How many megapixels does my DSLR need?

mega1Whenever I run into someone with a new camera the first thing they say after I notice and comment on it, is the number of megapixels it has. The megapixel war is apparently still going strong in the minds of all us photographers. But realistically, how many megapixels is enough for the average amateur photographer. Do you need 24+ megapixels or is 10 enough? Does 8mp meet the needs of the average consumer or do they need 14? Lets do little research and find out.

Where do we begin?

Most people are asking the question “How many MegaPixels do I need?” right before they make a pricey DSLR purchase. The problem is that most people do not know how many megapixels is enough. They all assume bigger is better and they should buy the latest and greatest camera out there. That assumption is not always correct. There are numerous factors that tie into the purchase of a DSLR when it comes to Megapixel size. Not only is the quality and or size of your images affected, but the equipment you use to process your images is drastically affected as well. More megapixels equates to larger file sizes, which equates to larger memory cards, which in turn equates to more hard drive storage, which equates to more memory and processing power required to edit the photos. This also means that larger files sizes will take forever to send to your mom on your DSL connection so you better upgrade your internet to a much faster cable connection. Didn’t think about all those did we? Most don’t. It never crosses anyone’s mind that buying a good high quality DSLR can require you to upgrade your Personal Computer, buy larger memory cards, bigger hard drives and also need faster internet. We haven’t even touched on printing yet.

What are you going to do with the images?

  • Facebook -If your just putting them up on Facebook to share with your family, and your never going to print them then the question of megapixels doesn’t even come into play for you. You could get by with an old 2mp camera and never look back. Except for the features that newer camera offer. My suggestion for you is to find the camera that you are the most comfortable with and has the features you want. Any megapixel will be fine. Though I would stay above 5mp if you can.
  • Printing small images - In reality, the majority of people who buy new DSLR’s and point and shoots rarely print images if at all. But those who do, the majority only print 4×6 photos to give to family or put on the mantle. They may occasionally print an 8×10 at the local Wal-Mart kiosk but that is about it. For these purposes a 2mp (though I recommend no less than 5mp) camera is sufficient enough to print the 4×6 photos all day long. You may notice a little graininess with larger image without some processing though.
  • Printing portraits for the Wall- If your going to get serious and print a lot of portrait sizes of 8×10 and below then we need to step up the megapixels a little bit. 6Mp ( I recommend 10MP) will give you excellent result with an 8×10 image, but if your planning on cropping the image it maybe a little less than stellar. For your info, when you crop an image, you effectively reduce the original image size down to a smaller image. Then when you blow it back up to a larger size you add noise as you stretch the megapixels. So the less cropping the better.
  • Printing larger portraits 11×17 - This size of imagery is when you really need to start paying attention to pixel sizes. Though you don’t need to have the latest and greatest, you will have to have at least a 10mp ( I recommend 12mp) camera to get good results for this size printing.
  • Printing posters – if your going to get into printing larger blown up poster sizes your going to be looking at a 14 mp camera. This wall allow you room to crop the image and still blow it up to poster size for relatively good print.
  • Banner printing – For large banner printing and lets be clear I am referring to 2′x8′ or 4′x5′ vinyl banners you can have printed just about anywhere now. your going to want at least a 14mp ( I recommend an 18-24mp) camera, the same as the posters size. Obviously more is going to make the image clearer, but the companies that print these banners will automatically inflate the images for you using a special software process that helped reduce image noise. they do this by increasing the image in very small proportions and applying sharpening and noise reduction techniques through each step. By doing this they can literally blow your images up to the size of a semi-trailer and it will still look clear from a distance.
  • Building Size Prints - If your looking at making prints like you see hanging off the side of museums during special events, then your asking the wrong questions. You should be asking who am i going to hire to take this photograph. Simply put, we as amateurs do no have the capability to reproduce this kind of image. Let the pros handle it with their 36-48mp medium formats and oodles of software and gigantic printers.

Rough Estimation of Print Sizes for each Megapixel

This is assuming you want a print quality of 300dpi which is about where the images in a magazine are printed at. This is pretty good quality for any print.

Megapixels Resolution Common print size
2 MP 1600×1200 4×6″
3 MP 2048×1536 5×7″
4 MP 2400×1600 6×8″
6 MP 3000×2000 7×10″
8 MP 3600×2400 8×10″
12 MP 4200×2800 14×9″
16 MP 4920×3264 16×11.5″
18 MP 5184×3620 17×12″  Roughly 35mm
24 MP 6048×4032 20×13.5″

These are rough estimations to get you close. With a little work you can take just about any image from about 5 MP and up and get a really nice blown up portrait. It all depends on how good you can be at post processing images.

