HDSLR: Very inconsistent exposures on a timelapse - GH5

[insch]

I am shooting timelapses across two cameras, one being a GH5. The shoot is of growth in two petri dishes. The other camera, a Canon, is behaving predictably but I am getting wildy different exposures on the GH5. It is set to manual with 400 ASA, f11 and 1/2" exposure. The lens is a Canon EF 100mm f2.8 USM Macro with a Metabones speed booster adapter. Since the fungi in this petri dish doesn't really like light I have set up a Dedolight (muted down) to switch on for 1 minute in every 10. The whole rig is shrouded in black cloth. Both cameras take their timelapse stills within that period. As I said, the Canon results are predicatble (with slight variations in exposure probably due to inexact lighting levels) but the GH5 has wide variations with many frames being totally overexposed. The test shots I have taken from the GH5 look fine.

Any advice, anyone?

Thank you

ps pix uploaded to show still thumbnails giving a guide on exposure levels.

 

[Bassman2003]

I would guess this is the lens iris changing in between shots. Do some searching on photography forums regarding timelapse exposure consistency. Basically, you want to turn the lens a little bit while installed to cut off the electronic contacts to the iris actually stays at f11. When modern lenses have the electronic connection they are programmed to return to wide open in between shots to give more light to the viewfinder (DSLR) and autofocus system.

 

[NorBro]

Could you try resetting the camera, updating FW (if applicable), taking the batteries out overnight, attaching and reattaching the lens; basically anything because that is bizarre.

Since the Canon looks normal you can rule out other light from anywhere/flashes/etc. affecting the process, so what's left?

Really only the GH5 settings somewhere...assuming it's all manual and the lens is locked and the adapter isn't bugging, maybe it's a mode? Are you bracketing exposure? (Probably not because you might have noticed all of the extra frames.)

If it's really not the settings and the camera isn't malfunctioning, maybe you could then consider if some type of automatic editing during the importing process is affecting each one but that doesn't just happen regularly and those above look like they are in a folder.

Maybe also test the Panasonic with a timelapse somewhere else?

 

[insch]

I would guess this is the lens iris changing in between shots. Do some searching on photography forums regarding timelapse exposure consistency. Basically, you want to turn the lens a little bit while installed to cut off the electronic contacts to the iris actually stays at f11. When modern lenses have the electronic connection they are programmed to return to wide open in between shots to give more light to the viewfinder (DSLR) and autofocus system.

Thanks. I didn't know that about manual focus. So I need to twist the lens to disconnect contacts and leave that way for the shoot? Feels a little precarious to have an unlocked lens?

 

[insch]

Could you try resetting the camera, updating FW (if applicable), taking the batteries out overnight, attaching and reattaching the lens; basically anything because that is bizarre.

Since the Canon looks normal you can rule out other light from anywhere/flashes/etc. affecting the process, so what's left?

Really only the GH5 settings somewhere...assuming it's all manual and the lens is locked and the adapter isn't bugging, maybe it's a mode? Are you bracketing exposure? (Probably not because you might have noticed all of the extra frames.)

If it's really not the settings and the camera isn't malfunctioning, maybe you could then consider if some type of automatic editing during the importing process is affecting each one but that doesn't just happen regularly and those above look like they are in a folder.

Maybe also test the Panasonic with a timelapse somewhere else?

I've done some resets. The FW seems up to date (2.7). I'm not bracketing and I would have seen that. This is random. I'm sure it's nothing to do with importing becuase I'm just copying from the cards to a folder on my Mac. I'll try a short timelapse on something else and see what happens. Thanks for your help.

ps I've now done a FW update on the Metabones adapter. Looks like there was an update from my last one. Fingers crossed.

 

[NorBro]

To quickly rule out something I'd try what Bassman suggested but hold the lens right up to the mount if you don't want to leave it unlocked.

I've always used Canon cameras for timelapses and actually never heard of that (meaning an aperture should not reset back to wide-open in a manual environment), but the possibility of electronics not communicating properly with each other is far too common so it could make sense.

 

[insch]

To quickly rule out something I'd try what Bassman suggested but hold the lens right up to the mount if you don't want to leave it unlocked.

I've always used Canon cameras for timelapses and actually never heard of that (meaning an aperture should not reset back to wide-open in a manual environment), but the possibility of electronics not communicating properly with each other is far too common so it could make sense.

