TTL or Manual, Different?

Is there a difference in colour, contrast or saturation when shooting in TTL than manual? I say this because over the past few days I have been diving with a diver who has the same set up as myself, yet he is shooting TTL, when we compare the images shot exactly the same settings his look slightly more colour, contrast and saturation and the exposure seems “fuller†is this right could a TTL exposure give a slightly richer look to an image or does exposure only do as the name suggests?

Camera in TTL vs. Manual or strobes in TTL vs. manual?

How are you comparing the shots? LCD on the cameras? Nikon View on a Laptop? Raw conversion? JPEG?

Subal ND2 using 2 DS125's strobes, one using manual the other TTL, shots comparedon the same computer side by side veiwing in photoshop cs2 RAW no conversion.

I doubt there is a color difference due to ttl or manual. Light is light, assuming the tubes are the same.

I would look at camera settings like color space, temperature, etc.

Cor

Agreed. It's probably the JPEG engine settings on the camera.

One thing that I do think about though is that a histogram that is more to the right but not clipped (and brought back to the left to get black if necessary) will yield more saturated colors. TTL may do that better than manual.

Cheers

James

Well, I'm definitely not an expert, but hey, what's a forum for if not uninformed speculation. Here's my theory on how TTL exposure could do what you describe.

I'm thinking within a given aperture and shutter speed, there's a range of acceptable exposure. His TTL setup is going to shut off precisely at the exact "ideal" exposure, smack in the middle of the range. In manual mode, you're within the range, but probably not right in the middle. Let's say a TTL setup is like a strobe with an infinite number of power settings, that automatically picks the right setting. If you had small enough increments on your strobe, you could probably find that center too.

So, maybe he's just slightly less exposed than you - deliberately underexposing is an old trick to increase saturation, right? Do you see any difference in the histogram?

What if you set up a shot that will require full flash discharge for both of you, so TTL's not part of the equation (or I guess you could get him to disable TTL, but that's no fun). If his is still better than yours, it's probably camera settings or something else.

I don't think that's correct TJ - if you expose to the right but don't overexpose, then you get maximum saturation and minimum noise. But I could be wrong about that.

Cheers

James

I don't think that's correct TJ - if you expose to the right but don't overexpose, then you get maximum saturation and minimum noise. But I could be wrong about that.

 

Cheers

James

Hmm....I think you may be right based on a quick Google search - found this article on Luminous Landscape that explains it really well:

http://www.luminous-landscape.com/tutorial...ose-right.shtml

Gonna have to do some more research on this - sounds like I'm behind the digital curve (pun intended).

I still wonder if my idea about strobe on full power has any merit.

Still not clear on both rig's camera settings. Are both cameras on manual shutter speed and manual aperture?

Hi guys,

Sorry to hijack an interesting thread, but, where is the starting position for shooting macro subjects with a strobe set to manual; 1/4, 1/2, etc...

And while we are it, what would/should the minimum distance from strobe to subject be??

Thanks for taking the time?

Bruce

I am with James - almost certainly JPG settings (as the JPG is used for the review screen) - or the actual screen differences that exist between D2X and D2Xs. Also the frame content will also have an effect. Subtle differences such as camera angles in wide angle (which determine the shade of blue that dominates the frame, for example) and compositional choices will also have a massive effect on the histogram.

Why not swap camera bodies for a dive - to see if the difference is the lighting or the camera settings.

Alex

First, are you talking about pure flash illumination on the subject of a balance of flash and available light?

Second, are the camera settings identical or are you leaving the camera to auto white balance? As Alex says, this could explain things well enough.

Third, why would you expect TTL flash exposure - an automatic exposure evaluation system - to produce precisely the same exposure as a manually controlled flash exposure? Unless the histograms are identical (ie absolutely the same subject and exposure) then there will be some, albeit subtle, variations which will affect the final outcome of the image.

Fourth, are the cameras using the same exposure measurement system (matrix, centre weighted or spot)?

I'm using a TTL set up on my Canon at the moment - it certainly appears to produce pretty 'accurate' exposures most of the time with a minimal amount of clipping - this is down to when the camera shuts off the flash, and this in turn is down to its programming - but these still often require tweaking in the raw conversion. My manually controlled flash exposures (I still switch to them when TL won't/doesn't produce the desired desult) generally don't clip because that's why or how I've manually decided to expose the subject but my pure manual flash exposures often look slightly darker and duller than some TTL exposures until they have been adjusted in the RAW conversion.

TTL is an automated system and works very well most of the time but in my experience so far, it is difficult to precisely match exposures from TTL and manual unless you watch the clipping and bracket very carefully around it.

Oh yes, and lastly, it may also be that there is some variation in the strobe outputs - they are not all identical, nor come to that are all cameras!

Thanks all, were going to swap cameras today and make sure 100% the setting throughout the camera are the same, also take some shots with the TTL camera but in manual strobe mode, I'll see if I can them post a few images to get your opinions.

Oh and Bruce yes that was a hijack, you should probably start a new topic.

I am with James - almost certainly JPG settings (as the JPG is used for the review screen) - or the actual screen differences that exist between D2X and D2Xs. Also the frame content will also have an effect. Subtle differences such as camera angles in wide angle (which determine the shade of blue that dominates the frame, for example) and compositional choices will also have a massive effect on the histogram.

 

Why not swap camera bodies for a dive - to see if the difference is the lighting or the camera settings.

 

Alex

I think he said shots were compared on the same computer in PS Raw converter. I like the swap camera idea - if it's strobe/camera angle or composition, that would do it. Actually, I think you and I should swap cameras, you get my pictures and I get yours .

Good thread - I learned something. My new theory: maybe TTL is consistently getting closer to the right side of the histogram w/o clipping, since it can cut out when it gets close. Alternate theory: I have no clue.

the same computer side by side veiwing in photoshop cs2 RAW no conversion.

1) Good, but not perfect. Remember, even though these are RAW images, the computer must apply settings for you to view them. The camera's JPEG settings come into play unless you tell PS to view them using a specific conversion setup.

2) TTL strobe will almost always produce a different result than manual strobe control. Theoretically TTL can produce an infinite number of flash durations, whereas manual can only do a handful.

3) Your identical setups are unlikely to be identical. Strobes must be exactly in the same position pointing at exactly the same angle. This is hard or near impossible in a controlled environment let alone underwater.

I would suggest that the same shot be taken by both cameras AND both manual and TTL.

I find it hard to believe a cause and effect of TLL on color and saturation beyond the impact of more or less strobe output.

I find it hard to believe a cause and effect of TLL on color and saturation beyond the impact of more or less strobe output.

Now that's an interesting one because I ASSUME that the preflashes are used in the white balance check by the camera so reduced or increased output will affect the white balance assessment which in turn may affect colour and saturation. If so, for a balanced light exposure then the colour and saturation might well change depending on what the assessment is by the camera. The same will I suppose also be true but to a lesser extent for macro. I must admit that as I always shoot RAW and white balance afterwards so I've not thought of checking this but it makes sense to me.

Anyone else want to comment?

I think we need to see 2 raw images so we can check this out ourselves

Cor

I think we need to see 2 raw images so we can check this out ourselves

 

Cor

agree with Cor, that way we could check the metadata for confirmation of settings too.

Unfortunately I didn’t get the chance today to try it out, other than to see the images again that he took. Work got in the way of play today , last chance tomorrow. But the more I see the more I’m convinced, we’ll see, may be I’m just hallucinating but I don’t think so.