In terms in size and bulk which one big in size the canon 5d mark 3 or Nikon d810?

In terms in size and bulk which one big in size the canon 5d mark 3 or Nikon d810? - 1

If you think it matters, you're wasting your time on either.

You buy the camera that feels best in your hands (I'd choose the Pentax K-1 over either), and if you're put off by size, a DSLR probably isn't for you.

The Canon 5d mark 3 is around 10% smaller then the nikon d810 but the d810 takes better quality pictures and has much better color depth and longer battery life

Here's a side-by-side comparison of features with a comparison of dimensions near the bottom: http://www.dpreview.com/...=ascending

If you're not concerned with super-fast continuous focusing, then you should also consider the Sony A7R II. Via adapters, it can use any lens by any brand. It has a 42MP sensor with 5-axis in-body image stabilzation which isn't in any Canon or Nikon who puts their stabilization within their lenses. With the Pentax K-1 and the Sony A7R II, any lens you use, even old lenses from the 70s, you will get a 4-5 stop stabilized image.

So, if you're not a sports shooter, but instead a landscape shooter or one that shoots hand-held in low light a lot, then skip Canon or Nikon and go with either the Pentax K-1 or the Sony A7R II.

Usually by the time a person is ready to buy a full frame digital SLR, they have had many years experience using other fully adjustable digital SLR cameras and know that performance is much more important than size or bulk.

Professional shooters like the mass of large cameras like the Nikon D5 or Canon 1Dx, Mark II. Massive cameras do not "float" around when the photographer is shooting, which is especially important when shooting sports. My colleagues who own Nikon D810 or Canon 5D, Mark III cameras also have a battery grip attached to them to add more mass and increase the number of photos they can take with two fully charged batteries.

When shooting many sports, it is important to be able to get at least 1000 shots from a fully charged battery. Here is how that relates to the Nikon and Canon "Flagship" cameras used mostly by pros

Nikon D5 = 3780
Canon 1Dx, Mark II = 1210
Nikon D810 = 1200
Canon 5D, Mark III = 950
Nikon D500 = 1240 (cropped sensor)
Canon 7D, Mark II = 670 (cropped sensor)

I recently shot for a Spartan Race near Virgin River, NV and as part of the requirement, I had to take multiple photos of each contestant. There were over 4,000 runners, so a camera which was miserly when it can to power use and one that used less power when shooting smaller image file sizes (a requirement of the event) was an important feature of the camera.

As Andrew stated, if size or bulk are your main concerns, you may not be ready for a full frame digital SLR camera

Choose your camera(s) based on AF speed, power usage, color depth, dynamic range and ISO performance. These five things are exponentially more valuable than the size or bulk of a camera.

Remember, a camera will not make you a better photographer, but it can hold you back or allow you freer reign

If you want to compare some of those important features between the 5D, Mark III and D810, visit the site below