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Peeved by D200's histograms V on screen pics

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jimthistle73
3 Oct 2007 - 11:21 PM

Evening all.

I've recently been doing a fair bit of product photography using my D200 and Interfit flash kit.

To keep things simple, I've been using a white canvas backdrop with the aim of producing photos with an 'invisible' burnt out white background.

The pics all look fine on the back of the camera, and the histograms look right - I even check the 'burnt out highlights' feature to ensure a white background.

But when I get the results up on the screen, they are invariably a lot darker than expected. The monitor is regularly calibrated using my Spyder 2.

What's all that about then?! Any ideas?

Obviously I can add a touch of compensation when shooting, or fairly quickly sort the BG out in PS, but feel that a correctly exposed pic shouldn't need to be sorted out at all - it's a lot of extras work.

All comments appreciated.

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3 Oct 2007 - 11:21 PM

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strawman
strawman  1021997 forum posts United Kingdom16 Constructive Critique Points
3 Oct 2007 - 11:28 PM

I guess the metering is reacting to the white background. When you say the levels look OK what is the shape of the histogram, is there a big bulge of data down at the black level. If so you know what to do.

The thing is metering goes for uniform grey. So give it white and it will want to turn it a dark grey. Sounds like your camera is working OK.

What mode are you in? Are you in average? or Matrix/Evaluative. If the later then it is no surprise. I would suggest spot metering on your subject, but remember to apply compensation on whether it is brighter or darker than mid-grey.

The other solution is to invest in a flash meter and use it.

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jimthistle73
3 Oct 2007 - 11:36 PM

Cheers for the response. Just to clarify, I do own a Sekonic meter (which I've used for years in medium and large format photography) and do use it as I shoot in manual mode. What I mean is, that I'm 100 percent certain that the pics are correctly exposed in camera.

It seems to be the case for all of my pics that they need lightening up using curves/levels before they look right on my monitor. It's been the case for so long in fact, that I treat it as a necessary pain in the proverbials.

Perhaps I need to be looking at my calibrating software?

In the meantime, I'd still be keen to hear from anyone else who's suffered similar problems.

Cheers!

Last Modified By jimthistle73 at 3 Oct 2007 - 11:39 PM
strawman
strawman  1021997 forum posts United Kingdom16 Constructive Critique Points
3 Oct 2007 - 11:44 PM

Silly question, are your lights set on a fixed power output or do they auto adjust to give you say F8 @ ISO 100? If fixed power how do you calculate the exposure. If auto then the light reflection could be fooling them.

And what happens if you just open the exposure on your camera? Is it just that your camera is at a slightly different sensitivity from the ISO you think you are setting? Is it possible to get what you want by opening the lens up a bit more?

For example I would swear that my camera at ISO100 is actually a bit more sensitive than that.

It could be that for the dynamic range of light you need to use curves to get the contrast change you want.

What is the shape of the histogram? What happens if you expose it so that the black has no info to spread the data out as much as possible?

Last Modified By strawman at 3 Oct 2007 - 11:45 PM
jimthistle73
4 Oct 2007 - 12:02 AM

Some food for thought there, thanks! The flash heads are completely variable and don't auto adjust (i.e. - non thyristor (spelling?!)).

If I simply open the lens up, I do get a white background and reasonably exposed pic but it looks washed out on the back of the camera and the histos are blocked right up - obviously this isn't ideal as it makes it hard to tell whether a shot is OK or not.

As I say, it's not just flash shots - it's everything from landscapes to close ups.

Prints from my calibrated monitor are usually spot on, after being lightened up - it just rankles me that my screen disagrees with my camera!

I've just uploaded an example of a product shot pre-processing. The camera showed burnt out highlights and a good histogram. I'd be interested to know what it looks like on your screen - on mine it looks reddish and far from white!!

Thanks!

miptog
miptog  83532 forum posts United Kingdom61 Constructive Critique Points
4 Oct 2007 - 12:10 AM

What White Balance setting were you using? Try Auto or Flash and see if there is an improvement. The EXIF info. for some reason states that it was taken with a D70s, and manual White Balance was used.

