Newbie Diving In

[Ian]

Re: Newbie Diving In

Ian....i aint half pleased you were replying to Andy cus I hadn't a clue what you meant. Hopefully it will make sense later.

Stephen thanks for the links

Pol Kettles on and I visited an online florist

Andy was including the 'boost' to the telephoto power of a lens of given focal length caused by the cropping factor of less expensive DSLRs that have a smaller sensor area than more expensive 'full frame' sensor models.

For your Canon EOS-400D you can multiply the focal length of a conventional 35mm format (or 135 format) lens by 1.6x to arrive at figure that is equivalent to the focal length of a lens that has the same field of view.

So, by fitting a 500mm lens to your 400D, you would see the scene filling your frame that a Canon EOS-1Ds full frame DSLR would see using a 500x1.6 = 800mm lens.

If Andy had meant that the target was to see the same field of view as a 500mm tele on a full frame camera, you divide 500 by 1.6 and get, roughly, 300mm.

But Andy confirmed he meant that you get a 500mm lens in order to have the narrower angle of view of a conventional 800mm lens.

Hope that makes sense now

Ian

[Pops]

Re: Newbie Diving In

Andy was including the 'boost' to the telephoto power of a lens of given focal length caused by the cropping factor of less expensive DSLRs that have a smaller sensor area than more expensive 'full frame' sensor models.

For your Canon EOS-400D you can multiply the focal length of a conventional 35mm format (or 135 format) lens by 1.6x to arrive at figure that is equivalent to the focal length of a lens that has the same field of view.

So, by fitting a 500mm lens to your 400D, you would see the scene filling your frame that a Canon EOS-1Ds full frame DSLR would see using a 500x1.6 = 800mm lens.

If Andy had meant that the target was to see the same field of view as a 500mm tele on a full frame camera, you divide 500 by 1.6 and get, roughly, 300mm.

But Andy confirmed he meant that you get a 500mm lens in order to have the narrower angle of view of a conventional 800mm lens.

Hope that makes sense now

Ian

Thankyou Ian...that was nicely explained.
Duly copied and filed away.

[philland]

Re: Newbie Diving In

Another Newbie trying to help. What Ian and Andy were talking about is the difference is the sensor size of a dSLR and that of a film camera. The sensor of the dSLR is smaller and that makes the actual focal length of a dSLR lens longer. In effect if you buy a 300mm lens, you are actually getting a focal length of between 430 and 460mm (1.3 to 1.6 times as long because of the smaller sensor). This is GREAT in the telephoto realm as you get even more than you bargained for; however, on the other end, the wide angle suffers (a 20mm lens is actually going to give you a 26 to 32 mm lens).

You guys will let me know if I said in thing in error there I pray.

Thanks,

Phil

[Ian]

Re: Newbie Diving In

Another Newbie trying to help. What Ian and Andy were talking about is the difference is the sensor size of a dSLR and that of a film camera. The sensor of the dSLR is smaller and that makes the actual focal length of a dSLR lens longer. In effect if you buy a 300mm lens, you are actually getting a focal length of between 430 and 460mm (1.3 to 1.6 times as long because of the smaller sensor). This is GREAT in the telephoto realm as you get even more than you bargained for; however, on the other end, the wide angle suffers (a 20mm lens is actually going to give you a 26 to 32 mm lens).

You guys will let me know if I said in thing in error there I pray.

Thanks,

Phil

Hello Phil, the only thing I'd say is that the 'focal length' is unchanged (that's a fixed attribute of the optical hardware) but you could say 'field of view is equivalent to' a lens of a given focal length when used with a full frame 135 format camera.

What's actually happening when you fit a lens designed for a full frame camera is that the smaller sensor is cropping the view seen by the full frame camera.

With 'digital' lenses, the projected image circle is limited to a diameter roughly equivalent to the diagonal of the smaller sensor and the projected angle of incidence of image forming rays onto the sensor is designed to be as perpendicular as possible in order for the microscopic sensor pits to collect light as evenly as possible from the centre of the sensor to its corners. But the 'cropping' factor remains the same for a given focal length.

Ian

[Pops]

Re: Newbie Diving In

'Nova Photo and Electronics' - that's the name of the ebay shop where David got my long cable switch.

It arrived very quickly, just a few days. it's very similar to the 18" Pentax cable switch but with a much longer cable attached - bulb mode included on the switch. The Pentax switch is smoother to use in but the 'Nova' switch is nevertheless very good too.

Pol

I'll go looking for one of those.
Mine is only the standard 2'

[philland]

Re: Newbie Diving In

Thanks for the clarification.