jerryc41 Loc: Catskill Mts of NY

This guy has been criticized quite a bit for his statements. The aperture is derived from a mathematical formula. Although an FX lens on a DX body does give the equivalent of different focal lengths, I don't see that happening with the aperture.

http://en.wikipedia.org/wiki/F-number

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Only if you believe the crap that Tony Northrop throws at you in his video. His reference only applies to depth of field. On a crop camera, a 100mm lens at F2.8 on a would have the same dof as a 150mm lens at F4.2, or some nonsense like that. It will still let in the same amount of light as any F2.8 lens. You will just have greater dof.

Peekayoh Loc: UK

It's possible that Northrop is an experienced Photographer and has some good thing to say, I wouldn't know but he appears to have a somewhat limited understanding of what's going on here. Just another instance of the uncertainties of relying on Internet pseudo experts.

paulrph1 Loc: Washington, Utah

The crop factor only has to do with focal length and nothing to do with shutter speed or aperture.

cactuspic Loc: Dallas, TX

I don't think the experiment addresses the OP's concern. In the experiment, the change in depth of field is due to the changing the focal length of the lenses. A 500mm lens at f4 will have a different depth of field than a 14mm lens at f4, even if they have the same fov. To test whether the depth of field changes by using a cropped sensor, I would set up a tripod and attach a lens that had a tripod mount (to minimize inadvertent position shifts and ensure the sensors of the test cameras remain in the same position) Then I would focus, choose my aperture etc and shoot. I would then change cameras, dial in the same aperture and shutter speed and take the image (in manual mode) without changing the focus of the lens. What you should see is that the two images have the same depth of field (a function of the aperture) but different fovs. By keeping the lens settings constant, the image circle remains the same for both cameras and should exceed the size of either sensor. The size of the sensor determines how much of the projected image the sensor sees, with the full frame sensor seeing a larger portion of the image circle than cropped sensor.

BebuLamar

Yes but it's 1 stop only. f/2.8 is like f/4.0 and not f/4.2

Cdouthitt Loc: Traverse City, MI

Ignore tony...and especially that video.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

He's just a Ken Rockwell with a video camera. Same nonsense, different face.

Cdouthitt Loc: Traverse City, MI

:thumbup:
Thanks for the good laugh this morning...I needed it. Tony's face always looks like he's constipated when he's giving his "anal-ysis" Just about every video of his is like that. Quite funny. He overthinks things way too much.

Delderby Loc: Derby UK

Does not the cropped sensor use the "best" area of the FX lens? If so, would this not also mean that that it could, potentially, produce a higher quality image than the full frame camera when using the FX lens?

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

That has been my experience - having owned both DX and FX lenses with my D70, D200, D300, D700 and D800. And avoiding nonsensical videos such as those from TN and his followers.

Wilsondl3

You are so right. A 100 mm lens is a wide angle on my 4X5 view camera. With some mid format digitels coming out are we going to start having a .75 crop factor and calling a 100mm lens a 75 mm lens? I would love it if folks would call lenses their true size and just remember what size sensor they are used on. - Dave

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Or not at all :)

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You are missing one thing here - smaller sensors have smaller circles of confusion, and this will affect the perception of sharpness. A perfectly sharp view camera lens intended for 4x5 film, which has a circle of confusion of .1mm - is pathetically soft when used with a crop sensor camera which has a CoC of .02mm.

You can read a very technical explanation of this, or just skip down to the section entitled Large Format, in the link below:

http://www.normankoren.com/Tutorials/MTF1A.html

Long story made short - there should not be a big difference, if any, between the resolution and sharpness of an FX lens compared to a DX lens - until you make a print - then any softness will be amplified thus making a lens that was perfectly crisp on an full frame seem a little less than crisp on a cropped sesnor. Needless to say, if you have an off the charts sharp lens, the difference will be imperceptible.

mborn Loc: Massachusetts

:thumbup: :thumbup: :thumbup: