Any mathematical geniuses here?

[_Paz_]

(I'm not sure I even spelled the title for this thread right!)

Suppose you had a Pany GH4 camera with a micro four thirds sensor - and that sensor was going to somehow make the 'effective' (or perhaps that is 'cropped') lens length approximately 2 x longer than the stated length of a lens..

That is, a 100mm (at 35mm) lens would look like what you'd expect a 200mm lens to look like, in terms of how 'zoomed in' it was. Or a 400mm lens would 'look like' an 800mm would look.

And then you added a 0.71 X speed booster to connect the lens to the camera?
(Or a .64 X speed booster.)

Is that going to make it look like it is even more zoomed in?

Anyone have a rough idea of what a 400mm lens with above setup would be like?

[Bob]

No geniuses required, it's basic arithmetic. The 2.0 factor is the crop factor for the camera sensor. The 0.71 and 0.64 values for the speed boosters are crop factors for the speed booster. The crop factor for the sensor plus the speed booster used together is simply the product of the crop factors. That is, 2x0.71 equals 1.42 and 2x0.64 equals 1.28. A 400 mm lens will look like a 568mm lens with the 0.71 speed booster or a 512mm lens with the 0.64.

[Steve Grisetti]

Thanks, Bob! You make it sound so simple!

[John 'twosheds' McDonald]

Doh! My brain hurts.

[sidd finch]

Wait... I have 3 apples, Sally has 2 more apples than Johnny. What is the drag coefficient of that apple that Sally throws at Johnny head....

Sidd

[Dave McElderry]

Wait... I have 3 apples, Sally has 2 more apples than Johnny. What is the drag coefficient of that apple that Sally throws at Johnny head....

Pretty low through air. Apples aren't real aerodynamic, but at least they're mostly round. How fast is the apple being thrown, what color is it, and what's the make and model?

[_Paz_]

A 400 mm lens will look like a 568mm lens with the 0.71 speed booster or a 512mm lens with the 0.64.

I was afraid of that. The speed booster takes away some of the gain of the micro four thirds sensor, right?

So... a 400mm lens will be either 568 or 512 with one or the other speed booster, while a say, 100 - 300 mm lens that comes with a micro four thirds mount will be approx 600mm at the longest zoom. Not to mention the cost difference of that L lens I've drooled over all these years. I see I need to hunt on YT for vids made with the Pany 100 - 300 to see what the lens quality looks like.

Thanks, Bob!

But, sorry... about that 'basic arithmetic' thingy... It wasn't until 4th grade when they started on fractions that 'arithmetic' became MATH !

@ Dave...

Granny Smith, green, PIE Model

[Peru]

Granny Smith, green, PIE Model

[Dave McElderry]

@ Dave...
Granny Smith, green, PIE Model

In that case the coefficient would be .573.

Approximately.

[momoffduty]

Granny Smith, green, PIE Model

PIE model!

[sidd finch]

In that case the coefficient would be .573

I knew it....rats I guessed 7. Even though I am not good at math, 6th grade was the best 4 years of my life....

Sidd

[Dave McElderry]

I knew it....rats I guessed 7. Even though I am not good at math, 6th grade was the best 4 years of my life....

[Bob]

A 400 mm lens will look like a 568mm lens with the 0.71 speed booster or a 512mm lens with the 0.64.

I was afraid of that. The speed booster takes away some of the gain of the micro four thirds sensor, right?

That's correct. If you really want that 400mm lens and keep the 2x crop factor, you could look for a smart adaptor without the optics. Metabones has this one. I also saw one from Kipon. I don't know whether your 400mm lens is compatible with these or not. I've never heard of Kipon before.

With long telephoto lenses like that, even a tiny bit of vibration will be magnified greatly. You will need a tripod, a fast shutter speed, and preferably a remote shutter release in order to get tack sharp results.

See this: [youtube]http://www.youtube.com/watch?v=RgzLfLa2acA[/youtube]

[youtube]http://www.youtube.com/watch?v=L1s0mKR49sU[/youtube]

[_Paz_]

Thanks, Bob. I have been looking for an adapter with electronics and without added glass since you confirmed my suspicions! A while back I came across the Kipon but didn't remember where I had found it - or the name.


I've been pleased with the 45-150 Lumix lens I bought but it simply isn't long enough. I want more. I've looked at Lumix 100-300 footage (not that much out there) now and somehow it hasn't grabbed me like the Canon super telephoto look does.

I've ordered the Kipon adapter. After you mentioned it I looked it over again. YouTube has some good examples. One impressive one shows how quickly it captures focus while in still mode. Hopefully it will find and hold onto focus in video mode. The only way to know for certain is to try it out. At half the price of the Metabones and since the Kipon will take my EF-S lenses too, it seems the way to go on my experimental journey for higher quality video images.

The Kipon is on backorder. I'll post results when it arrives.