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How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?

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ryan elder
How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Sep 30, 2018 at 3:18:52 am

Basically for my current short film shoot, I am getting the shots ready, and deciding on lenses, and I want to hook up a canon lens I have to a Sony A7s camera. It's a 300mm which was not available for the Sony, at least not in the same good price range.

So I have to put an adapter in between the lens and the camera to fit it on. However, I find myself not being able to adjust the aperture on the lens, cause the adapter is in the way, and preventing me from doing so it seems. Has anyone ever had this problem and know of any possible solutions?

Thanks anyone for any input. I really appreciate it!


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Blaise Douros
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 1, 2018 at 6:09:37 pm

Is it an old manual lens? If so, and something is blocking the aperture dial, you can take the lens off, adjust the aperture, and put it back on. Yes, it sucks, but if it's your only solution, then you'll have to live with it.

If it's a modern lens, and the camera isn't talking to the lens electronically, then I don't know what to tell you; if it doesn't work, it doesn't work.


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ryan elder
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 1, 2018 at 9:35:49 pm

It's a modern lens, and there is no lens ring, if that is what you mean. Yes the camera is not talking to the lens, but is there another way of changing the aperture? Does the camera absolutely have to talk to the lens to do this?


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Blaise Douros
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 1, 2018 at 11:11:38 pm

On a modern lens with no aperture ring, there's no other way to change the aperture setting--it can only be electronically controlled from the camera.

If your camera is not talking to the lens, then it's a compatibility issue. There is absolutely nothing you can do about it, aside from finding another brand of 300mm lens that will talk to the camera, or maybe making sure your adapter's firmware is up to date.

If you're using a 3rd-party lens like Sigma or Tamron, those are rarely supported by the manufacturers of the adapters like Metabones. Even some of the more obscure first-party lenses don't always work--I know Metabones doesn't officially support all of the Canon EF catalogue on their adapters.


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ryan elder
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 2, 2018 at 12:24:17 am

Okay thanks. The thing I like about putting an adapter between the camera and the lens, is that it causes the lens not to change aperture while zooming, which it will do, if the camera can talk to it. But if I disconnect the talking, then the aperture will not change through zooming. So that's the plus.

However, the disadvantage is, is that I cannot change the aperture. I found out that there are adapters where you can actually control the aperture on the adapter. But will that cause the aperture to change during zooming though, if I use one of those types of adapters?


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Blaise Douros
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 3, 2018 at 7:51:49 pm

The f-number is a ratio of the aperture size to the focal length, so it's not a matter of the aperture changing when you zoom, it's a matter of the focal length changing enough to alter the ratio. Higher-end lenses have a constant aperture, which adjusts the aperture based on the focal length to keep the ratio identical. If you don't have one of those lenses, no adapter will help.

Ultimately, even a constant-aperture zoom doesn't mean the exposure is the same; the Canon 24-105L, for example, is about a stop darker at 105mm than at 24mm, even though the constant aperture keeps the number at F/4. If you want constant exposure, you need to work with lenses that operate in T-stops, which means cine glass, which means lots of money.

This is a non-problem that you can't change anyway without the application of huge amounts of money. Stop thinking about it and go shoot. If you're worried about it, make sure you know how much exposure difference there is between the wide and tight ends of your lens, and adjust the exposure accordingly when setting up the shot. Unless you're making a western, you won't be doing much zooming while the camera's rolling, anyway.


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ryan elder
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 3, 2018 at 10:00:06 pm

Okay thanks. I actually wanted to zoom during shooting though. Like just during certain moments, like a push in to a character's face for emotion or something like that, I was thinking of zooming.

You say that an adapter will not help. But why is it that when I have put an adapter between the lens and the camera before, the aperture was constant? It's only when I don't use an adapter that the exposure changes.

Basically when the camera talks to the lens, it makes these clicking sounds during the zooming. Those clicks are changing the exposure. But if I put an adapter in between the camera body and the lens, there is no clicking and the exposure stays the same.

So why is that?


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Blaise Douros
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 5, 2018 at 3:45:05 am

Autoexposure. Plus, it's clear that your adapter does not allow your camera to talk to the lens. I already said that.


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ryan elder
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 5, 2018 at 3:56:21 am

But the autoexposure was not turned on and I had it switched to manual. So how can it keep the same exposure throughout the zoom, if the camera is on manual exposure mode then?


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Gary Huff
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 5, 2018 at 3:08:34 pm

[ryan elder] "But the autoexposure was not turned on and I had it switched to manual. So how can it keep the same exposure throughout the zoom, if the camera is on manual exposure mode then?"

You can't, nor can you zoom on a 300mm prime lens, so don't worry about it. Be more concerned with putting your camera on a tripod instead and getting basic, steady shots with the lenses you already have that work.


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ryan elder
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 8, 2018 at 6:03:57 pm

Well it's a zoom lens, not a prime though.

Look, with all do respect, even if a static camera on a tripod and nothing more is good enough for you, that is good enough for you. I feel I can do more than put a camera on a tripod, and I have done that a lot before, and want to do other things in filmmaking.


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Gary Huff
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 9, 2018 at 7:42:26 pm

[ryan elder] "Well it's a zoom lens, not a prime though."

A 300mm lens is not a zoom lens, it's a prime lens. A 70-300mm would be a zoom lens.


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Blaise Douros
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 8, 2018 at 4:53:57 pm

You might double check that the camera isn't set to Auto ISO. It will adjust exposure even in M mode.


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ryan elder
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 9, 2018 at 10:15:46 pm

Nope, I never use auto ISO and always manually set it. But it still changes exposure while zooming even if the ISO is locked.


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Gary Huff
Re: How do I change the aperture on a lens, if there is an adapter, preventing me from doing so?
on Oct 10, 2018 at 12:08:40 am

Then you shouldn't be zooming in a shot.


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