Recording Time Should Be MUCH Simpler!

#1

All -

This seems MUCH more difficult than it should be - making good observations with a common DSLR camera. The problem appears to be getting a time within a tenth of a second.

The camera that I am using (which appears to be comparable to newer cameras) is the Nikon D200, which apparently records several times, all to a couple of decimal places of accuracy. But to set the camera you can only do it by hand - and I bet that it is not routinely possible to set the camera correctly to a tenth of a second. That makes us wonder why the camera can record to an accuracy that will never be reliable! The camera has a GPS connection but the GPS time is kept separately from the camera time - why does the camera not set it’s internal time from GPS!

I have talked to a couple of sources of drivers for cameras (latest one was AstroDSLR by Peter Polakovic).

Could people answer here with: what DSLR are you using? What drivers? Does anyone know of any DSLRs that set time from GPS?

Several people have talked about latency, USB saturation, etc but it seems that a tenth of a second should be something that a camera could reliably record.

I am currently using a Nikon D200 (older camera) and the provided control software but am going to try some of the available drivers in the next week or so. The camera records GPS time to the second only.

Charles

#2

@CharlesHouston - Another possibility is using a computer to read-out images from the DSLR. Images can be timestamped by the computer, which can be synchronized with Network Time Servers via NTP (often good to better than 0.01s). INDI has drivers for many Canon and Nikon DSLRs.

#3

Yes I am trying to figure out how to control the camera from INDI, etc drivers. This should be something that we could figure out!

#4

For now - I am going to try just taking photos where I have set the time by hand. After trying a couple of times -> setting the time, taking photos of my iPhone when it is showing very accurate (I am told) time - this seems to allow me to get time to about a tenth of a second. By talking to people on the Digital Photography Review web forums I should be able to do better. But I am S L O W L Y working through the procedures.

#5

@CharlesHouston The easiest way I would know to start with INDI and a DSLR, is how I did it myself - Download KStars, and configure it to talk to your camera. It has the added benefit of being planetarium software that can also plot satellites.

https://edu.kde.org/kstars/

#6

There are certainly better ways to do this but for now I am hand setting the time in the camera - I use an app from Emerald Sequoia to display accurate time. I get my 21 year old son (who’s reflexes are better than mine!) to enter the time into the camera. The observations work well.

Now I have to examine the time of the end of the exposure - a separate issue seems to be that the Nikon may be set to take a 10 second exposure but it actually takes a different duration. EXIFTool tells me the actual exposure duration.

#7

@CharlesHouston One way to test your method of setting the clock on the camera would be to take a picture of a known-accurate-clock with at least seconds (milliseconds even better). If your shutter time is exactly the same as the clock in the picture, you’ve set it accurately enough.

You really do have to find a better way than manually setting the camera though – most camera/video observers are able to get time accurate to better than 0.1s

#8

I certainly agree that I am NOT happy with hand setting the time, it just seems that this should have been solved a long time ago. If the darn camera has a GPS connection and records GPS time - why would Nikon NOT have had the camera set time from GPS??? Why does the camera record several digits of accuracy on time when there is no way to set the time that accurately???

I am talking to a prof that posts a lot on the Digital Photography forum for scientific photography and he might have a solution.

Now that I have seen that this can be done in this area it is time to pick out a better camera and lens.

I just submitted two observations on USA 267, object 41334, and this was at a greater range than the objects I tracked before. I didn’t think that I would get it, I was just there early looking for USA 281 and gave it a try. Then my darn camera battery died (it is the original battery) and I didn’t get USA 281 at all. :frowning_face:

#9

Now it turns out that the Nikon D200 can set its time from a computer - there is a setting in a little used menu that allows that.