Posted by Michael Lowe on January 29, 2016 at 1:18 PM
I know the answer to my question is probably simple and obvious, but today I just have a case of brain lock. I just upgraded to a full frame camera, the d800. Still only have DX lenses though. My landscape lens is the Tokina 12-24. Let's say I'm shooting at 12mm which is equivalent to 18 on a fx lens. Do I set hyperfocal distance for 12 or 18mm? Thanks for any responses.
Posted by Tom Falley on January 30, 2016 at 1:07 AM
The concept of hyperfocal distance is based on the size of the out of focus circle of confusion on the film or sensor. Smaller formats which require more "enlargement" for an equilivelant final image require a smaller circle of confusion. So for your example the 18 mm would be the one to use. However the ultimate answer will be what the final image size is to be and how much resolution is required. Depth of field as a concept relies on the idea of a certain amount of being out of focus being acceptably sharp for the purpose intended.
Posted by Brad Strong on January 30, 2016 at 6:44 AM
It seems that you aren't really talking about hyperfocal distance but crop factor.
It's not really the lens that is different between full format and dx. Dx lenses produce a smaller image circle than "normal" lenses. They are the same focal length however. They don't completely cover a full frame sensor, so the corners are rounded off.
Crop factor is Caused by the size of the image sensor in a dx camera body. The smaller sensor in a dx is using a smaller part of the image circle produced by a lens. This Is referred to as crop factor. Taking a picture with a dx is the same thing as cropping a picture taken on a full frame. Multiplying the focal length of a lens by the "crop factor" of the dx, gives the effective focal length of the lens needed to make the same image on a full frame camera. Using a 12mm lens on a dx is the equivalent of using an 18mm lens on a full frame camera. Just to also note, this has nothing to do with MP of the sensors, only the physical size of the sensors. The reduced field of view makes it seem like a longer lens on a dx, and effectively it is. Things like hyperfocal distance and depth of field are dependent only on the physics of the lens and do not change with crop factor.
Hyperfocal distance is related only to the lens and not the crop factor of the camera sensor. So, you would use the hyperfocal distance of 12mm not 18mm regardless of which camera body you're using.
Congrats on the D800.
Posted by John Freeman on January 30, 2016 at 11:14 AM
Michael,
Here is an excellent discussion on the Hyperfocal0 distance in regard to lens and sensor size. Your D800 has a Circle of Confusion of .030 which is same as my Canon 5D3 or any 35mm film camera.
For any practical f-number, the added focal length is insignificant in comparison with the first term, so that
I made an Excel Spreadsheet to calculate for my lens. I would be glad to share with anyone that is interested in it.
This is sample for your lens at 12mm & 24mm
Discussion
3 repliesIt's not really the lens that is different between full format and dx. Dx lenses produce a smaller image circle than "normal" lenses. They are the same focal length however. They don't completely cover a full frame sensor, so the corners are rounded off.
Crop factor is Caused by the size of the image sensor in a dx camera body. The smaller sensor in a dx is using a smaller part of the image circle produced by a lens. This Is referred to as crop factor. Taking a picture with a dx is the same thing as cropping a picture taken on a full frame. Multiplying the focal length of a lens by the "crop factor" of the dx, gives the effective focal length of the lens needed to make the same image on a full frame camera. Using a 12mm lens on a dx is the equivalent of using an 18mm lens on a full frame camera. Just to also note, this has nothing to do with MP of the sensors, only the physical size of the sensors. The reduced field of view makes it seem like a longer lens on a dx, and effectively it is. Things like hyperfocal distance and depth of field are dependent only on the physics of the lens and do not change with crop factor.
Hyperfocal distance is related only to the lens and not the crop factor of the camera sensor. So, you would use the hyperfocal distance of 12mm not 18mm regardless of which camera body you're using.
Congrats on the D800.
Here is an excellent discussion on the Hyperfocal0 distance in regard to lens and sensor size. Your D800 has a Circle of Confusion of .030 which is same as my Canon 5D3 or any 35mm film camera.
https://en.wikipedia.org/wiki/Hyperfocal_distance
From the wikipedia artical:
For the first definition,
where
For any practical f-number, the added focal length is insignificant in comparison with the first term, so that
I made an Excel Spreadsheet to calculate for my lens. I would be glad to share with anyone that is interested in it.
This is sample for your lens at 12mm & 24mm