Mike

Last Modified By miptog at 4 Oct 2007 - 12:13 AM Helpful Post! This post was flagged as helpful
jimthistle73
4 Oct 2007 - 12:18 AM

Ah! Right enough - this was taken with the D70s but I'm surprised manual WB is showing up - I usually have it set to flash for this type of product photography.

Perhaps this points to the possibility that I'm not using my Spyder correctly? Are you seeing a reddish cast to the 'white' BG, and does the BG look white on your monitor?

TIA,

Jamie.

miptog
miptog  83532 forum posts United Kingdom61 Constructive Critique Points
4 Oct 2007 - 12:20 AM

Yep, mucky reddish, which suggests White Balance may be the issue.

Mike

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stevekhart
4 Oct 2007 - 12:21 AM

Your image is a little magenta and the bg is not burnt out, was it giving you flashing highlights?
Shoot a grey card to correct the wb.

jimthistle73
4 Oct 2007 - 12:28 AM

Hmmm. Thanks for that - at least I know then, that it's not my monitor, as the pic of the frisbee is entirely untouched.

Still though, the fact remains that 90 percent of pics taken with both my Nikons need a boost to look acceptable on monitor.

Most of the time, the WB is set to auto (both cameras). Perhaps I'll have to start using my grey card - bought it six years ago and it's left its packet approximately twice!

I may also start shooting with a permanent exposure adjustment - on the face of it, this would sort out the problems.

Thanks,

Jamie.Edit: Steve, just read your post. Yes, I was getting flashing highlights, which is why I'm so confused at the image on the monitor. See above for grey card comments Smile

Last Modified By jimthistle73 at 4 Oct 2007 - 12:29 AM
stevekhart
4 Oct 2007 - 12:32 AM

I'm confused with what you're trying to achieve here. If you're going for a burnt-out background in camera you need to light the bg separate from the subject in order to get a lighting ratio of at least 1 stop difference between the two. If your subject is resting on the background you can't do it without overexposing the subject and you'll need to alter it in PS to give the desired effect.

Helpful Post! This post was flagged as helpful
jimthistle73
4 Oct 2007 - 12:40 AM

Yup - wherever possible, that's what I'll do and this pic is probably a bad example. The pic in question was actually a reshoot - the original setup was: frisbee directly on top of a softbox to achieve the required ratio of BG light to subject, with the frisbee also being lit from directly above with a 2nd softbox.

Even with this setup, I was finding the BG needed selecting (magic wand) and lightening up using curves to get a true white BG. Again, flashing highlights in camera suggested this amount of post processing wouldn't be necessary.

As an aside, the client requested the reshoot as he wanted a more 'organic' look, with a few soft shadows - the originals did look a little like they were floating in space Smile Also, some of the more translucent items looked a bit weird given the underlighting treatment.

Last Modified By jimthistle73 at 4 Oct 2007 - 12:41 AM
stevekhart
4 Oct 2007 - 12:43 AM

Sometimes it's easier just to create the shadows in PS Wink Maybe try using the white-point dropper from the levels tool, it'll correct the WB as well as burning out the background.

I'd use my lightmeter rather than the histogram. If my bg is lit for f11 and I shoot at f8 I know it's burnt out, don't need a histogram to tell me.

Last Modified By stevekhart at 4 Oct 2007 - 12:45 AM Helpful Post! This post was flagged as helpful
jimthistle73
4 Oct 2007 - 12:51 AM


Quote: Sometimes it's easier just to create the shadows in PS

Fair point - there has been an extremely large box of frisbees and other 'throwy stuff' in the boot of my car for a while now...........

I guess the thrust of what I'm trying to get accross is that, no matter whether I use a light meter, histos, auto, custom or flash WB, the images which appear on my monitor are darker than those which appear to be perfectly exposed in camera.

I thought I'd remembered a thread from ages ago dealing with chronic under exposure using Nikons, but can't seem to find it.

Thanks to all for the help - fair few handy tips and lots to think about / experiment with.

Last Modified By jimthistle73 at 4 Oct 2007 - 12:54 AM
stevekhart
4 Oct 2007 - 12:54 AM

The nikons do have a tendancy to under-expose when metering, but you're not using the meter. What I don't understand is that a flashing highlight should be an RGB value 255 in at least one of the channels, but the example pic it was only about 230. That sounds wrong!
I love "throwy stuff"...

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