Confused re crop sensors

cortinaG

I think I understand the terminology re crop sensors as in 18mm on a crop sensor is equivelent to 27mm?? on an SLR camera etc etc.
I have a 24mm F2.8 olympus manual lens which I sometimes use with my Canon 350d with an adaptor.
My query is this, Why would an image taken on the manual lens have a wider field than shooting at 24mm on the stock Canon lens if it's still using the same sensor?
It doesn't really matter but I am just curious.

Paulw

http://www.slrlounge.com/school/cropped-sensor-vs-full-frame-sensor-tips-in-2/

I hope that helps.

DaireQuinlan

cortinaG wrote: »

Why would an image taken on the manual lens have a wider field than shooting at 24mm on the stock Canon lens if it's still using the same sensor?

In short, if I understand your question, it won't. It will be the same. If it's different then you're doing something weird

cortinaG

DaireQuinlan wrote: »

In short, if I understand your question, it won't. It will be the same. If it's different then you're doing something weird

That's what I thought,
I took 2 pics, interior shots, about 10 ft back, both starting at the same point on the left of the viewfinder,
the image taken with the manual lens showed approx the width of a laptop extra on the right of the image.

Now that I can finally upload images,
1st image with 18-55 canon lens @ 24mm;

[/IMG]

2nd image with fixed 24mm manual lens;

//[/IMG]

DaireQuinlan

A difference as small as that is probably down to focus breathing, more likely in the zoom rather than the prime though it could be either. Or the markings on the zoom aren't spot on. Too many variables at play. The focal length of a lens is specified as focused to infinity. The angle of view of a lens can change as you focus closer.

cortinaG

Thanks for that, I was just wondering.
The reason I took them was that I was anticipating getting one of those wide angle adaptors for the camera,
This is how it turned out, not bad for around €20

[IMG][/img]

DaireQuinlan

cortinaG wrote: »

Thanks for that, I was just wondering.
The reason I took them was that I was anticipating getting one of those wide angle adaptors for the camera,
This is how it turned out, not bad for around €20

It's about what I'd expect for €20 all right :-D

cortinaG

Haha, I was warned but had also read the macro filter was easily worth the 20 quid,

[IMG][/img]

I think it was.

CabanSail

It's all down to your perception of quality. If those are fine for your needs that all is good.

Please try to post images a bit smaller in the future. The size should be 800 pixels, these are about four times that size.

cortinaG

CabanSail wrote: »

It's all down to your perception of quality. If those are fine for your needs that all is good.

Please try to post images a bit smaller in the future. The size should be 800 pixels, these are about four times that size.

They were quick snaps, hand held at 1/25 sec, no flash.
I resized them on tinypic and copied the url for forums.
I guess I'm not professional enough for the mighty photographic section of boards yet.

Zillah

Your counter is making me crazy.