ND Filters...What's going on!

davidbridges

davidbridges

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David Bridges
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Hi guys,

Right, i spoke to JL earlier and we are a bit confused with ND filters.

But what im looking for is a ND filter (not grad) that will let in as little light as possible for around £30.

So for i've seen... http://www.warehouseexpress.com/product/default.aspx?sku=1013506

But i am baffled by this... With a light intensity reduction of ten f-stops


JL explain a 3rd of a stop is one click of my canon 400d wheel, so 10 stops is 30 clicks

Is this the same with F-stops ??

For example what would a reduction of ten f-stops take me down to with a shutter speed of 1/100" ?

Thanks
 
TriggerHappy said:
A quick search on google brought this up http://www.photonhead.com/beginners/stops.php - a far more comprehensive explanation than I could manage!
Click to expand...

See I just dont get that at all :| lol - stops in general have always confused the jeebus out of me. I get fstops and I get underexposing by 'a stop' but really don't get how this relates to filters that stop say 10 stops of light :|
 
Using 1/125 as the original shutter speed the following are the differences a stop would make:
Original 1/125 s
1 stop - 1/60 s
2 stops - 1/30 s
3 stops - 1/15 s
4 stops - 1/8 s
5 stops - 1/4 s
6 stops - 1/2 s
7 stops - 1 s
8 stops - 2 s
9 stops - 4 s
10 stops - 8s

As you can see one stop either way is either double or half. The same is true of aperture and ISO values.
 
Approximately 10 seconds
Click to expand...

No way!

"its principal field of application is the observation and documentation of industrial processes with extreme brightness, such as steel furnaces, incinerators, glowing filaments in halogen- and other bulbs". Thats a ND x1000, in daylight it's gonna be shutter speeds in minutes not seconds.
 
Jimmy_Lemon said:
See I just dont get that at all :| lol - stops in general have always confused the jeebus out of me. I get fstops and I get underexposing by 'a stop' but really don't get how this relates to filters that stop say 10 stops of light :|
Click to expand...

If you increase exposure by 1 stop you double the total light coming in.

This is comparable to increasing the f-stop by a whole stop (multiplying by 1.4) as this doubles the amount of time let through per unit of time.

Similarly doubling the shutter speed increases exposure by a stop as you still get the same light per unit time (aperture) but for twice as long


Sarin said:
No way!

"its principal field of application is the observation and documentation of industrial processes with extreme brightness, such as steel furnaces, incinerators, glowing filaments in halogen- and other bulbs". Thats a ND x1000, in daylight it's gonna be shutter speeds in minutes not seconds.
Click to expand...

Way!

In the example it was initially 1/125, multiply by 1000 gives 1000/125, which equals 8seconds

A 10 stop filter actually lets through 1/1024 the amount of light that without the filter to be pedantic
 
Uneducated_Rick said:
If you increase exposure by 1 stop you double the total light coming in.

This is comparable to increasing the f-stop by a whole stop (multiplying by 1.4) as this doubles the amount of time let through per unit of time.

Similarly doubling the shutter speed increases exposure by a stop as you still get the same light per unit time (aperture) but for twice as long




Way!

In the example it was initially 1/125, multiply by 1000 gives 1000/125, which equals 8seconds

A 10 stop filter actually lets through 1/1024 the amount of light that without the filter to be pedantic
Click to expand...

Try it, just black photos! The figures might seem correct but the reality isn't.
 
Jimmy_Lemon said:
See I just dont get that at all :| lol - stops in general have always confused the jeebus out of me. I get fstops and I get underexposing by 'a stop' but really don't get how this relates to filters that stop say 10 stops of light :|
Click to expand...

A "stop" is a doubling in the intensity of the light. Light Value/Exposure Value might be a better way of looking at it.

Look at the table here:
http://www.chem.helsinki.fi/~toomas/photo/ev.html

EV 12 to EV 13 is + 1 stop. EV 15 to EV 5 is - 10 stops. Got it? Increase aperture by one stop and decrease shutter speed by one stop and EV stays the same.

Shutter speed doubles every stop, ISO doubles every stop, ND grads are funny because different manufacturers use different naming systems, aperture goes up by a multiple of the square root of 2 every stop.

For aperture:
1*(sqrt(2)^0) = 1
1*(sqrt(2)^1) = 1.4
1*(sqrt(2)^2) = 2
1*(sqrt(2)^3) = 2.8
etc. You can work out fractions of stops the same way
1*(sqrt(2)^(5/3)) = 1.8, so f/1.8 is a 3rd of stop faster than f/2.

