Mega pixels and Cropping

This post follows on with a little more detail about the points I was raising about the number of megapixels and crop factors in this post, and prompted from a comment left by Julian on the same post.

Now I started taking pictures of this bird with my 1Dmk111, as it was already set up with the 500f4 and 1.4EFTC.

The first image below shows the full frame version of the image, just basically RAW converted with no photoshop work, including sharpening., just resized to 800 pix.

The second image is the with the same lens but with the 7D body that I changed over while the Sparrowhawk was looking elsewhere.

Now to put this in context, the end of the garden is about 27 metres from where I was shooting.  The female Sparrrowhawk is quite a large bird, up to 41cm for a female, compared to 46cm for a male Buzzard.

So if we crop the image to a useful size and format for  rough compositional purposes, we end up with this.  Again, only RAW converted in this case.

So what does this all mean.

Well for the 1Dmk111, this crop would leave 2572 x 1992 pixels, just 5.12MP.  If I sized at 240dpi for printing purposes, it would mean I could get a 27.22 x 21.08 cm print, or about 10" x 8" in old money.

For the 7D the equivalent size, bearing in mind with the 1.6 v 1.3 crop factor, we are left with a whopping 4260 x 3306 pixels or 14.08MP.  This would give us a print of 45.09 x 34.99 cm or almost 18 " x 14".

This is a huge difference and can mean the difference between getting a useful print or not.

Now if all you want to do is put your images on the web or make 'small - ish' prints, then that is fine, but if like me, you like to churn out A3 + prints then this gives you some real firepower.

Now of course the 1Dmk111 has now been superseded by the 1DmkIV.  But doing the maths roughly, it would mean that you would end up with an image of 3239 x 2508pixels or 8.12MP and a print size of 13.5" x 10.5", so still substantially less by virtue of the cropping factor and the lower numbers of MP.

Now I have previously stated many times that MP's are not everything.....and of course they are not the be all and end all, as it is the quality of those MP's that are important, when it comes to light gathering and noise.

But, for bird photographers in particular, where your subject is nearly always further away than the focal length of the lens that you happen to have, then hopefully what I have shown here is how the body can help you.

Now I know for the overwhelming majority of our astute readers, I have probably banging on about the bleedin' obvious, but it is not until you start to see it on a real life example, and what it means in terms of printing power, then I believe it does help.

Martin

PS, while checking the bird sizes, I also realised that this is still a juvenile female bird

Full Frame or Cropped sensor

I read a mag yesterday and it confirmed things that I have been saying for the last couple of years, since Full Frame cameras came out and namely the Canon 5D people on forums see them as a holy grail-something to aim for whilst having to 'put up' with a camera body with a cropped sensor. I have always believed that a cropped sensor with the correct amount of pixels (I will come to that bit in a minute) will give as good an image as a full frame sensor. When the full frame bodies came out people were over joyed at being able to get good wide angle shots-great for landscapers, but the camera manufacturers soon dealt with that by bringing out super wide and lenses like Canons 10-22 and Sigma's 12-24 so that advantage was gone, with the new bodies using the latest technologies in processing, noise isn't so much of an issue either until you hit a certain amount of pixel density and here's the rub. The magazine tested the Nikon D700 Full Frame against the D300 and found image quality on both to be excellent and quite evenly matched up to ISO 1600, they also tested the Canon 40D and 50D and noted that the 50D with 15 MP against the 40D'S 10MP lost on image quality due to too many pixels as that was producing lots of noise as I believe Martin mentioned a few weeks ago when he borrowed one, so it seems that with the cropped sensors we have reached the plateau of around 12 mp for optimum IQ and after that IQ starts to drop off, I am sure in the future new processors will somehow remove grain and allow higher and higher ISO's to be used. So now we see an advantage with Full Frame sensors where you can still get good IQ at ISO 1600 and above but how many of us actually use extreme ISO, the price difference between a Full Frame body and cropped sensor body is substantial, the lenses needed for the Full Frames a have to be the best and are extremely expensive, this goes for the 50D as well, the high pixel count does not take kindly to cheaper lenses, the cropped sensors give you the reach advantage as well-its like having a 1.5x extender on which for people like myself can be a real boon, yes I do have a Full Frame camera but I also have a Cropped one as well and I find myself reaching for the D300 more times than the D3. So it was summerised as saying that very few (normal i.e. not pro's that need high MP bodies for agency work) people would see an advantage when using a Full Frame body to a cropped body as few people use extreme ISO and very few people print over A3 which a 10-12mp body can do nicely, dont get caught up in all the snobbery of Full Frame unless you need to and can afford the lenses.

Dave