Full frame lens on crop body

[explore.thru.lens]

Dear community members,

I read somewhere that using a full frame lens on a crop body compromises the image quality. I am using a Canon 35mm f2 on a crop body (Canon EOS 450d). I researched a little more on the internet and found out that if I use Canon 35mm f2 on a full frame body like Canon 6d, the sharpness is 18 megapixel, but on my EOS 450d, the sharpness is 9 megapixel (source: www.dxomark.com). Its not that I dont trust these numbers, but would like to get your opinions on this.

Thanks.

 

[Braineack]

1. Stop reading Tony Northrup.
2. Be careful of the different mounts between Canon FF and Crop bodies.
3. If you put ANY lens on the 450D compared to something like the 5D R, the lens sharpness in DXO mark will drop significantly -- but that's a factor on how bad the 12MP sensor is, not the lens.

Think of it as: You want to watch a 4K movie (2160p), but only have a TV that's 480p. The data is all there, but your TV simply can't render it

 

[Designer]

You're getting incorrect "information".

Without reading the same article, I can't speculate about what their point was.

 

[ClickAddict]

Your 18MP vs 9 MP has nothing to do with which lens you use. It's a specification of your camera. It's like changing the tires on your car will not improve your Horsepower. You may get better traction and handling... but that's another story. And isn't the 450D a 12MP camera?

 

[480sparky]

Dear community members,

I read somewhere that using a full frame lens on a crop body compromises the image quality...........

The opposite is true. Using a full-frame lens on a crop body lets you use just the best part of the lens' image circle.... the center.

 

[tirediron]

1. Stop reading Tony Northrup.

A-freakin'-men brother!

 

[480sparky]

1. Stop reading Tony Northrup.
...........

Can I still watch his videos?

Better yet, can I still watch Chelsea's videos?

 

[beagle100]

"I read somewhere that using a full frame lens on a crop body compromises the image quality"
Ken Rockwell got another victim

 

[480sparky]

I read somewhere that reading Ken Rockwell compromises image quality.

Yes, you can quote me on that.

 

[robbins.photo]

I read somewhere that reading Ken Rockwell compromises image quality.

Yes, you can quote me on that.

Ok, done. You've been quoted on that.

 

[spiralout462]

I enjoy nice glass no matter what body it's on.

 

[bratkinson]

For the most part, the EF line of lenses are 'faster', thus allowing more light and thinner depth of field, when desired. They're generally more rugged than the EF-S lenses as well, in my opinion. The Canon L series lenses are better quality glass, coatings, construction quality, weatherized, and more expensive. 480Sparky noted that a crop sensor camera uses the 'best part' of the image circle...the center, which provides the sharpest image area and the least distortion.

Using EF lenses on a crop-sensor camera will narrow the field of view vs the same lens on a full frame body. The result is that it is sometimes necessary to back up a bit further to get 'everything in' you want in a picture.

And, should you decide to upgrade to a full frame body sometime in the future, the EF lenses will work perfectly with the new body. The EF-S lenses cannot be mounted to full frame Canons. Knowing I would one day upgrade (and did), I started by replacing my all EF-S lenses with EF lenses before I bought my 5Diii.

 

[Dacaur]

What he actually meant is that if you took an 18mp picture on a full frame body, then cropped the image to what you would see on a crop sensor body, it would be a 9mp picture.
While that may , be true it's useless information, and doesn't mean you will only get 9mp worth of resolution using the lense on a crop camera.

 

[Soocom1]

This is something I have had multiple arguments over.
But simply put, if you use a FF lens on a crop sensor, the image circle is exactly the same because the mount distance is the same. But the crop only reduces the actual Field of View of the image.
Its how you frame the image.

But the argument is actually over reproduction ratios. Thats the distance needed to bring an image to a specific size in making the print. That ratio is greater the smaller the image.

 

[petrochemist]

Provided you can get it close enough to focus you can use any lens on any camera.

If the lens is designed for a smaller format it may only give you a small image in the middle of your sensor but that can be cropped if required. In some cases a lens can cover considerably more than it's original format implies. I've used several Pentax Auto 110 lenses on APSC & FF, and was surprised to find the 50mm/2.8 actually covers FF to the point that no vignetting was visible in the viewfinder!

If the lens is designed for a larger format, you'll only see the central portion of the projected image (this is what the 'crop factor' refers to). The remaining parts of the image are normally lost but can produce flare etc. if you have reflective portions of the camera/adapter illuminated by spare image. In most cases the differences between the image from a larger format lens & a native lens of the same focal length & aperture will be practically indistinguishable (just differences in lens character).

Smaller format cameras often have higher pixel densities than larger format cameras, and sometimes the lenses will be designed to be sharper with this in mind (the designers will not have to worry about producing a larger image circle, which MIGHT simplify things). A modern camera may out resolve older lenses, but this is generally only relevant for pixel peepers, or buyers of really poor lenses.