Camera megapixel ratings - are we being fooled

[Scubatooth]

There seems to be some confusion over DPI or PPI are what quality

6-12 dpi is the resoultion for billboard printing

72 dpi is standard print resoultion for text and low res graphics, this is also the same resoultion as most computer monitors

150 dpi is high quality printing in offset printing

200-400 dpi is photographic quality depending on the printer and its set up



Puffer Fish

ok you have to understand that PPI and DPI are seperate issues. and let me correct that those printers out there (frontier and light jet) their resoultion is in PPI not DPI. DPI is a term that has come out with the advent of inkjet printers. The DPI's listed from talking to epson engineers is that the dpi listed are the number of mixed dots per inch not dots of colors so if a single dot require 3 colors it will mix them together to get that tone and it wont degrade the. as it was explained to me by one of there engineers that if a print is done at 300 dpi on a 7 color printer( epson 2200 asa example) there could be as many as 2100 dots at that resloution (ie there are actually 90k pixels per sq in of print at 300 dpi)

Jenny: i will agree with you there because commerical printing a graphics are a different end formatting because text and most graphics dont have to be at high resoultions due to the limits of the human eye in resolving detail some where around 150-200 D/PPI in print form.

Do you work for a firm or are you a independent designer?

Scuba Luke on the chart that compares various films to digital cameras out on the market, im gonna have to say that it isnt even close and isnt close. for example it says that the 1Ds MKII has more resoultion then Tech Pan, Velvia 50, and Tmax 100. personally i know that is BS because i have shot all of those films and i know what thay are capable of. For example i have a selection of Tech pan 35 mm and 6x7 frames that i have optically printed that at 20x24 have no grain in them even with a lecia loupe. i took these same negs to my pro lab that still does traditional wet black and white prints and they said they could take the 35 mm neg up to a 40x60 before grain became visable with a loupe. As for the 6x7 frame since they can only do a max of 40x60 in the dark room they mounted the frame on the tango drum scanner and set it for 11,000 PPI (reference for a 35mm frame is 10,500 pixels by 15750pixels and 6x7 frame is 24750x 26125 or prints on the short side of 35" (35mm) and 82" (6x7") and could only see individual grains when zoomed in at 150% (BTW that 6x7 scan was 5.5GB straight off the tango). as for the other two films velvia is very close to tech pan as well as the same for Tmax.

The biggest thing that effects image quality is if there are large areas(blue skies) that are the same tone is where grain and artificats start to show up. There are ways to minimize this but then it comes down to your development of the film, with color and slide theres not much you can do but with black and white theres many ways to reduce or eliminate grain and boost contrast or sharpness(ie over expose the film and then shorten the development to bring the highlights down while keeping the shadows and mid-tones the same.

before people start jumping on me about being a film guy and anti digital FYI i have shot 400+ rolls of film this year (mostly 100 speed or slow color (print & Slide) and black and white, but then again i shoot 35mm, med format (6x4.5cm - 6x7cm), and large format (4"x5"). but at the same time i have shot since september 50GB of digital images (mainly from a 20D, and a leaf digital back on a mamiya 645) and over 100GB for the year).

my deciding factor for using film or digital comes down to what type of work (paid or personal), turn around time and intended end useage, and in some factors clients still want to see negs or slides.

I mainly shoot digital if its only going to end up on the web or going to be printed no larger then a 11x14( for larger prints its film until a DSLR can out of the camera can produce a 13x19 print with minimal grain from @ iso 800(ie a Fuji NPZ neg i can scan on a nikon 9000) that is full frame and not cost more then $2000 then i will will go full digital as at that point i can process the image to make larger prints.

personally i think it will be a long time before digital totally takes over from film because there are alot of things that digital cant do that film can (B&W is one at this current time) unless you are willing to spend 50K+ and have all the gear to run it.


FWIW

Tooth

 

[Charlie99]

There seems to be some confusion over DPI or PPI are what quality

6-12 dpi is the resoultion for billboard printing

72 dpi is standard print resoultion for text and low res graphics, this is also the same resoultion as most computer monitors

150 dpi is high quality printing in offset printing

200-400 dpi is photographic quality depending on the printer and its set up

Don't forget LPI or "lines per inch". There is even more confusion when you are talking about commercial printing that uses color separations and halftone screens. Then you will see things like a 2400dpi resolution with only 100 lines per inch of halftone screen in order to get 576 dots per halftone cell. Or that same 2400dpi output device could generate 150lpi by sacrificing intensity resolution and only have 256 dots per halftone.

