Filters 'n Stuff

Filters come in a whole range of colours, styles and special effects. Photographers have used them for years to help alter the result of a photograph. For example, if you wanted to give a warm tone to a picture you could put a "warming filter" on the front of your lens. This can give the whole image a sort of orange glow and change the feel of the shot. Some cameras can now do this "in-camera" without the need of a filter.

The example I'm going to use in this post is what's called an ND-grad filter.

ND = neutral density which means that it should not put any additional colours in the shot as the filter is grey. But what it does do is cut out the amount of light reaching the lens. I've spoken about my ND10 before which cuts out 99.9% light allowing very long exposures even in bright conditions.

Grad = graduated, which means only half the filter is grey. The reason for this is that when shooting landscapes the sky is often brighter than the land. The ND grad filter blocks out some of the light from the sky but not the land and this balances the shot to allow for a better exposure of both foreground and sky.

This shot was taken today with the ND10 filter in place. It's straight out of camera with no photoshop work (except to make it a small file). The ND10 has allowed an 8 second exposure in the middle of the day and because of this the sea has flattened out and become smooth.

However, you can see how bright the sky is and there is not much detail there since it is over-exposed. I could shorten the exposure time but that might then make the rocks too dark.This is where the ND-grad filter comes in.

If we take the same shot again but with the ND-grad filter on the lens as well as the ND10 (filters can be stacked on top of each other to give multiple effects) you get a solution to the problem.

This is exactly the same shot, again without any tinkering in photoshop. Immediately, you can see how the sky has now been darkened to match the foreground. Quite a difference and certainly less trouble for the camera to distinguish between bright and dark areas.

Filters have been around for ages and although programs like photoshop can "fix" many digital pictures now it is still important to get the shot as correct as possible in-camera as that means less work afterwards.

Anyway, hope that gives you a bit of an insight into graduated filters. They are quite good fun especially the coloured ones but that's for another post.

A Trio of Pics

Ok, so there are tons of photo techniques and everyone has there likes and dislikes. Personally, I've had a thing for HDR for a while and now I'm keen to get the ND10 working a bit better. Actually, I think that the wide angle is the problem as it makes everything in the distance so small. Therefore clouds and distant hills etc seem tiny and this screws up the composition a bit.

Anyway, I thought you lot could decide what you like out of the three types of shots I would normally take.

First up is the "normal" shot. This was taken on a tripod on aperture priority at f10 and the camera chose to shoot at 1/50th of a sec. It was set on Matix exposure and you can see that it's done a not bad job of exposing everything quite well. However, it was still quite early in the morning and the sky was much brighter than the foreground and the detail in the rock is lost and even with fill light (in Adobe Camera Raw) I've not really been able to save the shadows. This can be a major issue with photography as I'm sure you might have noticed - shadows become silhouettes and bright parts of the photo can become almost white so all detail is lost in the highlight. You can manually "lock" your exposure when taking the picture in most DSLRs now using a button that says "AE-L" somewhere on the camera. Once you've focused on the main subject of the picture you can then press and hold the AE-L button to lock the exposure on that object and the camera will expose that correctly. Other options include using "spot metering" or "centre weighted metering" modes which will be in your manual. They are a bit tricky to use and if you've ever read Ken Rockwell's blog you'll know that he's a big advocate of just shooting in Matrix mode and nothing else. I guess it's the exposure version of "auto" mode.

Next up is the ND10 filter. This is a bit of black glass that blocks out 99.9% of light and therefore even in strong light you can coax the camera into keeping it's shutter for a really long time. This shot was a 30 second exposure. Over that length of time the movement in the water smooths out and the clouds can end up looking like they are streaming across the sky (not really happening in this one as they were moving too slowly). The other advantage of this style is that people and other moving objects disappear as they are not in the same place for long enough to register their photons on the sensor. Would you believe that a swan cruised past the front of this shot without leaving a trace. Cool eh? The main advantage of this type of filter is that it allows you to take long exposures and that gives you the sort of effect that you would get at night. However, at night time there isn't enough white light around to give good colour and that's when the ND10 comes into it's own. I'm still after that "special" shot with this filter but I'll keep at it.

