Take the 2-minute tour ×
Video Production Stack Exchange is a question and answer site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation. It's 100% free, no registration required.

Many of new model of lenses are defined as megapixel (i.e 1MP, 2MP, 5MP...).

My problem is that I did not find any difference between a standard lens and a "megapixel" one, in the focus quality. I suppose that a difference should be remarked in the focus quality during the calibration step.

I'm working with several megapixel sensors, and I'm still looking for a megapixel lens that could fit with my sensors. For example with a 2MP sensor, with a pixel size equal to 4um, the MTF should be at least 0.5 at 125 lp/mm. My working distance is about 15m and the illumination wavelength is 850nm.

share|improve this question
7  
Is it just me, or would this be more appropriate at the photography SE site? –  David Zaslavsky Apr 4 '11 at 7:40
1  
I believe this question is about video equipment, and as such is actually off-topic here, despite the migration from the physics SE site. –  mattdm Apr 4 '11 at 15:00
add comment

migrated from photo.stackexchange.com Jan 26 '12 at 4:03

This question came from our site for professional, enthusiast and amateur photographers.

3 Answers

This is a misnomer, if not pure marketing corruption of terms. The lens doesn't do anything to the "megapixel count", that's determined solely by the sensor. At most the lens might have the capability to resolve details to a level where a sensor of at least a certain element density is required to record them, but then you'd still not have a number of pixels as the size of the sensor as well as its element density determines that.

share|improve this answer
4  
It's marketing silliness +1 –  Georg Apr 4 '11 at 10:39
1  
Not quite silliness, if I am buying a lens for a 1/2" analogue camera with 240lines resolution I don't want to pay for one designed for a 1920x1080 HD chip –  Martin Beckett Apr 4 '11 at 23:59
add comment

Pixel count almost exclusively refers to detector quality/cost, it is the number of seperate elements capable of recording an image. The Modulated Transfer Function (MTF) is a quantative measure of the optical train in front of the detector.

It is important to differentiate between a monochromatic CCD and a CMOS sensor. In most retail digital cameras now there will be a CMOS sensor which works in three colours simultaneously, which has the effect of dividing your pixel count by three, but allows one shot colour pictures.

Also just because there are micron sized detector elements in the image plane this does not mean that your optics is capable of focussing to that level of detail. You need to consider the resolution needed in your image and set your pixel requirements accordingly.

share|improve this answer
    
Thanks for the answer. The sensors I'm working with, are all CCD B/W. All the CMOS sensors that I found are rolling shutter, that is not suitable for my application –  Raphael Apr 4 '11 at 9:37
add comment

The lens is related to the angular resolution, while the megapixel rating has to do with the capturing device, i.e., CCDs etc. I haven't done the calculations, but it may be that it is not the angular resolution that limits the resolution in digital images, but the the image capture technology. So the lenses from the different cameras may be similar.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.