Tagged with constant - Personal View Talks

What are the benefits of a constant aperture lens?

mpgxsvcd — Tue, 23 Sep 2014 08:01:39 +0000

It seems like all of the high end lenses are constant aperture. What are the benefits and drawbacks of a constant aperture lens?

The biggest benefit I can think of is that the exposure will stay constant as you zoom. You can fix the shutter speed, focal ratio, and ISO values and then zoom without needing to change them. That sounds great but do we really need that?

With cameras that have Auto ISO available in manual mode can’t you just let the auto ISO control the exposure while you zoom?

Also aren’t all lenses constant aperture, just not always at their wide open apertures? If you stop down to the minimum aperture of the lens then the aperture will remain fixed in aperture priority or manual mode while you zoom even if the lens isn’t a true “Constant Aperture” lens.

What happens as you zoom? Aren’t these lenses still changing the aperture in order to keep it constant? Doesn’t that mean that your depth of field will change as you zoom? If the focal ratio of a not constant aperture zoom lens increases as you zoom in could it then keep depth of field constant as you zoom if so desired? Would that ever be desirable?

Couldn’t a constant aperture zoom lens have a slightly wider aperture or slightly longer focal length if it wasn’t a constant aperture lens wide open? Aren’t they crippling the lens slightly in order to make it constant aperture wide open?

Also what about being parfocal. Isn’t maintaining focus as you zoom more important than maintaining focal ratio especially in cases where you can let Auto ISO solve the changing exposure issue?

I am just curious as to why we insist on having constant aperture lenses. To me the benefits of a constant aperture lens do not outweigh the benefits of a non-constant aperture lens as long as your camera allows auto ISO in the modes you are shooting with.

With that being said the 35-100mm F2.8 is pretty much the only lens I use on my GH4 now. However, I really don’t zoom that often while filming so I am not sure I use it to its full abilities.

Is there something wrong with my GH2?

apauloh — Sun, 04 Aug 2013 23:23:33 +0000

So I just bought a gh2 off ebay. Bought a 32gb class 10 sd card to accompany it. I uploaded a hack and it works I think. The thing is that pretty often, I am asked to reintall the 1.1 firmware page for the hack? So when I check my photos, it asks. When I turn off my camera and turn it back off, it asks. Is this normal or is something wrong with the internal firmware of the gh2?

GH2 - How to get a constant lens aperture?

willianaleman — Wed, 15 Feb 2012 01:56:57 +0000

Shooting in Movie Mode, no matter what lens I use, mechanic or electronic with GH2, the aperture in the camera changes accordingly with the light source as soon as I pan or tilt up/down. Is there a way to lock the iris within the camera, the ISO, shutter speed or wherever is causing this behavior in the camera? I'm looking for a zoom lens with constant aperture for the GH2.

Thanks in advance for any help.

Here is a list of lens used at the moment, they all behave the same:

Panasonic - 14-42 - 14 140mm

Nikon: - 135 mm 1:2.8 - 50mm 1:1.8 - 52mm 1:14 - 85-205mm 1:8 - 300mm 1:4.5