Finally, my favorite, the HDR shot. High dynamic range is a real love-hate thing. Many of the photographers out there hate it and think that it's a cheats way to turn a badly exposed and poorly composed picture into something that has a real "wow" factor. I'm more and more tending to agree that HDR can be a cheap fix however lately I've seen more and more examples of HDR being pushed to the limit. People have started to ignore the purists and have mastered all aspects of traditional photography and then HDR has allowed them to add something to the shot that makes it fly out of the screen/frame at you.

Regardless what you think, it still has some advantages. This shot (compared to the other) has more detail in the shadows and it has also make the picture a bit more eye catching. I agree that this can sometime be horrid but I think the skill of HDR it to make it subtle in a way that the haters end up going, "Hey, that's a great shot... wait a minute! That's HDR. How dare you."

To each their own, I suppose. Anyway, hope you like seeing the difference in these shots and perhaps trying several versions of the same scene will help you decide what style you like.

Home Studio

So this shot here looks like one of those fancy brochure pictures but actually it's quite simple to do.

This is something that puzzled me for a while - how do you make the background and the table disappear from the shot? I'd tried loads of variations of curved paper and home made soft boxes but nothing gave the result I was looking for. I'd also played about with the exposure settings and various other software tweaks but I really wasn't getting anywhere. Then I spotted a picture of how this is carried out and gave it a shot. The answer? Well the glass is resting on a sheet of perspex with a white backdrop and various forms of lighting cause the "white" elements to fall away.

So here's a pic of my set up. Simple enough? It should be but B&Q don't seem to stock perspex so I used a sheet of glass from a picture frame. Gave the same effect but I wouldn't want to use it too often in case I dropped something on it and smashed it. The light for the shot comes from one flash set to slave mode and I was using the onboard flash as a commander unit (one major plus for Nikon over Canon which can't do this on most of their cameras). There is a reflector to bounce back some light and there is also a workman's light which is pretty cool as it'll clamp onto most things and most angles.

There are some issues with this set up, namely a white wall would be far better as there was lot of wrinkles in the sheet that showed up before processing. Also the lamp I have is only 120W and most studios use 400 - 500W lamps. An probably the most important issues is CLEAN THE GLASS!!! This glass was boggin' and I didn't notice it until I zoomed in on the pic. Then had to spend ages editing out my grubby finger prints etc.

So hope that gives you something to try with the camera indoors when it's raining outside - which is frequently the case in Scotland.

More Leading Lines

This post is just a quick follow on from the previous "Leading Lines" post. In all honesty I just really wanted to post this shot as I totally love it. In fact, it's already in a frame on the wall in the kitchen.


This is the Palacio Da Pena in the hills of Sintra in Portugal. It's an incredible place to visit and I totally recommend it. I could have spend weeks in this one spot taking pictures of the palace's crazy architecture. Also it's a real HDR-users paradise: interesting skies, wonderful foreground and complex structures. It's just awesome.

Anyway, the point of this post was to show how the wall leads the eye into the main part of the picture which is the palace itself. Another example of leading lines. What I have noticed though is that the lines seem to work better if they start in one of the lower corners of the picture instead of the middle.

Project: try taking a picture of some tram lines or rail way tracks and see if the end result is better with the lines in the middle of the picture or off to the side.

Flash antics

I'm told that the most important things in photography (apart from talent and skill) are...

1. The camera


2. The lenses


3. The lighting

At least that's what the counter monkey at a local camera shop told me when he was trying to get me to spend a voucher I had on a flash gun. I don't know that they necessarily go in that order but he was probably right although I'm sure I could think of a few other things that are more important like "Did I remember to bring a packed lunch with me?" and, "are there toilets near the shoot?"

Seriously though, flash guns are really worth looking into. They take a bit of getting used too and I'm still pretty poor at using mine. Have a look at the link to "The Strobist" on the side bar and see just how versatile and useful they can be.

What I suggest is the following --> Set up a wee studio like this...

One tripod is for the flash and the other is for the camera. On top of the table is some black paper and I've set up a little still life that contains some random coins and notes (which, alas, are now defunct thanks to the Euro!)

Have a bit of a think how you would like the ambient light to hit the scene. I've got this placed in such a way that the light from the window isn't really a factor in the picture. The reason for this is that I want the flash as the main source of light and I want control over that. If it was a ridiculously bright day outside I'd have it miles from the window, perhaps in another darker room for this experiment. Sadly, it's grey and raining outside.

