Difference between 6 mp and 8 mp?

Discussion in 'Digital Photography' started by Macanadian, Sep 11, 2006.

  1. Macanadian macrumors member

    Sep 11, 2006
    I've been shopping around for a Digital SLR (I'm retiring my 35 mm Pentax Z1P).

    One salesman stated to me there is no difference between 6 megapixel and 8 megapixel. You only see a diff. between 6mp and 10 mp.

    The largest print I've made is 16 X 20 inches and a 12 X 36 inches. Using a cheap 5 megapixel Samsung compact camera. The 12 X 36 was actually three photo's mergered together to make the panoramic shot.

    Does anyone have experience with printing up larger prints from digital cameras.
  2. Old Smuggler macrumors 6502a

    Old Smuggler

    Sep 8, 2006
    Well the biggest difference you will see between a 6 MP and a 8 MP is the
    200$ you pay for 2 more Megapixels

    just kidding

    2816 x 2112 6 MP
    3264 by 2448 8 MP
  3. Kingsly macrumors 68040


    That salesman is an idiot™

    Of course there is a difference. (not that I could tell you, because my current highest camera is 6MP, but the difference between 3.2 and 6 is HUGE!!!)
  4. Silentwave macrumors 68000

    May 26, 2006
    Gainesville, FL
    Actually Kingsly, the whole MP thing has diminishing actual returns. The difference between 3 and 6mp can be 1000px linear but to get the same increase over 6mp you need to head towards 11mp.

    The diff. between a 6 and 8mp DSLR is about 500 pixels horizontally, maybe 300 vertically. Very small. You will see a bigger difference between 6 and 10, which is about 900px/600px.
  5. Kingsly macrumors 68040


    Whew. Good thing I put in that disclaimer. :eek: :eek: :eek:
  6. Macanadian thread starter macrumors member

    Sep 11, 2006
    thxs Silent Wave and Super Macho Man.

    6 MP I'll buy for now. All my three film cameras (2 Pentax and a Bronica) will be kept.
  7. Bibulous macrumors 6502a

    Jan 19, 2005
  8. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    Here is how you figure it out: Good quality prints require 300 pixels per inch. A 6MP camera is abut 3000 x 2000 pixels. So at 300 per inch a 6MP camera can make a print 10 inches wide. an 8MP camera makes an image about 3460 x 2310 so at 300 per inch it could be 11.5 inches wide. So you gain about 15%.

    The quickest way to compare MP counts is to take the square root. the square roots of 6,000,000 and 8,000,000 are about 2449 and 2828 respectively. Notice that 2828 is about 15% larger than 2449. In short print sizes are proportional to the square root of the pixels count. So to make a print twice as wide you'd need four times to total number of pixels. If a 6MP camera can make a 10 inch print you need a 24MP camer to make a 20 inch wide print.

    Print widths for a 6, 8 and 10 MP camera would be 10, 11.5 and 13 inches if you want to use 300 pixels per inch.

    Lets say you want a 16 inch wide print. For a print that large you might want to break the 300 per inch rule because the viewing distance is greater for a larger print. (while yo might look at a 4x6 from 18 inches away you'd look at a 16x10 from 2 or 3 ft away.) so assume 240 pixels per inch. a 10 MP camera could just do this.

    One more thing.... Do people really make prints any more? If the image i to be viewed on a screen then even 6MP is overkill. You will find that once you'v gon digital you will not make so many prints
  9. Silentwave macrumors 68000

    May 26, 2006
    Gainesville, FL
    and rules don't always apply- i have made great 8x10s from a 2.7mp DSLR :D
  10. weckart macrumors 68040

    Nov 7, 2004
    The most important thing in any camera is the quality of the lens. 15% more of meh is nothing to get excited about.
  11. ibilly macrumors regular

    May 2, 2003
    about 25%.

    I now am shooting at 8MP, but I've made a 30x40 inch print from a RAW, 6MP, low ISO, very carefully interpolated dRebel file. If you take quality pictures at the beginning and your sensor is larger than your thumbnail, then even a 6MP image has a LOT of potential. Also, viewing distance is crucial.
  12. wisredz macrumors regular

    Aug 4, 2006
    I plan to get a DSLR myself, so I've made some research. Everyone stated the lens quality is much more important than mp count. I have a Sony DSC-N1 8 mp, and 8 mp photos are of course bigger than 6 mp ones. My advice would be to get a decent lens.
    As fellow posters stated, the difference between 6 mp and 8 mp is not that important. If you want to see some real differences, then you should get 10+ mp cameras. I don't know what you do with a camera, but in my experience I've found 8 mp more than enough for my uses. Anything more than that is fine but not necessary.
  13. spicyapple macrumors 68000


    Jul 20, 2006
    I wanna get this one (39MP), but they say it's only for "studio use". ;)
  14. billy_d_goat macrumors member

    Mar 23, 2005
    MP are a big gimmic. For the most part, it seems to be touted to convince uneducated users that make 4x5s for their photo albums to pay a lot more. As has been already said, get a good lense. That is where you should put down the extra money.
  15. Macanadian thread starter macrumors member

    Sep 11, 2006
    Yes, I do make prints. I do Freelance Photography and some of my clients requested a 5 foot by 10 foot prints. A print of this size I just need a 6 MP printed up to a 8 X 10 inches and then scanned in on a flatbed. Or I can just rent a 4 X 5 camera, since I don't get too many of these requests.

