DX Camera and DX Lens question

[Lonnie1212]

Was listening to a YouTube photographer and he said that pictures taken with a DX Camera and DX lens can be cropped easier than FX camera pics. Not sure I am wording this statement correctly. It has something to do with the sensors ability to write information from a long DX lens.

But my question is why. Why is it easier to crop a DX picture over an FX picture.

He also mentioned that National Geographic photographers are using DX cameras with FX lenses.

 

[Designer]

Huh? That does not make sense. I would appreciate being able to view the video for myself. Can you post a link to it?

Upon reading just what you have posted, I have some comments: Cropping, per se, has nothing to do with the sensor size or pixel density, unless he meant to write "enlarge", in which case pixel density does affect the final image quality.

Also; since there aren't many DX lenses to begin with, and those are considered "entry level", it is no wonder that the pros use mostly FX lenses.

 

[astroNikon]

we're unsure of the context of that statement.
For instance, when I use DX I always use an FX lens. I have no DX lenses for Nikon.

A DX or FX image can be cropped (or trimmed) as that is after the image is taken.

A DX camera has a smaller width x height sensor than a FX sensor. So when you use an FX lens you immediately crop out the outer edges of the image as that part of the image does not fall on the sensor. The outer part of the image normally has the most distortion so that is a good thing in a way. Plus many quality lenses are not available in DX format, so many use FX lenses. Plus if you have both nikon cameras, just use the same lenses.

An FX camera can use DX lenses. But, if you put it in "DX mode" it will use less of the sensor, thus internally crop the image. If you do not put it into DX mode your images (for many lenses) will have a black circle around it as many DX lens do not produce an image circle large enough for a FX sensor.

 

[Braineack]

All things being equal, if I had two bodies, both 24MP FX and DX, and one lens, 200mm. If I needed reach I'd use the DX to shoot with -- then crop from there if needed.

A crop sensor is already a crop, but ultimately MP dictates the "ease"

 

[wfooshee]

Find a new Youtube "guru."

That's the thing about Youtube... people can make any kind of statement they want, and if it sounds like it might have substance to it, they get paid just for you to watch their drivel. Look at flat Earth, chemtrails, and all of that nonsense that's propagated through Youtube.

As for DX cropping being "easier," I can't imagine what that means. Hand me a JPG image file with no EXIF data, I'll crop it, without knowing what it came from originally. Cropping is not hard. But geez, don't tell me it's from a full-frame camera, or I'll never get it cropped! It'll be too hard...

The only thing I can even imagine stretching the subject to cover, and it's just because you titled the post "DX camera and DX lens," would be a DX lens on an FX camera. That lens won't cover the full sensor, and either the corners of the image will be dark, or the camera will switch to DX mode and only use the "crop" section of the sensor, making the camera behave as a DX camera. That makes the MP lower than with an FX lens, which might make cropping more difficult without losing resolution.

 

[Braineack]

All things being equal, if I had two bodies, both 24MP FX and DX, and one lens, 200mm. If I needed reach I'd use the DX to shoot with -- then crop from there if needed.

A crop sensor is already a crop, but ultimately MP dictates the "ease"

If I had two bodes: one 24MP DX and one 40MP FX.
And two lenses: a $400 70-300mm AF-P DX lens and a $2000 70-200mm 2.8 FX lens.

If I needed reach, I'd still shoot with the DX sensor and the 70-300 -- this would be like shooting 450mm on the FX body.

If you shot the 200mm on the FX, and cropped it down to a 24MP picture, it still wouldn't be as "zoomed" as the DX's shot. I'd have to crop the image to roughly ~14-16MP to achieve the same result the DX was able to get without dropping pixels whatsoever.

 

[Designer]

Huh? That does not make sense.

we're unsure of the context of that statement.

I can't imagine what that means.

If you can find that video again, please post a link or embed it so we can watch for ourselves.

 

[WayneF]

Was listening to a YouTube photographer and he said that pictures taken with a DX Camera and DX lens can be cropped easier than FX camera pics. Not sure I am wording this statement correctly. It has something to do with the sensors ability to write information from a long DX lens.

But my question is why. Why is it easier to crop a DX picture over an FX picture.

That cropped sensor topic is frequently not well understood. In same situations using the same lens on both sensors, "less" crop is possible for DX, perhaps that is meant by "easier"? Some users do think the smaller DX sensor provides a bit more magnification for wildlife or sports. It is Not the lens that does it, but is simply only because the DX sensor is smaller, and therefore simply must be enlarged more to be the same viewing size. Such additional enlargement of a smaller frame "looks" like zooming.

For example, if taking a picture of a distant duck with the same lens focal length on the two sizes of sensors, the images duck part itself is necessarily the exact same size in both pictures (which is the lens magnification), but the overall FX frame size is larger, with wider view on FX than on DX. But any tighter framing (by either the DX crop or a similar FX crop) then appears as if the picture was zoomed in to enlarge the duck. Which it didn't, but it does look the same. But any enlargement is only that the smaller DX image simply must be enlarged more to view it.

The FX image could be enlarged too, but then if cropped into the same DX frame size, the more extreme crop does lose 41% of its megapixels (which DX sensors can still provide), so the FX user would want a 1.5x longer lens, and would have a 1.5x larger image.

The DX solution just has the advantage that DX requires less price and weight than FX gear, but it still requires 1.5x greater enlargement of the smaller sensor image. Which is not a lot of downside to the perceived advantage. FX is basically just a larger image with a wider view (unless using a longer lens). The same lens focal length on both would show the same size duck.

My site at Understanding Camera Sensor Crop Factor and Equivalent Lens Focal Length. Calculators for Crop Factor has lots more about this.

 

[fmw]

The old expression is still true. Don't believe everything you encounter on the internet.

 

[Strodav]

DX sensors usually have a higher pixel density than FX sensors. So, if you put your FX camera into DX mode for an apples to apples comparison, you will be using less pixels than if you were using a DX camera. My 45.7mp D850 FX body has 7% less pixel density in DX mode when compared to my 20.1mp D500 DX body. So, if I am using the same lens at the same distance on both bodies, I will get a bit more resolution out of the DX body compared to the FX body, so I can crop a bit more. If you have a 24mp FX body compared to a 24mp DX body there is a much larger difference in pixel density in favor or the DX body.

FX sensors usually have bigger pixel buckets than DX sensors. So FX sensors usually have better low light capability, better SNR, and better color depth.

As far as DX vs FX glass, yes there are certain DX lenses that are sharper than more expensive FX lenses on a DX body, but it's not usually the case. You can see that by going through the DxOMark.com lens database. Examples include the AF-S DX 40mm f/2.8 micro and AF-S DX35mm f/1.8, which are sharper than many more expensive FX lenses, but I get exceptional results with my Nikon 600mm f/4 on the D500 and I don't know of a DX lens that can match it.

 

[choidavid]

Sounds like a liar.