focal length conversion DX vs FX: Hello fellow UHH's. I'm attempting to compare a couple of Tamron lenses by normalizing the equivalent Field of View on a DX (1.5 crop) vs FX camera. I...

photon56 Loc: North America

Hello fellow UHH's. I'm attempting to compare a couple of Tamron lenses by normalizing the equivalent Field of View on a DX (1.5 crop) vs FX camera. I realize that a focal length is the same no matter what camera is being used. I'm looking for the equivalent viewing area.

Formula for viewing area;
FX = DX x 1.5
DX = 2/3FX
( ref: http://www.scantips.com/lights/cropfactor.html)

The lenses;
Tamron 16-300mm Di II (DX)
Tamron 150-600mm Di (FX)

I need some help validating my numbers for equivalent viewing.

Is the 16-300mm DX lens equivalent to a 24-450mm FX lens?
and
Is the 150-600mm FX lens equivalent to a 100-400mm DX lens?

lighthouse Loc: No Fixed Abode

photon56 wrote:

......

Is the 16-300mm DX lens equivalent to a 24-450mm FX lens?
and
Is the 150-600mm FX lens equivalent to a 100-400mm DX lens?

I think you get it, but just to make sure I am going to restate what you have said in more specific terms.

A 16-300 lens on a DX camera will give you the same field of view as a 24-450mm lens on a full frame camera.
A 100-400mm lens on a DX camera will give you the same field of view as a 150-600mm lens on a full frame camera.
Unless .......... nah, we won't confuse by bringing the "unless" into it.

TucsonCoyote Loc: Tucson AZ

I think you are both mistaken and all mixed up .....this is not a good situation!
This all has been covered in a clear way over and over again.
Use the search feature!
Firstly a DX lens will never give you a full FX sensor coverage !

Apaflo Loc: Anchorage, Alaska

TucsonCoyote wrote:

Firstly a DX lens will never give you a full FX sensor coverage !

If you stand in one spot and make a shot with an APS-C sensor camera using a 100mm lens, and then make another shot with a full frame sensor using a 150mm lens...

The two images will have exactly the save field of view. That is, exactly the same "coverage".

Leitz Loc: Solms

And if you stand in one spot and make a shot with an APS-C sensor camera using an 85mm DX lens, and then make another shot from the same spot with a full frame sensor using an 85mm FX lens, the two images will have exactly the same field of view.

Apaflo Loc: Anchorage, Alaska

Leitz wrote:

And if you stand in one spot and make a shot with an APS-C sensor camera using an 85mm DX lens, and then make another shot from the same spot with a full frame sensor using an 85mm FX lens, the two images will have exactly the same field of view.

The lenses will have the same field of view, but the images captured will not.

Edit: See http://www.tawbaware.com/maxlyons/calc.htm

All calculations are for a 100mm lens with a subject distance of 10 feet.

With an APS-C (1.5 crop factor) sensor the field of view is:
Horizontal ... 2' 4.8"
Vertical ....... 1' 2.7"
Diagonal ..... 2' 10.6"

With a FF (1.0 crop factor) sensor the field of view is:
Horizontal ... 3' 7.2"
Vertical ....... 2' 4.8"
Diagonal ..... 4' 3.9"

lighthouse Loc: No Fixed Abode

Leitz wrote:

And if you stand in one spot and make a shot with an APS-C sensor camera using an 85mm DX lens, and then make another shot from the same spot with a full frame sensor using an 85mm FX lens, the two images will have exactly the same field of view.

No, this is not correct.
Not even close to being correct.
This is 100% wrong in every way.
The 85mm FX lens on a full frame camera will have a wider field of view.

(Download)

Leitz Loc: Solms

lighthouse wrote:

No, this is not correct.
Not even close to being correct.
This is 100% wrong in every way.
The 85mm FX lens on a full frame camera will have a wider field of view.

Your chart merely shows the effect of an FX lens on a DX sensor, it does not address my statement at all.

Apaflo Loc: Anchorage, Alaska

Leitz wrote:

Your chart merely shows the effect of an FX lens on a DX sensor, it does not address my statement at all.

A DX sensor will not produce images with a different field of view with an 85mm FX lens than it does with an 85mm DX lens.

But an FX sensor, using either of those same lenses will produce a very different image in terms of field of view.

That chart, and the calculator that I referenced, both clearly demonstrate that your statement is not correct.

Leitz Loc: Solms

Apaflo wrote:

A DX sensor will not produce images with a different field of view with an 85mm FX lens than it does with an 85mm DX lens.

But an FX sensor, using either of those same lenses will produce a very different image in terms of field of view.

That chart, and the calculator that I referenced, both clearly demonstrate that your statement is not correct.

:oops: I see my error. My edit of your previous comment should read "And if you stand in one spot and make a shot with an APS-C sensor camera using an 85mm DX lens, and then make another shot from the same spot with an 85mm FX lens, the two images will have exactly the same field of view." Obviously the field of view with an FX lens on an FX sensor will be about 1.5X greater. I'm glad you pointed this out, I do not wish to confuse any newcomers.

lighthouse Loc: No Fixed Abode

Leitz wrote:

Your chart merely shows the effect of an FX lens on a DX sensor, it does not address my statement at all.

An FX lens has no effect on a DX sensor.

A 50mm FX lens and a 50mm DX lens have exactly the same field of view when used on a DX camera.

Leitz Loc: Solms

lighthouse wrote:

An FX lens has no effect on a DX sensor.

A 50mm FX lens and a 50mm DX lens have exactly the same field of view when used on a DX camera.

Physically speaking, of course no lens has any effect on any sensor.

Shellback Loc: North of Cheyenne Bottoms Wetlands - Kansas

This might help too -

From the School of Digital Photography -

Understanding Digital Camera Sensors and Crop Factor
http://www.school-of-digital-photography.com/2012/08/understanding-digital-camera-sensors.html

Leitz Loc: Solms

Shellback wrote:

This might help too -

From the School of Digital Photography -

Understanding Digital Camera Sensors and Crop Factor
http://www.school-of-digital-photography.com/2012/08/understanding-digital-camera-sensors.html

That should clear up some misconceptions. I made my flubbed comment to dispel a rumour I've heard that the 85mm Micro-Nikkor DX was actually about 57mm, to give the same field of view as an 85 on an FX sensor.

Fotomacher Loc: Toronto

Unbelievable how there can be so much confusion regarding what more photogs now consider to be a red herring. I have a 3lb red herring on a DX platter, but when I put it on an FX platter it still weighs 3lbs, but covers only 2/3 of the plate. I wonder what would happen if I had a trout.........