photographic filters Archives - Laughing Frog Images

It’s the filter, stupid!

Posted on July 21, 2015July 19, 2015 by Kurt

So, when I packed the camera bag for vacation, I grabbed an old polarizing filter. By old, I mean “linear”. But it’s also 30+ years old. (Does that make it old old?

(Hint: if you’re buying a filter, buy the best filter you can afford. They don’t go bad. Indeed, they usually meet their maker by being dropped. Or being sat on and bent. Not that I know anything about that – I’ve just heard… Seriously though, if a filter’s price seems too good to be true, it probably is.)

Anyway, what’s the big deal about a linear polarizing filter? Well, linear filters were just fine back in the days when autofocus cameras were a fantasy and Kodachrome ruled. You rotated the filter to get your desired effect, pressed the shutter release, and went on about your business.

These days, with autofocus cameras, one needs to think and buy a circular polarizing filters Why? Your contemporary autofocus – autoexposure camera’s meter likes circular polarizers. It’s all about physics, and I’m not a physicist, so I’m not even going to try to explain it here. However, Bob Atkins does a pretty good job of explaining things, so if my word isn’t good enough, you can click here and read his article about linear and circular polarizing filters.

So why am I talking about this and why are you reading this? Well, there’s one other problem that you can have besides the meter producing bad exposures, and I encountered it.

If this image looks fuzzy, it’s not you.

On the other hand, if this image looks in focus, it’s you! Please visit your eye care professional immediately.

So… what’s going on here?

A linear polarizer can confuse a multi-point autofocus system, and this is proof positive of that.

I was shooting using the linear polarizing filter to remove glare on the water without a problem, perhaps because the sun was behind me. However, I found my camera not focusing on two subjects the next day in situations where the sun was at a 60-90 degree angle to me. Being totally relaxed on vacation, I didn’t think about the filter being the problem. Instead, I was annoyed / mad / worried thinking my lens had decided to break. I tuned the camera off, removed the lens, put the lens back on, turned the camera on, and same problem….! After repeating that twice (which usually resets everything), I’d given up on the lens for the rest of the trip.

The Frog was not laughing.

And then, later in the day, I looked at the lens. And saw the filter. And realized that I’d had that filter since the early 1980’s…

I took the filter off. I turned the camera on. It focused.

And, I said to myself, “it’s the filter, stupid…!”

If you’re interested in learning more about what a polarizing filter can do for you, click here and here to visit two prior posts on the subject.

Don’t forget to visit your local camera store when you go to get your polarizing filter!

Polarizing Filters, Part 2

Posted on February 25, 2015February 22, 2015 by Kurt

A long time ago in the blog, and far, far away… we talked a bit about polarizing filters and the technical details of how they work.

Well, it might have only been a few months, but that sounded like a good opening!

Anyway, we talked about polarizing filters and how they can help with glare, but we didn’t show you anything about them in the blog.

The least we could have done was to have shown you how they work right here in the blog! We’re going to fix that transgression compliments of back lighting and a koi pond.

First up, here’s what happens if you try to take the picture in these conditions without a polarizing filter:

[Nikon D5100, 60mm f2.8 lens, ISO 400, 1/200 sec., f4.5, no filter.]

Not so hot, eh?

So, let’s see what happens when you use your polarizing filter – this is the next image I shot:

[Nikon D5100, 60mm f2.8 lens, ISO 400, 1/200 sec., f2.8, polarizing filter – notice that I lost a stop on the exposure due to the polarizing filter.]

Impressive, isn’t it? If you’ve never seen this demonstration before, you might say it’s amazing. The technical details are found here.

I don’t claim to fully understand everything about the physics behind a polarizing filter – I just know that they work, and can help you get an image you couldn’t otherwise get.

If you can get your hands on one, they’re a great addition to your camera bag.

Polarizing Filters

Posted on September 22, 2014September 21, 2014 by Kurt

I was asked about polarizing filters recently. I usually have one with me when I travel. By usually, I mean that it’s usually in my bag except when I really need it, but that’s another story…

Polarizing filters can do some great things – reduce or eliminate glare, enhance colors, and manage reflections. If you want more on the how and why of a polarizing filter, click here.

So, when would you want to have a polarizing filter with you?

