Pentax Astrophotography Series | Part Five: Astrotracer
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- เผยแพร่เมื่อ 16 ก.ย. 2024
- Welcome to the fifth video in our Astrophotography series, brought to you by Pentax.
In this video our host Brad Le Brocque runs through how to use our unique "Astrotracer" function to create highly detailed, low noise shots of the night sky.
Stay tuned for future episodes where we dive deeper into not only the technical side of Astrophotography but also insights and tips on how to achieve stunning results.
Thanks for your tutorial! The entire 5-part astrophotography series was very concise but gave all the necessary information to shoot with my K1.
The 5 minute exposure time is really based on the amount of physical space that the sensor can move within. Depending on the focal length of the lens, your exposure time is going to also vary. Wide angle lenses will start to exhibit some distortion, particularly in the corners and the extreme edges after about 70 to 90 seconds. A lot of this is also going to depend on your shooting location and the direction you are pointing the camera. So, here are some suggested exposure durations based on focal length. These are just rough times based on some experimentation along with postings from the Pentax Forum
* 15mm to 40mm - 70 seconds
* 50mm to 150 - about 60 seconds, the longer the focal length, the shorter the exposure.
* 150mm to 250mm - about 30 seconds.
* Longer than 250mm - about 10 seconds
The Pentax astrotracer is really oriented towards the astro landscapes and the Milky Way core, essentially wide field astro.
With Astrotracer on a K-3II I have been able to consistently do 20 seconds for a 300mm lens and sometimes 30. With a 200mm lens, it is 40 seconds consistently and sometimes 60 seconds. Individual results can differ widely because the achievable accuracy of the calibration is a large variable. See www.astrobin.com/users/AlenK/
Hi. Thank you very much for the information on astrotracer tolerance. I would like to ask you if it is possible to configure and activate the Pixel-shift and the astrotracer at the same time.
@@SanchezCristo - According to the manual (page 107) you are unable to engage both at the same time. When you think about it - it makes sense for several reasons. The longest pixel shift exposure possible is 30 seconds - for astrotracking you want to go longer. Also, in that the earth is rotating, the stars will move. Pixel Shift does not work well when there is any movement. When nothing is moving you get an 4 frames with RGGB at each pixel location. If things are in motion, you are not going to be getting RGGB of the object in the frame, so it's going to throw everything off.
@@alenk738 I saw your astrophotography with the Pentax. Beautiful!!! May I ask what exposure time you chose for your M31 images w/ the astrotracer? Did you calculate read-out noise and background noise or did you just use the max. Exposure time that astrotracer allowed?
@@floryda4281 Late reply because I didn't check. If it still helps, I chose the longest exposure that got me round stars in every exposure (no discards). That varies from night to night, probably because of inconsistent calibration technique. It was 20 seconds those nights. But with such a short exposure I did up the ISO to 3200 in order to minimize read noise as much as possible. M31's core did not clip, so all was okay.
Thank you very much!
Thanks for this video. I just bought the Pentax Astrotracer (waiting for it to arrive) for my K-70. My question is, should I turn off the image stabilizer or leave it on? Thanks, Paul
It seems odd to me that OM System haven’t implemented this feature in the OM-1 / Mk2 or prior cameras, given that they obviously care about astrophotography with their Starry Sky AF mode. And considering their various computational and pixel shift modes like Hi-Res Shot, you’d think it’d be a no-brainer to implement Astrotracer.
I was wondering exactly the same! 😃
The sensor itself is on derotator that physically rotates the sensor to compensate?
Is that right?
Is it platesolving?
How does it know where it's pointing so it can apply the right correction?
I been shooting the stars with a canon 80 d I can't afford the full frame so my opinion is the kp or k70 what would you choose. Also in live view can you see you're setting change on the screen
Hey Tom, Both the KP and K-70 will offer similar image quality and require the use of the GPS module to take advantage of many of the features outlined in this series. Be sure to factor that in to your decision making when pricing them up.
The KP features a lot more external physical controls - very useful in the dark, and can be expanded with the optional battery grip to help give you longer battery life. Astrophotography is quite a drain on batteries, so this will allow the KP to shoot for much longer than a K-70.
The K-70 is obviously cheaper, but it also has the advantage of a fully articulating screen - useful for capturing a wide variety of angles and orienting the camera exactly how you want it. It's still fully weather sealed but the body is made from lighter materials, making it lighter but also slightly less rugged than the KP.
Overall, both cameras are equally capable for Astrophotography, much of the KP's advantages aren't necessarily required for Astro work (examples: more auto-focus points, more compact body). We doubt you'd be disappointed with either, each has strengths and weaknesses for different styles of Photography, but from a purely Astro perspective, they are both quite similar and will perform well.
Live View shows all your settings on the screen and can be customized using the user menus.
We hope this helps!
I’m interested in whether this works for deep sky stuff, like Andromeda or Orion Nebula? I have a K-3 and the GPS unit, along with a Sigma 70-200 f2.8, but I’ve never actually tried it.
