Fujinon MK lenses available in MFT

[W. Bill Magac]

Looks like the Fujinon MK 18-55mm https://www.bhphotovideo.com/c/produ...2855/KBID/3801 and 50-135mm https://www.bhphotovideo.com/c/produ...2855/KBID/3801 lenses will soon be available in the MFT mount. My question is what is the equivalent focal length of these lenses in 35mm terms? My Olympus 12-40mm MFT lens is equivalent to a 24-80mm 35mm lens and my 40-150mm MFT lens is equivalent to a 80-300mm 35mm lens. Coming from a still photography background I tend to think in 35mm terms.

[Seth Bloombaum]

Equivalent focal length (EFL) is dependent on sensor size, not lens design.

As you noted, you’re getting a crop factor of 2x with micro 4/3rds; that will hold for the Fuji as well. So, 18-55mm = EFL of 36-110mm on MFT.

[Christopher Young]

Sorry Seth how do you calculate that? Agreed if these Fuji MK lenses were full frame lenses but they are not. The MK series were originally designed for the Super 35 E-Mount on the Sony FS7. The FS7 has a 27.1mm image circle and a standard M4/3 [GH5 for example] has an image circle of 21.64mm. On that basis the Fuji MK lenses designed for S35 should have a crop factor very close to 1.25 on M4/3 I think you will agree.

Chris Young
Sydney

[W. Bill Magac]

Originally Posted by Christopher Young

Sorry Seth how do you calculate that? Agreed if these Fuji MK lenses were full frame lenses but they are not. The MK series were originally designed for the Super 35 E-Mount on the Sony FS7. The FS7 has a 27.1mm image circle and a standard M4/3 [GH5 for example] has an image circle of 21.64mm. On that basis the Fuji MK lenses designed for S35 should have a crop factor very close to 1.25 on M4/3 I think you will agree.

Chris Young
Sydney

Chris, getting back to my original question. If I set my LS300 sensor's VSM to 100% (S35), the Fujinon 18-55mm will behave as an 18-55mm lens in 35mm format terms. I was hoping it would be equivalent to a 35mm format 27-84mm focal length lens. I was thinking of replacing my Olympus 12-40mm MFT lens with the Fujinon lens. This lens would be used primarily for interviews.

Update: Yesterday, I asked this question on the B&H web page for this lens and today B&H posted the following response:
"The 35mm still film full frame equivalent FOV (Field Of View) perspective of this lens is 28.8-88mm.
Answered by Dennis A STAFF on Feb 11, 2019"

[Seth Bloombaum]

E.F.L., equivalent focal length, usually refers to 35mm EFL, that is, just how wide or tele is a shot on a crop sensor camera compared to a shot with the same focal length (or zoom lens FL setting) on a 35mm full-frame sensor.

Below is a chart I created a few years ago that has both the formula for computing EFL from a known crop factor, and, what I think of as the uses of these various equivalent focal lengths.

For more detail and math, I appreciate the work from the folks at Cambridge in Color.

Chris, while it may be helpful to directly compute EFL between various sensor sizes and focal lengths, the typical approach is to refer all EFL to 35mm full frame.

Here's a typical question: "I have a field of view I like, using a 35mm prime on a C100. My friend is bringing their Panasonic GH5, what lens should I tell them to bring?"

So, for the example above:
35mm * 1.52 (c100 crop factor) = 53mm EFL
53mm / 2 (MFT crop factor) = 27mm on an MFT. Better have your friend bring a 28mm prime.

Image circle of a lens is a bit different; it either covers a sensor without vignetting or it doesn't. It isn't related to EFL conversions, which only involve focal length and sensor size.