Affects on PC storage

The next factor when dealing with the megapixel war is the amount of storage you currently have in your computer. Do you remember when they first started offering digital copies of your images when you had your film processed. Your exposures would arrive with a Floppy disc inside the pouch with your pictures. A 1.44MB disc would hold an entire roll of film images. Of course back then they were only 1 to 2mp images on the disc. Now images are anywhere from 5MB to 100MB and that is before your done editing and saving them.

Everyone has seen a chart similar to this one on the back of memory card packages or in the manual of a camera they just purchased. But most people do not equate how this will affect their computer. If you take a picture you must be able to store it somewhere. The logic choice for most is of  course their hard drive in their computer. NOTE-  If this is your only storage place then you MUST read this article as well. Backing up your Digital Images.

Approximate Number of Images per Capacity

Camera type File Size 32Mb 64Mb 128Mb 256Mb 512Mb 1Gb 2Gb 4Gb 8Gb 16Gb
2mp 900Kb 35 71 142 284 568 1137 2275 4551  9102  18204
3mp 1.2Mb 26 53 106 213 426 853 1706 3413  6826  13652
4mp 2Mb 16 32 64 128 256 512 1024 2048  4096  8192
5mp 2.5Mb 12 25 51 102 204 409 819 1638  3276  6552
6mp 3.2Mb 10 20 40 80 160 320 640 1280  2560  5120
8mp  4Mb  8  16  32  64  128  256  512  1024  2048 4096
10mp  5.3Mb  6  12  25  51  102  204  409  819  1638  3276
12mp  5.7Mb  5  10  20  40  80  160  320  640  1280  2560

Lets assume for a minute you have an 8Gb, that is 8 Gigabytes, memory card for your camera. What this means is that every time you fill your memory card up, and off load those images to your computer it will take 8 gb of storage on your computer. If you go to your computer and click on Start, then click on my computer. Click the C: drive and you should see somewhere how large of a hard disk you have. Lets assume you have a relatively large drive that is 250Gb in capacity. A few years ago this was  HUGE drive. 1Tb or terabyte, has become the standard for new drives, which is 1000 Gigabytes.

Reduce that size by about 80Gb for your operating system and another 50Gb for any other software you have installed. This leaves you around 120Gb of space to store Photos. But you can’t fill this all the way up or you will cripple your computer, it has to have free space to run. So reduce that by another 20gb of storage. So we have 100 Gb of storage to utilize. If you fill your memory card up 12 times, you just filled your hard drive on your computer. It doesn’t matter how many megapixels you camera is, just you have an 8gb card that can be used 12 times before you fill you hard drive up. So the larger the megapixel of camera you have, the faster you fill the card, and the faster your HD fills up as well.  Solution? A good External USB hard drive. a 1Tb drive can be picked up for under a hundred dollars now. You can then offload all your images onto the hard drive.

Now if you just went out an dropped a fortune on the newest 24MP camera, keep in mind that is only 600 images per card load on an 8Gb card. If you also shoot in JPEG +RAW (which you should) your only getting 250 images per full card. If your utilizing a 2 or 3 year old computer, you are almost guaranteed to not have enough storage space. To give you an idea, I have had my 14.2 megapixels camera for about a year or so. I have taken over 8,000 images with it so far and with edits,RAW images, and cataloging, I am using over 300Gb of hard drive space to store all these images. That is more storage than most computers out there right now have to start with. I physically added an internal 1 Tb drive to start with, and have added two more since in anticipation of the future.

Processing Large Megapixel Images

I am a techie, and what that means is that when it comes to computers, I try to stay on the cutting edge of everything. I have 11 computers in my house that do varying functions for me and my family. I have everything from old Pentium 2 machines running Linux with 512 Mb of RAM all that up to Servers utilizing Dual 8 core processors and a gazillion bytes of RAM and Hard drive storage out the wazoo. So chance are I am going to find something that will process any image I take. But for the average consumer this may not be the case. You may have the newest, shiniest and fastest computer Wal-mart just got in, loaded with all the bells and whistles. You load it with the newest Photoshop CS6 and you load up an image. You make a few changes you click to process and export it, and that is all she wrote. Your brand spanking new PC just locked up tighter than your dad’s wallet on Friday night when you needed gas money. This story happens all the time when people don’t understand the kind of power it takes to work on these huge image files. It is not their fault at all. The megapixel wars going on are designed to sell cameras. More is better, and everyone has to have a bigger whatsit than their neighbor. But they don’t warn you about the trickle down affect of the megapixels war. You spend $1000 on a camera to take better pictures, only to find out your need to spend another thousand to upgrade your computer. Or $2000 to buy a new one capable of editing the mammoth images your taking. It then costs you another $50 a month to upgrade your Internet to a faster speed for sharing.