So the next thing to do is start playing about with all the settings on both the camera and the flash and see what effects you can achieve. I also have a few attachments that I've built for the front of the flash like a diffuser (made from cardboard and a folded up opaque sandwich bag) and a grid-spot (made from cardboard and straws). There's plenty of websites that can show you how to make these for pennies.

Just a quick dig at the Canon users out there... Most of the Nikon DSLRs work as commander units for flash guns and can fire them remotely without the need for a cable - Canon can't unless you have the top end models. Just set the flash unit to "slave" and the camera's inbuilt flash to "commander" and you're laughing (although remember to also set the camera's own flash to the "--" position or you'll have 2 flashes going).

Here are a series of shots using various changes to the flash (although all taken at 1/16th power). The effects are subtle but if you were to translate these to shoot portraits etc then they can become quite dramatic.


This shot has no flash. The ambient light is diffuse and there are no harsh shadows but it lacks focus and makes the image quite poor. Also the wrinkles and folds in the black tissue paper I've used are very obvious and quite distracting especially in the background. You could probably rescue this by reducing the power of the flash but mine only goes down to 1/16th so I'm stuck. A bit of Photoshop work might also have helped here.


This shot has the flash pointing down from the left of camera at about 45 degrees. The flash has pretty much ruined the shot. The shadows are harsh and this is particularly noticeable on the tissue paper crinkles. Also the metallic nature of the coins means that they are reflecting a lot of the light in the form of glare.


Again the flash is pointing down from the left at about 45 degrees with the diffuser on. You can see that the shadows are less hard and also there is now less available light (due to the thickness of my sandwich bag) so the black paper is less "lit up" and now the focus of the picture is moving more to the money.


This shot is the same as the others but I've put the grid-spot on the flash. It makes a huge difference by narrowing the light that comes out of the flash and focusing it on the center of the picture. The black paper is almost completely black now and the eye is drawn to the object of interest instead of the rest of the frame.

Click here to see a great blog post by QH Photography on how the grid-spot works and the amazing affect it can have on your pictures.

So was the guy at the camera shop correct? Probably. However, flashes are really tough to get to grips with. I would suggest that you probably shouldn't be using a flash gun until you understand the "manual" setting of your camera. Having said that you can always put it on the horse shoe and set everything to TTL (through-the-lens). That means that the camera will make most of the lighting decisions for you and won't let the flash over expose the image. Pretty nifty.

Project: buy/borrow a flash gun and try some stuff on a little home made studio like the one in the first picture. Once you've done that, hang a black sheet on a wall and get a willing volunteer to pose for some shots and see if you can get anywhere near the impressive quality of QH Photography or The Strobist.

Good luck!

Photomerge

So your back's against the wall and the lens you are using won't go any wider but you really want to capture more of the scene in front of you.

What are your options?

1. Buy a wider lens
2. Knock down the wall and take a few more steps back (probably not practical)

OR

3. Take more that one picture and join them together.

Please excuse the fact that I've used my cluttered kitchen but it's pouring outside today so it'll have to do... but here is a pic taken with the 35mm f1.8 lens.



As I'm sure you realise, this lens has no zoom function and is a "prime" lens so it is fixed at 35mm and can't give you a wider shot (unless I was to take a few more step backwards).

So instead I took 9 shots (3 top, 3 middle and 3 bottom) making sure each one over lapped with the next one. Then I went to Photoshop Elements 8 and did the following...

1. Goto "File" --> "New" --> "Photoshop Photomerge"


2. Click "Browse" and select your pictures. As I said, I used 9 here but you can use as mew or as many as you like. I saw a 57 image photomerge once!


3. Click "OK" and Photoshop should start trying to piece everything together.

Here is the result...



Instant wide angle! OK, so it's not instant and takes a wee bit of processing. Also you have to crop the result too as Photoshop will create weird shapes with each pic to try and keep the perspective correct. The whole thing works best if you have at least 20% overlap so bear that in mind when you're lining up your shots.

Anyway, give it a shot but just start with two or three pics before you start trying some crazy 100 image of the Himalayas.

Leading Lines

There's always some blurb in photo mags and web sites about this. Often you'll post a picture on flickr.com and someone will post "nice leading lines" but to start with I had no idea what they were on about.

