D800 Remote trigger

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ChrisR
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Post by ChrisR »

So it seems for TIFF and using 600X SD cards you must wait at least 7 seconds after the exposure before another trigger is sent
A few posts ago you said you were making exposures every 4 seconds (ish, if I understood).

So is your buffer simply filling up?
...but if it were, after the buffer is initially full, wouldn't you be losing a lot of frames if you keep making exposures faster than it can empty the buffer to the card...

If it's not that, Nikon s/w has a hemipteran?

mawyatt
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Post by mawyatt »

I guess the massive files from these 36MP cameras at 14 bits per pixel are choking the memory buffer and cards. I am making a run of TIFF now with a total 7.5 seconds between shots, this causes the green camera/memory busy LED just go out before the next trigger command, so no overlap.

I think the overlap is the issue as the buffer slowly builds up until it overflows and must wait for the memory card write, then resumes...but during this time the triggers are ignored by the camera. This causes out of sequence or completely missed exposures which show up after stacking as OOF ribbons.

I am counting the exposures now to see if any were missed.

About half way thru a 250 sequence now, will report results when finished.

mawyatt
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Post by mawyatt »

I got exactly 250 exposures but still a few very thin OOF ribbons which are due to vibration and not sequence issues. I watched the camera/memory busy LED and didn't see any missed trigger commands.

At least I understand the buffer memory speed issues now and can hopefully avoid this in the future. I suspect that Canon has similar issues with the buffer overflowing.

One interesting point is how much time it takes for the TIFF files. Since these are 110MB each, twice the size of D800 RAW files, they take twice as long to write. A high speed memory card is valuable here and the CF is faster than SD on the D800, so CF may be worth the extra $.

Now to just get the vibration issue under control again, probably go back to the strobes instead of the Ikea LED lamps.

Hopefully all this will help someone from fumbling through all this like I did!!

Thanks for the help Rik and Chris,

Cheers,

Mike

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Post by rjlittlefield »

I suspect that Canon has similar issues with the buffer overflowing.
Sure, any camera will do this. Whenever system throughput is less than bytes/frame * frames/sec, something is going to get dropped. Refusing to take individual frames is the usual behavior. All the other alternatives like writing partial frames or locking up entirely would be so painful that the camera manufacturers avoid those.
mawyatt wrote:still a few very thin OOF ribbons which are due to vibration and not sequence issues.
...
Now to just get the vibration issue under control again, probably go back to the strobes instead of the Ikea LED lamps.
I'm a bit confused...

If the ribbons are actually OOF, versus motion blurred, then the problem must be vibration along the depth axis. The usual problem is that you end up imaging almost the same depth twice, while missing an adjacent one.

But if the problem is depth axis vibration, then strobes won't help unless you can somehow sync them with the vibration.

Have I missed something here?

--Rik

mawyatt
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Post by mawyatt »

rjlittlefield wrote:
I suspect that Canon has similar issues with the buffer overflowing.
Sure, any camera will do this. Whenever system throughput is less than bytes/frame * frames/sec, something is going to get dropped. Refusing to take individual frames is the usual behavior. All the other alternatives like writing partial frames or locking up entirely would be so painful that the camera manufacturers avoid those.
mawyatt wrote:still a few very thin OOF ribbons which are due to vibration and not sequence issues.
...
Now to just get the vibration issue under control again, probably go back to the strobes instead of the Ikea LED lamps.
I'm a bit confused...

If the ribbons are actually OOF, versus motion blurred, then the problem must be vibration along the depth axis. The usual problem is that you end up imaging almost the same depth twice, while missing an adjacent one.

But if the problem is depth axis vibration, then strobes won't help unless you can somehow sync them with the vibration.

Have I missed something here?

--Rik
Sorry should have said blur ribbons instead of OOF ribbons.

Don't think most of the vibration is depth or Z axis, I suspect X and Y axis. I say this because my setup seems more rigid along the Z axis. I need to brace the long set of adapters to the focus rail, with the Raynox and objective hanging off the camera body it tends to swing a lot!!

