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After a failed attempt the other night when clouds snuck in under the radar, I finally found relatively clear skies last night on the beach! It was just below freezing and a pretty good offshore wind with 20+ mph gusts (and blowing sand EVERYWHERE). Even though I parked my jeep in a strategic location and tried to use my (shivering) body as a wind/sand break to protect the camera, the wind still made things difficult so my shots aren't as sharp as I wanted... I took 50 exposures last night and kept four that I thought were good enough to share. My tripod is relatively light weight, built for packing, and I should have brought a hand weight or a bag full of water bottles to help steady the tripod. I know I saw some recommendations for sturdy tripods that might be more suitable for long exposures in the wind, hopefully without breaking the bank, but I can't remember where I saw them!

Anyway, last night was really an exploratory mission using the 55-300mm F4.5-6.3 ED PLM WR RE as an astrophotography lens, particularly at the long end on my K3ii. All single shots, various settings used. It seems to produce pretty good results (it's currently my longest lens) but an older manual might have been better as the manual focusing ring on the PLM is electronic and spins forever (without any sort of stop for infinity) and turns perhaps a bit too easily for this purpose, for my tastes anyway. Luckily I had the light of a fishing boat near the horizon which I used with some success to *carefully* set my focus in magnified live view. A more calm night and I'll try my hand at stacking a collection of much shorter shots with it.

A few photos and then a few questions! Basic PP including a small crop here and there, profiled Noise reduction, proper white balance ("spot" instead of "camera" in Darktable) and a watermark.

I took the 16-85 out initially with plans of using the wide end for a stack of Milky Way but the wind (and cold) blew my plans. I DID use it for this wide angle of Orion and Taurus. 30 seconds at 16.0 mm, ƒ/4.0, iso 1600:



Climbed back into my jeep (with the heater on high), and after *carefully* shaking off any loose sand on the K3ii and myself, switched over to the 55-300 PLM. A bit of focus calibration and:
Pleiades, "the shoulder of the bull", 30 seconds, 300.0 mm, ƒ/8.0, iso 6400:




Orion's belt: 10 seconds at 98.0 mm, ƒ/4.5, iso 1600:




And the shot I risked hypothermia to get, M42: 30 seconds at 300.0 mm, ƒ/6.3, iso 1600:




I was pleased with the performance of my K3ii and the GPS/Astrotracer worked surprisingly well although it did not ask to be recalibrated(?) Should I have recalibrated anyway?

Without thinking about it I did my default tripod-nice-weather habit and had shake reduction turned OFF. Does it improve things with the astrotracer to have it on? Might it have improved the blurring caused by the wind?

What's the proper technique to shoot say, 30 images of the same exposure, perhaps 20 seconds each, with the astrotracer? Do I have to remotely release the shutter for each exposure or is there an in-camera method that will work in Bulb mode? 30 x 20 seconds is five minutes. Should I have to recompose somewhere during the attempt or will DSS (or Sequator?) handle a proper alignment?

I too am looking for a post processing workflow tutorial for astro, ideally using free software. Particularly I am concerned about shooting at higher ISOs as it seems to just introduce noise that I later have to remove, potentially damaging the sharpness (specifically DSOs)? What am I missing here?

Thanks in advance for any comments, tips, tricks and suggestions.

Huh! I almost threw this collection away because of the light pollution! I seem to have caught Andromeda! Not bad for a 16mm FL and around three minutes of combined exposure! Five images shot with the 16-85, wide open, different exposures, stacked in DSS.




100% crop:

You are getting there. Wind is your enemy as you found out. It was probably going to sabotage your focus even if you had managed to nail it. I love the wide shot showing the city light domes. And it shows the Double Cluster in Perseus near the top left as well. I also have the 300 PLM but gave up on it for astro since it exhibited too much CA for my tastes. My DA*300 is much, much better in this regard.

Those lights aren't city lights... the yellow ones are from a fishing boat, out on the horizon. The white ones in the lower right is some idiot baha'ing around on the beach with enough high intensity light bars to illuminate a small town. Five different shots caught him in five different positions. The glare from his lights reached center of frame in some of the shots and was the main reason I almost trashed these.

Really looking at the D FA 150-450mm myself, as birding (BIF specifically) is also a passion. Maybe try the 1.4x WR rear converter first.

I can't say for certain that AstroT disables SR, but I sure bet it does. And yes, you don't want SR when shooting long exposures from a tripod.

I got started with the Milky Way tutorials on lonelyspeck.com, and recommend those.

Stacking is nothing more than taking many measurements at each point and using the average. (Yes yes, kappa-sigma clipping and median replacement, fine -- it's essentially an average!). Noise is just variation around the "true" value for a pixel. And since you can average a lot of integer photon-count values to yield fractional floating-point ones, you can actually gain effective bit depth, yielding smoother tonal gradients.

Deep Sky Stacker and Siril are both free. For landscape work, you will want to shoot at least one frame with AT turned off so the landscape is nice and sharp, and then composite that with the stacked star images.

Some Milky-Way processing links I've found useful:

How to Photograph the Milky Way – Lonely Speck
How to Photograph the Milky Way - A Detailed Guide for Beginners
. This one uses Photoshop, but the principles remain the same for other programs.

