[Lew Dite]

How can I get a mirror-up delay with an external, wired intervalometer? Triggering the shutter through the wired remote port seems to ignore any of the delays I would normally choose when using the shutter button or an IR remote. I must be missing something obvious.

[stevebrot]

The remote shutter release works identically to the shutter button. Set drive mode to the 2s delay and it should work fine. At least that is how I have used it with my wired intervalometer. (Be sure to take the 2s delay into account when calculating the interval timing.)


Steve

[stevebrot]

Continuation...

If you want the mirror-lock-up function, you may be able to set the interval to 1/2 your desired with double the number of shots. Trip the mirror up on the first release and the shutter on the second.


Steve

[Lew Dite]

Thanks. I just tried it and it worked as you said in your first reply (I had no real doubt). I should have mentioned that when I couldn't seem to get it to work, I was using it in the dark for astrophotography (Astrotracer). I must have failed to switch the shooting mode to the 2-second delay, as I most often use an IR remote with Astrotracer and hence choose the IR remote 3-second delay. It's easy to make mistakes in the dark.

Luckily, I was using a very sturdy tripod and a 28mm lens, so I doubt lack of a mirror-up delay made any perceptible difference. But if I had been using a 300mm lens it might have been a different story. (My link on "300mm", not an auto-generated link.)

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Last edited by Lew Dite; 07-27-2020 at 09:15 PM.

[bwgv001]

nice pic of andromeda nebula; congrats

[AstroDave]

But if I had been using a 300mm lens it might have been a different story. (My link on "300mm", not an auto-generated link.

Nice Andromeda shot. Were you binning the pixels (3 by 3) in the composite? The Astrometry.net scale reported with your image is 8.750 arcsec/pixel . I have measured the scale of my K-3 and DA* 300 mm (also with Astrometry.net - here's a blurb I wrote about its use a while back: Easy Determinations of Camera Scale Factors (arcseconds per pixel) - PentaxForums.com ) and get a scale factor of 2.765 arcsec/pixel - about a third of your value.

By the way, while I do the full mirror up/2 second delay routine when astro-shooting, I think the concern here about blurring is a bit overblown. The time for the camera to settle is a fraction of a second, which is quite short compared to, say, a 20-second or more exposure. You won't see much of an effect on the image. Equally useful is to hold a black piece of paper in front of the lens as the exposure starts and then moving it out of the way as soon as the shutter opens.

[stevebrot]

The time for the camera to settle is a fraction of a second, which is quite short compared to, say, a 20-second or more exposure.

Yep...The blur contribution of that first bit is tiny.


Steve

[Lew Dite]

Nice Andromeda shot. Were you binning the pixels (3 by 3) in the composite? The Astrometry.net scale reported with your image is 8.750 arcsec/pixel . I have measured the scale of my K-3 and DA* 300 mm (also with Astrometry.net - here's a blurb I wrote about its use a while back: Easy Determinations of Camera Scale Factors (arcseconds per pixel) - PentaxForums.com ) and get a scale factor of 2.765 arcsec/pixel - about a third of your value.

The pixel scale is result of a 50% downsizing and then a crop. I downsized because I was using a 32-bit version of rnc-color-stretch to do stretching and it couldn't handle the full 24 MPixel frame. I didn't really need to downsize that far (to 6 MPixel) but that also made rnc-color-stretch run faster. I now use the 64-bit version of the program (actually, of Davinci, which rnc-color-stretch requires) and don't need to downsize. The additional crop was probably to get rid of edge artifacts from stacking but also for aesthetically pleasing framing.

By the way, while I do the full mirror up/2 second delay routine when astro-shooting, I think the concern here about blurring is a bit overblown. The time for the camera to settle is a fraction of a second, which is quite short compared to, say, a 20-second or more exposure. You won't see much of an effect on the image. Equally useful is to hold a black piece of paper in front of the lens as the exposure starts and then moving it out of the way as soon as the shutter opens.

Like you, I am just being safe. I have actually triggered the shutter using my finger when using a 200mm lens and seen no effect in the image. But the mirror-up delay costs me only two extra seconds per shot, so why not? As for the black paper trick (ages ago they used to talk about using a black hat), shooting a hundred or more subs with Astrotracer is enough work already!

Shooting the moon through a 762mm telescope, on the other hand, definitely needs mirror-up delay. It could also really use an electronic first-curtain shutter but the K-3II doesn't have that and never will. (I think we saw what will be the camera's last firmware update some time ago.) However, I have been successful with Pixel Shift Resolution a few times.