 

[Scubatooth]

I know thats why i dont deal with the printer end of it because it can get messy in a hurry.

I only work on the photo end for output unless its something special and i will set up the file the way the printer wants it. Its rarely that my work goes to a offset press but when it does i send it to a friend of mine who works as a a graphic designer and can do the seperations and half/tri/quadtones (if required)

 

[ScubaLuke]

<snip> Sony 828 is an excellent example of a lens limited camera.

Just take the size of the sensor compared to the resolution chart to see how this is becoming more and more of an issue.

That's interesting. Until you pointed that out I hadn't noticed. I went over to DPReview and compared resolutions versus sensor sizes for a few cameras. I saw a couple that were up in the 90 lpmm area or better. Put me in that learn something new everyday category.

Luke

 

[ScubaLuke]

Scuba Luke on the chart that compares various films to digital cameras out on the market, im gonna have to say that it isnt even close and isnt close. for example it says that the 1Ds MKII has more resoultion then Tech Pan, Velvia 50, and Tmax 100. personally i know that is BS because i have shot all of those films and i know what thay are capable of.

First, I think your general point is correct that film still has a quality advantage over most consumer digital imaging systems. But I've shot all those films myself plus quite a few others and I'm confident the graphic is correct.

As an exercise, you can go to Kodak's or Fuji's web sites and look up the technical data on the film. Look at the MTF curve to gauge the spatial resolution of the film. The rule of thumb is to take the point where the curve goes to 60% and use that for the resolving power of the film. If you do that you end up coming up with a number around 18MP to 20MP - just a little higher than the Cannon.

And that jibes nicely with my experience. I've used Velvia for years. Most of the images in my gallery were shot on Velvia and scanned at 4000DPI on a Nikon Coolscan scanner. That ends up giving you about a 20MP image and appears to be pretty close to limits of what my lens/camera combination can do.

But I do agree that films day is not over. In fact I just bought a Pentax 6x7 to use for landscape photography. Since digital has become so popular used film cameras have gotten really cheap. I'm even thinking about getting a 15mm lens for my Nikonos. You can get those things for less than half of what they used to cost.

Luke

 

[Puffer Fish]

There seems to be some confusion over DPI or PPI are what quality

6-12 dpi is the resoultion for billboard printing

72 dpi is standard print resoultion for text and low res graphics, this is also the same resoultion as most computer monitors

150 dpi is high quality printing in offset printing

200-400 dpi is photographic quality depending on the printer and its set up



Puffer Fish

ok you have to understand that PPI and DPI are seperate issues. and let me correct that those printers out there (frontier and light jet) their resoultion is in PPI not DPI. DPI is a term that has come out with the advent of inkjet printers. The DPI's listed from talking to epson engineers is that the dpi listed are the number of mixed dots per inch not dots of colors so if a single dot require 3 colors it will mix them together to get that tone and it wont degrade the. as it was explained to me by one of there engineers that if a print is done at 300 dpi on a 7 color printer( epson 2200 asa example) there could be as many as 2100 dots at that resloution (ie there are actually 90k pixels per sq in of print at 300 dpi)


Tooth

ScubaTooth - I would agree, except that epson does not use PPI, they use DPI. Which was the point. The explaination you used is correct, just that they (and because of them, a lot of others), use DPI, when they mean PPI. Makes it confusing, only because they want it to be. To know the actual DPI on an Epson, you have to know the number of print heads - example:

http://www.epson.com/cgi-bin/Store/...view&oid=-12806&category=Wide+Format+Printers

and then subtract any that are not actually color (the example above says 8, but it only prints in 6 colors at as time) or are not used.

An R1800 says 8 also, but only prints color with 6 also (gloss optimizer and one of two blacks). Their listed resolution is 5760 x 1400, or 960 x 233 dpi. The reason for them not printing the same on both sides is due to the print head moving, causing the spots to be ovals. This is more than twice the 90K you listed, and more than 400 dpi.

As it is easy to see the difference between a 2200 (which is roughly a 90K per inch printer) and a 1800, there would appear to be an advantage in higher resolutions than have typically been done. If you can get your hands on some of their design papers, they point out that the 200 - 400 traditional maximum printing is more a factor of the dot size, and until very recently, it has not been practical to print finer, because the dots would simply blend together.

My original post was because DPI is used to mean different things in different places. Your DPI is not what Epson uses, or Canon or HP.

