APS-C SPEED BOOSTER MATH

[tomsemiterrific]

Yawn, I'm sure this topic has been covered before but I can't seem to find it.

Here's the question: I have a dumb speed booster with a 0.71 reducer and a lens that is 100mm.

My camera asks me what lens angle of view I'm shooting so its internal stabilization will make the lens usable for hand held use.

What do I tell my camera to stabilize the 100 ff lens on my aps-c camera?

Enquiring math-challenged minds want to know.

[EthanAlexander]

You'd tell it to stabilize a 71mm (or whatever's closest.)

It's helpful to think of these as "focal length reducers" and then it's easier to remember that what you're really doing in effect is putting a 71mm lens on your camera.

[tomsemiterrific]

4 minutes ago, EthanAlexander said:

You'd tell it to stabilize a 71mm (or whatever's closest.)

It's helpful to think of these as "focal length reducers" and then it's easier to remember that what you're really doing in effect is putting a 71mm lens on your camera.

Ethan, would that be true for a MFT camera as well as a APS-C?

[EthanAlexander]

Yes. For instance, if you were to place a FF, non speed boosted 100mm on either an a6500 or a GH5, you'd tell both cameras to stabilize a 100mm. Same logic goes for speed boosted lenses, where you'd tell either camera the "focal reduced" length, in this case 71mm.

Just remember, any FF lens on a MFT will look exactly the same as the same mm MFT lens on a MFT. The only difference in those lenses will be the size of the image circle, but the MFT sensor will only ever see the same smaller portion.

Hope this isn't getting complex, so to summarize: Since all you're trying to do is figure out the math to tell the camera what focal length to stabilize, there's actually no need to do any math for the sensor size, JUST the focal reduction. All you've got to do is tell the camera what the "mm" is, and when you add a speed booster (0.71x), you're literally placing a 71mm lens on, whether it's APS-C or MFT.

[tomsemiterrific]

6 hours ago, EthanAlexander said:

Hope this isn't getting complex, so to summarize: Since all you're trying to do is figure out the math to tell the camera what focal length to stabilize, there's actually no need to do any math for the sensor size, JUST the focal reduction. All you've got to do is tell the camera what the "mm" is, and when you add a speed booster (0.71x), you're literally placing a 71mm lens on, whether it's APS-C or MFT.

Ausgezeichnet! Danke viel Mals. As clear as an unmuddied lake, sir. As clear as an azure sky of deepest summer.

[Deadcode]

I have a math question too!

Can you have fullframe look from the GH5 with the following terms:

GH5 in 6K 4:3 mode with Metabones Speedbooster XL = 1,28x crop 4:3

If i add an SLR Magic Anamorphic 1,33x lens to it, will it be a fullframe equivalent field of view (and 16:9) BUT with anamorphic oval bokeh and lens flare?

GH5: 2x crop x boosterXL 0,64x = 1,28. SLR Magic widens the image(?) so the crop factor will be reduced by 1,33 and on the 4:3 sensor the projected image will be 16:9.

So if i do this with a 50mm F1.4 lens it will be 50mm F1.8 in terms of fullframe blur/separation and F0,9 in terms of light transition (+1,33EV with the booster). am i right?

[PannySVHS]

10 hours ago, Deadcode said:

I have a math question too!

Can you have fullframe look from the GH5 with the following terms:

GH5 in 6K 4:3 mode with Metabones Speedbooster XL = 1,28x crop 4:3

If i add an SLR Magic Anamorphic 1,33x lens to it, will it be a fullframe equivalent field of view (and 16:9) BUT with anamorphic oval bokeh and lens flare?

GH5: 2x crop x boosterXL 0,64x = 1,28. SLR Magic widens the image(?) so the crop factor will be reduced by 1,33 and on the 4:3 sensor the projected image will be 16:9.

So if i do this with a 50mm F1.4 lens it will be 50mm F1.8 in terms of fullframe blur/separation and F0,9 in terms of light transition (+1,33EV with the booster). am i right?

My view:

1.28for speedbooster x 0.75 for 1.33 anamorph equals factor of 0.96 for field of view of Fullframe Lens.

Light transition will estimate to give 1.28 stop increase due to Speedbooster XL. Blur separation will be F1.4x0.96 equalling F1.344 for a F1.4 full frame lens.