Cool chart. I wish I thought in meters. So the 'subject' fills the frame at each point?
Thanks, it is simple to calculate using
this equation for magnification for known variables: in this case, Subject size, Distance and Focal Length. This can use different dimensions. Although I'm comfortable with some imperial measures (as in ballistics of English rifles), I tend to use metric for distances and weights
The image sizes are set at ~15mm (Black silhouette) and 20mm (Blue) using my deliberately chosen extremes for overall sizes of birds/small mammals... 5cm, 10cm and 30cm. So 30cm is an ideal proxy (from my experience in these environs since childhood), for a large galliform such as a guineafowl; or equally a larger raptor sitting/standing proud. These are often encountered at about 20m or luckily closer, but such situation still demand 800mm and more.
The elephant icon of 3m (300cm) is an average sized cow; bulls can stand much taller and always seem even bigger towering over one on foot (!)
I use similar back-of-envelope calculations for tight close ups to plan environscapes using Hyperfocal Distances. The rule is simple actually. In such situations forget any subject smaller than a lion/medium antelope with a lens of focal length longer than 35-40mm. This is if one wants to get acceptable sharpness out to the horizon. Moreover, f8 is often not enough, as f16 widens to the optimal DoF; and the 24-35mm range is the optimal focal length.
....note, I'm working with the framing of FX format, however.
That is a great chart and great work putting that all together.
In my experience reaching out that far is not going to net a good image anyways due to atmosphere. I've never shot in Africa but I would imagine it is among the worst places for atmosphere ruining shots. I think trying for frame filling in those scenarios is a fools game and the better image is probably a wider shot to show environment and be less affected by deteriorated IQ.
Yah Thanks.... atmospheric haze can be a huge problem on hot days especially over bare ground, such as calcretes in the Kalahari and bare granite domes etc. Much of the central African savannas are burnt off, especially across Zambia in the dry season which can be an even bigger factor IME especially on floodplains. However, one makes the best of the situation in the season of the year. Early morning is optimum obviously, but remarkable interactions can happen at any time of the day! And one learns to exploit the circumstances...remember Jay Maisel's quip - there's no such thing as bad light, only knowing how to use it. One can leverage dust as some photographers such as have shown very successfully.
Too often I encounter shy subjects when on foot, or a key opportunity is just too far from the road/track in a vehicle or fixed hide.
And often in my style I strive for tight framing eg portraits of medium sized to large mammals, which demands 800mm and more. It is all the question of what story one is trying to tell. I posted
some examples last October, and #8 holds as strong as ever. I now have acquired a Used 180-400 TC14... 800 PF is the next target with the Z-TC's.