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will a faster tablet let me have less dark time?

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#1 chasg
Hi All,

I'm having a problem with skipping frames when shooting sequences controlled by qDSLRDashboard, and I'm wondering if a faster tablet would help.

Recently, I shot a sunset sequence with a 9 second interval, with a max shutter speed of 6 seconds. There were about 20 skipped frames (not all together). The end of the sequence is useless :-(

The camera is a Nikon D750 (using smallest jpegs for transmission, auto-review turned off) connected with a TP-Link MR3040 to the tablet: a Google Nexus 7 (2013) with 16GB of RAM. One place I could be getting a slowdown is with the tablet (it's pretty old). 

Would it be worth it for me to get a newer (faster) tablet? Could I save a second or so?

Thanks in advance for any advice.

Chas
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#2 gwegner
Honestly, I don't think so. I'm using the same setup: D750, nexus 7 2013 and can work with 1 sec dark time. Only difference is that I'm using the internal Wifi. I guess it must be something else. Check the RAW files also, I mostly shoot with Lossy Compression. Use a fast SD Card. The less time the camera uses for saving, the more time it has for the preview transfer.
Use an external timer as well, best would be a LRTPTF https://lrtimelapse.com/lrtimelapse-pro-timer-free/ or another timer with the hack explained here: https://lrtimelapse.com/news/intervalometer-hack/
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#3 chasg
Thanks Gunther, for the informative answer. I have both the D750 and Nexus 7 (2013) because of your advice :-)

Today I had a successful shoot (no skips), but it's likely because I maxed out shutter speed at 5 seconds, with a 10-second interval. That's too long of a gap, for my tastes.

I was wondering if the internal wifi would be faster, but that's a lot faster. The only reason I haven't used it in the past is, if I lose connection to the camera for any reason, it seems like the internal wifi then turns off, and I have to stop the sequence to reconnect (it's rare, usually due to me not noticing how low the tablet battery is).

The card I'm using is fast, could perhaps having the camera save to two cards (they're identical) be an issue?

I shoot lossless compressed raw. I've never done a test with lossy raws. You're obviously happy with them, I take it you don't see a practical difference between lossless and lossy?

One thing I should have noted is that the camera is being driven by a DP NMX, so I can set the focus signal time to what I want (Jay at DP has suggested I set it to 0.5 sec, and trigger to 0.2 sec). But, for my other cameras, I already use the cable hack (I'm actually the one who posted which variation worked with Sony cameras). That said, I'm definitely preparing to build a few of your awesome intervalometers (I'm going to shoot more astro this year, and I want interval-ramping for that).

Ok, next sequence I'll definitely be using the internal wifi, and I'll try lossy raw. Many thanks for the tips!

Chas
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#4 gwegner
I always leave the table close to the camera and normally the internal wifi does not get lost when shooting. Of course, when shooting in areas with many WiFi accesspoints (cities) it might be better to go for the USB connection via OTG.

I never use two cards in parallel (why would you?) - try just configuring the camera to use the second card as spare.

There is not much difference between lossy and lossless raw. But the files will be half the size, this will speed up performance of writing (and processing).
OK - NMX is cool, your config too. Normally you should get much better performance with your setup.
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#5 chasg
good advice, all.

OTG on my most recent shoot (which I'm repeating tonight) would be tough, due to the position of the slider (over a river :-)). But I do have OTG adaptors, just in case, as most of my shooting is in London, radio-interference central! (this is why I try to keep my tablets as close to my cameras as I can).

And I always use two cards in parallel. I've had cards fail on shoots (besides, timelapse, I'm a commercial photographer), so two cards is a safety measure. But, to cut down on dark time, I'll use just the one, thanks for the advice.

I'm going to do some tests on lossy vs lossless. Speeding up performance is a big deal for me at the moment, so I'll shoot lossy this evening.

This camera was repaired after a fall last year. Given the very long dark time issues, I'm wondering if that has anything to do with it (an impossible question to answer, unfortunately, unless I acquire a brand-new D750 to test against, LOL).

Thanks again, I'll let you know how tonight's shoot goes with all the changes to my workflow you've suggested.
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#6 gwegner
I'd recommend to test all this at home doing some experiments. Don't try new setups on location when you have to "deliver".
Just try all the scenarios, check the differences. I don't know, if 1 or 2 cards will make a difference, you'll have to test it.
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#7 chasg
Well, it started raining, so I'm having to test at home anyways :-)
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#8 chasg
I've found a few references in various blogs to D750 slowdowns when writing duplicate images to two cards (backup mode). One post says this is because the camera writes to one card, and then to the other (it doesn't write to both simultaneously). If this is true, it'll be a big reason for my frame-skipping. I'll see if I can find an official Nikon confirmation of that.

Good call on your part.

Next I'm going to do tests with a stopwatch (shoot a bunch of shots, and time how long it takes for the camera to write to a single card, and then test to two cards).

Chas

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