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#21 ehanauer

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Posted 24 August 2004 - 07:08 AM

Hi. My name is Eric and after a brief romance with ttl during the last 3 years of my film life, I've abandoned her since switching to digi.

It's that 2 1/2 stop latitude on the dark side that got me hooked. Once I've locked in my test shots, I pretty much stay with what I've got, making occasional adjustments on the basis of what I see in the lcd.

Photoshop and RAW capabilities have made TTL dependence a thing of the past.
Eric
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#22 Lionfish43

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Posted 24 August 2004 - 08:01 AM

Very interesting thread. I find myself agreeing with arguments on both sides of the issue. Personally, I feel that TTL is a useful tool. I would rather have more tools available than fewer.
When I upgrade to my next system - D2X, D90, Fuji S3, whatever - it will most likely not have TTL and that will not be a problem. What I really lust after is better, more accurate AF and a better viewfinder. Hopefully at some point the strobe makers will catch up with the cameras and give use back TTL. More is better.

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#23 Alex_Mustard

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Posted 24 August 2004 - 08:36 AM

Suppose I am shooting wide angle.  The left side of the scene has a yellow sponge one foot away.  The right side of the scene has darker red sponge which is one foot away but angled away such that part of the sponge is 3 ft. away.  How do I properly light the scene using TTL?  (OK, this is a quickly thought of example, maybe with a little time I could come up with a better one).


That is a problem with TTL is that if both strobes are the same and both on TTL then both give the same amount of light. Meaning the red sponge will be underexposed. On manual you might end up with the right strobe 1 or 2 stops brighter.

Things get complicated when you have different strobes (or a subject that is not parallel with the film plane (sensor plane)). As the camera shuts both off when the whole scene has got the "right" amount of light. The faster discharging strobe will get more light out in this time, overexposing compared with the other. Now in reality the differences may be minor and we may never see them.

Alex

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#24 Alex_Mustard

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Posted 24 August 2004 - 08:43 AM

BTW, how many topside shooters use their respective speedlights in full manual mode?


Interesting comment, George. I actually think that strobe lighting is one area underwater photographers have little to learn from the average land photographer. We use multiple off camera strobes in just about every picture we take. Not many land photographers do this.

Most outdoorsy pros/semipros I know are not that good with a flash (there pictures come out, but they rarely use it creatively) - and only use it for fill for portraits and never use more than one - and always on top of the camera where the electronics expect it to be. In these circumstances I would expect TTL to be awesome.

I don't know much about studio photography - where multiple strobes are more common, but my feeling is that these photographers tend to favour manual settings.

Alex

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#25 JPS

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Posted 24 August 2004 - 09:15 AM

For me personally, TTL means both more available time/effort/attention for strobe placement, as well as less "wasted" shots when moving from macro to portrait or the like. Of course the first point is irrelevant for those that are able to pay enough attention to each and every photography aspect of their shots... :wink:

The TTL capabilities have been discussed in rather superficial fashion so far. Preferably TTL should be accompanied with conveniently available flash exposure compensation, and a variety of metering modes. If either is missing (or very inconvenient to use) sure using manual control can be preferable for fine-tuning. If both are available, those (and strobe placement) should work wonders for control.

One more comment: the argument that post-processing can save slight under/overexposure for manual applies also for TTL shots. It should be a question about which alternative performs better for you for the shots you care about.

My two cents,
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#26 manatee19

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Posted 24 August 2004 - 10:08 AM

[DISCLAIMER: This post is made as a contribution to the discussion and should, under no circumstances, be perceived as a direct attack on anyone, dead or alive, who engages in active u/w TTL photography.
Sworn before an officer of oath under the authority of her Majesty Queen Elizabeth II, Queen of England, of the Dominion of Canada and, more importantly: Queen of the Cayman Islands and Australia!]


Hi,

my name is Michel and I have been off TTL since 1974…. Mind you it was not hard then!