Yes it's obvious that they are talking about a "line" or "lines" in the picture and that they "lead" somewhere, but what's the point of them? Well they really can add something to a picture. They provide depth and 3-dimensionality to a shot and should act to draw the eye into the picture. Often this is from the foreground to the background (or to the main object in the shot) and this makes the picture more interesting.



This picture of the Tomar aqueduct in Portugal shows how the foreground part of the picture catches your eye and then the line or the aqueduct leads into the picture and almost forces you to look deeper into the frame. It's one of those composition things that the people in the know go on about but to be honest I've noticed that loads of folk use this in their shots without even realizing. I guess that's testament to how much they can improve a photography.

Project: Try it with roads, fences, railings, logs, railway tracks, etc.

Enjoy.

Spray

This is just a quicky!

Sometimes you take a picture and the lights or the sun in the picture form a star like shape. How does that happen? Well my understanding of it is that if you use a very narrow aperture (f22 or higher) then the light "sprays" through the small gap caused by the blades of the lens. It's almost like the opposite of what you are trying to get with bokeh and a wide aperture (which gives you blurry round lights in the background of photos).



Anyway, this shot was taken at 15mm f20 1/125th sec. The high f-number causes a narrow aperture and the light from the sun sprays out like a star. It's quite a nice effect but bear in mind the following...

1. Narrow aperture requires bright light or a tripod (for slower shutter speeds)
2. Depth of field lost with high f-numbers
3. Looking through the view finder at the sun is just stupid. Use Live View instead.

You can see here I've used some of the dappling from the trees to reduce the light coming from the sun or else I would have ended up with completely silhouetted trees and hand.

Go and have a shot just now. Try it on some spot lights first at f 5.6 and then f20 and see the difference.

Nice day for a... wet wedding!

So I was shooting a wedding last weekend and number of issues came up that are worth mentioning and what I did for each of those situations. To set the scene, it was supposed to be a fully outdoor wedding in a large open space which really is a dream come true for the photographer - loads of room to move around in, reportage-style, candids etc would have worked amazingly for the whole shoot. However, by 4pm the heavens opened and everyone ended up indoors in a narrow converted barn which posed a few photographic challenges...

Problem: Rain

This is the photographer's worst enemy as it can not only ruin your equipment but can also spoil the shots. First you can get water on the lens and this needs to be moved post production in PS etc. But worse for the wedding party/guests, their outfits/mood/patience etc can be hampered and it makes the shots difficult to create.

Solutions:

I always have an umbrella in the car. An assistant sometimes helps with this although I can wedge it into my backpack and it keeps me and the camera dry (plastic bags and elastic bands help with this too). Use your lens hood which may stop a few drops hitting the lens. Always point the camera down when not using it. Use the cap in between shots. Do the portraits etc quickly and slickly (but at the same time try not to look rushed). Have your shot program to hand to facilitate the speed of the shots. Finally you might have to accept that things need to be moved in doors so have a backup shot plan if that happens.

Problem: Poor Indoor Lighting

This is always an issue so you have to be aware of your camera's limitations and what you can do to get the most out of it and what you can and can't fix in post production. High ISO, large apertures and slow shutter speeds all generate further problems.

Solutions:

TRIPOD!!! This is a must. It keeps everything steady and reduces shake at slower shutter speeds. I also use a remote to activate the camera without having to touch it. I try never to go about ISO 1600 as I know that the noise the camera generates above this becomes difficult to remove in post production. Large apertures are worth trying but can cause "soft" images and aren't as sharp wide open so try not to open them fully and accept that the shutter speed has to be slower to counter this - which may result in blurry pictures from moving/animated subjects. To get around this pay close attention to your subject and wait till you think they are about to hold still then fire off a burst of shots. It's not an exact science but you should get one or two usable images each time.

Using a Flash Gun is also worth thinking about. However, don't buy today and shoot tomorrow (as with all equipment) as you'll just get frustrated when you realise you don't how to work it. I personally hate flash images but I reckon that's because I'm not very good at them. I do have one setting that works well...

35mm (prime) at 1/60th sec f4 and ISO 400 with 1/8th power on the flash. Seems to give good shots each time. But remember to "bounce" the flash off a white wall or ceiling or use a diffuser to try and stop harsh shadows. Also a tripod is not really possible as you need to be mobile so remember to "tripod" yourself on a wall or knee to steady the shot.

