Anyone using Alistair Chapmans MTS B4 mount on their F3?

Sorry John my math was incorrect afterall. The multipication factor is 2x for the extender built into your 2/3" lens, and another 1.5x for the MTF adapter. 2.5 total.

Your Fuji wide becomes f3.7, 11.25mm - 150mm.


Also for all the 4k owners out there, any direct B4 to camera adapter (without 1.5x magnifier) will allow you to shoot in 4k and crop out your image in post to end up with something around 2700x1500 resolution. You would need the 2x extender engaged to yield that resolution or you can crop it to HD 1920x1080. Without the 2x extender you would end up with something more like 720p resolution and the original focal length and speed of your 2/3" lens.
 
So then wouldn't that additional 1.5x magnification also cost me an additional stop or so on top of the f stop penalty of the 2x on the lens itself? So maybe f4 or even more?
 
yes you're probably right. Alister did say in his video that you will get about f4 out of a f1.8 lens, so sure f4 or close to it is probably more accurate.

Still nothing wrong with f4.
 
I might get the adapter in a week or so and try it with my J17 lens. I used it alot on the AF101 so I count on using it on the F3.
 
JCummings said:
So then wouldn't that additional 1.5x magnification also cost me an additional stop or so on top of the f stop penalty of the 2x on the lens itself
Click to expand...

A 1.4 converter take one stop of light - so 1.5 should indeed by 'a stop or so'

(of course this is F stop not Tstop) so light level may I guess be cut more.

Talking for simplicity an F2 lens surely it goes like this..

F2
Engage doubler and lose two stops, 4, 5.6
You are at 5.6
Add 1.4 converter (for simplicity not 1.5) 5.6 becomes 8

So F2=F8 DOF and probably T11 transimission

???

S
 
morgan_moore said:
A 1.4 converter take one stop of light - so 1.5 should indeed by 'a stop or so'

(of course this is F stop not Tstop) so light level may I guess be cut more.

Talking for simplicity an F2 lens surely it goes like this..

F2
Engage doubler and lose two stops, 4, 5.6
You are at 5.6
Add 1.4 converter (for simplicity not 1.5) 5.6 becomes 8

So F2=F8 DOF and probably T11 transimission

???

S
Click to expand...

Alister says in the video the whole loss is only 2.5 stops. ie. f1.8 goes to f4
 
my post ends with a question mark.

Point me to the hole in my logic. Im happy to hear it.

Its pretty simple - lenses - lights, when you project over a larger area it becomes less intense?

And my 400 2.8, with a doubler its 5.6 and with a doubler and a 1.4 converter its F8

Edit. I had it wrong above - I meant 2.8 goes to 8, so 2 would go to 5.6 and 1.4 to 4

So a 1.4 would go to 4 - I agree.

S
 
Well you can test and let us know. I'm very curious about this setup, a powered ENG zoom would be very good to have.

Your 400mm lens will turn into 1000mm !! Wow...
 
starcentral said:
Your 400mm lens will turn into 1000mm !! Wow...
Click to expand...

It can but gets so raddled with aberrations (let alone impossible to manage) that I do not consider it usable like that.

..but the sensor size is not changing so that is not an entirely fair comparisom

Id love to see some test of this set up (Als)

S
 
Editman Sweden said:
I might get the adapter in a week or so and try it with my J17 lens. I used it alot on the AF101 so I count on using it on the F3.
Click to expand...

Editman, I checked out some of the footage you did with the AF101 and it was pretty impressive. (like most of your stuff, by the way)
Let us know when you put the F3 test up! Considering how clean the F3 is at higher ISO's, I'm particularly interested in whether it could be used indoors with minimal lighting...
 
Ok, maybe a stupid question, but when you go to a lower resolution via the system settings on the F3, does that actually crop the sensor? If so, would that have any bearing on the getting the "sweet spot" on a setup like this?
 
@ 800 ISO you can get f4 - f5.6 indoors but needs to have large windows with light coming in. Corners and other areas further away get dark quick.

When I shoot in 1280x720 (for overcranking purposes ie. 60p) the FOV does not change from what it was at 1920x1080.
 
JCummings said:
Editman, I checked out some of the footage you did with the AF101 and it was pretty impressive. (like most of your stuff, by the way)
Let us know when you put the F3 test up! Considering how clean the F3 is at higher ISO's, I'm particularly interested in whether it could be used indoors with minimal lighting...
Click to expand...

Thanks! So far I've shot some test footage and coming from the AF101 this camera is so much better. The footage is just to boring to be shown but shows what this camera can do. Jaw dropping at times and so pleasing to look at. I'll probably shoot some sort of commercial Thursday/Friday and that I'll show when it's ready for air.

Still waiting for the B4 adapter to get into stock before plunging.
 
I did get it and did a brief test.
The first thing I noticed were two light leaks, one at the camera mount and one where the two halves of the converter join.
I think the weight of the lens was slightly stressing the adapter and that slight deformation was allowing light onto the glass inside. I only noticed the leak when direct sun was hitting the adapter barrel. I adjusted the included rail support and that fixed most--but not all--of the leak. A tiny piece of gaff tape got rid of the rest.
I was using a heavy wide zoom on the adapter so I think the lens will also need support in addition to the adapter itself.

As to how it worked, it looked fine in a quick test, especially outside. I did some tests inside near some large windows with available light. I did find I had to boost the gain a little (3-6dB) inside to get a decent level. The good news is the F3 looks pretty good pushed, so the lens is actually useable indoors with enough light and a little gain.

I rolled a little video but haven't had time to look at it on a real monitor. I'm going crazy with election shoots here in Ohio and on the road until the end of the week. I'll get back to looking at it next weekend.
So, my initial impression: It works as advertised, but not without issues. I'm guessing the build quality is not on par with the more expensive units. Once I get that additional support figured out, I'll give it a real look-see.
 
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