You can buy cameras now (if you have deep pockets) that produce images with 36 Megapixels of image quality. This may not seem that big a jump from say the 14.2 Mp I am shooting with now. But let me show you some numbers. 14Mp file size will roughly be 5Mb with a 7Mb RAW image. The 36Mb file size will be roughly 75Mb with a 125Mb Raw image. With an 8gb card you will gt less than 50  images when shooting both RAW and JPEG. Where as I get around 500 with the 14.2 Mp. That should clear it up a little bit.

Memory usage on a PC

Anyone who has run any version of Photoshop, whether it is Elements, Light-room, or any of the CS series knows that it takes a pretty decent computer to run it. It doesn’t like to run alongside other programs very well. It can be finicky on an underpowered PC. Now what happens when you add HUGE file sizes to this equation.

First Test -I opened Photoshop Elements 9 on my PC and loaded an image from my Sony A550 that is 14.2 megapixels and 4.2MB is size. I checked it in performance monitor and Photoshop was using 175Mb of ram. Each photo I added to the program added about 25Mb of memory used.  I then saved the image as a Photoshop psd file after some edits to preserve it. It created a 38.2MB image on my hard drive. Though these can get upwards of 100MB with a lot of editing.

Comparative Test -I had a friend of mine do the same on his machine with an image loaded from a Nikon D800 that is 36.1 Megapixels with a relatively small file size for that camera of 51.2MB. His Program was using 2.1Gb of Ram to process that single image. When he saved his image as a psd file after a few edits the file was almost 1GB. No that is not a typo, It is one Gigabyte. That is HUGE for anyone.

Internet / Network Speeds – The next big problem involves moving your images around. Be it on your local LAN or from your LAN to the internet to share with Grandma or even Facebook. If you just have you computer hooked up directly to your modem then you don’t have a LAN and you can disregard that  section. Withe the exception your computer still has a network card, if it is still a 10Mbs or really old, you will need to upgrade. The following section called WAN you still need to read.

LAN -If you have Router,hub or a switch between you computer and your modem then you have a LAN. If you have wireless in your house you also have a LAN of sorts. Modern computers are arriving with 1Gbs(1 Gigabit) network cards installed in them for hardwired LAN use. Laptops are coming with wireless N cards that can produce upwards of 360Mbs. If your sporting a new computer and network then your probably up to date on all of these. If your stuff is more than a year old, your probably not running this fast. If you still have 100Mb cards ten your still OK, if rather slow.  If you have older 10Mb stuff your not going to perform at all and need to upgrade.

WAN / Internet – The WAN or Wide Area Network is what you use to send you images to other people or services. This is also referred to as the internet. It is a public network just like the small one in your house. Many years ago 56Kbs dial up speeds were considered state of the art. These things could Fly!. but not really. File size back then were small and it didn’t take long to transfer most things. Today you start out with 1.5Mbs for DSL and basic cable systems but can upgrade all the way to 100Mbs systems. The problem is that most people don’t understand that even though you have 20Mbs internet, that you only have that on your download side. When your browsing the web and downloading images, you have 20MBs of bandwidth. Which is a lot. The problem comes upon upload speeds. Such as when you try and upload your photos to Facebook or Flickr.com. You then only have 2Mbs of upload speed with that 20Mbs account. With a 14.2 megapixel file this equates to about 40 seconds to upload when your network is fairly busy. With a 36 Megapixels image this equates to more than 20-30 minutes per image.

Summary

So the megapixels wars are probably going to continue for some time. At least until the current sensor size runs out of pixel stacking room and they increase it physically in dimensions. You as the consumer need to make sure your aware of what architecture you have in place to support any camera you purchase. You may or may not be able to utilize everything the camera has to offer if you don’t. You will be able to take great, high resolution images. But if you can’t edit or share them with anyone, whats the point.

If you just buying the monster pixel cameras for the prestige of saying you own it, then it is not a problem. just get into the setting and dial that puppy back to 14 or 16 megapixels and shoot away. Maybe in few years you will have enough computer, storage space and internet performance to actually use it to its full potential. If not, make sure you have what you need in place before you purchase or at least soon after. Otherwise you will be very frustrated when you cannot edit or share you images with out a lot of hassle. Below I have provided a checklist of items you should look at before purchasing.

