Blown Highlights

GerryNick2 · #1 (**permalink**) 19-09-2006, 09:50 PM

Hi All

My passion at the moment is photographing fungi in situ. and try to capture their natural colours for later ID. I use a Canon EOS 30D and EF 24-70mm f2.8 L USM lense for this subject matter. Aperture priority, usually f16 and a slow shutter speed, tripod mounted.

One of the problems I encounter is loss of image data in the highlights. A recent example was of a Fly Agaric, I experienced considerable clipping in the white flecks on the cap which spoilt an otherwise nice shot.

Any tips or advice in avoiding this would be welcomed.

Gerry

dustyshadow · #2 (**permalink**) 19-09-2006, 09:59 PM

Take your images using RAW and that will enable you to correct blown highlights.

GerryNick2 · #3 (**permalink**) 19-09-2006, 10:31 PM

Hi Dusty Shadow

I do shoot in RAW and use RAW Essentials Premium for conversion, whilst you can make some minor adjustment to overexposure or clipping in highlights you cannot bring back whats not there in respect of image detail. The question is what do I need to do to avoid the clipping in the first place.

Gerry

dustyshadow · #4 (**permalink**) 19-09-2006, 10:34 PM

Quote:

Originally Posted by GerryNick2

Hi Dusty Shadow

I do shoot in RAW and use RAW Essentials Premium for conversion, whilst you can make some minor adjustment to overexposure or clipping in highlights you cannot bring back whats not there in respect of image detail.

Gerry

Try underexposing the image in the first place before you take the shot, keep an eye on the histogram to avoid clipping.

You can also try lowering the contrast in in RAW Essentials.

Alan · #5 (**permalink**) 19-09-2006, 10:39 PM

Hi Gerry

Set your exposure compensation to underexpose the shot. With pale fungi start with something like - 1.0 (minus 1.0). Try a shot at that and check your histogram. You want to be aiming at a curve that is not cut off both sides. Referre to your manual about histograms if you don't know what they are. If that's too much at - 0.1, and the image is too dark, re-set it to something like - 0.7 and so on.

Hope this helps

Alan

edit: ^^ what dustyshadow says

^^

Boddie · #6 (**permalink**) 19-09-2006, 10:43 PM

The 30 D illustrates blown highlights on the shooting information graphic on image playback

carlj · #7 (**permalink**) 19-09-2006, 11:11 PM

I always shoot with -0.6 exposure compensation and rein in the highlights, so to speak. That way, I rarely if ever, blow too many highlights. A little lost is no hardship though.

eeyore · #8 (**permalink**) 20-09-2006, 12:18 AM

Quote:

Originally Posted by Boddie

The 30 D illustrates blown highlights on the shooting information graphic on image playback

yeah blinky highlights is a great tool - i think all canon dslrs have it - great for newbies and occasionally useful for even the hardened pros

GerryNick2 · #9 (**permalink**) 20-09-2006, 01:35 AM

Thanks for the advice.

Will give it a a go this weekend.

Gerry

DaiTheDragon · #10 (**permalink**) 20-09-2006, 04:47 AM

Why not use a neutral grey card and set custom white balance.

dai

Wild-Woman · #11 (**permalink**) 20-09-2006, 06:45 AM

I think I need to get a good photography book, with a jolly good glossary so I can understand what you're all talking about.

There was me thinking that blown highlights was about hairdressing!!

Andy Warne · #12 (**permalink**) 20-09-2006, 07:11 AM

Quote:

Originally Posted by DaiTheDragon

Why not use a neutral grey card and set custom white balance.

dai

If anyone wants a grey card these are pretty good,

Douglas Software, Photographer’s Grey Card.

jezlee · #13 (**permalink**) 20-09-2006, 08:31 AM

Quote:

Originally Posted by carlj

I always shoot with -0.6 exposure compensation and rein in the highlights, so to speak. That way, I rarely if ever, blow too many highlights. A little lost is no hardship though.

I think you're right, Carl .... a slightly under-exposed shot is always preferable to an over-exposed one - it's easier to bring some detail into the shadows in post production than trying to replace something in the highlights that's not there ....

Alan · #14 (**permalink**) 20-09-2006, 10:31 AM

Quote:

Originally Posted by jezlee

I think you're right, Carl .... a slightly under-exposed shot is always preferable to an over-exposed one - it's easier to bring some detail into the shadows in post production than trying to replace something in the highlights that's not there ....

Yes agreed, but it does depend on the camera. The D70 tends to under-expose too much if you're not careful, so I normally over-expose by +0.3 for normal midtone subjects and use that as a starting point to adjust for other tones. Now of course if you go manual like Dai suggests and either meter off a grey card or a mid tone subject like grass or some tree trunks, that's another way to learn.