Problem : Distance to Subject

Sometimes you can end up so far from the people you are photographing that you have to be quite inventive to get anything worth using. At one point at this wedding I was about 40ft from the top table and there was no way to get closer due to the other tables. Being so far away requires long focal lengths and the amount of shake is mental. The distance is not the only problem here but also the lighting because you can't use flash beyond certain distances.

Solutions:

See my points about having a tripod and then scrap the one you were going to buy and buy the best one you can afford. It's probably going to last longer than any other bit of kit you have so it's worth investing. I shot quite a few pics at 200mm and it took a good few seconds for the shake/vibrations to settle down each time I moved the camera. Also bear in mind that loud speakers/amplifiers will cause vibrations and shake will take place in your pictures so try to take your shots in between rounds of applause etc. Again use a remote.

Also scout the location in advance so you at least have an idea about where you will and won't be able to get to with the camera. If needs be, get set up way before the speeches and wait it out until they start so you can get the interesting shots.

On this particular occasion I shot most of the speeches at 150-200mm with ISO 800-1600 and 1/40 - 1/30th and just had to accept the limitations of the equipment and resort to post production "fixes" which, although not ideal, seemed to work out OK. Beware again how noise reduction software can make your pictures "soft" and they lose sharpness.

Anyway, I hope that's useful. It's certainly worth considering all of this in advance of an important shoot as you often only get one chance to get the "must have" shots.

Colour Selection

This is something I get asked about a fair amount. It actually is really quite easy and only takes a couple of minutes to do. There are several ways but here is the easiest (I think). Here's how...

1. Open your picture in any photoshop program
2. Right click on the layer in the right hand palate and select "duplicate layer"
3. There should now be 2 layers in the palate.
4. Make the top layer Black and White
5. Use the eraser tool to "rub out" any bits that you want the colour to show through.
6. Goto "layer" and flatten image then save your work

Easy!

ND10 Trickery

So you know how much I love my ND10 filter. Well I've discovered another thing it does brilliantly - it makes things disappear!

Confused? I'll explain. The next shot shows a shot of the Bass Rock off the Coast of Scotland (click on the images for a larger version).


Nice enough eh? I mean, I guess some of the charm of the Bass Rock is all those seagulls and gannets swirling around it and it's lovely white colour from all the guano! Well what would it look like without the birds? Have a look...


Voila! They've all gone. The second shot is a 30 second exposure with the ND10 filter. Everything that's moving doesn't stay in one place long enough to create an image on the sensor. "Ghosts" can be created by slow moving things or things that stop for a bit before moving on but these are easily removed by the clone or heal tool in any processing software.

Neat trick though!

Adobe Lightroom 3.2 beta

Adobe has released it's latest version of Lightroom in beta test format which is free to download until the full commercial version is available... and it's brilliant! It has all the usual RAW editing stuff but one of the things that I personally think is awesome is the gradient facility.

Bright sky is usually about 2 stops of light brighter than foreground and that makes it difficult to expose for both in the same shot. One of the best ways is using a graduated filter stuck to the front of the lens. What that does is block out some of the light from the upper portion of the picture and brings sky's exposure to that of the foreground. Therefore when you take the shot you can retain a lot of detail in the sky that would normally be washed out (or "blown out highlights" as those in the know call it). If you have a look at some of your previous pictures with sky in it (where the sky is not the major feature) you'll see that often that portion of the picture is completely white and over exposed.

So what do you do if you haven't got these filters?

Personally, I under-expose the shot slightly and then in Lightroom drag down the gradient filter effect. This means I can pull back some of the details that would have been previously lost. This shot is prior to using the gradient.



After application of the filter...



Makes quite a difference doesn't it? The icon is on the right hand side of the "Develop" module underneath the histogram and I hope you get the chance to try it out.

ISO and Noise

ISO in a nutshell is how sensitive your sensor is. In days gone by it was a measure of how sensitive your film was. ISO 100 was for shooting in bright light and ISO 800 or 1600 was for shooting in darker conditions. Point-and-shoot cameras often don't let you play with this and the camera chooses for you but it is an integral part of DSLR settings.

The main purpose for increasing ISO is usually to do with camera-shake. If conditions are getting darker then increasing the ISO makes the film (or sensor) more sensitive and therefore it picks up more light at a faster rate and therefore the shutter speed can be reduced - which helps prevent camera-shake.

