Astrotracer

rcolman · 09-21-2016, 09:20 AM

With limited test runs on a K-1, there are several factors:

1) Astrotracer movement - the sensor has to be moving in a rectalinear fashion, so, without an equatorial movement you are always going to get some AZ-AL errors and they build up as exposure time lengthens

2) lens - I like to shoot 20 mm and below to fisheye. The lens will always have distortions, particularly towards the edges of the frame.

3) declination - the further away you are from Polaris, the more movement for a given time. So, if you are shooting close to the horizon, like me, there are more issues.

Unanswered questions:

(1) If you put your camera on a mechanical tracking drive, AND then turned on Astro-tracer, would the internal camera function further compensate for mechanical drive errors, and give you even more time, or just make a big mess.

(2) how sensitive to camera calibration and GPS errors? Could you input more accurate GPS coordinates and get better performance?

That said, stacking many 60-sec exposures can provide spectacular results under dark skies, like the enclosed. this one is a stack of 31 exposures. [wrong date on logo] (notice the horsehead nebula peeking out ... here horsey ... want carrot ?)

Last edited by rcolman; 09-21-2016 at 09:27 AM.

Paul2660 · 09-21-2016, 07:22 PM - **2 Likes**

Astrotracer, was one of the main reasons for my move to the K1 from Nikon. I did not want to purchase a tracking base, due to added weight, and setup times.

Overall, I have to say that it's a very impressive feature, and can produce some excellent images of the night sky.

Main limitation I have found is that the for my locations I need 15mm to 20mm for night sky and foreground. Mainly using the 15-30 in the 15mm to 20mm range, F 4 to F5. 1.5 to 3 minutes ISO ranges from 800 to 1600. The rectilinear nature of the 15-30 does force you to have the Milky Way in the center of the shot, or it will blur as you move to the edge. The stars of course trail also no mater what, but for my work, that just adds to the nature of the shot as the trails are not a long as a normal 2 minute exposure.

When in focus the details are amazing. Vastly superior to anything I captured with Nikon or Canon in the 20 second range at ISO 3200 up to 12K. Tried the stacking methods also, which helps on noise but just adds a lot more work and still can't beat a single 2 minute exposure. Plus this type of work requires a fast lens in the 1.4 to 1.8 range and most of these in the 14mm to 20mm range have coma issues. With the Astrotracer, you can now be in the F4 to F5 range, which also helps on over DOF and composition.

Have learned that you need to calibrate the GPS from the Astrotracer screen, not the GPS screen as the two calibrations don't seem to talk to each other. So far have not had any problems with the GPS locking and staying locked. Calibration is always something that is a bit tricky as doing it with a camera strap on is impossible (at least for me).

Results just keep improving, my only issue is the dark band I get at times at the top of the frame. Not a light leak, but appears to be a known issue on some K1's. But the fixes I have seen make the band look even worse at times, so I will just live with it for now.

Vertical shots work great also.

Paul C

rcolman · 09-22-2016, 09:27 AM

Very nice shot! I particularly like the contrast of the white cliffs with the black starry sky. I do have questions and comments if you wish to continue this part on PM.

I would not agree with you about stacking. It is a routine part of both amateur and professional astrophotography, and would not be in such heavy use if it did not provide mega-benefits. In terms of noise and detail renditions, I can beat the "pants" off of any 2-minute exposure with a small number of stacked images. It is, however, a pain when including landscape foregrounds. Lucky for me my S.O. (significant other? starry other?) is a photoshop addict and does the hard part for me. I have also just started exploring "starry landscape stacker" on a Mac that emphases the foreground part, and easier to use.

I have owned the Tamron 15-30mm and rented the super-high price Pentax version. The performance is almost there for astro landscapes, but not quite. F2.8 is marginal. There is some astigmatism towards the edges of the frame. Worst of all, I can barely lift the lens + camera, which weighs in at about 4.5 lbs. let alone take it onto a hike.

