Will a Polarizer help with blown highlights?

[libby_ross3]

<p>I'm debating whether or not to get a Canon XSI digital camera body. It seems to be the best deal in the price range but I'm less than thrilled with its ability to handle highlight and shadow detail. I can't hardly complain for the price but I'm wondering if I can find away around this or if I need to suck it up and spend more money for a better body. Man I miss the days where a $500 body on a good piece of glass could get the same quality of image as the high end bodies with the same glass..<br>

<br /> I don't shoot digital so I am wondering for those of you who have experience with this, will adding a circular polarizer get rid of the blown highlight issues?</p>

[heller_harris]

<p>Are you using the lowest ISO setting? What about an Ultra-Contrast filter from Tiffen? That might allow you to expose for the highlights and retain some shadow detail. <br>

I think that you probably have to meter it as though you were using fast slide film.</p>

[Charles_Webster]

<p>Your digital camera doesn't have the same dynamic range as film (well, it's about the same as slide film), so you can't expect the same ability to handle highlight and shadow detail.</p>

<p>The best advice I've gotten is to expose so the highlights are not blown, correct the shadow exposure in post processing, and use noise reduction when shadow detail enhancement makes the shadows too noisy (grainy)</p>

<p>Shoot RAW so you can utilize every bit of dynamic range and can correct better in post.</p>

<p><Chas><br /></p>

[jcuknz]

<p>If the camera over exposes highlights without the filter it is likely to compensate for the light reducing effect of the the polariser and continue to blow them. Better is to adjust the EV settings to a minus amount or in other words tell the camera to under-expose. This will make the shadows darker but usually they can be lifted in a good editing programme which has the Levels and/or Curves tool without blowing the highlights which occurs with the simple brightness control of a basic editing programme.</p>

<p>A quick and simple correction for blown highlights is to set the camera up for them using the 'half trigger' technique. Point the camera to include more highlight proportionately in frame, half press the trigger to set the camera up, hold H/T while re-framing for the shot you want and then full press the trigger. With a bit of practice it becomes second nature and no hassle at all.</p>

<p>I would suggest it is better to put your money into a good editing programme than spend it on filters. I use the former a lot and the later very rarely. </p>

[tobey_bilek]

<p>Polas are used to help tame reflections and deepen the blue of the sky if it is already blue, not grey. Photoshop works better on the skies.</p>

<p>meter the brightest tone in the pic with the camera spot meter, then give 1.5 to 2 stops more exposure so it goes light but does not blow out. Fix shadows later or use HDR or other ps tricks to bring up the shadows.</p>

[libby_ross3]

<p>I have CS4. I'll have to play with it see what I can do with highlight and shadow detail.</p>

[david_henderson]

<p>If the highlights concerned are a light blue sky or the sort of specular highlights that are affected by polarisation, and the angle is such that the polariser can have an effect, then the use of a polariser can reduce the subject brightness ratio in your composition and make it easier to fit your composition onto the dynamic range available on your camera (or film). This is because polarising filters do not just have a neutral density effect, as one poster has perhaps implied above. Thats why, despite auto exposure compensation, a polariser tends to saturate skies and reduce the brightness of reflections in water, from leaves etc. It can and often does make the bright bits darker even when an exposure overall looks similar.</p>

<p>But there are all sorts of caveats. These range from the fact that a polariser won't have an effect beyond its ND effect when you have the sun in front or behind; the fact that the skies that blow out most easily seem to be white not blue and as such are not saturated by the filter; the fact that you don't want to keep a polariser on your lenses all the time; and this list goes on. In short whilst a polariser can provide occasional assistance in this area it wouldn't be wise to view it as a perpetual solution to this problem. </p>

<p>If you can meter successfully for slides I have no doubt you will cope with exposing digital slrs quickly, making sure that there is sufficient highlight detail to work on later but this achieved, getting as much light into the shadows as you can. If what you're used to is colour neg film or b&w its going to be more of a challenge. But the reality is that there are lots of photographers who have learned to expose films like Velvia very well, despite a low dynamic range. Digital is a little easier than that IMO. Whether by grads, or fill flash, or by post manipulation, and with occasional help from a polariser, you'll find a way.</p>

[dbcooper]

<p>If the blown highlights are due to glare or glare-induced reflections, or light scatter like in white clouds, then I'd say a CP would probably help. Otherwise, probably not. The only solution I know for that is to get the exposure right and bring up shadow detail in post. If bright skies are the problem, you might consider using ND grads.</p>

[bill_tuthill]

I think you got the correct answer: sometimes.

 

Have you tried setting highlight tone priority? It doesn't work as well on your 450D as on the 500D, but it does work. Also, many of my images benefit from exposure bracketing, an old slide film trick. Probably the 450D has a setting for that. XSi = 450D.

[phule]

<p>[[it seems to be the best deal in the price range but I'm less than thrilled with its ability to handle highlight and shadow detail.]]</p>

<p>Really? </p>

<p>http://www.dpreview.com/reviews/canoneos450d/page21.asp</p>

 

[John Sully]

<p>It seems rather odd to me that you might think that digital has less dynamic range than slide film or even negative film. For a long time digital has been thought to have a greater dynamic range than film. It used to be (at least for slide film) that you would expose for the shadows. With digital you "expose to the right". This means that you look at the histogram and expose for the highlights because you can recover detail from the shadows in post processing, if you are using RAW rather than JPEG. </p>

<p>As far as using a CP filter, it won't help with blown highlights, although it will help control specular highlights. I would say that there are only two types of filters you need with a digital camera -- a CP and whatever ND filters you might need for effect, if you like water and what not. </p>

<p>Bill makes a great point here, bracketing (AEB) is a very useful trick. I would say that it is not a trick, for serious images it should be a necessity. One of the cool things about using AEB is that you can use something like Photomatix (version 1.2 is free) to merge your bracketed exposures into a single image which has a huge dynamic range. </p>

<p>I started shooting with a digital SLR about ten years ago and one of the first things that I learned was that digital (read Canon CMOS) sensors had a greater dynamic range than slide film. You should not really be worried about blown highlights, just know that you have to expose differently than you have to for film. Remeber, expose to the right and look at the histogram. Digital is better at handling shadow than film.</p>

[bill_tuthill]

If you think digital has as much highlight dynamic range as film, you should see <a href="http://www.janrik.net/MiscSubj/2007/FilmVsDSLRTests20070528/A_Comparison_of_Film_and_DSLR_Images.html">this excellent study by Rik Littlefield</a>. Kodak Gold 200 yields results seven (7) more stops after the Canon 300D has given up. As a tradeoff, digital has 3-5 stops more shadow range, although Gold 200 is not the greatest film for shadow detail.