Here’s a list to consider:

Taking a bus or train or plane trip where you’ll be shooting through windows.
Shooting shiny or glossy objects in bright sunshine or under bright lights.
Heading to the beach.
Shooting things on or in the water.
Photographing colorful things like fall foliage on a cloudy/hazy day.
When you’re going to have to deal with reflections on a glass/clear/glossy surface.
When you’re shooting in stark sunlight or mid-day.

In other words, they’re not a bad thing to have in your bag. All of the time…

One thing to remember is that any time you have a filter on your lens, there’s a chance for internal reflections between the surface of the filter and the lens. These reflections can be good – or they can ruin a shot.

The photo below shows a polarizing filter used to help bring out the colors on a gray day, and it shows an unintended “star” effect from the filter. In this case, the star effect on the headlight and ditch lights arguably helps make this picture. It wasn’t something I set out to do – but it works in this case.

I had to take a breath and a step back, because I wasn’t happy with this as a “train” picture. For most people, it seems that this is a fall foliage picture that happens to have a train in it, and the star effect adds to the picture. The law of Unintended Consequences reinforces the fact that we all see different things in the same picture.

For more examples of a polarizing filter used to enhance fall colors (that would look great on your wall, or on a mug), check out this gallery on Laughing Frog Images.

If you’re interested in getting a polarizing filter for your camera bag, start with your local camera store! Without your patronage, we won’t have them – and we need small businesses like them!

Happy shooting!

Your friend the Neutral Density Filter

Posted on September 18, 2014September 21, 2014 by Kurt

Ever wonder how a photographer made an image in which the water flows like smooth liquid? And the image was made during the day? And you’ve tried – but you can’t do the same thing!

Well, it’s time to meet your new friend the neutral density filter.

What’s a neutral density filter? Well, in really simple terms, it eats light. Well, not really, but what it does is cut down on the amount of light that ultimately gets to your image sensor or film. Or, you can simply just say it eats light. This allows you to increase your shutter speed to get that flowing effect and to increase your depth of field to get more detail in your image. If you want all of the technical info – check out this link to Wikipedia for all the tech stuff.

In order to use a neutral density filter, your camera at least needs (1) the ability to mount a filter and (2) a “M” [manual], “A” [aperture] or “S” [shutter speed] setting so you can adjust things. And, there are a couple of other things that you’ll need that are really, really, really, important: (3) a tripod, and (4) a remote control or a remote/cable release. (Nobody is that steady….) If your camera can’t take a remote control or a remote/cable release and it has a self-timer, you’re in business – use the self-timer in place of the remote control or remote/cable release.

Does a ND filter work on the Automatic (a.k.a. “idiot-proof”) setting? Honestly, I don’t know, as I’ve never tried that – but I don’t see why it wouldn’t, at least from a process standpoint. I’ve always sought to get the longest possible shutter speed in conjunction with the highest (smallest) aperture I can when using a neutral density filter and used “M” or “S”. If anyone out there has the answer to this question – let us know!

If you’re curious, the Frog has the following ND filters: 0.3, 0.6, 0.9 and 1.8 in various sizes. You can stack them to increase the effect, but image quality may be compromised. In general, the fewer things you have on the front of your lens, the better. I tend to limit the number of things on the front of my lens to exactly one (1). If you’re shooting with a DSLR or an advanced hybrid and wanted to get just one – I’d go for a 0.9 at minimum.

I have a 62mm variable ND filter for when I’m traveling light with just my 18-270mm Tamron, but I have yet to use it. Some love them, and some hate them. I’ll let you know what I think when I finally get a chance to use mine.

The image below of the Merced River as it flows east out of the Yosemite Valley was taken at 5:45PM. Without the neutral density filter, this would have been impossible. However, with the 1.8 neutral density filter and an ISO of 100, it was possible to take a 10-second exposure at f29 to get the resulting image. (Hint: it looks great as a metal print! Or a print on Fuji Pearl paper!) The camera was a Nikon D5100, and the lens a Sigma 70-200mm f2.8. I had the big tripod along for the trip (the “Mother Pod”) as this is a heavy lens, and used a cable release.

These critters aren’t necessarily cheap. If you’re going to get a neutral density filter, get the best one you can afford. While you may not need the most expensive one out there, if there’s a significant price difference – go to your local camera store and/or read the reviews and consider the comments. If the price is too good to be true, it probably is. And… if your filter has a flaw, so will your image.

This image can be found in the Laughing Frog Images’ galleries by simply clicking here. It would look great on your wall. Or on your water bottle. Or on your coffee mug. Well, it’d probably look great however you’d like to get it!

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