Aperture numbers are approximate, there's quite a bit of rounding off involved.

EV 0 is 1 second at f/1 at ISO 100.
 
Can't post the photo but...

EXIF:

Exposure: 305
Aperture: f/25.0
Focal Length: 23 mm
Exposure: +0.70
ISO Speed: 100
Exposure Bias: 0 EV

305 seconds - 5 mins 5 seconds @ f/25
 
That is your real life example - what was the shutterspeed without the filter?

If it wasn't 1/100 or close to it then it doesn't prove a lot for the example asked above
 
Couldn't tell you the shutter speed without the filter, it was a while ago. It was 09:43 on a bright but overcast day thats about all i can tell you. All i know is that whenever i've used them it's on bulb and counting in minutes. It may well be 10 seconds if you're photographing extremely bright things like the description of the filter says it's used for but for general daylight conditions it's time for a snooze before the shutter clicks the second time!
 
Uneducated_Rick said:
It may well be that the op isn't using an aperture of f/25 hence the much shorter shutter speed
Click to expand...

True but i suspect that he won't be photographing furnaces or incinerators either? Either way, this filter is a specialist bit of kit that won't see the light very often - no pun intended:lol::lol::lol:
 
Sarin said:
True but i suspect that he won't be photographing furnaces or incinerators either? Either way, this filter is a specialist bit of kit that won't see the light very often - no pun intended:lol::lol::lol:
Click to expand...

Well the OP does state
davidbridges said:
But what im looking for is a ND filter (not grad) that will let in as little light as possible for around £30.
Click to expand...
so it appears that this could be precisely what they need.
 
Sarin said:
Can't post the photo but...

EXIF:

Exposure: 305
Aperture: f/25.0
Focal Length: 23 mm
Exposure: +0.70
ISO Speed: 100
Exposure Bias: 0 EV

305 seconds - 5 mins 5 seconds @ f/25
Click to expand...



No wonder you cant post the photo cos its my bloody photo you theiving scum! Thought i reconised the Exif data, jeez what next???
 
Sarin said:
Couldn't tell you the shutter speed without the filter, it was a while ago. It was 09:43 on a bright but overcast day thats about all i can tell you. All i know is that whenever i've used them it's on bulb and counting in minutes. It may well be 10 seconds if you're photographing extremely bright things like the description of the filter says it's used for but for general daylight conditions it's time for a snooze before the shutter clicks the second time!
Click to expand...

How do you know so much when you didnt take the picture??? Think you should apologise for making up that you were taking the photos simon.
 
Think you should apologise for making up that you were taking the photos
Click to expand...

I didn't say that i took the photo.

yeah and it aint his picture.
Click to expand...

I didn't say that it was my picture.

How do you know so much when you didnt take the picture???
Click to expand...

The exif data was a big giveaway.

One thing i cant stand is people lying.
Click to expand...

I've not lied. I never stated that it was my picture. All i have done is stated my experiences with this type of filter! I tend to trust what my mates tell me.

Slamming your mates on a public board - morally questionable?
 
Sarin said:
I didn't say that i took the photo.



I didn't say that it was my picture.



The exif data was a big giveaway.



I've not lied. I never stated that it was my picture. All i have done is stated my experiences with this type of filter! I tend to trust what my mates tell me.

Slamming your mates on a public board - morally questionable?
Click to expand...

It certainly read to me like you were claiming to have taken the photo... :nono:

Either way, you could at least retract the rubbish you posted about ND filter factors.
 
When I was aksing about using a 10 stop (3.0) full ND filter the most useful info I was provided with was the difference in the metering with and without filter on

Unfiltered meter Filter in place

1/8000: 1/8s
1/4000: 1/4s
1/2000: 1/2s
1/1000: 1s
1/500: 2s
1/250: 4s
1/125: 8
1/60: 15s
1/30: 30s
1/15: 1min
1/8: 2mins
¼: 4mins
½: 8mins
1s: 16mins
2s: 32mins
4s: 1hr 4mins
8s: 2hrs 8mins
15s: 4hrs 16mins
30s: 8hrs 32mins

Hope that helps?
 
Best way with a really dark ND filter is to shoot a test pic and take a look at the histogram.

Some ND filters also give a very slight colour cast, which of course you can get rid of in post processing. But if you want to get it right straight out of the camera, you can dial it out with the white balance. Do some tests with custom white balance adjustment. If it's quite a strong orangey cast, setting tungsten white balance will fix it but that's often too much for most ND filters as you only need a tweak.
 
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