[Ducky13]

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@MossyRocks thank you so much.

Is an intervolometer the same thing as a remote shutter?

The one that you posted doesn't seem to be available in the UK. Do you reckon the alternative that I suggested would do the job?

[interested_observer]

Thanks all. Any recommendations for an inexpensive wired shutter release that will hold the button down? I found THIS on Amazon. Will it be sufficient?

Thanks @interested_observer. Unfortunately that one isn't available. I've found an alternative (see above), but not sure if it's suitable. Any thoughts?

Yes, that one will work too. Notice the dark arc above the button in the images. That is where the button will slide to when you depress the shutter and slide it to maintain it in an active engaged state. Also, if you click on the bottom video, it indicates that you can lock the shutter this way. You really do not need to be in bulb mode to lock it. It should lock in any of the camera modes.

Also as pixelsaurus posted...

You could probably dispense with a self locking cable switch by reprogramming the shutter release button in B mode (page 51 in the KP Users Manual. You will find it in the Custom Menu, ( item 7 on a K70 : Bulb (B) Mode Options), set it to Type 2 - it will push to open, push to close. Back in the day, it was designated T setting.

Setting the push to open, push to close will work also, and will also work with a remote shutter. I use both together on my K1. The less I touch the camera body while the shutter is open the better.

[Grimmus]

For doing star trails I am not a real big fan of intervolometers either built in or external as there is a delay between of 1 to a few seconds typically between shots. Depending on how point like the stars are and what focal length is used this may result in start and stops in the trails. You are correct in that they would allow for several minutes of exposure but in that case a bad single frame (god knows I have gotten a lot when out at night) would make a big gap in the trails.

100%. I can see the advantages in using continuous shooting and this is definitely a lower risk way of composing the trails. If something goes wrong with a frame, you only have to throw away 30 seconds, which will still leave a gap but may not be terminal for the image. It also gets rid of having to calculate or test to find the minimum interval you can adopt for saving the image if you use the internal intervalometer (except on the Kp where you can choose minimum). The stupidest thing I discovered while testing and making mistakes is that a 15 second exposure is actually 16 seconds and a 30 second exposure is actually 32 seconds ..... got lots of really gappy trails finding this out (why camera makers object to using the actual shutter duration escapes me?).

But you can make it work with the internal if you want and the question is really whether you want to risk a 30 second gap or a longer gap if a frame goes wrong - a lot of night stuff seems to end up with questions of risk and reward (and equipment procurement ).

The image below was with the K-3, you can't set minimum so the interval was set to 33 seconds and the shutter to 30 seconds (32 actual seconds) so produces a 1 second gap - which is pretty hard to spot at 100% (35 mm lens, f5.6, ISO800, 60 frames stacked).

[MossyRocks]

Is an intervolometer the same thing as a remote shutter?

The one that you posted doesn't seem to be available in the UK. Do you reckon the alternative that I suggested would do the job?

An intervolometer is a more capable remote shutter control. It can be set to take X number of pictures that are Y in length with Z time between them. Often times they have an option for an initial delay period that can be set. There are other options they support as well but they are handy. The one I posted also has a regular shutter release button and the ability to hold the button down so you can also use it as a regular shutter release cable.

That shutter release looks like it may work. the biggest things is making sure that the part that plugs into the camera is the right connector. I know on the K-3, K-3ii, k-3iii, and K500 that the connector is a 3 conductor 2.5mm plug. That one says it is for the K-70 but looks like it is a 3.5mm (the more standard headphone plug) connector. It may be that that K-70 uses a 3.5mm connector instead of the traditional Pentax 2.5mm one but I don't have a K-70. .

[Ducky13]

Hi All, so I had a somewhat clear sky last evening, but my first attempt wasn't great. I use a wired release cable to take a sequence of night sky photos over the course of 35 minutes. I've attached one of the photos (resized) to this post (see attachment "Example for PF"). You can clearly see the stars even though there was quite a bit of ambient light. The settings that I used were -

• 15mm lens
• Manual focus (set to infinity)
• F6.3
• 30 seconds exposure
• 100 ISO
• Drive mode set to high speed continuous
• Slow shutter noise reduction off

I then followed these steps -

1. Deleted a handful of photos in which an airplane flew overhead
2. Loaded the remaining 38 photos into DeepSkyStacker - By default they were "light" files
3. I had also taken a couple of photos with the lens cap on with the same settings, as per MossyRocks advice. I loaded these into DeepSkyStacker as "dark" files
4. Clicked on "Check All" and then on "Stack checked pictures"

The final result is attached - See attachment "Stacked for PF". I wasn't expecting any spectacular results out of this as there was plenty of ambient light, but I thought that I would at least see some faint trails, but the stars look static. I have a feeling that I am missing something very obvious here

Any advice or insight on what I am doing wrong?

