What resolution is actually needed?

[David Mitchell]

Hi all,

I am just wondering about this as I am looking at CSCs at the moment (although won't be buying one this year as I will wait for the technology to get better). I am wondering about what resolution is actually needed with a camera for the different sized sensors. The screen I am using at the moment has a resolution of around 2 megapixels, so therefore if I shot a 2MP image I could use all the pixels on screen - obviously not good if you are wanting to blow up an image larger though.

The Nikon D3200 has 24 megapixels and my D3100 has just over 14, if shooting normally on them surely you can't actually see all of the pixels when viewing the whole image?

Also due to the different sensor sizes I am guessing not all pixels are equal - a bit like how a 1080p larger screen TV won't be as sharp as a 1080p smaller screen as the pixel count is the same but spread out over a larger area.

I know that a single frame of 35mm film is around 85 megapixels or there about and my scanner should be able to get a good scan from that to digitize it, but i'm limited to what i'm actually seeing on the screen lol.

Is there a good 'working' number of megapixels I should be looking at for prints up to say A4? I haven't yet actually printed anything, its all shown online on here or on Facebook. Should I just look at the features and dynamic range of the camera rather than the resolution?

Hopefully they will bring out a Foveon CSC soon as it seems i'm after a better dynamic range rather than megapixels count - I don't shoot images for billboards lol.

 

[Dave Moss]

For A4 size you would need 6mp A3 8mp and A0 12mp I only looked it up because all the reviews for the HS reckon that instead of shooting at the headline 16mp your better shooting at 8mp which uses 2 pixels on the sensor for each pixel It does make me wonder if we are getting to the stage where there over populating the sensors

 

[David Mitchell]

Ah, I have just found the settings in my D3100 for the different image sizes, either large, 4608x3072 @ 14.2 MP, 3456x2304 @ 8 MP or 2304x1536 @ 3.5MP.

I have set it to shoot @ 8 MP but on RAW, I will try some test shots at some point to see the difference, I haddn't thought of reducing the resolution in camera. I guess its like bumping up the ISO by making the sensor more sensitive its maxxing out whats possible. Would the native size for the camera be at the 14.2MP?

 

[Hamish Gill]

Hi all,

I am just wondering about this as I am looking at CSCs at the moment (although won't be buying one this year as I will wait for the technology to get better). I am wondering about what resolution is actually needed with a camera for the different sized sensors. The screen I am using at the moment has a resolution of around 2 megapixels, so therefore if I shot a 2MP image I could use all the pixels on screen - obviously not good if you are wanting to blow up an image larger though.

What do you mean by needed?
If you are an amateur, you have to ask your self what your goals are?
Are you looking to print? often?
Do you crop much?

Quantity of pixels can be important, size of pixels can be important, the sensor its self is important...

The Nikon D3200 has 24 megapixels and my D3100 has just over 14, if shooting normally on them surely you can't actually see all of the pixels when viewing the whole image?

in what sense can you not see all the pixels ...?

Also due to the different sensor sizes I am guessing not all pixels are equal - a bit like how a 1080p larger screen TV won't be as sharp as a 1080p smaller screen as the pixel count is the same but spread out over a larger area.

yes... old but relevent Pixel Pitch

I know that a single frame of 35mm film is around 85 megapixels or there about and my scanner should be able to get a good scan from that to digitize it, but i'm limited to what i'm actually seeing on the screen lol.

were you not scanning at 1200dpi ... thats not gonna give you 85mp

Is there a good 'working' number of megapixels I should be looking at for prints up to say A4? I haven't yet actually printed anything, its all shown online on here or on Facebook. Should I just look at the features and dynamic range of the camera rather than the resolution?

Yep, look at all features and choose the camera that is right for you ... I have never bought a camera on pixel count!

Hopefully they will bring out a Foveon CSC soon as it seems i'm after a better dynamic range rather than megapixels count - I don't shoot images for billboards lol.