I’ve seen some else say “yes it’s definitely possible” (Allen K I think), but I don’t know where to begin in terms of setup and workflow. Do I just locate the target, set it at 20 seconds and fire off a series of exposures, recentering for each one? Is it ‘hit and miss’ for exposure time, or is there some equations to use? So, if it set my lens (for arguments sake) at 200mm and f4, with an ISO of 400, is there some metric to calculate what the best exposure time will be?
I know it works best with wider shots, but I’m more interested in trying to get deeper sky objects, as the foreground blur thing with astrotracer seems to limit its practical application (without blending multiple photos in photoshop, which I don’t have. I just use Lightroom).
Will work well with both of those objects, attach lens, calibrate gps , Focus object carefully using magnified live view on a bright star ,centre object with camera on tripod, try iso400 to start, begin exposure and then re centre for next exposure. most important think is to get out there and have a go
@@zardos123ut Thanks for the reply. There’s very little info available on actual use / results with the astrotracer. I do know that other tutorials have used a 70-200, but there’s nothing out there for Pentax. If I get some decenct results I’ll do my own tutorial for others.
Help!! When I try to do calibration with the K1 ii (a rental) the GPS light goes out, turns off, as soon as I move the menu to precise calibration. So I cannot get calibration confirmation.
Hey Dan - that's definitely unusual behavior but unfortunately hard to diagnose. We are based in Australia but we highly recommend you get in contact with your nearest local service center to talk through the issues and hopefully find a resolution.
You can find a listing of all service centers around the world here: www.ricoh-imaging.com/inquiry/americas.html
Good afternoon! Can a Pentax 645Z camera shoot like this?
Do you know if the auto tracker can work at the same time when it’s on a tracking mount so you can track for for longer periods, especially if you tracker is a bit off?
Generally speaking, no - the module will still function, but it was designed to function with a stationary camera, so you will most likely produce undesirable results combining it with another tracking mount as there is no way for the two systems to communicate.
Astrotracer is indented to be used in place of a (simple) tracking mount, not in combination with one.
Is the default User-mode "Astrophoto" discussed anywhere? There's a lot of hype regarding Pentax's astro-photography capability, yet this feature seems to be totally undocumented. I find if I choose this user mode the LiveView screen becomes so dim as to be virtually unusable, necessitating reverting to a more "conventional" setting for actual framing and focussing. I've had the O-GPS1 unit for five months now and am still struggling to get consistent results from it :(
Sorry to hear you've had issues - it does take practice to get consistent Astrophotography shots and while the features offered by Pentax are aimed to make this simpler, there's still a great degree of skill and patience required. If you've watched all the videos in this series it should give you a good idea of how to get everything setup.
We recommend using the Manual and/or Bulb settings and following our videos if you really want to push your results to the next level. The Custom User mode is designed as a basic introduction to the Astro feature set, automating some of the functions to allow users to get familiar with it. Different lenses and shooting conditions may make these functions unnecessary and potentially hinder your capacity to achieve the consistency you're aiming for. The User modes are designed to guide you in the right direction, but we always recommend setting it up manually for the absolute best results.
Are you by any chance shooting from on top of a building? I have had issues shooting from the roof of my house and eventually found it to be due to the rebar interfering with the magnetic compass of the O-GPS1, just as it does with an ordinary old style magnetic compass. The direction indicated by the compass can be even 90 degrees off.
I managed to get decent shots anyway by carefully moving the camera to a location where the the compass indicates the correct direction. It is quite an inconvenience but I have managed to get reasonably good exposures at 10 seconds with a 500mm lens with only some two or three pixels of blur.
Out in the open there is no such problem and I always get perfectly tracked shots, though I have to make sure I am some distance from the car as even that tends to distort the magnetic field somewhat.
Also always remember to do the 'precise calibration' procedure just before you start shooting.
Does the external gps unit work well with a K50? I can see there's an Astrotracer option in it's menu. - thanks.
Yes, the Astrotracer software is virtually the same no matter which camera. Obviously newer cameras have slightly better performance due to upgrades in the hardware, but you can still get fantastic results with older cameras like the K-50
@@CRKennedyPhoto Cheers guys. Seems a lot more convenient than a small tracking mount which pretty much has the same time constraints unless you get into autoguiding. I’ll pick one up for the K50.
Do you know of any list which tells you how long you can shoot max with which lens? Haven't found anything like that so far.
It depends not only on the lens but also on where you are, in what direction and what elevation.
Thomas Hedlund yup, understand that, but I guess a list for different focal lengths would be a very handy starting point.
Example: putting the dfa 150-450 onto a K-1 should result in a pretty short duration - but HOW short can I expect?:)
I provided a general table based off of experience and various postings at the top level of the comments.
Hi. What Pentax lenses should we use for astrophotography. Pls tell
There are quite a few options available, and there are no lenses made specifically for this purpose.
The key things to keep in mind are that ideally it should be bright and often the wider the better (depending on what you're going for). The DA* 11-18mm f2.8 and HD D FA 15-30mm f/2.8 are both obvious options (depending on your camera). Being wide but also quite bright. However, even kit lenses like the DA 18-135mm f/3.5-5.6 WR are just as viable if you take your time and follow the steps in this series.
@@CRKennedyPhoto thank you
Irix 15mm works well for me. Samyang/Rokinon 14mm would be another option