90D Live Shooting vs Interval Timer

[skibumdon]

I sometimes do astrophotrography on my 90D  with 1 sec exposures (I don't have the sky-watcher yet for my tripod). When I go through the camera settings menu, I notice that with the mirror down, on page 5 I have interval timer available, but if I put the mirror up to lessen vibration, this option disappears. Can anyone explain why?

If I buy an intervalometer "Vello ShutterBoss II Timer Remote Switch for Canon with Sub Mini Connection", will I be able to shoot live (mirror up)?  

I probably will by the sky-watcher so I can move from a 1 sec exposure to 30 sec, then this is not as much of an issue.

[jrhoffman75]

I think that mirror lockup behavior is a safety feature. If one forgets that the mirror is up the shutter and sensor could be damaged if the camera is pointed at the sun. The 1D X Mark III has an option to control mirror down by the Set button.

Have you run tests? 1 second is generally long enough to not be affected by mirror bounce.

[Waddizzle]

The behavior could be a safety feature.  I could not say one way or the other.

When you using mirror lockup mode, the shutter button must be fully pressed twice for the camera to fire the shutter.  Once to raise the mirror.  A second time to fire the shutter, and release the mirror.  The mirror does not stay raised.  

The internal interval timer blindly simulates a single press on the shutter button at whatever interval that you set.  I have always thought that this was the reason why the internal interval timer would be disabled whenever you enabled mirror lockup mode.  

As for your wired remote, you might be in the same boat.  One button press per interval, not two.  I recommend downloading the User Manual to see how it is programmed.  This is a best practice for any purchase that you are considering.

[skibumdon]

I went over to B & H and asked the question after bringing up the intervalometer.  Next clear night, I will try again with a 5 second delay between the photos, and perhaps I will order the tracker and move to 30 sec exposures

[jrhoffman75]

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@skibumdon wrote:

I went over to B & H and asked the question after bringing up the intervalometer.  Next clear night, I will try again with a 5 second delay between the photos, and perhaps I will order the tracker and move to 30 sec exposures

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Are you doing deep sky astro? What tracker are you considering?

I shoot Milky Way and use the NPF rule for spot stars.

For star trails I use a four minute exposure and take a total of 20 exposures.

[skibumdon]

Yes I am just starting out. If I do order a tracker, it will be Sky-Watcher Star Adventurer 2i Pro Pack.  One of the videos I watched compared shooting a nebula with and without. Without his calculation was about 1 sec per and with he found he could go to about 30 sec per before the individual image degraded. Total exposure time of the two methods was the same and he used deepskystacker to merge. With the Sky-watcher he was able to pull a bit more detail out of the nebula. Here is the video I am talking about:  https://www.youtube.com/watch?v=mYucAuUrdTs