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Barmaglot

Member Since 30 Mar 2017
Offline Last Active Today, 10:49 PM
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Posts I've Made

In Topic: Manual and TTL

Today, 11:40 AM

Learn something new every day... it's called FEL lock rather than FV lock, but it looks like it can be used to do precisely that - meter on a subject with a pre-flash, then recompose and use the metered value for the next shot, which skips the pre-flash. Thanks!


In Topic: Manual and TTL

Today, 07:00 AM

Interesting - Sony doesn't appear to be this sophisticated. Looking at the user manual, I see this:

  • Multi - Measures light on each area after diving the total area into multiple areas and determines the proper exposure of the entire screen (Multi-pattern metering).
  • Center - Measures the average brightness of the entire screen, while emphasizing the central area of the screen (Center-weighted metering)
  • Spot - Measures only the central area (Spot metering). This function is useful when the subject is backlit or when there is strong contrast between the subject and the background.

I don't see how AE-lock would help - it'd need to fire the pre-flash, then give you time to recompose before firing the main flash, and to my knowledge no camera does that. Still - I don't know whether it's my rudimentary composition skills, or the weak strobes, but so far I've found TTL to be pretty accurate.


In Topic: Manual and TTL

Yesterday, 05:51 AM

Your examples reaffirm my belief in strobe lighting after the duds I got recently.  I'll continue the struggle for TTL.

 

As soon as the UW-Technics becomes available, I'll do the tests you mention and report here.  If the ST-100 fails, then I'll be looking at the

Z330 or Retra.  I suppose I should lock in the Retra pricing within the next 10 days and cancel later if needs be.

 

Believe me, I got plenty of duds as well - those photos are cherry-picked from a dozen dives, and I'm sure that in the eye of an experience photographer, they represent nothing more than a newbie stumbling around.

 

At the risk of being somewhat argumentative, I have yet to find a TTL solution that really works consistently when shooting wide angle.

 

Whilst the mechanics of metering and flash exposure are technically possible, the TTL circuits have no way of actually determining which part of the image they are actually lighting. To balance using strobe light to light the foreground and ambient light for the rest of the image is a challenge. 

 

Even with spot metering? I mean, as I understand it, the challenge with TTL underwater is that the camera doesn't know that it's trying to light up water and ends up over-exposing the foreground in a vain hope to light up the entire scene, but I used spot metering on that trip, which only evaluates the center, and with some exceptions (mostly where strobe power was totally insufficient), the exposure looked pretty good to me, even if the camera had to raise the ISO setting way up. I can see how it will fail if the center of the image is water (there's no way to move the metering point), but other than that, it seems pretty good...


In Topic: Manual and TTL

13 December 2018 - 10:28 PM

Basically the best value for money would still be ST-100, if you could drive it with an LED trigger to enable its full output, and if the metering in this TTL-only mode is sufficiently accurate. The 2.8ms full duration isn't far off from Z-330's 3.3ms, and the bulbs themselves are probably not that much weaker. I'm still kind of on the fence about the Retras - while they're undoubtedly excellent strobes, €1478 plus import taxes is still a lot of money - if someone verifies that either the Turtle or the UW-Technics trigger works properly with ST-100s (i.e. reaches full power when needed and provides reasonably accurate exposure), I might cancel the pre-order and stick with the SeaFrogs solution. Even as it is, my setup produces some shots that I'm quite happy with (example), but it is kind of frustrating that 2/3 of the strobes' power is locked away and inaccessible.


In Topic: Manual and TTL

13 December 2018 - 03:47 AM


I really don't follow what you are doing with your tests.  The YS-03 is TTL only and ST-100 I don't know how it performs, but your test indicates it is underpowered.

 

 

Regarding ST-100, the problem is not that it is underpowered, but rather that it has a really stupid optical trigger circuit - it basically works the same as YS-03, blindly following the triggering signal without modifications. When the camera flash only burns for 0.9ms, and the strobe needs 2.8ms to fully dump its capacitors, this effectively restricts its output to 1/3 of maximum. Manual operation is the usual counter to this issue, but on ST-100, manual operation works only with wired triggering, and optical TTL compensation is not implemented - it's basically a bulkier YS-03 with a focus light. An LED trigger might help, provided the strobe is sufficiently sensitive, but I don't know of anyone who has tested that combination.