Exposure with Grad filters,

[Graeme Buckland]

Could anyone help me here as I have a few of grad filters and I was wondering do you take your exposure before you place the grad filter into place? or do you take it after you have placed it down to where you want it.

[David Kembrey]

Hi Graeme, I tend to get the exposure with the filter already in place, not sure if thats the correct way of photographing with filters but seems to work for me

cheers

David

[Analog6]

Gut feeling says after as it is TTL metering on DSLRs. I'm going to experiment tonight as my (knockoff) Cokin filter rings arrrived and I have a Grad Tobacco filter to play with niow I can fit it to the camera.

[kiwi]

I would have though after, if you did first surely it would be underexposed

[ricktas]

I always do after! Get camers setup as you are will be using it, then look at settings/metering etc.

[Graeme Buckland]

Thanks, and I ment to include this question as well, to how do you find out what size grad you will need as in 3stop 6 or 8 stop I think thats the cokin range.

[ricktas]

i just visually judge it more than anything. The brighter the sky, the more you need. I will use an ND2 for dawn, ND4 just as sun is rising and ND8 after sun has risen. If particularly bright I will stack the ND8, with the 2 or 4 as well.

[Graeme Buckland]

Thanks Rick

[arthurking83]

I do what's appropriate.

sometimes you may have to take a reading and then compensate for an amount that coincides with your filter. If the light levels are already low and you can't get a reading already then placing any darkening filter is not going to help this happened to me the other night and all I did was to set the meter for where I wanted to expose, and then compensate by three stops to allow for the darkening effect when I metered for the darkened part.

if you spot meter, it really depends on where you meter(within the frame).
So if you're using a GND and spot at the lower part of the image, where it's using the clear section of the filter you may lose 1/3rd of a stop of light, and hence be underexposed in that part by 1/3rd, if you meter before placing the filter over the lens.

As everyone has already said though do your metering with the filter on.

I don't normally use Matrix metering(or full scene metering, or whatever Canon call it), so I can't remember, on those occasions when I have used Matrix what I did.

[bigdazzler]

My understanding is the textbook way to meter for grads is to take a reading from the sky, then a second reading from the foreground, calculate the difference and choose the appropriate grade filter (or closest too) that you have for the job. eg. 3 stops difference in light between sky and foreground, choose a GND8, put it on, meter just below the horizon and shoot away.

[IanB]

i just visually judge it more than anything. The brighter the sky, the more you need. I will use an ND2 for dawn, ND4 just as sun is rising and ND8 after sun has risen. If particularly bright I will stack the ND8, with the 2 or 4 as well.

Rick, do you find it easier; or, is it better to use filters rather then use adjustments in PS or LR.??

[ricktas]

Rick, do you find it easier; or, is it better to use filters rather then use adjustments in PS or LR.??

hmmm. I could write a Tannin length reply to this one!!

Firstly PS and LR will only let you recover so much detail, in both highlights and shadows, so they are worthwhile tools but they have their limitations. If you adjust to much you will notice a lot of noise creeping into the result, especially from darker shadow areas. However the current sensor tech has certainly improved what can be effectively recovered. I can get a lot more leniency out of my D3 sensor than I can from by D200 sensor.

But used well, under the right circumstances, your results will be good.

Filters on the camera, easier? Well carting them with you, screwing them on, working out which ones to use, making sure they are clean, aligning them to your scene. It all takes time and I would say doing it in PP is definitely easier. BUT, the end result is worth it. You can balance the exposure between sky and land at the time of taking the photo, and then if you want to do any more adjusting in PP, you have either less to do (see comments in paragraph above about over-adjusting) and it gives you space to make larger adjustments without experiencing noise issues, cause you started with a well balanced exposure in the first place.

And even today, they cannot replicate a true Polariser effect in PP. Some do a reasonable job, ie they manage to make the skies look bluer, but they certainly haven't achieved the removal of glare on water etc, so the use of a polariser is something that can only be done (properly) by using the filter on the lens at the time of taking the photo.

If you want to have a look at a good set of PP filters, have a look at Nik Software's Color Efex Pro 3 (download the 15 day trial). They have ND and NDGrad filters in the set, that can do quite a surprisingly good job of replicating these filters. But I still prefer to do it in the field.

Sometimes though you lack time. You might look out the window at home one evening and think..hmm..that sky is getting interesting, grab your gear and bolt for the nearest sunset 'spot', You get there just as the sky becomes 'perfect'. Now getting out the tripod., mounting the camera, attaching the filter holder, finding the filters you want to use, mounting them, adjust the grad so its in the right spot in your viewfinder to balance the scene, takes time, and time is something you do not have right NOW. So using the PP method to get a nicely balanced exposure can be a godsend at times, Hell, I even use it (notice I managed to get God and Hell in one sentence..woohoo).

So in the end, i would use the filters over the PP method, but the PP method can be a useful tool.

(Tannin would be happy with the length of this reply..No?)

[IanB]

(Tannin would be happy with the length of this reply..No?)

Will I'm impressed with if; thanks for all that Rick; sort of as I expected. I think digital tends to make us lazy photographers if we are not careful; there have been times lately I have upped the ISO instead of using a tripod and the same goes for filters; only have a poly and ND (never used) for the Canon lens. Will check out the filter link.

Cheers

PS Your reply would take me half a day to write and check and recheck and recheck

[bigdazzler]

At the risk of statin the obvious, the key to using grads successfully is get there early and be ready .. of course, things occur and that cant always happen, but if youre well prepared, 99 ties out of 100 your pictures will be better ..

[arthurking83]

.... if you're well prepared, 99 times out of 100 your pictures will be better ..

agree 101%


Ian: the difference between using real filters as opposed to using virtual filters is that with real filters you are balancing exposure, whereas with virtual filters you are compensating for a lack of balance.

The difference will be obvious mainly if your print sizes are large, or you're simply pedantic and prefer to capture the best possible data in the image in the first place.

Filters can't recapture the colour information once the detail has been lost.

They are not the same thing. The alternative to using real filters is not actually virtual filters via software, but HDR.
Of course there are situations where using real filters is not possible(or more correctly... not ideal!).