Thanks,
Ducky

[Grimmus]

I have not heard of Deep Sky Stacker (DSS) being used for trails. DSS is typically used for aligning images of deep space so I would assume that it has overlaid all the stars on top of one another as it is meant to and hence you have points for stars. Try Startrails. StarStaX or Sequator - all free for PC. DSS creates dark images that typically need "stretching" to get out the detail.

Shooting at ISO100 and f6.3 is too low (suggest you go to 800 at least) - you may need to push all of your frames by 2 to 4 stops before stacking. If you do this in Lightroom, then you have to export the pushed images for use in other 3rd party software like the programs listed above.

For a more manual method, put all your images into GIMP or Photoshop as layers and set the blend mode to lighten as per @Mossyrocks method above.

[gifthorse]

Hi, Ducky. Your images are very underexposed. Modern DSLRs will easily handle 1600 or 3200 ISO. I'd suggest ISO 800 as a starting point and be ready to increase the ISO if needed. At to the "static" appearance of the stars, you focal length is too short for the length of the exposure. According to the 500 Rule, the stars won't begin to trail until 23 seconds of exposure. If you are limited to 30 second exposures, use the DA 50. It will triple the (apparent) length of the trails.

[Ducky13]

Thanks both. Very useful tips. I don't own photoshop or Lightroom, but will download one of the software options that you listed and revert back with my second attempt.

[Ducky13]

It's pretty overcast today, so I'll try taking a new batch with the suggested settings whenever it clears up next. In the meantime, I downloaded Startrails and loaded the same sequence of photos. The results are more in line with what I expected (see attached), but I don't understand why the trails are so squiggly. Agreed that my tripod isn't top of the line, but it's definitely not that bad and it wasn't windy at all. Any camera settings that might be causing this?

[Grimmus]

I haven't come across something like this. I have used a light travel tripod and it was fine. The wonky trails are a mystery to me and I can only offer a couple of wild guesses:

• Avoid touching or refocussing during shooting as focus can cause minor changes to field of view even on primes.
• Assuming your tripod is on something solid (really clutching at straws here - sand? verandah?)
• Make sure all photos for stacking are treated identically and do not use lens corrections, cropping or level adjustments before stacking.
• Shake reduction off (I think this happens automatically for 30 second exposures)

I very much doubt these are the issues. Also suggest don't throw away any frames and just live with the plane trails or whatever until the technique is down pat. Keeping them all may help work out what is going on.

GIMP is free and takes a while to work out but is very powerful if you don't want to pay a monthly fee to Adobe - some form of layer and mask control software is nearly essential once you start playing with photography in the night. I use an old copy of Lightroom (before monthly subscription was the only way to go) which allows me to process 1 image and then sync changes across all before stacking which greatly helps trial and error that seems to be a big part of learning night stuff.

[Ducky13]

Thanks Grimmus. I went through the settings are noticed two things that were on that should probably be turned off -

Shake reduction (although this should be disabled automatically for long exposure, as you mentioned)
Astro tracer - This option was on. Perhaps this is what was causing the squiggles. I've turned it off now.

Hopefully my next attempt will be better. Hopefully I'll have a clear sky soon.

[Grimmus]

Astro tracer - This option was on. Perhaps this is what was causing the squiggles. I've turned it off now.

That could be it. If you had it on but not calibrated then it could be telling the sensor to do strange things during exposures - OGPS unit probably better in your pocket when attempting trails . It might also explain the leaky smears along the bottom of the frame which confused me and the occasional points of light in the trails. It still amazes me how many things can go wrong, or how many settings there are on modern DSLR's that stuff up things during night photography. Isn't there a saying about not progressing if you're not making mistakes......probably coined by a night time photographer? I've got a few Gb of mistakes on my hard drive, for reference about what not to do.....but still finding new ways to stuff things up!

[Ducky13]

Getting better

At least the trails are straight now.

[Grimmus]

Looking good!

Not sure what your settings are but more exposure (aperture or ISO still required) - you can push 3 or 4 or even 5 stops in post with the ISO invariant sensors that Pentax use - try to get the histogram off the left hand wall (about a quarter of the way across for the big peak representing the dark sky). Do this before stacking although some of the star trail stacking software allows you to add exposure during the stacking. Avoid blowing out the colour in the stars though. The Kp does produce a bit of purple amp glow at the bottom so the dark frames help.

[gifthorse]

Good job! It looks like you've got a handle on star trails. The trails will be straighter when the camera is aimed to the east or west. Aiming the camera to the north or south will produce lines that are more curved . You mentioned that you are in the London area. It is possible to shoot star trails in urban areas. This image was taken about 5 km from downtown Reno, Nevada.

I unfortunately don't have the exif data but it was taken with a 200mm Super Takumar on a K5ii. At a guess, it is probably around 20 one minute exposures stacked in Startrails program.

If you get bored with star trails you can do long exposures of cars


airplanes


and the International space station