Help! Trying to learn how to use ND Filters!

[twilner]

Hi there!

So I received my dream camera for Christmas, a Canon Rebel EOS XSi and have two lenses for it. I recently spent some time online looking at different ND Filters and ended up purchasing a multi-layered UV protector filter by Hoya as well as a 0.9 (8X) ND Filter.

I bought these and they're certainly great but I can't seem to get anything in focus with them. All of my photos I've been taking have been coming out all fuzzy. Mainly I've been using the 8x filter, I've been practicing long exposure shots.

I've been reading online. Should I not be ever using autofocus with this filter on? I'm trying to use less and less of it anyway so maybe this is a good time to stop altogether?

Any help or information regarding these filters and how they work or the measurements for that matter (i.e. what does .9 or 8x even mean?) would be awesome!!

Thanks!

[Digidave]

Any help or information regarding these filters and how they work or the measurements for that matter (i.e. what does .9 or 8x even mean?) would be awesome!!

The Hoya 0.9 (8x) filter is a 3 stop filter. Let's say you were getting proper exposure at f/8 & 1/500sec.. When you put the filter on you would either adjust your aperture to f/2.8(that's 3 stops) or decrease your shutter speed to 1/60sec. to get the equivalent exposure.

If you have a higher quality lens you shouldn't have to much trouble with focusing. If you have a lower quality lens it may have a hard time finding the proper focus. When people use the darker ND filters, like say a 9 or 10 stop filter, they will absolutely turn autofocus off. Then they would focus on their subject, put the filter on, & then take the shot. This may be what you need to do.

Hope this clears things up a bit for you.

[availablelight]

Originally Posted by twilner

Hi there!

So I received my dream camera for Christmas, a Canon Rebel EOS XSi and have two lenses for it. I recently spent some time online looking at different ND Filters and ended up purchasing a multi-layered UV protector filter by Hoya as well as a 0.9 (8X) ND Filter.

I bought these and they're certainly great but I can't seem to get anything in focus with them. All of my photos I've been taking have been coming out all fuzzy. Mainly I've been using the 8x filter, I've been practicing long exposure shots.

I've been reading online. Should I not be ever using autofocus with this filter on? I'm trying to use less and less of it anyway so maybe this is a good time to stop altogether?

Any help or information regarding these filters and how they work or the measurements for that matter (i.e. what does .9 or 8x even mean?) would be awesome!!

Thanks!

maybe you could post some examples of shots with and without the filters... Stacking lots of filters can make a difference to image quality, but one on its own shouldn't make a lot of difference, although your AF may be getting affected by the ND8.

Try it with manual focus and see if you can get sharp images, if you can't it may be your lens just isn't up to the kind of treatment, in which case, go back to the same water, stream or ocean just after the sun has gone down and take the shots you aspire to without a filter...

best wishes, Alister

[inkista]

Just checking, but are you sure the fuzziness is from misfocus, and not from camera shake blur or subject motion blur? With long exposures (with an unstabilized lens, for me, this would be anything slower than 1/30s), you need some form of stabilization, like a tripod, not to have camera shake blur fuzzing up the works. And with a longer lens, this shutter speed requirement becomes higher (1/focal_length is the usual rule of thumb, so if you were shooting with a 200mm lens, you'd need to be at 1/200s or faster to safely handhold).

Whenever I use my 10-stop ND filter, I've got my camera on a tripod, and I'm usually using a cable release and mirror lock-up.

[twilner]

Thanks all for the advice all! I took my camera out this morning and tried some shots. I didn't seem to be having quite as much problem with blur, I tried manual focus in combination with Liveview mode 10x zoom to focus. This seemed to help quite a bit although still not as sharp as I would hope. Thanks Avail for that!

The other problem I've encountered is that the photos are coming out really overexposed. I guess there is probably not anything I can do about that other than get a faster shutterspeed, I maxed out aperture, and I don't really want to bump up the ISO because it will look all grainy. But I might be wrong there..

Anyway. If you guys could take a look any feedback would be great! Thanks again!

IMG_1382 on Flickr - Photo Sharing!
IMG_1376 on Flickr - Photo Sharing!
IMG_1375 on Flickr - Photo Sharing!

Inkista, I have been using a tripod so I don't think it's motion blur, but thanks for the advice anyway, I'll keep in mind that shutter speed tidbit!

Also, for future reference should I post directly on forum with photos or is Flickr better? Thanks

[kirbinster]

My autofocus works fine with my 10 Stop ND filter.

[Digidave]

My autofocus works fine with my 10 Stop ND filter.

I have yet to use ND filter so i can't speak from experience. Which lens are we talking about here. Good quality?

twilner: If you want to take shots in broad daylight at 10 seconds, you're going to need something like a 8-10 stop filter. Your apertures on those shots were f/32 & f/36. That's way farther than you should be going. If you put your camera in Manual mode instead of Shutter priority you could have easily brought your aperture down to f/22 which would help. That would be 1 stop darker exposure. An 8 stop filter would take your aperture from f/32 down to f/5.6. Much more reasonable value.

[kirbinster]

This photo was taken with my Nikon D90 and Nikon 24-70 f/2.8 lens with a 10 stop ND filter using autofocus with the following settings:

Exposure: 10
Aperture: f/7.1
Focal Length: 62 mm
ISO Speed: 200

[inkista]

Yes, you have to go for a faster shutter speed. You're as low as you can go on the iso, and as low as you can go on the aperture. What you probably really should be doing, if you desperately want that 8s shutter speed is to stack another ND filter on top. Your 8x filter, btw, is NOT an eight-stop filter, it's only three stops. 2³ = 8. [linky] So, if you meter without the ND lens, all you can do is multiply the shutter speed you get that way by a factor of eight when you stick the ND filter on. In bright sunshine, you simply aren't going to reach seconds-long shutter speeds without something more like a 9 or 10 stop filter.

To me, it looks like you had a very sunny day. By the sunny-16 rule, iso 100, f/16, you'd have a good shutter speed of 1/100s. Slapping a three-stop filter on, and stopping down to f/22, you'd be able to get four stops (2⁴ = 16), or 16x the shutter speed, which would still only be 1/6s.

And, as digidave points out, you're using aperture settings that are small enough to get diffraction effect to noticeably reduce your sharpness.

[wilswong]

After looking at the pictures I totally understand where is the issue. But first allow me to say something about Liveview.

Liveview - it is a much poorer cousin of the optical view but better than the EVF of the prosumer cameras. Never a fan of liveview as it is a sucker off your battery and also never helps that well with focusing. Optical is still the best and it forces you to close in on the camera and thus improve the stability of your shots. And optical view finder will confirm the focusing much better.

On to your shots.
- The issue will always be the snow since it will always reflect back sunlight so the picture will be extremely bright. So I don't find it necessary to up the ISO to the high heavens and should max out the aperture (even to F22 or more).
- EV compensate +1 as the camera will meter the snow and thinks that the picture is too bright and
- If you are on tripod, the shutter speed would be ok at high F settings and low S setting
- since the shutter speed is already slow, you would have that silky effect off the stream in the first place so there shouldn't be any need for the ND unless the sun and snow really cause havok to the metering.

In any case, my practice is to take out the UV and add in the ND. Reason is that two filters, more obstacles to light hence will affect image. Two filters will also cause the corners of the photo to be darkened.