Below, there is a K-1 image take with a tamron 28-70 zoom at 70mm (not exactly a "stellar" lens) using 60 sec exposures. In this case I had nothing better to do, since I was camped out and took the exposures right next to the car. So, this is 30 stacked images with no foreground to worry about. Notice the horsehead nebula peaking out? Not bad for a casual shot.

Paul2660 · 09-22-2016, 10:23 AM

Originally posted by rcolman

Very nice shot! I particularly like the contrast of the white cliffs with the black starry sky. I do have questions and comments if you wish to continue this part on PM.

I would not agree with you about stacking. It is a routine part of both amateur and professional astrophotography, and would not be in such heavy use if it did not provide mega-benefits. In terms of noise and detail renditions, I can beat the "pants" off of any 2-minute exposure with a small number of stacked images. It is, however, a pain when including landscape foregrounds. Lucky for me my S.O. (significant other? starry other?) is a photoshop addict and does the hard part for me. I have also just started exploring "starry landscape stacker" on a Mac that emphases the foreground part, and easier to use.

I have owned the Tamron 15-30mm and rented the super-high price Pentax version. The performance is almost there for astro landscapes, but not quite. F2.8 is marginal. There is some astigmatism towards the edges of the frame. Worst of all, I can barely lift the lens + camera, which weighs in at about 4.5 lbs. let alone take it onto a hike.

Below, there is a K-1 image take with a tamron 28-70 zoom at 70mm (not exactly a "stellar" lens) using 60 sec exposures. In this case I had nothing better to do, since I was camped out and took the exposures right next to the car. So, this is 30 stacked images with no foreground to worry about. Notice the horsehead nebula peaking out? Not bad for a casual shot.

Very nice shot indeed.

I fully agree stacking works with deep space objects, and can work on the style of work I do, however I just find I can get by much better with the Astrotracer feature. I don't work the deep space shots, but for sure would be stacking on those. You are also right that the K1 and 15-30 is a heavy combination. But it's solid for sure.
There is a bit of variance in the 15-30's of all the lenses I have purchased, I have had more trouble with that lens. I need the 15mm side of things so rectilinear causes it's own set of issues.

For the work I do, mainly landscape, combined with Milky way, I just find the results much better. With Nikon I was forced to shoot at min 3200 or even 6400, with a faster lens. All of which means, coma problems, (which IMO look much worse than the slight trailing I see), noise, much more noise, DOF at 1.4 to 2.0 non existent. Causing a lot more work in the foreground. Stacking still creates a blurred foreground. You are correct on the F 2.8 vs F 4.0 and I do tend to stay more wide open now. The F 4.0 to 5.0 gain in DOF is lost due to the blur of the tracing. So an additional frame or two must be taken for that. I have tried many of the best 1.4 lenses for Nikon and really none of them are coma free, and the coma issue just ruins a shot at least for me. This true also for most of the fast Sigma glass, only the lowly Samyang (pun) can produce a coma free output wide open, but it's such a pain to focus. The best Nikon the D810A can do better but at 2x the cost of a single K1 and the D810A is rather limited for other photography.

I looked at the iOption, but again weight and setup at night were more than I was looking for, but again I agree results can be amazing. I may still go there but will still have the same issue with the wide lenses I need so for now staying with the Pentax feature.

Wasn't trying to state stacking is bad, by any means. I still stack for star trails all the time using partial moonlight for illumination and love the results, but it's a lot of work for a shot most people don't being to appreciate the time involved, and also now all believe it's fake. sad.

The advantages of the startracer just work better for me in the type of shots I am trying to produce.

Paul C

rcolman · 09-22-2016, 10:51 AM

I almost never do deep space shots anymore. All of my stuff is landscape/astro, etc. However, when I have some spare time at 3AM, I set up the camera and let it go for a while.

I have been through the lens issue time and time again. AND I HATE COMA ... it ruins any shot. The best compromise is Samyang/Rokinon. if you get a good copy, then image quality can be superb with no coma and little astigmatism. The problem is that quality control sucks, and i had to go through SEVEN copies to get three good ones. Vendors hate me. i HATE doing it. I would gladly pay an extra $100 if they would cull the bad ones first. As for a pain to focus, they are ALL a pain to focus.