Thank you. I'll see how the current test goes with updated FW on the Metabones adapter but will try disabling the lens electronics after that.

 

[Bassman2003]

Bear in mind, this is timelapse info from the DSLR days. I shot Canon and to get consistent timelapse exposures one had to set the aperture then slightly rotate the lens to stop any kind of internal lens activity. Then all of the images would be the same. Mirrorless changed the game in many ways, so this might not still apply. But then again it might as well. Easy to check on a few test shots.

 

[NorBro]

So weird, I have never done that or remember anyone ever talking about that. (Maybe I missed an entire topic out there.)

In the DSLR days we used wired remotes since the cameras didn't have the built-in timelapse movie feature yet and it was perfectly fine.

Then when I started using the built-in movie feature on the R, R5, R6, etc. it worked even better (because it made a video clip out of the frames).

___

If one critically ponders, why would it reset with a timelapse but not when shooting [quickly] regularly or in a burst mode?

A timelapse is nothing special and it's just automatically taking a picture, and the camera shouldn't be going back to wide-open to look for light or anything like that unless it's instructed to.

 

[Bassman2003]

I was thinking old school timelapse of individual photos taken, processed in Lightroom then placed on a video timeline right next to each other. So each a separate photograph. It was really a stills exercise until they were placed on the video timeline. Does that help?

I did one for a week once where a photo was taken every 3 minutes or so.

 

[NorBro]

That's the only way to do it before the movie feature - but the exposure still didn't change unless changes in light were affecting it (or camera settings).

For example, I brought the 5D Mark II to the beach all of the time and took random timelapses with a ShutterBoss. On some days, the sun was in and out peeking through clouds and I could expect radical changes because I had the aperture and shutter locked.

But if I set the camera up in a darker room with no lighting, there were no changes because there was nothing to change the exposure (fully manual).

Also, because the changes are so extreme in the example in this thread (P1022749 looks underexposed while P1022737 is completely white), the camera would have to be overriding its own manual f/11 exposure. And what's the rhyme or reason for the randomness?

I understand maybe opening up to focus during the non-activity period (if there's time), but not taking the picture at a different f-stop to let in more light. That's broken.

 

[Bassman2003]

I do not know about this example. Just relaying my experience with exposure shifts and timelapses (which probably do not apply to mirrorless cameras). But it was a real thing as it was discussed on DPReview and it solved my issues back in the day. I can only guess the adapter is playing a part? Maybe try a native lens and see if it continues?

 

[insch]

Bear in mind, this is timelapse info from the DSLR days. I shot Canon and to get consistent timelapse exposures one had to set the aperture then slightly rotate the lens to stop any kind of internal lens activity. Then all of the images would be the same. Mirrorless changed the game in many ways, so this might not still apply. But then again it might as well. Easy to check on a few test shots.

Thank you. When you say rotate the lens, do you mean disengage the electronic lens contacts?

 

[insch]

I was thinking old school timelapse of individual photos taken, processed in Lightroom then placed on a video timeline right next to each other. So each a separate photograph. It was really a stills exercise until they were placed on the video timeline. Does that help?

I did one for a week once where a photo was taken every 3 minutes or so.

Thanks. I am working with a series of stills, bringing them into Davinci Resolve where they are complied into a sequence. I can see in the folder of stills that many are overexposed.

 

[insch]

Updating the adapter firmware seems to have improved things with less overexposed frames but they are still there...

 

[NorBro]

I think all that's left is trying a native lens and that will likely fix everything :thumbsup:

 

[Bassman2003]

Thank you. When you say rotate the lens, do you mean disengage the electronic lens contacts?

Yes, with the lens attached, press the release button and rotate the lens just a little but and it will lost the electronics. But, on a mirrorless camera, this might shut everything down. This was a DSLR tactic where the cameras where not as "smart" as they are today.

 

[insch]

Series of shots at f1.8 - slight variations but I can live with that. Does point to issues with aperture accuracy - lens or camera or Metabones adapter? Hmmm. Now trying f4...

 

[insch]

After changing to f4 the problem has come back - not as extreme but the variation is there. Not sure if this is the camera, Metabones adapter or lens but I'll keep experimenting...

 

[NorBro]

People have had issues with adapters since their creation. Some don't even speak to certain cameras or lenses and support features like AF or IS at all (hence communication problems).

Wouldn't it be soothing to buy a $25 MFT lens on eBay or try something at a camera store and resolve your issue immediately?