Will I lose DoF with ND filters

MileCreations

MileCreations

I'm sorry if this is a stupid question, I'm only just coming to grips with stuff to do with lenses.

When I put my ND filter on my DSLR lens depending on the filter will my image essentially go from being say a f1.8 to a f2.8 or something and will that make my DoF less narrow?

I haven't bought one yet so I can't simply just test it... The guy at the store said I would 'lose a few stops'

-Brendan
 
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knightly said:
They'll darken your scene and allow you to open your iris wider (i.e. moving from a 2.8 to 1.8 if your lens goes that low) for a shallower DoF.
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Yeah I knew they darkened it, I've used them on high end Sony video cameras in the past but never took much notice as to what they were actually doing (apart from obviously darkening it)

So all it is doing is tinting it. The narrowness of the focus will be the same whether I have it on or not?
 
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Your DoF will stay the same if you'll put ND on a lens. The amount of light that hits the lens doesn't change. ND filters modify the INTENSITY of light, not its amount.
 
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knightly is correct. An ND filter allows you to drop that f-stop (or to use the prime lens you desire to use). By allowing a lower f-stop, an ND filter will only help to make your depth of field more shallow.

Your experience using them with a camcorder doesn't really relate, since you weren't able to control your aperture. In other words, on a camcorder, an ND filter pretty much just darkens the image. But when you have interchangeable lenses, you can keep the same level of brightness, while decreasing the depth of field.

EDIT: Haha. I guess me and Dima were typing at the same time, but it took me a couple extra minutes to make the post. Anyway, I didn't intend my post to sound dick-ish, especially with my man, D-lev! :)
 
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Cracker Funk said:
knightly is correct. An ND filter allows you to drop that f-stop (or to use the prime lens you desire to use). By allowing a lower f-stop, an ND filter will only help to make your depth of field more shallow.

Your experience using them with a camcorder doesn't really relate, since you weren't able to control your aperture. In other words, on a camcorder, an ND filter pretty much just darkens the image. But when you have interchangeable lenses, you can keep the same level of brightness, while decreasing the depth of field.
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It wasn't a camcorder but I understand what you're saying.


Sony_HVR_Z7P.jpg

No official use of image. Reference: Google :P

I think my question is answered now thanks :)
 
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dlevanchuk said:
Your DoF will stay the same if you'll put ND on a lens. The amount of light that hits the lens doesn't change. ND filters modify the INTENSITY of light, not its amount.
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Sort of.

That is if you use an ND filter to remain at a certain aperture to have a certain dof. Eg, you want a desired dof which an aperture of 5.6 is giving you in your scene with your various distances established. However, lighting is beyond your control and you're blowing out. ND filters are your solution to keep those settings and get to a 'proper' exposure.

However, if you want to do the reverse, change the f/stop or shutter speed to be able to catch something specific with those particular settings and the light isn't allowing you to do so, ND filters are your solution again.

It can be a little confusing at first but, basically, you use ND filters when (a) you want certain camera settings and the light won't allow for it, or (b) you want to capture something which is beyond your camera's capability and you need and ND filter to make the situation fall within it.

In the end, they're a bit like sunglasses for your lenses. They either help you stay at your desired settings or allow you to change the settings to the ones you desire.
 
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Ernest Worthing said:
Sort of.

That is if you use an ND filter to remain at a certain aperture to have a certain dof. Eg, you want a desired dof which an aperture of 5.6 is giving you in your scene with your various distances established. However, lighting is beyond your control and you're blowing out. ND filters are your solution to keep those settings and get to a 'proper' exposure.

However, if you want to do the reverse, change the f/stop or shutter speed to be able to catch something specific with those particular settings and the light isn't allowing you to do so, ND filters are your solution again.

It can be a little confusing at first but, basically, you use ND filters when (a) you want certain camera settings and the light won't allow for it, or (b) you want to capture something which is beyond your camera's capability and you need and ND filter to make the situation fall within it.

In the end, they're a bit like sunglasses for your lenses. They either help you stay at your desired settings or allow you to change the settings to the ones you desire.
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I would just bump up the shutter sped but I've recently learnt that is not the best option...
 
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The shutter, ISO and aperture (f-stop) make the exposure triangle. If you increase one, you have to decrease another to let the same amount of light into the sensor/film plane.

Shutter is how long the camera accepts light (makes motion more or less fluid)
ISO is how sensitive the camera is to light (adds noise/grain if you go too high with it)
Aperture is how much light the lens lets in at once (increases/decreases DoF)

Opening the aperture by one click (stop, smaller number) will let more light through, so you need to drop the ISO or increase the shutter speed to make up for that extra amount of light getting in.

If you don't want to have to change any of your settings, there's a 4th option in the triangle... reduce the amount of light coming into the camera... either by dimming the lights, or putting "sunglasses" over the lens.

A polarizer is a special filter that only lets direct light through, no bounced, off-axis light that could contaminate your shot by amping up the light values on any give pixel with information from stuff other than what you see in front of the lens... it's like microscopic venetian blinds for your lens. It eats some light, but really makes colors pop (especially the sky 90 degrees from the sun and leaves)!
 