I cannot recommend this book highly enough if you want a good grounding in the principles and techniques of long-exposure low-light astrophotography: Charles Bracken's The Deep-Sky Imaging Primer. It is aimed more at the telescope-and-equatorial mount crowd, admittedly, but he does a superb job explaining the physics and how it relates to photographic technique. For example, where does the noise come from, and how does stacking ameliorate it?

I'm still stuck on finding the ideal pentax work flow for shooting a stack with the astrotracer. I have an IR blaster app on my phone, which of course means keeping it pointed at the camera for the duration of the stack, and I just bought a JJC TM corded remote as well but for the life of me I can't seem to figure out how to get it to reliably work with my K3ii. I also have a flucard installed but wondered about it's wifi transmission further messing with the accuracy of the astrotracer so I haven't bothered trying to shoot a stack over wifi (yet)?

So far the most reliable method for me seems to just press the shutter button on a 2 second timer, for each exposure. Wait for it to get done, press it again. This seems like a pretty primitive way to take what should be a fairly straight forward "Switch to B(ulb) mode -> calibrate Astrotracer -> mount on tripod -> find focus -> align on target -> set program line including X seconds of exposure done N amount of shots -> start shooting"?

I can't help but wonder why Pentax hasn't included some firmware update that beyond switching with the o button from B(ulb) to timed astrotracer exposure allows one to also set the number of exposures to take with the given parameters? Further, this would seem to be quite useful integrated with the "mirror lockup" mode.

The JJC TM remote has delay, bulb exposure, interval, and number of shots, but no matter if I have "Bulb" mode on the camera set to 1 (expose as long as shutter button is pressed) or 2 (press once to start exposure, press a second time to end exposure) I can't seem to get it to take N number of shots. Say I'm trying to shoot a stack of 10 shots, each 20 seconds long... I can set the bulb mode timer on the remote for 10 seconds ("Bulb" also set on the astrotracer function, not timed exposure), set interval for 21 seconds (since it seems to shoot more reliably with that extra second in there, between exposures) and I've tried setting the number to twice the exposure I want so it sends the K3ii two shutter presses for Bulb mode #2. I can get it to work... sort of. But sometimes, especially with longer exposures, it's like the K3ii loses sync with the remote and it messes up the number of shots.

Ideas? Suggestions? Shared experience?

A new stack from last night... a bit breezy, less than crystal clear, but I made do. K3ii + 55-300 PLM, 10 x 20 sec @ ISO 1600

I know the detail is there but finding the best pre and post techniques is proving quite the challenge!

Did you mean to say that you set the bulb timer remote to 20 seconds, not 10? That would make more sense if you want to take 20-second exposures. Regardless, I am not suprised you need an interval of 21 seconds for a 20-second exposure since there needs to be some delay between closing the shutter and triggering the next exposure. For more reliable triggering, I would actually increase the delay to two seconds, just in case there really is a timing difference between camera and timer.

In any event, I see no reason for you to avoid timed-exposure mode in Astrotracer. If you use it you won't need bulb mode on the timer. Just send out a normal shutter trigger every 22 (say) seconds, with bulb mode on the camera set to 1.

With Astrotracer and a telephoto lens, triggering multiple exposures automatically with a timer is less useful than you would think. That is because every two or three subexposures you should really re-center what you are photographing in order to minimize the cropping you will need to do after you stack your subexposures.

To amplify that: The sensor shift compensates for the apparent motion of the stellar field during an exposure, but then it returns to center for the next one. So the object has moved 15 seconds of arc per second of exposure time, as well as during the interval between exposures. So as he points out, you need to keep manually moving the camera on the tripod.

At 300mm that's somewhere in the neighborhood of 4 pixels per second of exposure.

To add some info on processing images here is a series of video tutorials on deep sky image processing that I wish I had found earlier.

More info I should probably become familiar with.

Thanks guys! It is discouraging to try and blunder one's way into a new hobby, especially when it involves very late hours in the middle of winter

I know the PLM isn't the ideal lens for DSO and I fear the 150-450 that I'm drooling over for BIF won't be much better. Maybe I need to find an older 300 prime, at least something with a hard stop for infinity?

That's what I was hunting for when I got some Christmas money and bought the Stellarvue instead. I'm imaging at 336mm these days, so that focal length will let you bag a LOT of really tasty deep-sky objects. I was unable to find a 300 or 400 on the cheap, but you might get luckier. I did some work with a Tamron 500mm mirror lens; not exactly APOD quality but surprisingly effective. Didn't get anything good with that till a friend let me use his iOptron Skytracker, though, the Astrotracer time on that lens would have been a handful of seconds at best.

E.g.

I guess the one I have on Astrobin is a better edit: M31 ( fewayne ) - AstroBin

Wow, that shot is gorgeous. Last week I took a look at old lenses and I was wondering if the 200mm f/4 was good for astrophotography. Then I discovered about the 500mm mirror lens, it interested me at the beginning, but I was not really satisfied with with images I have seen on the Internet.
The image you got really changed my mind. I may look forward buying one of those in the future.

WOW! THAT was with a 500mm mirror?!?!? I haven't been impressed with terrestrial photos that I've seen taken with the 500mm mirrors but maybe astro is it's sweet spot?