[Christopher Young]

Originally Posted by W. Bill Magac

I asked this question on the B&H web page for this lens and today B&H posted the following response:
"The 35mm still film full frame equivalent FOV (Field Of View) perspective of this lens is 28.8-88mm.
Answered by Dennis A STAFF on Feb 11, 2019"

Bill

The B&H answer without nit-picking is pretty close to correct. In broad terms an APSC sensor is considered to have a crop factor of 1.5 over a FF sensor. If we take a FF 35mm sensor as having a diagonal of 43.3mm and divide that by the Sony S35 sensor diagonal of 27.1mm you actually end up with a crop factor of 1.597 in the case of the FS7. Close enough to call 1.6.

With the LS300 it has a 16:9 variable sized window for video capture. At its maximum size the window’s resolution is 4464x2511-pixels. AltaSens specifies the window to have a diagonal of 26.72mm at its maximum size, this capture window closely matches that of 3-perf Super 35 film format.

If we now apply the same equation factors of a FF at 43.3mm to the JVC's LS300 AltaSens sensor at its maximum quoted capture size diagonal of 26.72mm we would get a crop factor of 1.620. That's if we were using a full frame lens on the 300. On that basis the 55mm MK lens at its wide end of 18mm with a crop factor of 1.620 applied would in FF terms deliver a 29.16mm wide end. At the long end of 55mm that would become 89.1mm. Its field of view would be basically that of a FF lens that went from in round terms 29-89mm. Very close to the 28.8-88mm that BH Photo quoted you.

For interviews I am frequently using a FF 24-105 Sigma ART with a Speed Booster Ultra which is of course pulling the wide end back to 25.68mm with the SB crop of 1.07. So the Sigma 24-105mm basically becomes an F2.8 26-112mm, works well. I also use Sony's own 18-110mm F4.0 on the FS7 for interviews. Again works well. Those Fuji MK lenses with their T2.9 apertures and parfocal optics are perfect in my opinion for interviews. A very nice look is generated by both of them. If you are concerned about the Fuji MK series performance on S35 check out the following video. They perform very, very well for the price.

https://www.thehurlblog.com/zoom-len...mm-filmmaking/

Chris Young
Sydney

[W. Bill Magac]

Originally Posted by Christopher Young

Bill

The B&H answer without nit-picking is pretty close to correct. In broad terms an APSC sensor is considered to have a crop factor of 1.5 over a FF sensor. If we take a FF 35mm sensor as having a diagonal of 43.3mm and divide that by the Sony S35 sensor diagonal of 27.1mm you actually end up with a crop factor of 1.597 in the case of the FS7. Close enough to call 1.6.

With the LS300 it has a 16:9 variable sized window for video capture. At its maximum size the window’s resolution is 4464x2511-pixels. AltaSens specifies the window to have a diagonal of 26.72mm at its maximum size, this capture window closely matches that of 3-perf Super 35 film format.

If we now apply the same equation factors of a FF at 43.3mm to the JVC's LS300 AltaSens sensor at its maximum quoted capture size diagonal of 26.72mm we would get a crop factor of 1.620. That's if we were using a full frame lens on the 300. On that basis the 55mm MK lens at its wide end of 18mm with a crop factor of 1.620 applied would in FF terms deliver a 29.16mm wide end. At the long end of 55mm that would become 89.1mm. Its field of view would be basically that of a FF lens that went from in round terms 29-89mm. Very close to the 28.8-88mm that BH Photo quoted you.

For interviews I am frequently using a FF 24-105 Sigma ART with a Speed Booster Ultra which is of course pulling the wide end back to 25.68mm with the SB crop of 1.07. So the Sigma 24-105mm basically becomes an F2.8 26-112mm, works well. I also use Sony's own 18-110mm F4.0 on the FS7 for interviews. Again works well. Those Fuji MK lenses with their T2.9 apertures and parfocal optics are perfect in my opinion for interviews. A very nice look is generated by both of them. If you are concerned about the Fuji MK series performance on S35 check out the following video. They perform very, very well for the price.

https://www.thehurlblog.com/zoom-len...mm-filmmaking/

Chris Young
Sydney

Thanks Chris. You have answered my question.