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knightly said:
A polarizer is a special filter that only lets direct light through, no bounced, off-axis light that could contaminate your shot by amping up the light values on any give pixel with information from stuff other than what you see in front of the lens... it's like microscopic venetian blinds for your lens. It eats some light, but really makes colors pop (especially the sky 90 degrees from the sun and leaves)!
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Is this different to an ND filter?
 
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MileCreations said:
Is this different to an ND filter?
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Yes, though most Polarisers also cut light, similar to an ND.

An ND's sole purpose is to cut the amount of light coming in to the lens; whether that's so you can stay at a certain aperture, or simply because you're metering at f/22 or f/45 but your lens only closes down to f/16.

It's much more prevalent with the new digital systems, like Alexa, that are natively 800 ISO, so you end up with ND 1.2, 1.8, cutting 4 and 5 stops respectively (though on digital cameras you need IR+ND's, or a seperate hot mirror filter). Lee make an ND filter called the 'big stopper' that cuts 10 stops of light. Maybe useful for shooting at 1.4 in the snow ;)
 
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MileCreations said:
I would just bump up the shutter sped but I've recently learnt that is not the best option...
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Since this is mostly a film forum, I was assuming you were talking about shooting video and not photographs. Shutter speed is open to you in photography but you can really change it when doing video if you want cinematic motion blur.

Just double the shutter to the closest setting it can be compared to your frame rate.
 
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Ernest Worthing said:
Since this is mostly a film forum, I was assuming you were talking about shooting video and not photographs. Shutter speed is open to you in photography but you can really change it when doing video if you want cinematic motion blur.

Just double the shutter to the closest setting it can be compared to your frame rate.
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Yes I'm shooting video. Previously I had put the shutter speed up in the hundreds to get the exposure right. But I had comments about how the lack of motion blur and such wasnt in my favour in order for it to look good. Which is why I'm now looking around at ND filters.


In talking to a sales dude at photography shop in suggested an ND filter that is variable in its strength, rather than buying multiple that are just one strength. Because I also have lenses with different sizes I'm looking at purchasing the variable ND filter and an adapter from one size to the size of the filter so I can use it on different lenses. is a 'variable' strength ND filter a good idea?
 
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The quality is what's important, not the type. People tend to spend hundreds on a lens and then attach a $20 dollar filter in front of it which doesn't let the lens capture the image up to its full potential.
 
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Mannie Bothans said:
Okay, which ones are good ones? If you can't try them locally, how do you know what's quality and what's crap?
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Yeah, I'm interested in the "is it really worth it" aspect between a $35 Polaroid or a $305 Heliopan?
$35: http://www.adorama.com/PDPLFFDND58.html?gclid=COGawuaQlLQCFYG-zAodaBkAxQ
$305: http://www.adorama.com/HP58VND.html?gclid=CLeXrKCRlLQCFY-6zAodPnwAhA

Often good enough is good enuff.
And sometimes gilding the lily is appropriate.



MileCreations -
I don't know if you parsed through all the help that a ND filter really has zero effect on the DoF.
DoF is entirely aperture setting.
Primarily it'll just drop down your auto shutter speed to avoid that SAVING PRIVATE RYAN choppiness in brightly lit environments, which is what I gather you're looking to avoid or "cure."

Here's what'll happen:
It's a beautiful sunny Ausie day like you have in your avatar picture: Sun's a burning, shadows are razor sharp and black as midnight, highlights are all blown out bright. Basically, contrast is a polar extreme nightmare.

For the shot you want you DON'T want your entire DoF to be in focus; you DO want to keep just your immediate subject in focus and the rest of the range blurred out of focus.
To achieve this you need to run down your fStop to a big ol' opening which dumps a ton of light on your CMOS sensor.
Fine.
But now you're going to have blowouts galore.
Fine.
Your camera will likely auto correct with a sky-high shutter speed >150 = SAVING PRIVATE RYAN choppiness.

If you manually set your shutter speed to <100 - BAMMO! - everything goes sunny side of Mercury white.
Not good.
Pop on your "sunglasses" ND or variable ND filter and "Ahhhhh!" the aperture can stay open, the shutter speed can stay low, and the subject's movement won't be jittery-jumpy.
 
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rayw said:
Yeah, I'm interested in the "is it really worth it" aspect between a $35 Polaroid or a $305 Heliopan?
$35: http://www.adorama.com/PDPLFFDND58.html?gclid=COGawuaQlLQCFYG-zAodaBkAxQ
$305: http://www.adorama.com/HP58VND.html?gclid=CLeXrKCRlLQCFY-6zAodPnwAhA

Often good enough is good enuff.
And sometimes gilding the lily is appropriate.



MileCreations -
I don't know if you parsed through all the help that a ND filter really has zero effect on the DoF.
DoF is entirely aperture setting.
Primarily it'll just drop down your auto shutter speed to avoid that SAVING PRIVATE RYAN choppiness in brightly lit environments, which is what I gather you're looking to avoid or "cure."
Click to expand...

Yeah I got that figured :)

Now my 'quest' is the first part of your reply, trying to decide if I should go with single stop or multiple stops. I'll probably go with the multiple one because especially when I have lenses of different widths it will end up cheaper in the long run
 
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