Extra Megapixels Useless?

[Helen B]

The issues about resolution degradation that Derrel mentioned apply to film just as much as digital. Bear in mind that many films have a resolution of over 100 lp/mm, and some have a resolution of over 200 lp/mm. The really high resolution films like Tech Pan did show up the flaws in your equipment and technique. Equally well, the graininess of pushed High Speed Ektachrome, Scotch 640T or even relatively recent film like Ektachrome 320T would hide a lot of flaws.

Though not every situation benefits from high resolution, that doesn't mean that it is entirely useless - why would we shoot medium and large format if we didn't need high resolution (in terms of lp/picture height) images?

Referring to Derrel's post about making coffee - there would usually be a list of everyone's preference for coffee and tea pinned to the wall in the lab. It is surprising how many people liked Dektol in their coffee. I preferred PQ Universal. Meanwhile, the subject of how to develop Tri-X that had been exposed at EI 1600 was a very hot topic, with stand development in 1+3 D-76 for 90 minutes being quite popular.

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[Derrel]

Oh, Helen....Scotch 640T...whoa! flashbacks!!!!!!

[Helen B]

I still have one boxed roll, just for the memories... My precious...

[c.cloudwalker]

...It is surprising how many people liked Dektol in their coffee.

Wow! I'm not the only one who likes to drink Dektol?






"Though not every situation benefits from high resolution, that doesn't mean that it is entirely useless - why would we shoot medium and large format if we didn't need high resolution (in terms of lp/picture height) images?"

What I have found is that it is a lot easier and cheaper to err on the side of better. Redoing a shoot because the image editor/client doesn't like the resolution in 35mm would have been quite costly. No matter what the client said, I always shot in the highest resolution/IQ/whatever terms someone else understands I could shoot in that was practical for the shot.

It is easy enough to mess up a picture to make it look like a cheap camera was used. Not so easy to do the opposite.

[unpopular]

i liked mixing microdol and rodinal for a bitter-sweet brew. I don't remember the proportions tho.

[EchoingWhisper]

Just thought of something. Think I'm right though. If you plan to print smaller (smaller than the suggested size at 300PPI), a higher megapixel (more than the resolution limit lens) would be better (cause' you'll be downsizing and hiding the noise, if you were to print larger, you will upsize and the size of the noise would increase with the picture), if you plan to print larger, a lower megapixel (exactly at resolution limit of lens) would be better (cause' you'll be upsizing the picture without resolution loss and you won't increase the size of the noise).

[EchoingWhisper]

I think I was dead wrong at the starting of this thread. At the center of the Samyang 24mm 1.4 on D3X (which is currently the sharpest lens tested by DxOMark), the lp/mm is about 80. So given that the AA filter on D3x robs away 30% of sharpness per pixel, the real lp/mm of the Samyang lens is 115. This gives it a circle of confusion of 8 micro meters, and maximum pixel pitch 3.5 micro meters for sensors. Which means, to out resolve this lens without any artifacts like moire, aliasing etc (given that the lens has no AA filter), you'd need 71 megapixels on full frame and 31 megapixels on DX. We still haven't reached the end of the megapixel race, and the race goes on whenever a lens sharper than the Samyang 24mm 1.4 is made.

[murlis]

another thing, whether it has been discussed or not, that if you have more megapixels, they will have to be smaller, what does this mean, well in everyday use not a lot, but they will not be as sensitive to light, and therefore more susceptible to noise, smaller pixels tend to give a much "messier" image when you crop them. this is a result of many things such as the bayer filter on the sensors, because they only measure the intensity of light rather than the colour itself, they make the pixels go in order of red, green, blue, green, red, green, blue etc... as a result the sensors have to "Borrow" colour data from the pixels on either side. This is only normally noticeable when you shoot on very small sensors in compacts that have high megapixels, especially when the noise is high, but it can be found on ANY camera that uses this system. Now the next photos I have included were all taken at the same time, but with different cameras.

This was taken on a Kodak Easyshare bridge camera, that comes in at 12MP


This on a Sony Cybershot compact camera that is 8MP


and this on a Sigma DP2 at *ONLY* 5MP


the clarity of the sigma, with less pixels on a much larger sensor always seems to amaze people, and has been rated as being able to upscale to about 12mp worth in DSLR terms. The Sony camera shows the pixel colour borrow issue most, on the leaves on the plant. They look wobbly.

Just my input, tom.

[EchoingWhisper]

another thing, whether it has been discussed or not, that if you have more megapixels, they will have to be smaller, what does this mean, well in everyday use not a lot, but they will not be as sensitive to light, and therefore more susceptible to noise, smaller pixels tend to give a much "messier" image when you crop them. this is a result of many things such as the bayer filter on the sensors, because they only measure the intensity of light rather than the colour itself, they make the pixels go in order of red, green, blue, green, red, green, blue etc... as a result the sensors have to "Borrow" colour data from the pixels on either side. This is only normally noticeable when you shoot on very small sensors in compacts that have high megapixels, especially when the noise is high, but it can be found on ANY camera that uses this system. Now the next photos I have included were all taken at the same time, but with different cameras.

This was taken on a Kodak Easyshare bridge camera, that comes in at 12MP


This on a Sony Cybershot compact camera that is 8MP


and this on a Sigma DP2 at *ONLY* 5MP


the clarity of the sigma, with less pixels on a much larger sensor always seems to amaze people, and has been rated as being able to upscale to about 12mp worth in DSLR terms. The Sony camera shows the pixel colour borrow issue most, on the leaves on the plant. They look wobbly.

Just my input, tom.

Not really, if you display all pictures at the same size, they'll look the same if the sensor design is the same. You do realise that on 100%, the one with higher pixels will be larger. Read this to understand more - The Real Megapixel Myth

[DiskoJoe]

It good to have extra pixels when you crop a shot.

[murlis]

The whole point is that the sensor design is not the same :P I have maybe put this erroneously here as the Sigma actually has 14 megapixels, but then downscales it to 5. And i made reference to sensor size rather than sensel size!

[Jeremy Z]

Thanks for the great thread.

I've suspected this all along, but have not known how to prove it.

I've found that I rarely need more than 4 MP, and most of those times, it was needed as a digital zoom, when my PnS ran out of telephoto.