The Exercise
This was an exercise to understand the differences that focal length makes. The photos were taken with a zoom lens set at 24mm, 50mm and 70mm using a full frame digital camera and therefore with no crop factor.
The photograph is taken from my balcony at Oceana on Palm Jumeirah in Dubai. The view looks out across The Palm and as such has some close up objects (the marina) and some distant objects (Atlantis Hotel).
The exercise was to take the three photographs from the same position at the three focal lengths, to then print our on A4 paper and assess how close the eye each photo needed to be in order to make it life size when held up in front of the real scene from the same spot as the photos were taken.
Assessment Result
For consistency, I carried out the exercise by using the Atlantis Hotel as the object to achieve same size.
The photograph taken at 50mm is close to a natural field of view and had to be held 17cm from the eye; a comfortable and reasonably normal reading distance.
The photograph taken at 24mm I could not get close enough as the paper reached my eye before Atlantis was the same size.
The photograph taken at 70mm had to held 26cm away.
As the focal length increases, the change in distance between paper and eye to achieve the same size of object decreases.
Other Observations
The results above are what I would have expected based on my past experience, however I did observe and learn two new things.
1. The difference in field of view between the 24mm and 50mm is changed by far more than the difference for the 50mm and 70mm photographs (even though is a smaller change). It seems that when at shorter focal lengths, the field of view is appears to be affected by higher amount for a given change in focal length than at longer lengths. This is similar to the distance observation.
2. I carried out the exercise focussed on the Atlantis Hotel, which is in the distance. If the exercise is carried out on the close up marina, the distance are 7cm, 20cm and 36cm. The distances to hold the paper are much larger than when carrying out the exercise for a distant object. The magnification of objects close up is affected more than the magnification for objects in the distance.
This was an exercise to understand the differences that focal length makes. The photos were taken with a zoom lens set at 24mm, 50mm and 70mm using a full frame digital camera and therefore with no crop factor.
The photograph is taken from my balcony at Oceana on Palm Jumeirah in Dubai. The view looks out across The Palm and as such has some close up objects (the marina) and some distant objects (Atlantis Hotel).
The exercise was to take the three photographs from the same position at the three focal lengths, to then print our on A4 paper and assess how close the eye each photo needed to be in order to make it life size when held up in front of the real scene from the same spot as the photos were taken.
Assessment Result
For consistency, I carried out the exercise by using the Atlantis Hotel as the object to achieve same size.
The photograph taken at 50mm is close to a natural field of view and had to be held 17cm from the eye; a comfortable and reasonably normal reading distance.
The photograph taken at 24mm I could not get close enough as the paper reached my eye before Atlantis was the same size.
The photograph taken at 70mm had to held 26cm away.
As the focal length increases, the change in distance between paper and eye to achieve the same size of object decreases.
Other Observations
The results above are what I would have expected based on my past experience, however I did observe and learn two new things.
1. The difference in field of view between the 24mm and 50mm is changed by far more than the difference for the 50mm and 70mm photographs (even though is a smaller change). It seems that when at shorter focal lengths, the field of view is appears to be affected by higher amount for a given change in focal length than at longer lengths. This is similar to the distance observation.
2. I carried out the exercise focussed on the Atlantis Hotel, which is in the distance. If the exercise is carried out on the close up marina, the distance are 7cm, 20cm and 36cm. The distances to hold the paper are much larger than when carrying out the exercise for a distant object. The magnification of objects close up is affected more than the magnification for objects in the distance.
.jpg) |
| 24mm |
.jpg) |
| 50mm |
.jpg) |
| 70mm |