Topside, TTL is the greatest tool and Nikon has mastered the art of TTL flash fill (in its film cameras at least). Underwater though, TTL has been a mixed blessing and, even though I realized that on some occasions I could have used it to achieve better results, I never did simply because I felt manual gave me better control… at the expense of some missed shots.

My wife/partner Danielle would never try u/w photography unless she had a TTL system. Eventually she bought a Nik V and suitable TTL strobe. Her first rolls were mostly BADLY exposed! I then asked her if she could read a little cue card with 10 numbers on it. (exposure for 1' to 5' in 1-foot increments?) She agreed to try it and… BINGO, exposure was MUCH better!

Those were slide days when film latitude was measured in neutrinos…

Then came digital RAW. Our tests and experience so far have taught us that, for example, with 2 SS200 (place Ikelite logo here) at 1/2 power, an exposure of f/16 on a D100 (stick Nikon logo here) would lend acceptable/salvageable results from 1 to 3 feet… talk about latitude.

No need to talk about the so-so performance of D, i, X, Y or Z-TTL underwater.

So what is the conclusion: Go in a pool, make exposure-bracketed shots at various distances (we favour 1:1 working distance and then 1' to 5' in 1-foot increments). Then analyze your results and write down an exposure table. (We print them on a laser printer, laminate the small piece of paper and affix it to the housing with Velcro (Velcro logo here). Works wonders.

Add to this the instant feedback from the LCD screen and you can have both control over your lighting and good exposure.

Mike Haber (yes the one who works with Steve and teaches the famous Jim Church courses) was talking to me at the last Beneath the Sea show and he told me that one of the things he had to teach his students (as I do with mine) is that: A) It is not that complicated to take properly exposed underwater pictures; and B) that giving up TTL does not mean that you will run out of air faster or that your images will all be badly exposed!

One final anecdote: I was giving a workshop and explaining my very simple and effective manual exposure system. A student insisted on the fact that TTL delivered good results and that one could use compensation to tweak exposure when the lighting was tricky. He was so adamant that, at one point, I had to take out of my briefcase a pile of at least 8 pages where someone had posted, on an u/w photo mailing list, the various compensations he was using depending on the conditions. I then asked the student if he would rather carry those 8 pages or my 2"X3" laminated exposure table during a dive… That was the end of the discussion.

My $ 0.02 (Canadian)


Michel

#27 richorn

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Posted 24 August 2004 - 12:01 PM

It looks like the "no TTL" side is a bit more "well represented" in this discussion, but then again, I do have James on my side!

I purchased the S2 instead of the D70 simply because of TTL. I would always prefer to have a tool in the toolbox that I don't need at the moment than later find I need it and can't get one.

As much as I love the TTL the Fuji offers, I can turn it off and shoot manual in the same time it takes to adjust strobe intensity... best of both worlds! :wink:
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#28 james

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Posted 24 August 2004 - 12:50 PM

I'd also like to correct what I see is a mis-perception about "exposure latitude" with Digital SLR's.

Yes, it is possible to correct an exposure after the fact - we all know that. But correcting an exposure has certain penalties too.

If you overexpose the background, you end up with a large proportion of ugly blown green and blue channels. If you overexpose the foreground (strobe) then you have blown white highlights. Neither of these situations is easy to recover from. Also, it's important to get a balance of foreground and background exposure (balanced fill flash) and if you miss that, you are hosed.

If you underexpose a stop or two you can almost always bring up the exposure using the RAW converter. But guess what is happening when you do that? You are essentially just increasing the ISO - and increasing the noise at the same time. If you were shooting the D100 at ISO200 and you push your shot up 2 stops, you just pushed it to ISO800. Look at the noise in the shadows - with the D100, it's pretty bad. I almost NEVER push a shot from the D100 up by more than a stop if I can help it.

So in reality, you don't actually have 2 stops in either direction to play with in post processing. You have some latitude, but at the same time, you also get some loss of quality. Hence it's better to get a balanced properly exposed flash shot the first time. TTL can do that.