I tried an ioptron and skytracker portable camera drive, but, you know, i just don't have the endurance to carry all the extra gear, and I don't have the time to do a polar alighment ... pain.

Paul2660 · 09-22-2016, 11:10 AM

Originally posted by rcolman

I almost never do deep space shots anymore. All of my stuff is landscape/astro, etc. However, when I have some spare time at 3AM, I set up the camera and let it go for a while.

I have been through the lens issue time and time again. AND I HATE COMA ... it ruins any shot. The best compromise is Samyang/Rokinon. if you get a good copy, then image quality can be superb with no coma and little astigmatism. The problem is that quality control sucks, and i had to go through SEVEN copies to get three good ones. Vendors hate me. i HATE doing it. I would gladly pay an extra $100 if they would cull the bad ones first. As for a pain to focus, they are ALL a pain to focus.

I tried an ioptron and skytracker portable camera drive, but, you know, i just don't have the endurance to carry all the extra gear, and I don't have the time to do a polar alighment ... pain.

I hear you on the QC for Rokinon/Samyang. I tried 4 14mm for Nikon before I got on centered, Pentax only took 2, and the 2nd one is excellent.

I am still hoping their new 20mm 1.8 will be a good lens, but nothing out on that yet.

The other I am waiting on is the Irix 15mm 2.4. As it's filter friendly, if it works well, may replace the 15-30 with it. Still not sure how it will handle coma however.

Paul C

rcolman · 09-22-2016, 01:46 PM

What I have seen about the 15mm Irix is that there is too much coma for my taste. Another one bites the dust.

I had so many returns that Amazon kicked me out ... after 15 years of membership.

Most photographers don't care about coma, or don't know what it is. Always at the bottom of the list for fixing aberrations.

09-22-2016, 09:27 AM	#18
rcolman Senior Member Join Date: Jul 2016 Photos: Albums Posts: 118	Items & Issues Very nice shot! I particularly like the contrast of the white cliffs with the black starry sky. I do have questions and comments if you wish to continue this part on PM. I would not agree with you about stacking. It is a routine part of both amateur and professional astrophotography, and would not be in such heavy use if it did not provide mega-benefits. In terms of noise and detail renditions, I can beat the "pants" off of any 2-minute exposure with a small number of stacked images. It is, however, a pain when including landscape foregrounds. Lucky for me my S.O. (significant other? starry other?) is a photoshop addict and does the hard part for me. I have also just started exploring "starry landscape stacker" on a Mac that emphases the foreground part, and easier to use. I have owned the Tamron 15-30mm and rented the super-high price Pentax version. The performance is almost there for astro landscapes, but not quite. F2.8 is marginal. There is some astigmatism towards the edges of the frame. Worst of all, I can barely lift the lens + camera, which weighs in at about 4.5 lbs. let alone take it onto a hike. Below, there is a K-1 image take with a tamron 28-70 zoom at 70mm (not exactly a "stellar" lens) using 60 sec exposures. In this case I had nothing better to do, since I was camped out and took the exposures right next to the car. So, this is 30 stacked images with no foreground to worry about. Notice the horsehead nebula peaking out? Not bad for a casual shot. Attached Images

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09-21-2016, 09:20 AM	#16
rcolman Senior Member Join Date: Jul 2016 Photos: Albums Posts: 118	With limited test runs on a K-1, there are several factors: 1) Astrotracer movement - the sensor has to be moving in a rectalinear fashion, so, without an equatorial movement you are always going to get some AZ-AL errors and they build up as exposure time lengthens 2) lens - I like to shoot 20 mm and below to fisheye. The lens will always have distortions, particularly towards the edges of the frame. 3) declination - the further away you are from Polaris, the more movement for a given time. So, if you are shooting close to the horizon, like me, there are more issues. Unanswered questions: (1) If you put your camera on a mechanical tracking drive, AND then turned on Astro-tracer, would the internal camera function further compensate for mechanical drive errors, and give you even more time, or just make a big mess. (2) how sensitive to camera calibration and GPS errors? Could you input more accurate GPS coordinates and get better performance? That said, stacking many 60-sec exposures can provide spectacular results under dark skies, like the enclosed. this one is a stack of 31 exposures. [wrong date on logo] (notice the horsehead nebula peeking out ... here horsey ... want carrot ?) Last edited by rcolman; 09-21-2016 at 09:27 AM.

