Macro Lens on Crop Sensor DSLR

[sgrimshaw]

On the basis that there are no stupid questions ......

If you put a 1:1 macro lens on a DSLR with a 1.5x crop factor ..... is it still a 1:1 macro lens?

[ExPat2B]

Well, the term 1:1 means that the lens can produce an image the same size as the 35mm sensor. So a full frame 1:1 macro lens is a 1.5 ( or 1.4 on Nikon ) on a crop sensor.

There are a few factors working against you and for you.

Its very hard to get a perfectly sharp macro image at 1.5 on a high megapixel body, lots of factors working against you, camera shake, iso degradation, the lens is softer, and diffraction kicks in earlier.

These mean that it is quite hard to actually realise the full benefit of the supposed increase in magnification, unless you use a properly diffused flash to totally freeze motion and have the iso at base level.

Working for you is the fact that if you frame the subject the same, you will be further away, which means greater depth of field and more working room.

[RobDickinson]

Same size ON the sensor.

So crop factor has nothing to do with it, no impact at all.

Mfd is the same.

But crop sensors tend to have higher pixel density so this gets you more ability to crop I'm or get detail so does help

[Simpo Two]

RobDickinson said:

Same size ON the sensor.

So crop factor has nothing to do with it, no impact at all.

If the lens is designed to throw a 1:1 image onto a 35mm sensor then surely on a crop sensor the image will be cropped (like any other lens)... hence more magnification, no?

[RobDickinson]

Simpo Two said:

If the lens is designed to throw a 1:1 image onto a 35mm sensor then surely on a crop sensor the image will be cropped (like any other lens)... hence more magnification, no?

If you have the same pixel density on both cameras then no. if its 4mm long at 1:1 it will be 4mm long on both sensors.

It will appear bigger on the crop camera but unless the crop camera (which they normally do) has more pixels its no more magnified, you have just lost some stuff from around the edges.

So if you shoot a macro with a 20mp crop and a 50mp ff there is no difference. a 24mp crop vs a 22mp ff there would be quite a difference. But thats all down to pixel density

[Yellabelly]

Just to put the record straight, the crop factor on Canon Dx is 1.6x whilst on Nikon Dx it is 1.5.

As the Dx sensor is smaller than with full frame(35mm), you get a narrower field of view. Thus you'll still get 1:1 magnification but covering a smaller subject area than with 35mm film. So if you print both images at say 6 x 4 then surely the Dx image will be magnified by the relevant crop factor?

[RobDickinson]

Yes if you print the whole image constrained to a physical size.

Still all falls back to pixel density tho.