Foveon is good for daylight, but not so good for much else ... I wouldnt buy a foveon csc ... buy a nex! or wait to see how awesome the fuji xpro2 is

you would do worse to read all of this Digital Photography Tutorials

- - - Updated - - -

Ah, I have just found the settings in my D3100 for the different image sizes, either large, 4608x3072 @ 14.2 MP, 3456x2304 @ 8 MP or 2304x1536 @ 3.5MP.

I have set it to shoot @ 8 MP but on RAW, I will try some test shots at some point to see the difference, I haddn't thought of reducing the resolution in camera. I guess its like bumping up the ISO by making the sensor more sensitive its maxxing out whats possible. Would the native size for the camera be at the 14.2MP?

if its on 8mp it wont be on raw

 

[Ralph Thornton]

Pixel count vs Resolution.
The highest quality printers working in color are usually satisfied with an image that has a "resolution" of 300 pixels per inch. It used to be referred to as dots per inch but most everyone now thinks in terms of pixels. That to me is the resolution or how many pixels are in a certain length of space.

Take an image 3000 pixels by 1800 pixels. If you print that image at 300 pixels per inch it will be an image 10 x 6 inches in size. You could also say it in reverse, i.e. print a 3000 by 1800 pixel image at 10 x 6 and your resolution, as long as the printing device doesn't throw away pixels, will be 300 pixels per inch.

Take the same image and print it at a lower resolution which is fewer pixels in a given distance, say 100 pixels per inch (ppi) and it will come out 30 inches by 18 inches. Now the larger image printed with the same number of pixels will be of lower quality because there are fewer pixels in a given space. If you want the same quality as in the first image that 30 inch wide image needs to be 9000 pixels wide.

Comparing cameras might help understand the concept. If the two cameras have the same size sensors but one camera is 6 megapixels and the other is 21 you should be able to predict which camera will take more detailed images. It will be the camera with more pixels in the same space.

I would always recommend taking an image at the greatest number of pixels the camera supports. You can then crop the image with more flexibility to still allow enough remaining pixels to produce a quality image. You can always use software to reduce the number of pixels in an image without losing much. But there is a real limit to how many pixels you can add without losing quality.

 

[Chris Dodkin]

What Ralph said!

 

[Hamish Gill]

What Chris said!

There is also viewing distance to take into account ... Ralph's 100dpi image would be perceived as as good quality as his 300dpi image if veiwed from further away.
(in the voice of father ted - "these pixels are small, those pixels are far away" )

 

[David Mitchell]

What Hamish said oh wait, that doesn't work as the OP lol

Thanks for your help on this guys, I am getting tempted by an NEX at some point as I know you can get lens adapters for basically anything due to the shorter flange distance it has normally. I do like how the CSC cameras at the moment like the NEX are basically just like film backs with a lens attached lol

What I mean about not seeing all the pixels when looking at a photo is if the image is 4608 pixels wide but my screen only has 1080 pixels wide, surely some pixels would be missing (unless I zoomed in).

I forgot about cropping the image, I would need more pixels initially before it gets into post production, I guess i'm just wanting the best quality of pixel rather than the volume though. I am rather worried that the different makes are basically trying to outdo each other with more and more pixels and the detriment of image quality. If I am in need of making a large image or print I would take out the 4x5 speed graphic lol.

 

[Ralph Thornton]

What Chris said!

There is also viewing distance to take into account ... Ralph's 100dpi image would be perceived as as good quality as his 300dpi image if veiwed from further away.
(in the voice of father ted - "these pixels are small, those pixels are far away" )

Agreed!

 

[Larry Bolch]

On a forum some years ago, someone was being a fountain of misinformation. He ponitificated that with desktop printers, a minimum of 1440 pixels per inch was needed, though a large format print could get away with 720 ppi. I decided to do some tests. I chose a perfectly exposed medium format negative, shot on ISO100 film, with a Linhof and Schneider lens. The idea was that the original exposure should not have weaknesses. Viewers would be judging the print quality, not the photograph.

My scanning software allowed me to make a selection on a negative, set the target size and the resolution in ppi that I wanted. I chose 5×7 as the target size, since that would let me print two images side by side on a single sheet of letter-size paper.

My first pair, was 720 and 360 ppi. Absolutely no visible difference. Nothing whatever gained by 720.

