lmTrying Loc: WV Northern Panhandle

I'm trying to figure out this Full Frame/Crop Frame vs. Mega Pixel thing. But one thing at a time.

Keeping the sensor size the same (either FF or Crop), increasing the mega pixels from 12.1 to 24.2 should give an increase in fine detail. Yes or no?

Is this fine detail visible on a 4"x6" photo? Or is it not visible until the photo is made larger, like 8"x10" or 24"x36"?

Bill_de Loc: US

For 4x6 prints 2 megapixels is more than enough.

Convert the dimensions to 300/inch and then multiply length times width.

Most home printers work well with as little as 240/inch.

So, in most cases 12mp is more than enough for an 11x14

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BebuLamar

To see the fine details in a 4x6 photo that coming from a 24 MP camera the printer must be able to print 1000 ppi which I don't know of any printer that can do that. Typically maximum printer resolution is 300 ppi (while a printer dpi could be 4800 dpi but it can only print no more than 300 ppi).
In this regard talking about 4x6" photo a print make from a 35mm negative printing using the optical method could render finer details.

rjaywallace Loc: Wisconsin

Answer to Question #1 - Yes
Answer to Question #2 - Maybe, but it wouldn't matter much for a regular print that size.
As Bill_de points out, you could make an acceptable 4x6 casual print to give away to friends from an image captured by a sensor with a much lower number of megapixels. Even if you are printing larger images (8x10, 11x14, etc.) to display in your home many cameras with 16-18MP sensors would be ample. If you are printing very large for display in an art gallery or a museum, then the MP number of whatever camera you are using might be significant.

Apaflo Loc: Anchorage, Alaska

Whatever your out of camera pixel size is, for a Canon or HP printer divide by 300 and for Epson divide by 360. That gives the optimum size in inches for a print. Resizing smaller reduces resolution. Larger does not add resolution, but does not significantly reduce it either.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

There is a lot of misunderstanding and mythology regarding this subject. It is really simple. The closer your eyes are to the print, the higher the ppi you need.

A 4x6 needs 313 ppi to look sharp and crisp.
A 40x60 needs 32 ppi.

2 mp will produce a "fair" quality 4x6. 3 mp would be better.

The difference is your viewing distance for a 4x6 is typically 11" and a 40x60 would be around 108"

If you anticipate people walking up close to view a large print, you need to adjust your ppi to accommodate anticipated viewing distances.

If you print a very high resolution print to a large size, it won't look any different than a lower res one.

The Apple iPhone 6 was 8 mp, but when you saw images printed to billboard size they looked amazing.

A 4K cinema projector at the local multiplex is 4096 × 2160, or 8.8 mp. Viewing distance is usually greater than 20 ft.

People who are advising you that you can decide what resolution you need without taking into consideration all the factors are giving you bad advice.

http://www.photokaboom.com/photography/learn/printing/resolution/1_which_resolution_print_size_viewing_distance.htm

This is scientifically based, advice - and pretty much standard in the large printing industry like movie posters (you see them on the way to your movie screening room at the theater), billboards, vehicle graphic wraps, etc.

Image resolution is not the same as printer resolution -

Bill_de Loc: US

Gene,

Do the print drivers for the typical home printer do their own interpolation or interpretation of whatever we feed them?

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Apaflo Loc: Anchorage, Alaska

They always resize for the PPI the printer uses. That is 300 PPI for Canon and HP and 360 PPI for Epson printers. (Some can do high res at twice that, which is fine for text and line drawings but not for photographs.)

Apaflo Loc: Anchorage, Alaska

So why always add so much needless confusion.

DGStinner Loc: New Jersey

PPI = Pixels Per Inch
DPI = Dots Per Inch = the number of ink droplets a printer can place per inch
They are NOT the same thing. It has become commonplace to refer to PPI as DPI, even though PPI refers to input resolution.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Yes.

TheDman Loc: USA

... From the king of adding needless confusion.

Gene is right. That's all you need to know.

Bill_de Loc: US

Thanks.

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selmslie Loc: Fernandina Beach, FL, USA

Because what you said is irrelevant when you don't take into account viewing distance.

Put your calculator down and use some common sense.

jerryc41 Loc: Catskill Mts of NY

As with many things, bigger is often better, but a lot depends on the camera. All 20MP cameras will not produce identical results. A better camera will produce better results, but "better" can mean yuou have to zoom in to see small differences. It's like saying a car that will do 0-60 in 5.0 seconds is better than one that will do it in 5.5 seconds.

Some info -
http://design215.com/toolbox/megapixels.php
https://improvephotography.com/34880/how-big-print-with-megapixel-camera/
http://www.kenrockwell.com/tech/mpmyth.htm

MP in color, print size on outside.