Focus Breathing: Macro Lens Focal Length at Minimum Distance

Robert OToole ·

The Irix 150mm f/2.8 MACRO 1:1 lens test on this site brought up some questions from visitors about the effective focal length at minimum distance and the effect of focus breathing on other lenses. There is a unique site with an excellent virtual optical bench resource. The site is called Photons to Photos: https://www.photonstophotos.net/. There you can load a lens optical diagram, the Irix 150mm Macro for example, and watch how the internal focus works as you focus to minimum distance with a slider and watch as the effective focal length slides from 155mm to 69mm!

Irix (TH Swiss) 150mm f/2.8 MACRO 1:1 lens
Focal length at infinity: 154.06
Focal length at minimum : 69.09

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/WO2020-119907_Example01P.txt,figureOpacity=0.25,AxisO,OffAxis

Press focus, then drag the focus slider all the way to the right to see the minimum distance or just hit play. Give it a try yourself it is really interesting to see how the older lenses focus, compared to modern lenses.

These are some macro lens highlights from the PhotonstoPhotos with FL at infinity and minimum distance with Photons to Photos website link below each entry.

Image Source: https://www.photonstophotos.net/ > Menu > Optical Bench

Sony FE 90mm F2.8 Macro G OSS
Focal length at infinity: 92.61
Focal length at minimum : 45.88

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/WO2016-136352_Example02P.txt,figureOpacity=0.25,AxisO,OffAxis

Sigma APO Macro 150mm F2.8 EX DG OS HSM
Focal length at infinity: 149.99
Focal length at minimum focus: 78.23

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/JP2012-063403_Example02P.txt,figureOpacity=0.25,AxisO,OffAxis

Sigma APO Macro 180mm F2.8 EX DG OS HSM
Focal length at infinity: 174.60
Focal length at minimum focus: 103.47

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/JP2013-104994_Example02P.txt,figureOpacity=0.25,AxisO,OffAxis

Canon RF100mm F2.8 L Macro IS USM
Focal length at infinity: 100.80
Focal length at minimum focus 1x: 45.0 (WD=92)
Focal length at minimum focus 1.4x: 36.0 (WD=112)

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/JP2021-047297_Example01P.txt,figureOpacity=0.25,AxisO,OffAxis

Canon EF 100mm f/2.8L Macro IS USM
Focal length at infinity: 100.00
Focal length at minimum focus: 74.00 (WD=134.76)

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US007864451_Example01P.txt,figureOpacity=0.25,AxisO,OffAxis

Sigma Macro 105mm F2.8 EX DG OS HSM
Focal length at infinity: 101.71
Focal length at minimum focus: 75.68 (WD=144)

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/JP2012-058682_Example04P.txt,figureOpacity=0.25,AxisO,OffAxis

Nikon AF-S VR Micro-NIKKOR 105mm f/2.8G IF-ED Lens
Focal length at infinity: 103.97
Focal length at minimum focus: 75.87 (WD=152.47)

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US007218457_Example03P.txt,figureOpacity=0.25,AxisO,OffAxis

Nikon AF-S DX Micro Nikkor 85mm f/3.5G ED VR
Focal length at infinity: 85.04
Focal length at minimum focus: 71.53

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US20090190220_Example05P.txt,figureOpacity=0.25,AxisO,OffAxis

Nikon AF-S DX Micro Nikkor 40mm f/2.8G
Focal length at infinity: 40.02
Focal length at minimum focus: 36.27

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US20110176215_Example01P.txt,figureOpacity=0.25,AxisO,OffAxis

Konica Minolta AF 100mm F2.8 Macro
Focal length at infinity: 100.00
Focal length at minimum focus: 93.23

Link: photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US004764000_Example08P.txt,figureOpacity=0.25,AxisO,OffAxis

Sony E 30mm F3.5 Macro
Focal length at infinity: 29.11
Focal length at minimum focus: 20.61

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/JP2012-159613_Example01P.txt,figureOpacity=0.25,AxisO,OffAxis

Olympus Zuiko Auto-Macro 90mm F2 1:2
Focal length at infinity: 89.98
Focal length at minimum focus: 94.65 1:2

Link: https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US004792219_Example03P.txt,figureOpacity=0.25,AxisO,OffAxis

This is a list of all the lenses available on the Photons to Photos Optical bench:

https://www.photonstophotos.net//GeneralTopics/Lenses/OpticalBench/OpticalBenchHub.htm

Let me know if I missed any interesting entries!

200mm Tube Lens Test is Now Online

Robert OToole ·

The latest tube lens test is now online, this time on a full frame body with the following lenses tested with the Mitutoyo M Plan 5x 0.14 objective:

  • Fuji EBC Fujinon GX 210mm f/5.6 medium format lens

  • Raynox DCR-150 +4.8 208mm add-on close-up lens

  • Rodenstock Rodagon 210mm f/5.6 enlarger lens

  • Schneider Kreuznach Componon-S 210mm f/5.6 enlarger lens

  • Schneider Kreuznach G-Claron 210mm f/9 process lens

  • Thorlabs ITL200 f=200 tube lens

This is the first in a series of tests coming out in the next couple of weeks. Next up is the 240mm Full Frame Tube Lens Test and then Mitutoyo APO HR 5x test right after that.

Let me know if you have any questions or comments.