Hi Gunther,

I use a variable-ND adaptor to put my Nikon lenses on my Sony cameras, and I use the VND to make exposure changes through holy grail shoots. I use all 8-stops of the VND before adjusting shutter (which is before adjusting ISO, of course). It's nice to have extra room to adjust exposures, before I have to start adjusting ISO. I usually make the VND exposure changes very small but, of course, I can see the sawtooth pattern of these changes in LRT.

What would you suggest would be the best tool in LRT to smooth these changes?

Usually, if they are small enough, I deal with them with the Visual Deflicker tools, but sometimes I'm a bit late in making VND adjustments, and the jumps are larger. At the moment, to deal with these larger jumps, I put 4* keyframes on each frame on either side of the change (e.g. I've made a VND change at frame 100, so I put a 4* keyframe at 99, and at 100). Then in LR, I adjust these two side-by-side keyframes to match exposures (I have to do this by eye, for some reason LR's "Match Total Exposures" doesn't work in these cases, not sure why). I've tried giving these two frames 2* and 3* keyframes and using the Holy Grail Wizard, but I'm guessing that, because the EXIF doesn't indicate a settings change (shutter, ISO, aperture), this tool doesn't work the way it does when EXIF shows a settings change.

This issue also applies for changes with manual aperture rings (I have a fully-manual lens that doesn't report aperture changes, which I sometimes make while shooting, if I have to).

Is pairs of 4* keyframes the best way to go, or is there a smarter tool in LRT that you would recommend?

Cheers!

Chas

Basically I don't recommend working with variable ND filters for timelapse at all. Those filters are very weak, even in there strongest settings (compared to a 1000x ND) and the strong settings create weird artefacts becase they don't dim the whole area consitently. That means the usable range of dimming is even more limited.

That said, of course it's up to you how you shoot your timelapse so let's answer your questions.
As you already figured out, LRTimelapse needs Exif Data to do the Holy Grail Wizard (that's why it wouldn't detect any changes on the ND filter. The same goes for Lightroom's "Match Total Exposures" - it won't work without different EXIF Data on the images, that's why it also doesn't work.
In your case I'd go for a combination of Visual Deflicker and the subsequent 4* keyframes as you are doing it.

For manual lenses you can also use the "Tag Aperture" feature in the Menu to write the real aperture into the exif data, which would then also allow the HG Wizard. If might also be possible to use this feature to cheat aperture values into the Exif Data for the ND Filter changes, but I'd not recommend it since it's kind of messy. Just to let you know, that there is this option.

I'd think about leaving the ND out for HG shots and do everything with Exposure/ISO/Aperture ramping. That's what I (and many others) do. I use static ND filters which I leave on all the time depending on the shooting range: 1000x, 64x and 8x. If you don't go until the milky way for most HG shots in city areas, you can normally even leave a (good) 64x filter on all the time without sacrificing image quality.

Hi Gunther, great reply.

Thanks for all that info. I'll keep editing the way I have been, I'm glad I figured out the best way, already :-)

I wasn't aware that LR's exposure matching tool required exif data to work, that's very good to know (thanks for solving that mystery), but I was quite sure that LRT did for 2* and 3*. Tagging aperture with manual lenses does seem quite messy, especially as I make those moves _very_ small (so as to avoid any vignetting issues). No worries, 4* and deflickering to the rescue!

As for the VND adaptors I've been using (https://fotodioxpro.com/collections/sony...thrtl-cine), I've shot hundreds of sequences with these, with no colour shift or uneven exposure issues at all. If the VND moves are small, and I don't plan to go to/from night shots (the lowest value the VNDs can be set at is 2-stops or so, and that's a lot of light to lose for astro!), then they are hugely useful tools, and allow me to use mostly shutter speed to make adjustments (once the VND has been moved to its max/min). I, of course, have used all three normal tools (shutter, ISO, aperture) to shoot many sequences, but if I can keep it to shutter only, I can avoid possible vignetting and all noise issues.

I should note that these VND adaptors have physical stops to avoid the dreaded "cross" issue, which I'm well aware of. I have an early screw-in VND that I rarely use with no hard stops at all, and it can easily be pushed too far, resulting in very uneven areas of bright and dark. If I'm shooting a daytime non-Holy Grail, I trust these adaptors enough to work even at their high values, but I will frequently use a 10-stop or 8-stop (or even a 14-stop) screw-in or square filter instead. It all depends :-)

I think that they're worth giving a second chance, you just have to know them and use them carefully (like any piece of kit :-)

Thanks again for the info, I really appreciate it.

Cheers!

Chas

Sounds good, I didn't know about those types of adapters - thanks for telling me! If they have a hard stop to prevent the "cross" issue then of course it's another story and you really seem to know what you are doing. Most people asking about VND filters, don't ;-)

Ha ha, I'm sure that you've gotten a _lot_ of "LRT doesn't work with VND" comments over the years :-)

Not really because it's not too much that I could do in LRT to support it and most of the people don't have such advanced solutions like you, that if I saw that correctly are implemented in a special lens adapter which requires the usage of the right lens and camera.
I stay with my general opinion that "normal" VND filters shouldn't be used for timelapse and that they cause more harm than good. After hearing from you I'd add that this is a general recommendation, but of course there might be exception for people that really know what they do and want to go that route. :-)

That's a good point, as I only know one other timelapse photog who uses a VND regularly (and I know several pro timelapse photogs who don't :-)