BTW I could get the D800E to freeze up by manually triggering shutter at a high rate and continuing after buffer overflowed. Had to remove battery to shut it off. I have had this happen on a number of occasions when shooting large stacks.

Chris S.
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Post by Chris S. »

Interesting, Mike. Having never shot TIFF, I hadn’t thought about how much bigger TIFF files are than raws, but of course, they are. Is there any reason you would want to shoot in TIFF? I use both raw and jpeg workflows for macro stacking, but have never found a reason to produce TIFF files in-camera. (Saving Zerene Stacker output is another story—I definitely use TIFF for that.)

Is there something you find beneficial in shooting TIFF?

Cheers,

--Chris

mawyatt
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Post by mawyatt »

Chris S. wrote:Interesting, Mike. Having never shot TIFF, I hadn’t thought about how much bigger TIFF files are than raws, but of course, they are. Is there any reason you would want to shoot in TIFF? I use both raw and jpeg workflows for macro stacking, but have never found a reason to produce TIFF files in-camera. (Saving Zerene Stacker output is another story—I definitely use TIFF for that.)

Is there something you find beneficial in shooting TIFF?

Cheers,

--Chris
Chris,

A while back I found that JPEG files seemed to produce a very slight banding in the final stacked chip image. This wouldn't be noticeable in most subjects, but with chips it shows up because of the unique surface structure I assume. Anyway I didn't see as much with RAW files, but Zerene requires JPEG or TIFF formats. I would shoot in RAW and translate to TIFF in LR, this took some time with large stacks. Then I found out the D800/E can produce TIFF directly, and have been doing this ever since.

I believe the banding is caused by a slight variation in exposure in the JPEG image processing. Some of the earlier chips had large areas of aluminum metal conductors covered by a plastic called polyimide (polyimide is the top layer passivation used on some IBM processes). This produced a amber color similar to gold. If you looked closely you could see slightly different gold color bands across these large metal areas in a zebra fashion.

At first I thought this was due to variations in illumination, and tried a bunch of things related to such, including waiting longer for the strobes to recharge. I even monitored the 120VAC line voltage. I would pre fire the strobes to warm them up having read somewhere that the strobe color temperature can shift with internal temperature, and warming up can help stabilize the strobe internal temperature. Nothing seemed to resolve the problem until I switched from JPEG format.

Sometimes I'll still see a very faint banding with RAW/TIFF, but not as pronounced as with JPEG.....so I just shoot with TIFF now to save the hassle of the LR transformation from RAW. I may revisit shooting TIFF because of the additional memory card write time and return to RAW.

Regards,

Mike

Chris S.
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Post by Chris S. »

Mike, thanks for sharing your experiences, which are interesting. If I were getting jpegs that showed banded color for given subject, I’d use another format, too. And a subject that resembles a flat, golden mirror intuitively seems like the sort of thing that might produce banded color.

This said, once you have the other issues ironed out, I wonder something: If you retest the jpeg format with your subjects—with quality level set to “large, fine,” color rendering set to “neutral,” and in-camera sharpening set to “none”—is the banding gone?

Nikon’s jpeg engine is quite good, and I wouldn’t be quick to bet against it. I use jpegs when I can get away with them, raw files when I need them. BTW, if you haven’t tried Nikon’s NX-D software for raw conversion, it produces excellent results and is free. (It’s also somewhat buggy and has a clunky interface—but has good batch capability, which comes in handy for deep stacks.)
At first I thought this was due to variations in illumination, and tried a bunch of things related to such, including waiting longer for the strobes to recharge. I even monitored the 120VAC line voltage. I would pre fire the strobes to warm them up having read somewhere that the strobe color temperature can shift with internal temperature, and warming up can help stabilize the strobe internal temperature.
Flash is notoriously variable, no matter how careful you are with it. Rik made an interesting post that demonstrated random shot-to shot color variation with a speed light. Charlie made another interesting post on shot to shot intensity variation. My own observation (which in my foggy memory, accords with Charlie’s observation, but may not), the most variable flash units can vary 1/3 stop between shots; the least variable, 1/10 stop. This is true even with care given to fully recharge the capacitors between shots. I once had a set of flash units that demonstrated almost no variance, but they were old, are now burned out, and I have no idea why they were more consistent. Zerene Stacker handles this sort of variation quite well, but I prefer continuous light, which can be very consistent.
I use manual mode for everything, and am using an objective in front of a reversed Raynox....so no lens selection for AF.
For others who may read this thread, let me repeat for emphasis: With Nikon camera bodies (at least), even if the lens assembly has absolutely no provision for autofocus, you may want to turn autofocus off at the camera body. Otherwise, the camera may sometimes fail to fire if its autofocus system does not detect crisp focus—which can easily happen when focus-stacking.