    One of my most important clients (my mother) does not own a computer. So prints are still made for her.
  16. n8236 macrumors 65816

    Mar 1, 2006
    If regular paper film is good enough for you, then 6 MP is fine because that's what those are rated at. Otherwise get the higher MP.
  17. beavo451 macrumors 6502

    Jun 22, 2006
    It is all perspective. If large prints were viewed at a proper distance, the difference between 4, 6, 8, or 12 MP is nearly indistinguishable. One cannot tell you the MP count of a camera from looking at a print alone. If one looked at 12 and 4 side-by-side, you can say which one is higher resolution. But they both will look good from an appropriate viewing distance. Some of those billboards you see out there are made from 2 and 4 MP cameras.
  18. FritzTheWonderM macrumors member

    Dec 12, 2003
    Planet 10
    You could use Genuine Fractals then your starting resolution becomes irrelevant.

    Does anyone remember having this discussion about film ISO and film grain size? Or am I just that old... :eek:
  19. sushi Moderator emeritus


    Jul 19, 2002
    Wow! That is a serious camera for sure.
  20. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    Yes, You would need to rent a 4x5 camera for a 60 inch print. And of course I did not meant you'd never make a print. But I bet you will make fewer prints.

    Print quality does depend on viewing distance. Bilboards can have quite poor quality because there is no way for a viewer to get close but if a 60 inch print is to be hug on a galery wall people may be able to get within two feet of the print. When deciding on a MP requirement you really do have to start with the final product and work backwards. The math is VERY simple. For example if you decide your 60 inch print only needs 100 pixels per inch (because of the 4 foot minimum viewing distance then you will need 6000 pixels across. This works out to 24MP total. Which means either a very expensive medium format digital camera or scanned a 4x5 negative.

    The key is to pick the prints pixel per inch requirement correctly. Basically 300 gives "photo quality" and 50 gives you "newspaper quality"

    The other thing is the dynamic range. Shooting digital is more like shooting slide film then negatives. If you blow out a highlight it is gone s you expose so as to leave some details in the whites and let the shadows go black if need be. Digital also means you have the possibility of doing much magic in post production. More pixels gives you more possibilies later on the computers. Operations like straightening the horizon or changing the perspective (like a raise on a view camera) work best if you have lots of pixels, more then you need for the print.
  21. xrays macrumors member


    Jan 6, 2005
    Toronto, ON
    I have a Canon 20D, and a few decent lenses. I've made numerous prints up to 16x20 without any visible signs of pixelation (and with the better photographs, it's hard to even tell it was once a digital signal). However, I've printed two images at 20x30 and I could instantly see the tell-tale signs of a digital image at large (pun intended).

    The short story is that 6mp or 8mp are nearly the same when it comes to a well-shot photo printed up to 16x20. For larger prints that will be viewed up close on a wall, you should be thinking of 12mp or higher. For 8x10 images, any camera above 3mp will probably give you quality results. However, none of this information has any merit if you don't have a quality photo to start with - and that includes exposure, content, colour balance, resolution, etc.


    PS> The 300dpi rule doesn't necessarily apply to digital photo prints as they are not printed with a screen process like with a traditional 4-colour press. Generally, at 150dpi (with a good photo and printer), you shouldn't see the pixels without a magnifying glass.
  22. MacSA macrumors 68000


    Jun 4, 2003
    Keep an eye out for the new Pentax K10D, press release should come out tomorrow, from what we've seen so far it's unmatched in terms of features and price.

    The specs were accidentally leaked on www.steves-digicams.com and have since been removed. A PDF is available here though: http://ericcloninger.com/albums/DPRShots/StevesK10DRelease.pdf
  23. devincco macrumors member


    Aug 19, 2006
    To the naked eye, there really isn't a difference between 6MP and 8MP. Now, on that note, if you were able to find a 8MP camera for the same price as a 6MP, go ahead and get the 8. The MP count is only going to go up in the future, so you won't be hurting anything getting the camera with more MP's (future proofing). Now, if there is a couple of hundred dollar difference, don't waste your money.

    For DSLR, pick the glass you want to use (Nikon, Canon, Pentax, etc) and then pick the body from there. Your investment will be with the lenses, not the body. The camera bodies will be updated much faster then the lenses will be. Thats one reason almost all DSLR's can use older lenses. Even ones that fit on 35mm.
  24. Macanadian thread starter macrumors member

    Sep 11, 2006
    I'm not pleased on how digital Pentax cameras are. From what I've seen they are still using AA batteries (yechh). Maybe a CRV3 will fit. That is the only thing I hate about them right now.

    Has anyone here used a Pentax Digital SLR?

    Currently I'm leaning to Canon Rebel or Nikon D50.

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