Cheers
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#29 Alex_Mustard

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Posted 24 August 2004 - 01:07 PM

An important point, James. I think the RAWoholics sometimes forget that large (over a stop) exposure correction does not come free. And that there certainly isn't as much overexposure latitude in digital as we like to think.

On of the problems I had with TTL on digital is that it is inclined to cause exactly one of the problems that you mention. In a common shooting situation where the foreground/main subject does not fill the whole frame and it is is set against open water (no reflection of strobe light) TTL will often overexpose the subject. An example of this is a fish against open water - hardly an unusual situation for us UW snappers.

Basically the TTL metering does not think it has given the subject enough light (because not enough has reflected back) and winds up the power and overexposes. The problem is particularly prevalent if the subject is off centre - which compositionally may be desirable. So you take another shot with the subject a bit bigger and in the middle and it TTL nails it. So TTL compensation doesn't help.

On film that bit of overexposure from the TTL would be fine. On velvia rated at 50 it might even help the image. But on digital this overexposure is a problem. Now ideally I guess I should be filling the frame with the subject - a situation where I'd back TTL 99 times out of 100. But when it is that once in a lifetime chance - a different type of fish spawning in front of me for the first time - I'd rather be in control than trying to guess what the TTL will make of the situation.

Alex

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#30 scorpio_fish

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Posted 24 August 2004 - 01:16 PM

I had to take out of my briefcase a pile of at least 8 pages where someone had posted, on an u/w photo mailing list, the various compensations he was using depending on the conditions.


A well known pro explained how you can use TTL with wide angle. Just dial in EV comp of between .7 - 2.1 and you've got the correct exposure. It was never clear to me how to select a number in that range, so I decided it was easier to use manual strobe power and guide numbers for wide angle.

#31 Alex_Mustard

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Posted 24 August 2004 - 01:19 PM

There are definitely times as a photographer where I take an image purely on speculation. I have no idea it will come out. And I think that this is something I do a lot more in these digital days - when I have so many shots to play with. I do think automation is very helpful at these times.

This is an example. The lionfish was swimming down the reef, and I just stuck my camera underneath him and fired.There was no room to get my head behind the camera and look through the viewfinder. It was a case of blatting off 3 or 4 shots and trusting to luck, AF and TTL.
Posted Image

I don't believe I would have got this shot shooting on manual. I needed TTL.

Alex

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#32 richorn

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Posted 24 August 2004 - 01:40 PM

Wow Alex!

Every time I try that I take a great shot of a fin or something! :mrgreen:
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#33 MikeVeitch

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Posted 24 August 2004 - 02:25 PM

Wow, that is a great shot, i really should try macro one of these days...

That said i do agree with various people who have mentioned that TTL is a good tool for when your subject completely fills the frame. But seeing as 95% or more of my photography is WA i have gotten so used to manual that i just naturally use it on those rare occasions where i do shoot macro.
However, one of the things that i think this forum is addressing is that a person really should learn how to shoot on full manual first. Learning how to use a camera on manual gives a person a much better understanding of how lighting, fstops etc affect photography. Not only can it be used for compositional purposes but what happens when the TTL dies? I have encountered many people whose Nik Vs flooded and i was able to fix it in the field. SOmetimes the TTL worked after and sometimes not. For those people who understood manual this was not a problem. For those who relied strictly on TTL they had to start from scratch to learn exposure all over again.

I agree with Michel on cue cards, great tool that i utilize myself and learned from the great Jim CHurch who did this for his students right off the bat.
TTL does have its place, its great when it works well, but don't be so TTL dependent that you don't learn to do things manually, you never know when you may have a camera problem. (especially around water)
I too often use TTL on land based stuff but as was mentioned earlier, the intricacies of strobe arms, placement, power settings for composition etc make UW a different ballgame altogether.

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#34 UWphotoNewbie

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Posted 24 August 2004 - 02:50 PM

Hi my name is Chris and I've been off TTL for 2 years now.

I started with TTL on my Canon S300. I went with Ike strobes for the greater power and of course the possibility of TTL. It never quite worked out. The TTL controllers don't work with the little Canon and I've since exchanged them for manual controllers.


