Hello Gunther,

I am able to reproduce the missing shots when I shoot HDR (2 shots per trigger) with interval ramping.

Camera setups: Canon 5dIV Manual mode. Two exposure bracketed shots at 0 and +3 (1/60 and 1/8 sec respectively), drive mode, continuous shooting. No camera settings change during the entire test.

LRT PRO Timer settings: Tmelapse, 3 seconds interval, 50 shots. Once it starts shooting, do the interval ramping immediately to 5 seconds interval within 2 minutes.

Result: (please refer to the attached screenshot) when the interval was ramped to around 4.7 seconds, there were two missing triggers, and somehow I started to get only one single shot for each trigger afterwards, i.e. one trigger is the 1/8 exposure shot, and the next trigger is the 1/60 exposure shot. It ended up with 76 shots total.

If I don't do interval ramping (still using the 3 seconds interval, 50 shots), I will get the total 100 shots successfully.

This is reproducible almost every time right now. And I did not use the USB controller (Unleashed) for the above tests.

Please let me know if you need more info or if I can provide any logs that may help your investigation.

Thanks a lot!

How are you triggering the shooting of those two shots? You cannot use the default short trigger timer in the regular TL modes for that. You'd need to use Custom TL and set the trigger time as "Exposure time" in order to get a longer trigger time of for example 1 second (that should be good for your scenario). But if in another scenario you do exposure ramping you'd need to set the trigger time for the camera even longer, I'd set it to the longest of the first exposures + at least 0.5 secs. If your camera looses shots, even longer.

Personally, I've talked again and again about why not to use HDR bracketing for timelapse because it complicates everything and brings nearly zero advantage but many disadvantages. Use the search feature, we discussed this many times here.

I'd need a precise scenario (pro timer and camera settings) with which I'd be able to reproduce that. Best without HDR because I don't have a Canon Camera and my nikons would need a much longer trigger for a bkt shooting (as I explained). I find it strange, that missing shots should be related to the interv Ramping.

If you get missed shots in that HDR scenario, are both shots being dropped (which would suggest the camera doesn't get released by the PT at all) or only one of the pair?

Both shots were dropped at first (two times) then somehow it started to one single shot for each trigger, similar to when you manually press the release button twice separately. You can see the these drops and messup afterwards from my attachment.

The first drop is at photo number #52 in my attachment showing an interval of 8.9 during the interval ramping from 3 sec to 5 seconds.

Hmm, but that seems even more strange. You said that your camera only requires a short trigger in order to do both shots in HDR mode. So it seems to be receiving that trigger and the sometimes it does both and sometimes only one?
Could you please try and increase the release time in the PRO Timers settings. I Increase it by 50,then try again. If it continues failing, add another 50 and so on. See if that helps.

One trigger will fire two shots. Yes, sometimes it does both shots and sometimes only one shot. When only one shot is released, the camera is flashing and waiting for the second trigger, as it is a two-shot sequence. When the second shot is triggered, it goes to either normal two-shot sequence or repeat the problem again.

Thanks for pointing out the release time.

The default release time is 200ms. It continues failing until I set it to 500ms. The initial interval is 3 secs. I started interval ramping (to 5 secs in 2mins) immediately once the TL shooting began.

With 500ms release time, I was not able to reproduce the issue 5 times in a row.

However, I was able to do a regular TL successfully with only 1 sec interval without interval ramping even with release time being set to 200ms. The camera settings are identical: shutter 1/60, 1/8; ISO 200; Aperture f/4.

It seems most of time the issue occurred during 4.5~5 seconds ramping period. It worked fine at the beginning like from 3 seconds to 4.5 seconds. Once it reach the constant 5 secs interval, it becomes normal.

Thanks for your help!

For me it sounds as if the camera just needs a longer release time in HDR mode. I'd suggest that you'd leave it at 500ms for now when working in that mode since this seems to solve your issues.

This post was last modified: 2021-07-29, 23:46 by zoom.

Sure, but this will limit the minimum interval to 500ms + 200ms = 0.7 seconds, which is not perfect for my moonrise/moonset sequence with a large zoom lens (I usually use 0.5 secs). Anyway, this is much better than dropping frames.

Just out of curiosity, how does a longer Release Time fix the missing shots issue? All settings are still the same. There's no interval change from the LRT timer, and no camera settings change either. Do you change the signal timing? I doubted it, as we keep the same intervals.

Thanks.

It's just the time the timer "holds" the release button. Obviously in HDR mode your camera requires a slightly longer time.