Letus Loss of Light in f stops

[cousinavi7]

Hey Guys,

I just wanted to discuss the loss of light on my letus adapter and see if anyone else has experienced the same issues.

I have a letus flip (a bit older than the extreme but still delivers an upright image) and am extremely happy with the depth of field it delivers. However the loss of light is KILLING me.

They advertised that the flip lost about 4 stops. I find this to be a huge understatement. I tested my DVX100 with both my Canon 28mm 2.8 and 135mm 2.8 against the camera with no adapter.

In order to match the camera wide open with adapter and lenses wide open, the camera without adapter had to be set at f/11. Thats a FULL 7 stop difference!!

Has anyone else ran into this? Or maybe I've got settings off on my camera? Of course the ND filter was off during the test.


I've been really happy with the letus and what it can do. I'd actually like to upgrade to the Letus Extreme soon, but I'm curious about how much light you ACTUALLY lose? They advertise a half stop, but I'm doubtful about that number. Do any actual users have an idea how much light you lose?


Thanks guys

 

[Barry_Green]

The Letus Flip Enhanced loses 1.5 stops. If you're using 2.8 lenses, that's probably costing you another 1 to 1.5 stops.

 

[cousinavi7]

So what your saying is that to match my



1. camera full open and my letus with lens set to 2.8

2. the camera without letus should be set to

f/4.0. (letus flip 1.5 stops and lens 1.5 stops = 3 stops)

but this isn't the case. I have to set my camera down to f/11 without letus, to match the amount of light I have available with the letus and lens attached.

I would love to know if I am doing something wrong so I could get it back to f/4.O as you discussed.

 

[davide]

F/4.0 isn't three stops down from f/2.8. It's one stop. F/8 would be three stops down. F/2.8--F/4--F/5.6--F/8.

 

[cousinavi7]

But I'm starting from wide open on my DVX100. Wide--f/2--f/2.8--f/4.0. Thats 3 full stops of lightloss. (there's even half stops in there on the DVX. 1.7, 2.4, 3.4, 4.8, 6.8, 9.6)

And as I said before, I'm at f/11 before the image is equivalent to wide open with the letus attached. I think I was off but its 6 full stops of light I'm losing.

Are you guys experiencing this? If I've got my camera set up wrong I'd love to know. To match your image with the letus attached, where do you have to set your camera without the adapter?