DSLR Sensors - A Guide

madbalsam · Jun 20, 2011

This may be out of topic but I am actually curious about the flash lights that I need to use with my DSLR. I do not know which types of lights to use or whether to use lights at all (especially for outdoor shoots). Also, I am curious about sufficient lighting within the house.

geraldsoh · Aug 3, 2011

great stuffs....cant wait for your next post! i do have problems when it come to night shots as i dont have a flashgun. thus, high iso = noise!!!

jasonkip · Dec 14, 2011

It seems to me that full frame is the way to go. It'll be my next significant purchase. I'm looking forward to getting more out of my wide-angle lenses the most, I think.

Retocuher · Dec 21, 2011

Highly informative thread.Huge thanks Neil.

Crollo · Dec 26, 2011

A crop sensor does not change the focal length of the lens. it merely magnifies the FOV.

AngieQ · Dec 28, 2011

Thanks for taking the time to write this, very helpful!

The_Duke · Apr 26, 2012

good to know, thanks!

bratkinson · May 1, 2012

I strongly protest the incorrect statement that mounting a lens on a crop-sensor body changes the focal length. This is 100% FALSE!! A lens does not "magically" transform into some kind of zoom such as a 100mm lens becoming a 160mm on a crop body. I also strongly disagree with the phrase 'added reach' referring to mounting a lens on a crop body, for the same reason.

Mounting a lens on a crop sensor body effectively puts "horse blinders" on the lens, limiting the angle of view of what the camera 'sees'. Effectively, the 'peripheral vision' of the lens is reduced. That is =ALL= that happens! While the image produced by the lens is UNCHANGED, regardless of what body it is mounted on, the smaller sensor size in crop bodies only 'sees' the inner portion of the image. The rest of the image falls on the black plastic/metal backside of the camera.

jamesshook2001 · May 1, 2012

Great job and incredibly helpful!

belial · Aug 29, 2012

bratkinson said:
I strongly protest the incorrect statement that mounting a lens on a crop-sensor body changes the focal length. This is 100% FALSE!! A lens does not "magically" transform into some kind of zoom such as a 100mm lens becoming a 160mm on a crop body. I also strongly disagree with the phrase 'added reach' referring to mounting a lens on a crop body, for the same reason.

Mounting a lens on a crop sensor body effectively puts "horse blinders" on the lens, limiting the angle of view of what the camera 'sees'

this isn't totally correct either and this statement gives a whole list of its own misconceptions. At the extreme ive seen a aps-c user concerned he only has part of a camera like somehow 135 format was the end all of photography. Smaller formats give a smaller field of view so in that respect a 50mm would behave like a 85mm. But you're correct the other properties of the lens do not change including its actual focal length. Another thing to consider is if you use a lens made for a smaller sensor theres virtually no fall off as compared to a lens made for 135 format on the respective sensor.

CanonJim · Sep 3, 2012

belial said:
...in that respect a 50mm would behave like a 85mm.

I have to respectfully disagree - a 50mm lens mounted on a crop-sensor body is still a 50mm lens. The distance between whatever lens elements and camera body parts are used to measure the focal length is 50mm, not 85mm and not anything else. It does not "behave" like an 85mm lens. What it DOES do, is give you the FIELD OF VIEW that an 85mm lens would give you on a NON-CROPPED sensor. Field of View is not the same as focal length. BRAtkinson's post is entirely accurate.

All this confusion is mainly the manufacturer's fault for not explaining it correctly and clearly in the first place, and making you think that if you buy a crop sensor camera and put a 100mm lens on it, you get a 160mm telephoto instead. Pure marketing BS.

If I take my 100mm EF Canon lens, mount it on my crop sensor 50D, and take a shot, and then mount my 18-135mm EF-S lens and move the zoom to 100mm and take a shot BOTH SHOTS LOOK EXACTLY ALIKE in terms of their Field of View. The EF-S "crop sensor" lens does not make 100mm look like 160mm. Just look at these two test images which I just took a moment ago. BOTH have exactly the same field of view.

Now, that said, if I take my 100mm EF Lens, and mount it on a 5D, it would have a wider field of view, because of the relationship of the larger sensor to the lens elements. And if I could magically mount my EF-S lens to the 5D, which I can't, and moved the zoom to 100mm ON THAT LENS, it would look as though I had mounted a 160mm lens on my 5D, because of the geometry of the lens elements and 5D sensor size with that particular combination.

The terms "magnification" and "crop factor" should never appear in the same sentence together.

Goldcoin79 · Sep 4, 2012

Can some one explain the relationship between sensor size and megapixels on the sensor? If I had a camera with a full frame sensor which was 14 mps and a camera that had a 4/3 sensor and was 14 mps is it just the fact that the full frame sensor receives more light therefore more info that the picture would be better or is there more to it?

My canon sx30 is has a sensor that is smaller than a 4/3 sensor and it can only go as high as f8 (or smallest apeture setting however you want to put it) would the sensor being smaller be why I can't select a higher f number and if so can you explain?

CanonJim · Sep 5, 2012

Goldcoin79 said:
Can some one explain the relationship between sensor size and megapixels on the sensor?

From what I understand, the big thing here is that on a "full-frame" sensor, the individual pixel elements are both, or at least CAN BE, larger in physical size, and spaced farther apart. This gives a 'cleaner' electrical charge, and reduces cross-pixel noise. Obviously, a 35mm sensor would not be as 'crammed full' as one only 20 or 24mm in dimension, if they both offer the same number of pixels.

I am not sure if there's an absolute relationship between sensor size and the widest aperture available on a lens on a P&S or bridge camera. I would suspect that's more a question of cost. The f/ number is a ratio of aperture opening to sensor plane or something like that, so conceivably it could be f/1 or f/100, with no regard for the size of the sensor itself. But I welcome a more knowledgeable answer if there is one.

Goldcoin79 · Sep 5, 2012

I understand all about apeture and f numbers but my sensor is a 1/2.3 size and you cannot increase f number higher than f8. I have had a similar discussion on here about this and the best answer I got was because of diffraction if the apeture was made smaller it would cause the image to not look as sharp because a sensor this small needs needs to increase the image size to display it, I don't fully understand what is meant by increaseing image size to display it because if this is the case doesn't every sensor size have to increase image size to display it.

Maybe some one can make this clearer for me.