Filter advice

[KWB]

Does anyone have any experience with filters?

I've got a Sigma 5omm prime lens on my D90 and whilst i love it in low light it has a tendancy to suck in too much light (and therefore over expose) at wide apertures in bright conditions. It's not always practical to up the shutter speed so i quite often find myself putting in a fair bit of exposure compensation to get a decent exposure.

I'm thinking of getting a Hoya HMC ND X2 filter so i can stop it down a bit further - does this sound sensible or does anyone have any advice they can offer?

Cheers,

Kev

[TimKelly]

If you can't get a fast enough shutter speed to counteract the wide aperture then a ND filter will help. I think a 2x filter would only give you one stop of exposure reduction.

This mania with shooting wide open is a bit daft though. If you camera goes to 1/4000 or so, and you've got the ISO rating down to it's lowest setting (100 or less), then stop the lens down to F4 or 5.6 to get the correct exposure. If you really must have the background even softer use photoshop!

A polarising filter will give you 2-3 stops of light reduction, as well as some nicer saturation features, but you have to adjust it for each picture, and after the lens has focussed if the front element turns during focussing.

[winkler]

Are you shooting RAW Kev?

Using ND Grads ( Neutral Density Graduated) is the norm for split exposure shots, even when pp can make things better it is preferable to get the shot good in camera.
I'm not familiar with the Hoya's that you mention but, guessing the 50mm Sigma is a 67mm thread? A cokin P series holder with a couple of 1&2 stop soft grads will help. It will take a bit more time to set up but "no pain, no gain"... Or, if using a tripod, and hdr image, 3 exposures into Photomatix Pro..

Cokin are here:
http://www.cokin.co.uk/pages/main.htm

A good cheaper alternative to Lee filters..

[Les_Paul]

Does anyone have any experience with filters?

I've got a Sigma 5omm prime lens on my D90 and whilst i love it in low light it has a tendancy to suck in too much light (and therefore over expose) at wide apertures in bright conditions. It's not always practical to up the shutter speed so i quite often find myself putting in a fair bit of exposure compensation to get a decent exposure.

I'm thinking of getting a Hoya HMC ND X2 filter so i can stop it down a bit further - does this sound sensible or does anyone have any advice they can offer?

Cheers,

Kev

What kind of shots are you trying to achieve? Sounds like you are working in manual mode selecting a wide aperture and a low shutter speed. In bright conditions it will overexpose in that condition so if you can give an example of the shot your trying to get, moving target, portrait or blurred background etc it will give us a better idea how to solve it with correct exposure.

[KWB]

Thanks guys,

I can get a decent exposure given the time but i mainly shoot candid portraits so i tend to need to fire off quick shots as i see the chance arise. Bracketing doesn't seem to have enough effect when there's a lot of light.

I was thinking that a polarising or ND filter would give me a more reliable start point to work from.

Tim - i rarely ever shoot wide open, i'm talking anything below f3.2. For the candid stuff shooting wide works really well for me.

Les_Paul - thanks for the advice in an earlier thread about the 16-85, i picked one up last month and really like it!

[TimKelly]

If you put the camera in aperture priority mode (AV?) it should take care of the exposure for you. Most cameras have a shutter speed of about 1/4000 or less which should allow you to shoot with a fairly wide aperture on all but the brightest days with the sensitivity set to 100 iso or lower.

I'm struggling to see where you're having the problem a bit?

[Les_Paul]

Seems your on the right track but as Tim mentions if you work in aperture mode the shutter speed will adjust accordingly so exposure should be on the mark. As you are shooting candids wide your shutter speed in bright conditions will be pretty fast easily stopping the action and providing good bokeh. There must be something else going on. A couple of things.

1/ Is the 50mm Sigma a 1.4 ? If so in bright conditions it may be flaring giving you an issue. has it got a lens hood? I recommend always keeping the lens hood in place to prevent flaring and give added protection.

2/ Do you have a clear / skylight / UV filter in place already? These filters in certain light can also cause ghosting or flaring.

3/ Check exif data, possibly you may have inadvertently added exposure? If you can cut and paste the exif then can you post it here with an example as this will help find a solution.

4/ Is the D90s active D lighting set to on? If so kill it because it will automatically attempt to lighten the shadows and probably skew the highlights.

5/ Did you select spot metering? If so the central area will expose OK but in bright conditions the outside areas may easily blow. Centre weighted metering works well for portraits.

6/ Does this happen with your 16-85? ( Rule out a camera fault ) possibly a fault with the lens?

7/ If you shoot raw you can adjust exposure in PP without too much of a hit, and also reduce blown highlights selectively. That might save a pic but you still need to get to the bottom of what is going on.

If you have a raw file handy where it happened I can run it through NX2 and see what has happened and what the answer is.

[MartinJ]

I had problems with over exposure and found the problem to be option 5/ below.
Your spot metre has 3 settings 6, 8 or 10mm, mine was set to 6mm. When I changed it to 10mm it made a big difference.

My Active D setting is on Auto and I'm not getting any problems

Seems your on the right track but as Tim mentions if you work in aperture mode the shutter speed will adjust accordingly so exposure should be on the mark. As you are shooting candids wide your shutter speed in bright conditions will be pretty fast easily stopping the action and providing good bokeh. There must be something else going on. A couple of things.

1/ Is the 50mm Sigma a 1.4 ? If so in bright conditions it may be flaring giving you an issue. has it got a lens hood? I recommend always keeping the lens hood in place to prevent flaring and give added protection.

2/ Do you have a clear / skylight / UV filter in place already? These filters in certain light can also cause ghosting or flaring.

3/ Check exif data, possibly you may have inadvertently added exposure? If you can cut and paste the exif then can you post it here with an example as this will help find a solution.

4/ Is the D90s active D lighting set to on? If so kill it because it will automatically attempt to lighten the shadows and probably skew the highlights.

5/ Did you select spot metering? If so the central area will expose OK but in bright conditions the outside areas may easily blow. Centre weighted metering works well for portraits.

6/ Does this happen with your 16-85? ( Rule out a camera fault ) possibly a fault with the lens?

7/ If you shoot raw you can adjust exposure in PP without too much of a hit, and also reduce blown highlights selectively. That might save a pic but you still need to get to the bottom of what is going on.

If you have a raw file handy where it happened I can run it through NX2 and see what has happened and what the answer is.

[TimKelly]

Take the camera off spot metering! Unless you understand exactly what you're pointing it at you will get wildly variable results! A spot meter reading needs to be taken on a "mid grey" tonal area in the frame, so you have to be able to look at what you're photographing and take a meter reading on a mid toned area, or point the meter at what you're interested in and then compensate for the bit you're pointing it at to get the tonal range you want it to be. Cameras have very sophisticated multi zone meter programs now which are very much more successful than the old centre weighted styles that used to be common and you should be able to rely on the standard matrix or whatever they call it setting for 90% of the stuff you do.

[winkler]

Any improvement Kev?

I assumed that you were struggling with landscapes, but since rereading it may be in general? Do you check the histogram to see what's going on? As Tim said, spot metering could be a reason, check which is being used ..

Let us know how you get on anyway..

[KWB]

Thanks again guys,

O.k, some progress - i had a bit of a play around at the weekend and the active D lighting seems to be playing a part, i've switched it off and it seems to help. Also spot metering was also partly to blame, i've gone to matrix and it all seems o.k. (I must have left it on spot whilst trying a few different shots).

It wasn't a problem i was getting a lot but it was a bit annoying when it did happen, I guess at a shallower depth of field the out of focus areas where being blown by a combination of the above.

Cheers,

Kev