Next, I did a pair at 240 and 360. A small number of people thought they could see a slight difference, buy no one would venture which was the better print.

At 180 and 240, at reading distance, one could perceive which was which, but at arm's length, the difference vanished.

At 180 and 120, the difference was clear, but the lower resolution image still looked remarkably good. If one made a print at 120 ppi and just left it on the table, viewers would not likely notice that it was a bit short on detail.

Viewing distance is a critical factor. For decades, Kodak had an 18×60 foot photomural on display high above the concourse in New York City's Grand Central Station. Many were shot with 35mm cameras. Close up, the dye clouds were the size of tennis balls, but from the floor the image looked crisp and clear.

The same is true of any large print. When you are at the proper viewing distance, the print will generally have more resolution than your eye. A dozen years back, I did a head-shot of a macaw with a Nikon Coolpix 990—3.34MP. A friend and noted authority on the parrot family of birds wanted a print for his living room. He wanted it 24×36. I cautioned him, but he was a stubborn as an old Dutchman could be. When I saw it in place, I was quite taken aback. From anywhere in the room, it looked great. Only when I came within reading distance could I see it was a bit short on crisp detail. Sure, more pixels would have been nice, but no one noticed. The original size was 2048×1536, meaning that it was around 60 ppi!

Which is to say, amazing images can be printed from a remarkably few pixels. Having more does not hurt, but as one approaches the nominal 300 ppi at which printers are commonly compared, returns diminish. How many is enough? Impossible to answer, but a lot fewer than camera salesfolk would like us to believe when printing very large with viewing from a proper distance.

 

[Paul Lange]

Just to sum up my experience for what if it worth, hopefully it will give you the same information already stated but from another viewpoint. For printing 240 to 300DPI is more than enough. The more megapixels the larger the image. However many professional printers and consumer printer software is capable of producing decent prints with much lower resolutions. I have had some 50x30cm prints professionally printed from 7MP jpegs. I have had 1.5 meter x 1 meter prints from a 6MO image that was in camera extrapolated to 9MP (some of the older Fuji bridge cameras). The most useful consideration I have found is that higher MP means greater possibility to crop the image but you have to weigh this up against pixel density and at what ISOs noise becomes a problem with your particular camera. Some of the modern cameras have high pixel count and pretty good noise performance.

 

[Brian Moore]

The discussion of pixel counts and PPI and DPI boggles my mind. I obviously need to learn this stuff. But as I read through the posts it struck me how, at the end of the day, the notion of viewing distance weighed so heavily. It's analogous to viewing a painting at a museum. Stand back and you percieve what that artist wanted you to see. Get up close and you see the individuals dabs and brush strokes that you were not meant to percieve.

 

[Larry Bolch]

The discussion of pixel counts and PPI and DPI boggles my mind. I obviously need to learn this stuff. But as I read through the posts it struck me how, at the end of the day, the notion of viewing distance weighed so heavily. It's analogous to viewing a painting at a museum. Stand back and you percieve what that artist wanted you to see. Get up close and you see the individuals dabs and brush strokes that you were not meant to percieve.

Exactly so.

 

[Andy Boardman]

I have been told that the human eye can not see anything over 300DPI so what ever you print above that is a bit of a waste & I think viewing distance is more important to take into account, if you have to get your eye close up & say you can see pixels then you are in the wrong game & should have your driving licence taken off you to LOL.

 

[Mike Milton]

If you are printing inkjet, you also need to keep in mind that the ink mixes as it is adsorbed by the paper (intentionally) and, as mentioned earlier, the driver works to manage the fact that the pixels in the image may span a great many pixels on the device as well.

In the real world, quite good results can be had at surprisingly low resolutions. For example, Michael Reichman was doing wonderful print work early on with the modest resolution of an EOS 30D. I had that camera as well and printed up to A3 with results that viewers said were excellent.

Now, I'm not arguing against using whatever resolution you have. Not at all. I would argue that while much of the math above is accurate it greatly overstates what is necessary.

I'd also observe that printing on photochemical paper via colour laser seems to be more demanding and (at least to me) less pleasing at any resolution, but particularly if the file is relatively low res.