Understanding Crop Factor

[Killakoala]

I hope this helps to explain the myth about Crop Factor.

http://www.stevekilburn.com/cropfactor/cropfactor.htm

or

http://www.stevekilburn.com/cropfactor/cropfactor.pdf

EDIT: Version 2 now available

[stubbsy]

Steve

Excellent. Let's hope this puts that one to bed.

Thanks for doing the work.

[Raydar]

Thanks for that killa!!

Cheers
Ray

[sirhc55]

Plus

http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml

Chris

[Onyx]

You should stick in numbers for the Width of 35mm frame: 36mm(!) and width of Nikon's DSLR sensors: 24mm.

[digitor]

The pictures and diagrams in the article certainly help with the understanding of crop factor, but I'm going to get picky here, and point out this incorrect statement - "The total physical area of the 35mm film is 66.6% larger than the physical area of the CCD. This equals a factor of 1.5"

The area of a 35mm neg, at 24x36mm is 864 sq mm, while a D70 sensor at 15.7x23.7 (near enough to 16x24) is about 370 sq mm. This equals a factor of about 2.33.

It's the linear dimension which is the one used for determining crop factor, not the area. The crop factor is near enough to 1.5, exactly it is 36/23.7=1.52. (Or if you use the other dimension, 24/15.7=1.53) The aspect ratio of the two formats is not identical, which accounts for this slight difference.

Apologies if I'm being overly picky here, I've been reviewing a lot of documents this week at work, perhaps I haven't wound down yet...

Cheers

[atencati]

Brilliant Explenation! Even a monkey could understand that. I hate trying to explain this concept to people, I don' tknow why it is so hard to grasp. anyways....expect more traffic to that page

Andy

[MattC]

As someone who has never shot 35mm film, I really do not understand what all of the fuss is about. Okay, for a given focal length the shot is going to be cropped and that may or may not produce undesirable results if compared to a full frame shot with the same lens. I am thinking perspective here, and the effect of cropping that image. For a given aperature, focal length... the d70 is going to have a deeper DOF. I am sure there is more.

At the end of the day, is it not more important to be aware of what can be acheived at a given focal length, aperature... for the format of choice. After all, the same arguments, debates, analysis, whatever could be equally applied to a comparison between 35mm and medium format.

Cheers

Matt

[Killakoala]

Digitor makes a very valid point. Thanks for pointing that out to me. I will adjust the wording to make it more correct.

The point of the article is to make it easy for new users of DSLR's to understand the difference between DLSR and 35mm cameras. I wanted to avoid being technical otherwise some people might not only be confused but ge bored half way down the page. I know i have this problem reading things technical. (bad for an Electronic Technician )

[MattC]

Steve, my previous comments are not intended to belittle your effort in putting such an article together (I read this into my previous comments, I did not read this from your last post). It is quite informative for a basic laymans explanation and your use of images makes it clear. For me at least, the question of 35mm or DX sensor is academic, as I have never used a 35mm format camera. I am sure that there are many first time SLR users in the same situation as myself.

Cheers

Matt

[Killakoala]

I recently completed a course on frontline management and during the course i discovered that i am a 'visual' person. I prefer pictures to words when learning something new.

I think this helps me to understand why i write the way i do. I like to explain things as i imagine it, or see it. That's why i like to put so many pictures in my articles.

I think that might even go some way to explaining why i love the visual arts, photography included.

So i hope the article on crop factor is easy to understand, in a visual kind of way.

Thanks for the kind words everyone.

(An worry not Matt, i appreciate your comments from a perspective i never even thought of. We make use of what we see in the viewfinder )