Before  upgrading your camera, check these things first.

  • Card Storage How large an SD/flash card you will need. Being able to have 250 images when shooting in RAW and JPEG is a comfortable size.  That’s 4Gb for 14Mp and 32 GB for 36Mp. Remember it is better to have several cards that hold a few hundred images rather than one large one. This way if you lose one, or it gets corrupted you do not lose everything you have taken.
  • Hard Drive Storage Make sure you have the hard disk space on your computer to not only store your image but edit them as well. I would recommend at least 1Tb of Hard drive space to start. 2Tb would be even better. Using external USB drives is a good option that can be easily transferred from one PC to another. I also recommend that you make sure your pc has USB 3.0 as the transfer rates are way faster than 2.0.
  • Home network speed Your network at home should be fast enough to move files around easily.
    • Hard Wired
      • 1000Mb or 1Gb is great, your fine.
      • 100Mb you will probably be ok, it will only appear slow when transferring to other computers.
      • 10Mbs you will not even be able to transfer files between computers without long delays. Upgrade or perish.
    • Wireless 802.11x-  Most wireless is going to be a little slow, but the faster the better. Keep in mind distance decreases speed.
      • A or B  up to 11Mbs To slow for anything – Upgrade not even worth it.
      • G up to 54Mbps not terrible but slow for large file sizes. Better than 10Mbs Wired.
      • N up to 150Mbs Good speed, still a little slow for large file sizes. Better than 100Mbs wired.
      • ac or N(DRAFT) upwards of 867 Mbs but 300Mbs is pretty standard right now. This works pretty good for just about everything. But is slower than 1Gb wired for in house transfers.
      • ad 7000Mbit/s Screaming fast, but way too expensive for anyone right now. Announced in Dec 2012 with a 2014 release date.
  •  Internet Speed – Internet speed fast enough to share the files of the images you take.
    • Dial up or Country WiFi - Both utilize very slow, very out of date network speeds in the region of 56Kbs, you see that K? that is Kilobits per second, or one one thousandth of a Megabit.
    • DSL - Dsl has for eons pretty much just sucked when it came to anything that required speed. Many don’t have any other option but it is has been slow ans still is in some areas. They have recently up the speeds dramatically and can give somewhat better service. They are advertising speeds of 7Mbps but that is only with 756Kbs upload. Very slow upload. OK for about 8 Mp cameras and still takes all day to upload a few images.
    • Cable – Just because you have cable doesn’t means it is fast enough. They recently have been coming out with slower plans to compete with cheaper dsl pricing lately/. But they are offering download speeds in excess of 100Mbps in many areas, with 10 Mbps in the slower spectrum.  Keep in mind that Internet plans are rated on their Download speed, not the upload rate. SO event though your getting 10 Mb of download speed, your only getting 1.5 Mbit upload. I recommend at least a 20Mb download with the 2mb upload speed. The 50mb down with 5 Mb up is of course even better, but get it as part of a package, otherwise it is not worth it. Right now 100mb is overkill unless your going to do a lot of video transfers, then you must have it.
    • Fiber-Optic – You are seeing a lot of Fiber Optic services popping up, and I do believe they are the future of the internet. They are capable of tr4emendous speeds and int eh future I think will be the way to go. The problem right now is they are controlled mainly by DSL services and are still limited beyond what they should eb abd priced accordingly.

Recommendations

You have looked at all the items here, and are up to date on what you need to know. You still have no idea what you need in a camera. So here is a very loose suggestion for you to consider. Do not run out and buy the biggest megapixel camera on the market right now. 36Megapixels, or even 24 for that matter right now will probably tax your existing infrastructure more than it was designed for. I recommend a camera in the 14 – 18 Megapixel range. It will give you great images, and will ensure your able to shoot for years to come.

Look at your current hard drive space, your internet speed and the size of the files from the model your considering and make an educated decision based on those criteria. Later on when you computer is new, and your internet is faster and your storage is larger, then you can pick up the latest and greatest camera to fit your capabilities. I have included below, a list of some good models that  you may like to look at.

Till next time Keep shooting Str8.

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Is an amateur photographer and writer who enjoys sharing information with others. "Technical information sharing is a critical part of helping everyone become a better photographer. If you don't know it, you can't do it!" From Film to Digital, photography has changed a lot, but the idea of learning hasn't.

One comment on “How many megapixels does my DSLR need?

  1. John Camaney says:

    Long post, but good stuff. Thanks for the info. I’ve been reading up on this all day because I’m looking at upgrading my almost 10 year old 6 megapixel Nikon camera.

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