/18200_diII.asp web site claim 18-200mm lens, as i go thru the catalogue, i saw this statement of 28-300mm* 35mm eqn, what does this mean??? i am lookin at a D300 body so wat is the range? 18-200mm or 28-300mm?

 

[lsisaxon]

hi all, i am lookin at http://www.tamron.com/lenses/prod/18200_diII.asp web site claim 18-200mm lens, as i go thru the catalogue, i saw this statement of 28-300mm* 35mm eqn, what does this mean??? i am lookin at a D300 body so wat is the range? 18-200mm or 28-300mm?

Optically, physically and actually the lens is 18-200mm. The 27-300 comes about because many people who have come from the 135 format film ages are used to the angle of view given by these focal lengths, the angle of view given by the 18-200 using a DX sensor is like that of a 27-300 used on a full 135-format

 

[compro_1975]

so on a camara on D300, what is the range i can use?

 

[lsisaxon]

so on a camara on D300, what is the range i can use?

18-200, as what is stated. The angle of view of which would be like what a 27-300 would give on a full frame camera. It doesn't become a 27-300.

 

[compro_1975]

18-200, as what is stated. The angle of view would be like what a 27-300 would give on a full frame camera.

oic, tks tks

 

[tunster]

that's the "angle of view", but the shape of the photo will look different too.
meaning...even the angle of view is similar to 27-300, the shots will look much more "compressed" than the real 27- 300

 

[lsisaxon]

that's the "angle of view", but the shape of the photo will look different too.
meaning...even the angle of view is similar to 27-300, the shots will look much more "compressed" than the real 27- 300

That's why I always emphasize the focal length is still 18-200, only the angle of view is similar to that of a 27-300mm on a full 135-format frame.

Similarly for those PnS, the actual focal length is around 4.7mm (depending on sensor size) which gives an angle of view similar to a 36mm on a full 135-format frame.

 

[Youhong]

Actually your question have been answered quite a number of times already...

Check out on Wikipedia on Crop Factor, it gives the full answer to your question.