I believe the D50 is spot on with metering Jez, so as I say, it often depends on the camera.

Beryl · #15 (**permalink**) 20-09-2006, 10:40 AM

I have a D50 Nikon. I keep it on auto action. I don't fully understand the manual , well lets just say I can't read the thing, but I find with the automatic , my ISO is auto along with everything else. I'm probably guilty of tryingto get photos of things just a little too far away and I like action more so than stills. I don't care for the unsharp mask , usually go for levels.
I am hoping to et a 80-300mm ths month, that should hepl with the long shots but as for blown highlights that as Wild-woman says is the hair department for me too.

Chalk Downlanders · #16 (**permalink**) 20-09-2006, 12:10 PM

A little trick I use when I over or under expose an image is. Save the same RAW file twice as a TIFF. One over exposed and one underexposed. Load the two into Photoshop and using the eraser, I remove the over / under exposed areas on the top image and merge the composite images. If you use a very gentle eraser it blends quite well.

Kev

Andy Warne · #17 (**permalink**) 20-09-2006, 12:46 PM

Quote:

Originally Posted by Chalk Downlanders

A little trick I use when I over or under expose an image is. Save the same RAW file twice as a TIFF. One over exposed and one underexposed. Load the two into Photoshop and using the eraser, I remove the over / under exposed areas on the top image and merge the composite images. If you use a very gentle eraser it blends quite well.

Kev

To take it a step further you could bracket your exposures and then sandwich them together using some software to create a high dynamic range image.

HDR photo software & plugin - Tone Mapping, Exposure Blending & HDR Imaging for photography

They're got some examples on their website.

Chalk Downlanders · #18 (**permalink**) 20-09-2006, 12:54 PM

That looks quite impressive Andy. I'll have a better look later. Maybe it can be done in Photoshop but I am not aware that it can.

carlj · #19 (**permalink**) 20-09-2006, 01:09 PM

Grey card? Why not open a blank page, new fill layer, fill with 16% grey and print to a4 card?

As for spot metering - know what would count as a midtone or you'll blow the exposure completely. It is the most accurate, but also the most difficult to use correctly.

Kev Lewis · #20 (**permalink**) 20-09-2006, 01:52 PM

Quote:

Originally Posted by DaiTheDragon

Why not use a neutral grey card and set custom white balance.

dai

The 18% grey card can be used to set an average exposure value and to set colour balance. However for white to be white you need to OVERexpose from the metered reading or the exposure will try to make the whites 18% grey as well. Use the histograms and metering according to the situation.

To maximise the detail in any image you should always try to maximise the exposure as much as possible without blowing the whites i.e push the histogram to the right without clipping.

SteveHL · #21 (**permalink**) 20-09-2006, 04:18 PM

Lastolite produce a deffuser which if placed between the light and the subject should produce nice deffused light. Just a thought it may help.
Regards

GerryNick2 · #22 (**permalink**) 20-09-2006, 04:28 PM

Quote:

Originally Posted by SteveHL

Lastolite produce a deffuser which if placed between the light and the subject should produce nice deffused light. Just a thought it may help.
Regards

A fold up reflector or diffuser had crossed my mind. Has anyone had any experience of using one of these in the field.

On occasion have used the wife to block out the light which works a treat.

Gerry

Andy Warne · #23 (**permalink**) 20-09-2006, 04:41 PM

Quote:

Originally Posted by GerryNick2

A fold up reflector or diffuser had crossed my mind. Has anyone had any experience of using one of these in the field.

On occasion have used the wife to block out the light which works a treat.

Gerry

I'd never go anywhere without my reflector/diffuser, I bought a Kood one, it has white, gold, silver and black surfaces and is also a diffuser. Great in strong sunlight to either diffuse it or lighten the shadows, can also be used as a windbreak. Buy one now!
Got mine from 7dayshop, about £15.

Jon · #24 (**permalink**) 20-09-2006, 04:43 PM

It is really as simple as this: pale objects need to be over exposed and dark objects need to be under exposed because you camera tries to convert anything to grey. The problem here is that your subject may have a preponderence of light or dark and you are not sure which is the most influencial on your camera. Look at your histogram, to the right is bright (it rhymes!) to the left is dark. If everything was neutral you would expect the peaks of the histogram to be in the middle, therefore if most was light you would expect most peaks to be to the right - don't get your peaks too far over to the right. A very simple expedient is to routinely underexpose your shots by 1/3 to 2/3 of a stop and then bring the exposure up to the level you require using Photoshop or similar. Jon

digi · #25 (**permalink**) 20-09-2006, 06:46 PM

I agree with Jon keep the histogram peaks away from the far right. I usually shoot at 0.7 or 1 full stop down this stops highlights from being blown on my 30D, although the 1D does not suffer as much from blown highlights.