How large is the Rebel's sensor? (noob question)

[DocFrankenstein]

I know it's a lame question, but I am a bit confused...

On one site it said the matrix is a size of a fingernail, on the other it says it's the same as 35 mm film.

Please tell me

[robertwgross]

That sensor size is specified in the manual, Major Specifications, Image Size.

It is neither 35mm size (36x24mm) nor is fingernail size.

---Bob Gross---

[cmM]

22.7mm x 15.1mm
6.30 effective MP (3088 x 2056)

[DocFrankenstein]

DOH - thank you

So basically, if you're using the lenses for 35 mm you lose about 70 percent of the light... so that only 30% of the image hits the sensor...

right?

[G3]

No. I think the Drebel image sensor is about 40% of the area of a 35mm frame. That results in a 1.6 crop factor when using 35mm lenses. When the image is printed or displayed at the same size as a 35mm frame for the same lens (at the same zoom setting if it's a zoom) that translates to a 1.6 magnification factor. What that means in practical terms is that you will lose substantially on the wide angle end (a 28mm on the Drebel will act like a 45mm would on a 35mm camera), and you will gain substantially on the telephoto end ( a 300mm on the Drebel will act like a 480mm would on a 35mm). There is no change in light transmission, f4 is still f4.

[DocFrankenstein]

But you still lose... kinda


If you had a sensor as large as 35 mm film, it would get 2.5 times more light with the same lenses. Which translates into better quality...

Cause here we have lenses with the capability to put a sharp image on a wide area, and we're only using 40% of it. So we couldv'e scaled down the lenses by a factor of 2.5 and still get the same results... :shock:

[cmM]

Quality ? No
what you lose is "quantity". The quality of the light going through the lens is the same, but you have less pixels to record the image on. So the only thing that could be in your way is print size. If you want huge prints, then obviously a full frame sensor will give you better quality since the area is 1.6 times bigger than the one on the Rebel.

[ron chappel]

Your pictures won't be any darker because the smaller sensor (than 35mm film) just cuts the edges off.The center section that is left is still the same brightness....hope that makes sence

[dtrayers]

The amount of light per unit area is the same.

Yes, you lose the field of view advantage you get with a larger sensor, but you gain in apparent focal length with the same aperture. My 70-200mm f/4 performs like a 112-320 f/4. A 100-300mm f/4 Sigma costs $300 more and weighs twice as much.

But here's the real benefit. The image quality of most lenses degrades towards the edges of the image circle and with some lenses vignetting sets in. The smaller image sensor is centered in the best part of the lens, so the resulting image quality can be higher than with a full frame sensor.

Put another way, you can get the same image quality with a lesser quality lens. That's why the kit lens with the 300D works as well as it does. It doesn't have to make a good image all the way to the edges, just the center.

[Andy_T]

...I know a guy whose fingernails are *exactly* the size of a 35 mm negative... so the answer to your question is 'somehow'

Just kidding.

The only real advantage of smaller sensors is that they are cheaper to produce. (which is mainly an advantage for Canon). You can always improve the zoom capability of your film body loaded with Velvia using a pair of scissors...

Image quality won't benefit the same way, though...

Best regards,
Andy

[CoolToolGuy]

Put another way, you can get the same image quality with a lesser quality lens. That's why the kit lens with the 300D works as well as it does. It doesn't have to make a good image all the way to the edges, just the center.

Well, not exactly - the kit lens is designed to produce a smaller image circle than the normal EF lens. It must still be sharp to the edges, but to the edges of a smaller frame (the Drebel sensor). The kit lens is essentially made for a smaller format. Same reason why lenses for a Mamiya 645 are more expensive than those for 35mm.