Let's have a technical discussion here regarding photography.

Ask anything about technical wise in photography, be it camera interior technology, exposure basic, types of camera, basic essence of photo and etc

Don't be shy as we are noob in certain way or aspect. Try let other forumers answer ur doubt, what u want to know, why it happened etc..


Pls refrain yourself to ask how to improve ur composition (unless ur composition problem got anything to do with technical aspect), what camera to buy or one liner spamming(eg. "googled it"). This is thread for technical discussion.


Let me have a start.

Why the heck CMOS sensor have better noise control than CCD sensor? I'm from engineering background but just couldn't get how MOS transistor can control noise better than capacitor

I have another question: What is DOF preview? I know some DSLRs have this feature.

From the back of my head, remembering that noise is something due to the electric static charge on the sensor or whatever... CMOS is better because there isn't so much of that electric charge... or maybe i'm totally wrong.. i dunno... haha!



When you fit on a lens, what you see through the view finder is at the widest aperture... (i.e, through your viewfinder a 50mm f/1.4 will be brighter than a 50mm f/1.8 for example because it's aperture is wider) ... which is also why these lens are generally better at focusing through the dark as well!

Because of this "default" setting, it can be quite hard for your to gauge what is necessary for to get front-to-back razor sharp images (i.e, how much aperture you need to get tackly sharp images)... so you turn the aperture smaller (higher f number), and select the DOF button... What you camera does is then close the aperture size to what you set. (The side-effect however is a darker viewfinder)

Hope this helps!

CMOS basically are transistors which exhibit better current or voltage control than capacitors, thus better performance.

Today, most digital still cameras use either a CCD images sensor or a CMOS sensor. Both types of sensor accomplish the same task of capturing light and converting it into electrical signals.

A CCD is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges are converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information.

A CMOS chip is a type of active pixel sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip converts the voltage to digital data.

Neither technology has a clear advantage in image quality. CMOS can potentially be implemented with fewer components, use less power and provide data faster than CCDs. CCD is a more mature technology and is in most respects the equal of CMOS.

Two important characteristics of CMOS devices are high noise immunity and low static power consumption. Significant power is only drawn when the transistors in the CMOS device are switching between on and off states. Consequently, CMOS devices do not produce as much waste heat as other forms of logic, for example transistor-transistor logic (TTL). Low power consumptiom -> low static accumulation -> lesse noise

The info that i get is that CMOS processing electronics is nearer to individual photo cell compare to CCD.

It might br true that lower static power consumption that reduce static charge accumulation and hence reduce noise but noise can come from a lot different sources too such as temperature, radiation and etc..
It might be one of the factor

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