The Mega Pixel Myth

[milkyjoe]

Hi folks,

Just thought I'd share this with everyone, it is a very interesting read... The Megapixel Myth.

Regards,

Richard.

[pete_l]

Yes, even "High definition" TV is a mere, 1990's quality, 2 Mpix. Hardly ground-breaking.

I've always considered the whole thing to be mere marketing. The idea of having a camera in a phone that's 3, 5, 10 or more MPix and then havind a cheap plastic fixed-focus lens in front of it is pointless. However if you make this known to the proud owners of said phone, they get the hump.

Even dafter is trying to display a 5MPix image on a computer screen,.Most of these are only 1 - 2 MPix (1280x1024 is 1.25 MPix) so you can never see the whole thing at native resolution, let alone process it properly without panning all the time.

The only advantage a lot of megapixels gives is the ability to crop an image. But very few people do this (even in astronomy).

[FLO]

Very good article. Back when Canon went from a 3mp DSLR to a 6mp DSLR they confessed only around 5% of their lenses could truly challenge such a high resolution sensor.

Steve

[drewzilla]

Yeah really interesting! Cheers

[Nova]

Good read, cheers. I have always judged a camera, in part on its megapixel rating. Guess you could say I was sold on the marketing just as pretty much everyone else is. The article has opened my eyes

[Keiran]

MP does mater if you are wanting to crop an image though.... But otherwise it is true, made for a good read

[FraserClarke]

The idea of having a camera in a phone that's 3, 5, 10 or more MPix and then havind a cheap plastic fixed-focus lens in front of it is pointless.

It's even worse than pointless -- it gives you a poorer image! Because the image is sampled at a much higher resolution, the light is spread over more pixels, so you reach the 'read-out noise limit' much quicker in faint light. So you get a noisier/grainier image!

Mobile phone cameras would perform much better if they had fewer, bigger, pixels in them.

Marketing makes us buy things that are worse, yeah!

[pulsar pete]

Richard,

Absolutely agree with the article. Anything above 8mp needs very high quality lenses to give you any further benefit unless you are cropping to a large extent. The limitation on most DLSR cameras 8MP upwards is the quality of the glass in front of the sensor, not the sensor.

Peter

[milkyjoe]

That's an interesting point you both make. I have a 5mp camera on my iphone, but during the day the images are acceptable, but in low light, forget it! lol

It's even worse than pointless -- it gives you a poorer image! Because the image is sampled at a much higher resolution, the light is spread over more pixels, so you reach the 'read-out noise limit' much quicker in faint light. So you get a noisier/grainier image!

Mobile phone cameras would perform much better if they had fewer, bigger, pixels in them.

Marketing makes us buy things that are worse, yeah!

[milkyjoe]

Richard,

Absolutely agree with the article. Anything above 8mp needs very high quality lenses to give you any further benefit unless you are cropping to a large extent. The limitation on most DLSR cameras 8MP upwards is the quality of the glass in front of the sensor, not the sensor.

Peter

Hi Peter,

Is the same true for astrophotography as no lens is needed?

Regards,

Richard.

[dph1nm]

Something of a counter-argument here:

www.Clarkvision.com: The Megapixel Myth, Image WOW Factor, and Digital Images

NigelM

[blackparticle]

An interesting read.

For astro use, sensor and pixel size is probably more important than the number of pixels, especially when your mount is unguided.

Smaller pixels mean increased resolution but at the expense of sensitivity and how long you can keep the shutter open before mount tracking errors creep in.

Obviously, if you're wanting to make decent sized prints from your images then a higher MP count helps preserve the fine detail when closely examined. Higher MP's do also allow for increasing the image sharpness by resizing the image downwards.

I find a good rule-of-thumb here is that if it looks good on your monitor screen at 100dpi, it will look good printed at 100dpi, really good when printed at 150dpi (2/3rd size) and excellent at 300dpi (1/3rd size). 600dpi+ printing really only comes into it's own for B+W text or more technical images that are usually derived from vectors rather than pixels. (or in the case of the second article whereby the film images are scanned at massive dpis.)

Asking yourself the question of whether you are just imaging for the screen or also imaging for print can really help with camera choice when it comes to choosing how many pixels your camera has.

Personally, I'd like to give myself the option of both so if I do capture a stunning image, I can get it printed out at approx A2 or even A1 poster size for the wall. As a minimum that requires approx 1600 x 1200 for A2 and 3200 x 2400 for A1.

Stacking software with a good x3 drizzle function can also help here. It's certainly better to upscale a 100dpi image using x3 drizzle and then printing at 300dpi rather than printing the original image at 100dpi.

I'm surprised that Canon stated that only 5% of their lenses would challenge the sensor though. I read an article recently that suggested that a good quality film stock would easily out-resolve any decent small apature scope whereas the same scope would have optics that would out-perform even the largest of todays high MP cameras.

But like any type of photography, focusing and image sharpness is always the key factor. Garbage in / garbage out and all that..

Alan

[themos]

It's not about how many megapixels you have but about how mega (greek for "big") your pixels are.

[bish]

It's not about how many megapixels you have but about how mega (greek for "big") your pixels are.

Very true. The size/quality of the pixels is the thing. As mentioned above you need excellent optics for high megapixel cameras. I still use my old 5D (12.8mp) alongside my 5D2 (21mp). I don't need such huge files but wanted the higher ISO capability. I would have liked a Nikon D3s (12mp) but don't have that kind of money and would have to change all my lenses.