I have all of the above Epson printers at work, used for high accuracy printing and because some of what I do requires much higher color and resolution accuracy than any normal person would ever expect, know far more about them than I would like.

 

[Puffer Fish]

That's interesting. Until you pointed that out I hadn't noticed. I went over to DPReview and compared resolutions versus sensor sizes for a few cameras. I saw a couple that were up in the 90 lpmm area or better. Put me in that learn something new everyday category.

Luke

Thanks ScuaLuke,

Unlike some of the very knowledgeable people posting here, I work with calibration systems for digital camera's, monitors and prints to produce exact duplicates of images. A lot of what I do is test equipment. The objective is to capture an image, transmit that image some rather large distance and reproduce it exactly as it started.

For example,you can go to http://www.wilhelm-research.com/
and get what appears to be enough information on durability of paper/inks, but that information is not good enough for my work. I have to have reproducability within .3 Delta E (total color difference = the smallest amount the average human can see) and stability for at least 6 months at that level. No existing epson paper/ink is capable of that, except the mat and water color, and they cannot print the range of color I need.

DPreview's work on resolution has matched what tests I have done (but I only have done testing on 4 camera's so far), so I am comfortable using his work to screen equipment.

 

[Scubatooth]

Puffer

what or who do you work for that requires such high resoultion rates and Delta E's for images. as for calibration any good place that does color sensitive work is going to have everything calibrated and profiled from capture through production.

as for the rest im gonna leave it at where its at because you deal in a arena different then what i work with and your standards for output are much different then what i use for epson 2400 & 10600, frontier 350, 70, 90's, and lightjet machines i use for photo prints.

to each is there own!

 

[Puffer Fish]

Puffer

what or who do you work for that requires such high resoultion rates and Delta E's for images. as for calibration any good place that does color sensitive work is going to have everything calibrated and profiled from capture through production.

as for the rest im gonna leave it at where its at because you deal in a arena different then what i work with and your standards for output are much different then what i use for epson 2400 & 10600, frontier 350, 70, 90's, and lightjet machines i use for photo prints.

to each is there own!

I mostly just work with high end spectrophotometers (currently a I7 gretag - prototype of the soon to be released technology). But my use of images is for color matching actual products (images are for wood), made in China, Canada and the US (three locations). We are matching images of real objects that have to go together - quite different from making a nice looking picture.

What people in the printing industry would consider a great profile is about 10 worse than I can use. I currently do not have a single piece of calibration technology that has been released to the public at this time.

The typical spectrophotometer used for profiling has great repeatability, but terrible machine to machine agreement. Gretag's eye-one, for example is only within +/- 1 delta E. x-rite is not that good. This is changing next month, with the release of profiling for the calibration spectrophotometers.

The detail issue is a bit strange, in that we use the mean and distribution of each R, G and B range to define the color, and appearance aspects. For this to work, the resolution has to better than the microscopic variation in the actual wood. 6 meg per square foot is right at the minimum needed. So if you want to capture a 2 ft square area, you need 12 meg. Loss of resolution (as in it has 6 meg, but does not have 6 megs worth of data) has been a major problem.

RGB profiling of 6 color printers, also is not accurate enough. In fact, this is currently the only issue that still needs to be improved. I got around it by only profiling in a very narrow range of colors.

Having the printed image stay that way after printing has also been a major issue. Best we have so far is commercial Ilford 9ml satin paper, printed on any of the R800 - R1800 or similar commercial epson. This is not an optically brighten paper. One year testing has shown a color shift after drying of less than .2 delta E.

If you would like to understand how difficult this is, take a picture of a solid color - print an image of it and lay it next to the real object.

Because I have calibrated lighting, calibrated flash units, calibrated camera's, calibrated monitors and calibrated printers/paper. Doing regular photo printing no longer requires any form of test printing. There are some real benefits to getting to work on all this stuff, when it comes to general image photography, because the smallest print I ever make is a 8.5 x 11, because that is the smallest you can buy the paper in.

Hope that explains things.

Thanks for asking.

 

[ScubaLuke]

<snip>
DPreview's work on resolution has matched what tests I have done (but I only have done testing on 4 camera's so far), so I am comfortable using his work to screen equipment.

Thanks Puffer Fish,
It's good to know that somebody working professionally in the field is happy with DPRreview.

One of the great things about Scubaboard is that you run into to people of such diverse backgrounds and areas of knowledge.
Luke