09-21-2016, 07:22 PM - 2 Likes	#17
Paul2660 Forum Member Join Date: Jun 2016 Posts: 67	Astrotracer, was one of the main reasons for my move to the K1 from Nikon. I did not want to purchase a tracking base, due to added weight, and setup times. Overall, I have to say that it's a very impressive feature, and can produce some excellent images of the night sky. Main limitation I have found is that the for my locations I need 15mm to 20mm for night sky and foreground. Mainly using the 15-30 in the 15mm to 20mm range, F 4 to F5. 1.5 to 3 minutes ISO ranges from 800 to 1600. The rectilinear nature of the 15-30 does force you to have the Milky Way in the center of the shot, or it will blur as you move to the edge. The stars of course trail also no mater what, but for my work, that just adds to the nature of the shot as the trails are not a long as a normal 2 minute exposure. When in focus the details are amazing. Vastly superior to anything I captured with Nikon or Canon in the 20 second range at ISO 3200 up to 12K. Tried the stacking methods also, which helps on noise but just adds a lot more work and still can't beat a single 2 minute exposure. Plus this type of work requires a fast lens in the 1.4 to 1.8 range and most of these in the 14mm to 20mm range have coma issues. With the Astrotracer, you can now be in the F4 to F5 range, which also helps on over DOF and composition. Have learned that you need to calibrate the GPS from the Astrotracer screen, not the GPS screen as the two calibrations don't seem to talk to each other. So far have not had any problems with the GPS locking and staying locked. Calibration is always something that is a bit tricky as doing it with a camera strap on is impossible (at least for me). Results just keep improving, my only issue is the dark band I get at times at the top of the frame. Not a light leak, but appears to be a known issue on some K1's. But the fixes I have seen make the band look even worse at times, so I will just live with it for now. Vertical shots work great also. Paul C

09-22-2016, 10:23 AM	#19
Paul2660 Forum Member Join Date: Jun 2016 Posts: 67	Originally posted by rcolman Very nice shot! I particularly like the contrast of the white cliffs with the black starry sky. I do have questions and comments if you wish to continue this part on PM. I would not agree with you about stacking. It is a routine part of both amateur and professional astrophotography, and would not be in such heavy use if it did not provide mega-benefits. In terms of noise and detail renditions, I can beat the "pants" off of any 2-minute exposure with a small number of stacked images. It is, however, a pain when including landscape foregrounds. Lucky for me my S.O. (significant other? starry other?) is a photoshop addict and does the hard part for me. I have also just started exploring "starry landscape stacker" on a Mac that emphases the foreground part, and easier to use. I have owned the Tamron 15-30mm and rented the super-high price Pentax version. The performance is almost there for astro landscapes, but not quite. F2.8 is marginal. There is some astigmatism towards the edges of the frame. Worst of all, I can barely lift the lens + camera, which weighs in at about 4.5 lbs. let alone take it onto a hike. Below, there is a K-1 image take with a tamron 28-70 zoom at 70mm (not exactly a "stellar" lens) using 60 sec exposures. In this case I had nothing better to do, since I was camped out and took the exposures right next to the car. So, this is 30 stacked images with no foreground to worry about. Notice the horsehead nebula peaking out? Not bad for a casual shot. Very nice shot indeed. I fully agree stacking works with deep space objects, and can work on the style of work I do, however I just find I can get by much better with the Astrotracer feature. I don't work the deep space shots, but for sure would be stacking on those. You are also right that the K1 and 15-30 is a heavy combination. But it's solid for sure. There is a bit of variance in the 15-30's of all the lenses I have purchased, I have had more trouble with that lens. I need the 15mm side of things so rectilinear causes it's own set of issues. For the work I do, mainly landscape, combined with Milky way, I just find the results much better. With Nikon I was forced to shoot at min 3200 or even 6400, with a faster lens. All of which means, coma problems, (which IMO look much worse than the slight trailing I see), noise, much more noise, DOF at 1.4 to 2.0 non existent. Causing a lot more work in the foreground. Stacking still creates a blurred foreground. You are correct on the F 2.8 vs F 4.0 and I do tend to stay more wide open now. The F 4.0 to 5.0 gain in DOF is lost due to the blur of the tracing. So an additional frame or two must be taken for that. I have tried many of the best 1.4 lenses for Nikon and really none of them are coma free, and the coma issue just ruins a shot at least for me. This true also for most of the fast Sigma glass, only the lowly Samyang (pun) can produce a coma free output wide open, but it's such a pain to focus. The best Nikon the D810A can do better but at 2x the cost of a single K1 and the D810A is rather limited for other photography. I looked at the iOption, but again weight and setup at night were more than I was looking for, but again I agree results can be amazing. I may still go there but will still have the same issue with the wide lenses I need so for now staying with the Pentax feature. Wasn't trying to state stacking is bad, by any means. I still stack for star trails all the time using partial moonlight for illumination and love the results, but it's a lot of work for a shot most people don't being to appreciate the time involved, and also now all believe it's fake. sad. The advantages of the startracer just work better for me in the type of shots I am trying to produce. Paul C

