Tamron 24-70mm Lens Low Light Issue

[Tom Van den Berghe]

Chris, made a new test and again the NX3 needed the less gain .

NEX-EA50 vx HXR-NX3 vs HC-X920 - YouTube

All cameras were in 1/50 (pal). Is it because the NX3 is wider than the samyang like you said?
I need a wider lens like the stocklens?

And the iris wass full open, I checked it.

I also included the little panasonic HC-X920. This one has a bit more noise.

Can I conclude my new sony HXR-NX3 is a really good low light performer?

[Chris Harding]

Hey Tom

I'm no lens expert at all but I would compare the stock lens in full auto and then put the Samyang also with the camera in full auto and allow it to choose the gain for you. In that dark environment the stock lens will be at 1/50 and full open (F3.5) once to put the manual lens on, open the iris full and see what gain the camera chooses .... it should be at least 12db lower than the stock lens ..I'm not sure if you set the manual in manual to 3db or the camera chose it. Manual lenses on the EA-50 work perfectly in full auto!

Chris

[Tom Van den Berghe]

Chris,

I tested the stocklens against the samyang 1.5 24mm in full auto. It's been shown in the movie.
The stocklens needed 21db @ F3.5 1/50 shutter and the samyang needed 12db, iris full open 1/50 shutter.

So a difference of 9db. The stocklens is much wider (18mm APS-C) then the samyang 24mm (this is a full frame lens I think) So the wider the lens goes how more light it captures, Correct me if I'm wrong.

Maybe a 18mm F1.5 will make a "big" difference against in samyang in low light.

[Chris Harding]

Hi Tom

I would have expected more than a 9db difference to be honest. My Sigma 18-35F1.8 makes a HUGE difference to my Tamron F2.8 lenses which are faster than the stock lens and between the two is a big jump. As already said I'm no lens expert but the Sigma lets in a stack more light and having an 18 - 35 zoom is a big advantage too. I got rid of all my prime lenses!!

[Aaron Jones Sr.]

Hi James,

Originally Posted by James Manford

Now when it comes to these electronic dumb adapters that supposedly allow iris control. Do this. Turn on the camera, hit AUTOFOCUS ON (on your lens body) you will see the lens will try and hunt for focus (but it also opens the iris for you and brightens the image). Then switch AUTOFOCUS OFF. Now you can use the lens in manual focus with active stabilization if you have it available.

Yes, this is what I came up with. But for me I have to switch Auto Focus on and off on the Tamron lens. When I do it on the EA50 cam body I just get the nag screen. whether if the switch on the body is on or off the Tamron will try and focus. So i keep the switch on the body off. On the lens I turn the AutoFocus on to get a brighter picture then turn it back off. Then I adjust my focus ring to compensate.

James thank you for the feedback. At least I know my Tamron is not haunted, LOL! It did surprise me the first time I seen it do this. To be honest it only did this with the Commlite. I never recall it doing it with the Viltrox. Just a observation. I think the Viltrox is the lesser of the two evils in a matter of speaking comparing to the Commlite. The viltrox cost a little more than the Commlite as well. I paid $125US for the Viltrox NEX II and $85US for the Commlite.

[James Manford]

I think what it really comes down to, is the fact they're not native E-MOUNT lenses. We are talking about converting signals from lenses made for an entirely different camera system.

All these fancy adapters claim a lot, but can only do so much for "VIDEO" use. Hence we have to work around their limitations.

I say video use. Because unlike photos. Video useage requires minimal lag and flawless communication between the electronics "on the fly". Where as with photos, a bit of lag and communication glitches can go unnoticed as you aren't changing settings "on the fly" so to speak.

[Tom Van den Berghe]

So the sigma 18-35mm F1.8 special made for a APS-C sensor like the nex-ea50
or keep my samyang 24mm 1.5 (fullframe) and buy a metabones speedbooster.

Chris,

Did you ever tested your sigma 18-35mm against the stocklens? I have a difference of 9db.

[Chris Harding]

Hi Tom

I don't have any stock Sony lenses now so I cannot test that for you. I have an idea that Jody has a Sigma 18-35 and also his stock lens. Maybe he can do it for you.

The Sigma zoom and Samyang prime are around the same price here ($795.00) I wouldn't pay the crazy $500 + prices for a Metabones though ..I use a dumb adapter off eBay that cost $15.00!!

The Sigma with the Nikon mount is for DX only so that's only APSC!

Chris

[Tom Van den Berghe]

I hope someone can clear this out.