Cheers,

--Chris

rjlittlefield
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Post by rjlittlefield »

Chris S. wrote:For others who may read this thread, let me repeat for emphasis: With Nikon camera bodies (at least), even if the lens assembly has absolutely no provision for autofocus, you may want to turn autofocus off at the camera body. Otherwise, the camera may sometimes fail to fire if its autofocus system does not detect crisp focus—which can easily happen when focus-stacking.
I will happily underscore this point. In fact the Zerene Stacker website's "recipe" for using Nikon with StackShot says
12: Be sure that camera body and lens (if any) are both set in manual focus mode.

The reason that comment is in the recipe is undoubtedly because I tripped over the problem myself, and had to struggle to figure out how come the thing wouldn't work.

--Rik

Inseewincesee
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Post by Inseewincesee »

Just a shot in the dark.
But check to see in your D800/e camera setting if you have 'Long Exposure Noise Reduction' set as ON.

I suppose it depends if you are using Live View On during creating the whole stack, if this might be your problem

What happens is, if this is set to ON, the camera will take another exposure with the shutter closed with the same settings , basically a black frame, the camera then tries to determine 'Hot Pixels' from this black frame, and tries to fix them before writing them to the card.

The camera might be overriding your stackshot commands to take this 'Black shot', thus putting everything else out of sync, causing the banding since the timing of commands will now be out of sync.

This is meant for Astro Photography, but when you think about it, I suppose it might kick in depending on something in the cameras OS that detects the actual sensors pixel state at any one time, over a 500+ shot stack, I guess that might trip it up.

I don't think it hard to imagine that the software could get confused when making that may shots in a row.

Maybe pre programming of slabs of stacks, then a partial shutdown, re start etc might fix the problem of hot pixels detection [is that is indeed what's happening], if turning off long exposure noise reduction doesn't seem to work.

mawyatt
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Post by mawyatt »

Inseewincesee wrote:Just a shot in the dark.
But check to see in your D800/e camera setting if you have 'Long Exposure Noise Reduction' set as ON.

I suppose it depends if you are using Live View On during creating the whole stack, if this might be your problem

What happens is, if this is set to ON, the camera will take another exposure with the shutter closed with the same settings , basically a black frame, the camera then tries to determine 'Hot Pixels' from this black frame, and tries to fix them before writing them to the card.

The camera might be overriding your stackshot commands to take this 'Black shot', thus putting everything else out of sync, causing the banding since the timing of commands will now be out of sync.

This is meant for Astro Photography, but when you think about it, I suppose it might kick in depending on something in the cameras OS that detects the actual sensors pixel state at any one time, over a 500+ shot stack, I guess that might trip it up.

I don't think it hard to imagine that the software could get confused when making that may shots in a row.

Maybe pre programming of slabs of stacks, then a partial shutdown, re start etc might fix the problem of hot pixels detection [is that is indeed what's happening], if turning off long exposure noise reduction doesn't seem to work.
Good point about the Long Exposure NR, I don't believe it was ON but can't say for sure. I just checked and it's off.

I have done a few tests the past few days and it appears the out of sync issue is related to the memory card write time and buffer overflow, but as you mentioned if the Long Exposure NR was on, this would increase the time when the camera was "busy".

Cheers, and Happy New Year,

Mike

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