09-22-2016, 10:51 AM	#20
rcolman Senior Member Join Date: Jul 2016 Photos: Albums Posts: 118	I almost never do deep space shots anymore. All of my stuff is landscape/astro, etc. However, when I have some spare time at 3AM, I set up the camera and let it go for a while. I have been through the lens issue time and time again. AND I HATE COMA ... it ruins any shot. The best compromise is Samyang/Rokinon. if you get a good copy, then image quality can be superb with no coma and little astigmatism. The problem is that quality control sucks, and i had to go through SEVEN copies to get three good ones. Vendors hate me. i HATE doing it. I would gladly pay an extra $100 if they would cull the bad ones first. As for a pain to focus, they are ALL a pain to focus. I tried an ioptron and skytracker portable camera drive, but, you know, i just don't have the endurance to carry all the extra gear, and I don't have the time to do a polar alighment ... pain.

09-22-2016, 11:10 AM	#21
Paul2660 Forum Member Join Date: Jun 2016 Posts: 67	Originally posted by rcolman I almost never do deep space shots anymore. All of my stuff is landscape/astro, etc. However, when I have some spare time at 3AM, I set up the camera and let it go for a while. I have been through the lens issue time and time again. AND I HATE COMA ... it ruins any shot. The best compromise is Samyang/Rokinon. if you get a good copy, then image quality can be superb with no coma and little astigmatism. The problem is that quality control sucks, and i had to go through SEVEN copies to get three good ones. Vendors hate me. i HATE doing it. I would gladly pay an extra $100 if they would cull the bad ones first. As for a pain to focus, they are ALL a pain to focus. I tried an ioptron and skytracker portable camera drive, but, you know, i just don't have the endurance to carry all the extra gear, and I don't have the time to do a polar alighment ... pain. I hear you on the QC for Rokinon/Samyang. I tried 4 14mm for Nikon before I got on centered, Pentax only took 2, and the 2nd one is excellent. I am still hoping their new 20mm 1.8 will be a good lens, but nothing out on that yet. The other I am waiting on is the Irix 15mm 2.4. As it's filter friendly, if it works well, may replace the 15-30 with it. Still not sure how it will handle coma however. Paul C

09-22-2016, 01:46 PM	#22
rcolman Senior Member Join Date: Jul 2016 Photos: Albums Posts: 118	What I have seen about the 15mm Irix is that there is too much coma for my taste. Another one bites the dust. I had so many returns that Amazon kicked me out ... after 15 years of membership. Most photographers don't care about coma, or don't know what it is. Always at the bottom of the list for fixing aberrations.