Sounds great? Well yes, but there is a trade off as always and that's "noise".

Noise is something people don't really notice until it's pointed out to them... certainly, I didn't. After reading this go and have a look at some pics you've taken in low light conditions and you'll see it when you zoom in. In some cases it can be quite obvious.



Here is an example. These pictures were taken in a restaurant under relatively low light without a flash. The first picture was taken at ISO 200 with f3.5 and a resultant shutter speed of 1/10th of a second. The picture below that was shot at ISO 3200 and f3.5 and allowed a shutter speed of 1/250th of a second.

Obviously the shutter speed of the second picture in much faster and so it's less likely to show camera shake as the chances of you moving the camera much in 1/250th of a second is highly unlikely. However if you compare the 2 close-ups of each picture you will see a grainy artifact on the ISO 3200 picture. That is noise.

Personally, I try to shoot in the lowest ISO possible. Normally, I have the camera locked at ISO 100 or 200 but I never let it go above 800 as the noise on the D90 is quite noticeable above this. There is software to remove noise but the results vary. Therefore my advice would be use as low an ISO as you can and add a flashgun if need be.

Or carry a tripod/monopod with you everywhere to prevent camera shake!!!

35mm f1.8 vs 50mm f1.8

So I love my 50mm lens. I've told you before why it's a great purchase but essentially here are the reasons in a nutshell...

1. Cheap
2. Wide aperture and great bokeh
3. Good in low light
4. Weighs nothing
5. Superb for portraits

However, the problem with the crop sensor is that it magnifies the 50mm to 75mm which really is quite zoomed in and I found that at parties and nights out (where this lens should come into it's own) the pictures were too close and I was having to stand miles away which can be an issues in a busy restaurant etc. Also, in properly low light the lens would struggle unless the ISO was boosted - sometimes to unusable levels e.g. 3200.

What were the choices (aside from buying a flashgun)?

Well I decided that the 50mm f1.4 was prohibitive from a cost point of view (>£300) and it still didn't solve the problem of being too close. So I had a rethink and decided to go for the Nikon 35mm f1.8 for about £160.

This didn't solve the low light problem as the aperture was still only f1.8 max (or so I thought) but it did mean I would have a wider amount included in each picture. With the cropped sensor it still equated to 52.5mm but that was greatly improved on the adjusted focal length of the original 50mm.

That was reason enough but I'd also read some reviews saying that it had better colour and contrast than the 50mm so after it arrived (today) I decided to put it to the test.

Here is a series of pictures taken at different apertures in low light. I fixed the ISO at 200 and let the camera choose the speed (not much of a difference there).



I think the most immediate thing that stands out is in fact the contrast and the colour like that review said (and how consistent the 35mm is). At f4 there isn't much of a difference but at either extremes there is huge differences. Although the shutter speed is much the same for both lenses and probably won't help much in low light conditions there is a massive difference in how "usable" the pictures are.

I also noted (although it's hard to see on this blog) that the bokeh with the 35mm (especially at f1.8) is far superior and much more aesthetically pleasing. The 50mm blur is super soft at that aperture and, blown up, looks terrible.

A final point is that the 50mm needed a 35cm minimum distance from the subject to take the picture whereas I could still focus at 20cm with the 35mm which just gives a bit more flexibility.

So all in all I think it was a good purchase and I don't think I'll be using the 50mm again. Having said that, the 35mm is for DX sensors and the 50mm can be used with both a cropped and full-frame sensor so if I ever get round to buying a Nikon D3x or something insane like that then at least I'll have one lens I can use!

Circular Polariser

I'll not go into the optics of these and telling you how they work is a bit pointless - except that they work best at 90 degrees to the sun and reduce the light coming into your camera by about 2 stops.

What you need is to actually see the difference between a picture taken with the filter and one without. Both of the following pictures have been taken as JPEGs in camera with no post processing.



This is the original without the filter. It's OK but the sky is boring and the sea has a lot of glare.



This is with the polariser on. You can immediately see that the sky has changed to a more contrasty blue and the clouds are more interesting. The sea has lost it's glare and again becomes a deeper blue. The overall image is more pleasing and it's one of the very few effects that Photoshop has trouble replicating. If you are ever going to buy a filter this is the one.

One thing I would say is not to buy a cheap one as they don't work that well and it's a total waste.