Trying to understand the Widelux filters ... Help!!!

[Keith]

Being lucky enough to have the filter set is one thing but understanding them all is another it seems.

There's a UV which even I can understand but then it gets harder. There's an ND which has a '4' marked on the back which makes little sense to me because checking with my light meter it appears to block out two stops of light. The others are blue, yellow, light orange and dark orange. The blue, yellow and light orange appear to make little difference in terms of EV when checking with a meter but the dark orange one appears to be worth a stop but has a '6' marked on the back?

Here's what there is in the set:

UV ... has '0' on the back.
W2 ... has '1.2' on the back. (light orange)
Y2 ... has '2' on the back. (yellow)
C4 ... has '1.5' on the back. (blue)
YA2 ... has '6' on the back. (dark orange)
ND ... has '4' on the back (but only appears to be two stops?)

What I'm really not getting here is the relationship between the ID that tells you what the filter is and the number on the rear. Considering I've never used a filter in my life I'm at a bit of a loss as to why I actually need to know this! 😛

 

[raid]

It may be extended exposure.
A 4 implies using an exposure that is four times as long. Same as two stops.
I am guessing, Keith.

 

[Keith]

It may be extended exposure.
A 4 implies using an exposure that is four times as long. Same as two stops.
I am guessing, Keith.

That makes sense Raid and after looking at how filter factors relate to exposure I can see that an ND with a factor of 4 will be two stops.

The '6' on the orange filter really puzzles me though because that would have to be three stops ... can this be right?

 

[kena]

Widelux Filter explanation

Widelux Filter explanation

You may find this helpful-

 

[Keith]

You may find this helpful-

Ahh ...thanks for that, really helpful. I searched the net for something like this and came up blank. 🙂

 

[rpsawin]

Keith,

My B+W Orange filter has a filter factor of 6 and that equates to a 2.5 stop reduction. Hope that helps...

 

[Keith]

Keith,

My B+W Orange filter has a filter factor of 6 and that equates to a 2.5 stop reduction. Hope that helps...

OK ... so it is what it says! It just seemed like a lot for an orange filter to me.

But what would I know? 😀

 

[mfogiel]

The filter factors are referring to the linear multiplication of exposure time, so:
1 = same
1.5 = 50% longer = half a stop
2= twice as long = one stop
3= three times longer = one and a half stops
4= four times longer = two stops
6= six times longer = two and a half stops
8= eight times longer = three stops

 

[Monz]

Hi Keith,
The ND is the most useful filter given the fastest shutter speed of 1/250.
I have a flickr buddy who has taken his two least used filters and replaced the glass with a +0.5 and +1.0 dioptre lenses respectively. This allows him to get in closer to the subject (the default focus distance of the swing lens is 11 feet).

 

[Keith]

Hi Keith,
The ND is the most useful filter given the fastest shutter speed of 1/250.
I have a flickr buddy who has taken his two least used filters and replaced the glass with a +0.5 and +1.0 dioptre lenses respectively. This allows him to get in closer to the subject (the default focus distance of the swing lens is 11 feet).

I saw that when I was searching for info ... damned clever! 🙂

And the ND is the useful one ... nice to go out with 400 film and know you're not going to have to overexpose it on a bright day.

 

[raid]

The filter factors are referring to the linear multiplication of exposure time, so:
1 = same
1.5 = 50% longer = half a stop
2= twice as long = one stop
3= three times longer = one and a half stops
4= four times longer = two stops
6= six times longer = two and a half stops
8= eight times longer = three stops

So it is what I suggested above. 😀