focal length vs "18x".... please help!

[Rudders]

I'm looking at upgrading my Fuljifilm S8000fd to a DSLR, probably a 550d/50d or d90.

The S8000fd is 8.0mp & has an 18x zoom on it.

The 550d is 18 megapixels

The 50d is 15.1 megapixels

The d90 is 12.3 megapixels

My question is... if I took a photo of a bird on the feeder in my garden what focal length of lens would I need to get a similar sized image (say after cropping) as an example printed at 6x4?

I know that the quality of the image with the DSLRs should be much higher.

I've probably worded this question badly and make a totally wrong assumption but if someone could enlighten me...

 

[chris321]

If you look at the spec of the fuji, it says the lens is "27 - 486 mm eq". I.e. to get the same field of view on a 35mm (full frame) camera, you'd need a 27-486mm lens.

The canons have a 'crop factor' of 1.6, and the Nikon of 1.5. So, a lens to get a similar field of view as your fuji on the Canon would be 17-303 (divide both numbers by 1.6). You won't find a lens like that though as it would be either hugely expensive, rubbish, or most likely, both

So get a 70-300, and be prepared to crop a little. The more MP you have, the more cropping you can do. All of the ones above should be more than capable!

Chris

 

[HoppyUK]

If you look at the spec of the fuji, it says the lens is "27 - 486 mm eq". I.e. to get the same field of view on a 35mm (full frame) camera, you'd need a 27-486mm lens.

The canons have a 'crop factor' of 1.6, and the Nikon of 1.5. So, a lens to get a similar field of view as your fuji on the Canon would be 17-303 (divide both numbers by 1.6). You won't find a lens like that though as it would be either hugely expensive, rubbish, or most likely, both

So get a 70-300, and be prepared to crop a little. The more MP you have, the more cropping you can do. All of the ones above should be more than capable!

Chris

Cropping is worth trying as a last resort, but it's no substitute for getting the right lens in the first place. And I don't know of any 70-300mm lens (eg Canon 70-300 IS - good though it is) that will max out a sensor at the long end so pixel count is kind of moot anyway. On top of which, you can't just count up the extra pixels and convert that into a pro-rata increase in effective reach. It just doesn't work like that.

If you can stretch to a Canon 100-400L, that's about as good as it gets for sensible money. On the 50D would be good Even then, you'll still want a longer lens - you always do, birding isn't easy!

 

[Clickawaymedia]

IMO the closest equivalent you can get on a crop sensor is the tamron 18-270mm f3.5-6.3 Di II VC. This isnt the cheapest option coming in at around £400 new.

You could save money by getting a 18-70mm and a 70-300mm, and you will have slightly more range at the top end (300mm instead of 270mm)

 

[trencheel303]

The more MP you have, the more cropping you can do.

No. The more MP you have, AND the better lens you have, the more cropping you can do.

There is no way a 70-300 will have enough resolution to crop heavily on a 15MP sensor - in fact I'd not be at all surprise if the sensor is outresolving the lens already with NO cropping.

Mind you, coming from a bridge camera it's not as if quality expectations will be paramount anyway...

 

[eccles]

As already suggested, it's not only about megapixels but the quality of the glass. My 12mp sensor gives 4272x2848 resolution. I use a 70-400mm Sony lens that is very good wide open at 400mm. I can get a pretty good A4 print from a 1/4 crop by area, e.g. 2100x1400, provided I've done a decent job in actually taking the photo. The latter point is probably the most important, and using a DSLR after being used to a compact involves quite a steep learning curve.
All of the above cameras will produce very good photos with good glass, to the point that I doubt if you'd tell the difference when looking at final printed output.