exposure flickering? Auto Aperture problem

[ScaSer]

Hey. i have just made a test video.. and i have a question...

the video is here: http://www.youtube.com/watch?v=G1tbK8kDxi8

when i zoom out. the lights flickers.. i thought the lens was changing apeture. but i have recorded everything at F8

is it automatic iso which is changing, or is it some exposure?

ive recorded using Av program

[PressureFM]

What lens?

[ScaSer]

sorry..

sigma 50-500 4,5-6,3

http://www.sigmaphoto.com/product/50-500mm-f45-63-apo-dg-os-hsm

[Audionut]

dmilligan has a good post (I think in this section) regarding T-stop with variable aperture lenses.

If you search for "lens", by him, in this section, that should narrow down the search results.

edit:  Actually, it was probably in the "general help Q&A" section.

[ScaSer]

i found it here: http://www.magiclantern.fm/forum/index.php?topic=8850.0

but is kinda a adobe plugin? - i dont use adobe programs right now..

is there something in the ML menu in the cam i can change to get better results?

[Audionut]

http://www.magiclantern.fm/forum/index.php?topic=9776.msg94338#msg94338

[ScaSer]

so basic no solution?

[dmilligan]

If you can't use my script and you can't afford a new lens, then you could try holding the 'absolute' aperture constant by slightly unscrewing the lens (the blades will stay in the same position and the camera won't move them as it can't communicate with the lens motors anymore). As you zoom in and out the image will get brighter/darker, but you can more easily fix that since the change in brightness will be smooth. Of course that also means that you will be underexposed when zoomed in.

[ScaSer]

hmm afford er new lens... well i dont know any that would do the job better then the one ive bought.

i was mostly hoping for some software that could soften the hard change out. so you wont notice it, or fix it with a smooth exposure?

is there no way for ML to lock the lens at for instance. F10, for is it the lens it self.. that auto changes the apeture? you cannot unscrew the lens.. the LW will turn off and ask you to put the lens back on

[dmilligan]

you cannot unscrew the lens.. the LW will turn off and ask you to put the lens back on

ML menu > Movie > Movie Tweaks > Force LiveView => Always

(Or just press the LV button again after the switch, at least that's the way it works on my 60D, not sure about 5D3)

[Audionut]

Same for 5D3.

[ScaSer]

milligan.. that actually solved the porblem 100%... i shoot with Av program... and the auto ISO solves the light problem UN NOTIABLE!!!

but i really cant run around with a unfastened lens... it there a way software wise that can turn of this auto apeture function? ML??? hack?

or is the low tech best solution to cover some of the connections on the lens with a piece of tape? - that i think is very unproffesional

[dmilligan]

but i really cant run around with a unfastened lens... it there a way software wise that can turn of this auto apeture function? ML??? hack?

Not that I know of

or is the low tech best solution to cover some of the connections on the lens with a piece of tape? - that i think is very unproffesional

A small piece of tape would work.

[ScaSer]

tape worked. but even that i only cut out the apeture control, then i still loose ability to take pictures and and using lens stab. not very good... also i wouldent like to fiddle with tape at a site.

i hope this can be done ML wise.

[ScaSer]

i have now proposed it to the dews...

http://www.magiclantern.fm/forum/index.php?topic=10615.0