Comparing pixel density of FF vs. crop-sensor bodies

[normadel]

I've been wondering about all this stuff for some time, finally just reading a very excellent article comparing Full-Frame to Crop-Sensor benefits & drawbacks. that explained why, with equal megapixel counts, the crop-sensor has MUCH higher pixel density and gives MUCH higher resolution.

So I did some basic math myself to illustrate how my EOS 60D (18 MP) and 6D (20 MP) compare. MP not the same, but close.

18 MP = area  of 330 square mm. = (rounded) 54,500 pixels /square mm.

20 MP = area of 864 square mm. = (rounded) 23,000 pixels /square mm.

Thus, the 6D has LESS THAN HALF the pixel density of the 60D, and a Full-Frame sensor would have to be 47 MP to have the same density and equal resolution as the 60D.

So I said to myself, WOW!  Does this make sense? 

This leads me to wonder WHY a full-frame sensor camera costs so much more than a crop-sensor camera, with all else being substantially the same, as with a 60D and a 6D.

[normadel]

I'm 72, started doing photography as a 12-year old. I've also taught it in the film days. Been a Canon devotee since my new AE-1 Program. Always been a technician of the field, maybe at the expense of the artistic side. Learning the nuts & bolts of digital has been ongoing since my first digital camera, an Olympus Camedia-something. First Canon digital was a Powershot G5, still on my ready-to-use shelf along with a G11, Rebel T1i, 50D, 60D, most recently a 6D, and a few pocket PowerShots. The G5 and the 60D are the only ones bought new. 

So sorry about your misfortunes. You sound like a guy I'd like to know and hang with.

[Tronhard · Accepted solution]

I have a similar history to you.  I was originally trained as a teacher, then ended up in the military, working in intel.  When I got out of that I went into engineering, and in my late 20's did what we all in NZ as the 'Big OE'.  Since NZ is one of the most isolated countries in the world (our nearest neighbour, Australia, is 2,000km away) and many of our population hail from Europe, it was a sort of right of passage to go there to see the world. 

I began learning photography before that, intending to both document my travels and earn along the way.  My first stop was Oz, where I got a job as an engineering on a big project in the Outback, but they also hired me as a site photographer - and so began my photographic career.  Flush with money after that contract, I started travelling and taking stock images, using a couple of Nikon F3's and Canon A-1's, using predominantly Ektachrome film.  In a year of travelling around Oz and NZ, I met and married a Canadian woman, and we eventually travelled overland through Asia and Europe to live in Canada, where I had to work as an engineer while doing photography on the site to keep a regular income.  I studied IT and became a trainer for the college I studied at, and spent the next 12 years of so working in IT as a trainer and interface designer - I actually worked on the interface of Windows and Office 95, so I am extremely familiar with the right mouse button that Waddizzle refers to in his signature! 

I returned to NZ in '97 for family reasons and worked as an IT engineer, and eventually taught IT management until I retired.  All that time I was shooting part-time- doing corporate, wildlife and landscapes, while teaching photography - I love teaching and seeing the light of understanding in someone's eyes.

I retired some years ago (I'm 70) and was happy to embrace photography as my hobby.  I still love the tech and the creative sides and run a couple of local photography groups to encourage those who want to learn about dedicated cameras to come to grips with them.

As to gear... too much to list here, but check out my profile and it's listed there!

Feel free to PM me and I'll send you an email address to engage out of this forum, if you like.

[unclejace54]

Thanks for the link to your Equivalence article. It really helped me summarize thinking on all the new variables with digital cameras (In many ways I miss dealing with the Holy Trinity of photography alone, but not all the variables of the chemical process.)   One of the things I have been curious about that relates to Normadel's post is pixel density and DoF. It seems with higher resolution sensors and larger finer displays that DoF is an issue. Pixel size and pixel density play a big role in what one uses for a Circle of Confusion (CoC) . Maybe a topic for another discussion.

[johnrmoyer]

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@unclejace54 wrote:

Thanks for the link to your Equivalence article. It really helped me summarize thinking on all the new variables with digital cameras (In many ways I miss dealing with the Holy Trinity of photography alone, but not all the variables of the chemical process.)   One of the things I have been curious about that relates to Normadel's post is pixel density and DoF. It seems with higher resolution sensors and larger finer displays that DoF is an issue. Pixel size and pixel density play a big role in what one uses for a Circle of Confusion (CoC) . Maybe a topic for another discussion.

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Depth of field is a function of focal length and sensor size (or film size).
This has a good explanation: https://www.cambridgeincolour.com/tutorials/depth-of-field.htm

[normadel]

Most basically, DOF is a function of MAGNIFICATION and APERTURE SIZE.  Magnification is determined by focal length and distance to the subject.