I've been happy with manual on the Canon as a way to add some exposure control to a fully automatic camera. Now that I've moved on to a D70 I am content with manual. One advantage of manual that you will never get with TTL is the ability to override the camera's maximum shutter speed (sync speed) allowed by TTL. With only the manual hotshoe pins connected you can set any shutter speeds you like and as Alex has shown you get better sunbursts at very high shutter speeds. I now shoot most of my shots by adjusting only the strobe power which makes things simple. Adjusting the exposure compensation gives me a broad latitude in exposure.

I must come clean and admit that I still do lust after a time when I can return to TTL. I dream of the day that Ike retrofits my D70 housing to do TTL with my DS125 strobes. But even then I will want to use flash exposure comensation as a pseudo manual when TTL fails. Then I would truly have the best of both worlds.

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#35 richorn

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Posted 24 August 2004 - 03:23 PM

Sync speed really doesn't have anything to do with TTL, as far as I know.

It only has to do with the speed of the shutter, and making sure the light hits the entire "sensor" before the shutter (or is curtain a better word to use here?) closes. If you set the shuuter speed to fast for "sync", the shutter closes before the entire frame (beit film or sensor) has been exposed. This can normally be seen as a blank band over part of the image.
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#36 Craig Ruaux

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Posted 24 August 2004 - 03:35 PM

Sync speed really doesn't have anything to do with TTL, as far as I know.  


In an indirect manner it does, in that the presence of a TTL strobe may limit the camera's willingness to be bent to your will.

Obviously to be able to do TTL, the camera needs to know that TTL-protocol fluent strobes are attached. But, if the camera knows that there is a strobe attached, it is typical for the camera to refuse to set a shutter speed greater than the "specified" maximum shutter/strobe sync speed.

Thankfully, the strobe firing contact on many camera hotshoes triggers with every shutter release, and so if you use a strobe that is only attached to this contact, you can fire it at higher shutter speeds. It is only when you bring in the quench, ready light and so on pins that the camera becomes aware that there is a strobe there and changes into the mode where shutter speed is limited.
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#37 UWphotoNewbie

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Posted 24 August 2004 - 04:00 PM

Sync speed really doesn't have anything to do with TTL, as far as I know.



It was for the limits on the camera shutter speed imposed by the camera's TTL system as Craig explained that I brought up Sync Speed.

I might add that myself and others have shown that with electronic shutters as on the D70 you can actually push the camera beyond its sync speed limits without experiencing any of the problems typically experienced with the camera not syncing. I have made good pictures with my D70 underwater at shutter speeds up to 1/8000 s without any blank bands appearing because of the electronic shutter. Starbuck has some at 1/2000 s. Alex did some great tests at 1/1000 - 1/2000. I think most would agree that his highest shutter speeds gave the most appealing sunbursts.

Now you do get some light falloff with strobes such as the DS125 at full power because the strobe needs 1/250 s to do its thing. But if you don't need all of the flash or you are using fractional power settings you can get all the light you need at very high shutter speeds.

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#38 Alex_Mustard

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Posted 24 August 2004 - 04:00 PM

Wow, that is a great shot, i really should try macro one of these days...


What really frustrates me about the lionfish shot is that I thik the composition is very strong. And this is the full frame. Its my picture and I can't accept any of the credit because I wasn't even looking through the viewfinder!

That would have never happened if I was shooting manual java script:emoticon(':wink:')

#39 MikeVeitch

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Posted 24 August 2004 - 04:21 PM

I know what you mean Alex, this is pretty much point and shoot as well. But with the Nik V and a 15mm so i didn't have to worry about focus. But then again never kick yourself for having some good luck!
Everything set manual with emphasis on the fact i knew approx strobe to subject distance

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#40 Craig Ruaux

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Posted 24 August 2004 - 04:38 PM

Its my picture and I can't accept any of the credit because I wasn't even looking through the viewfinder!


Hogwash, the camera didn't decide to fling itself under the lionfish afterall...
:roll:
Why would I take a perfectly good camera underwater??
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