Orion

[Ben]

 

[Ben]

Details on the shot:

 

This shows part of the Orion constellation, a rather busy part of the northern hemisphere winter night sky. You can see 4 signature nebulas horsehead, running man, orion and the flame nebula. I tried to bring out the fainter interstellar dust lanes but succeeded only in parts due to shooting only from a bortle 6/7 region.

 

I used the A7rII with an adapted Nikon 300/4.5 Ai Ed IF from the late seventies on an equatorial tracking mount (Star Adventurer). The stack, that is the basis of this image, consists of 197 x 30sec exposures and 1 flat frame (a calibration frame to counter the vignette). It was combined using sigma-kappa clipping method in deep sky stacker. This method is a good compromise between rejecting outliers (like planes or satelites) and increasing the precision.

 

I had to do a rather fiddly post processing from there since the picture contains an enormous dynamic range. After stretching the image to a base line that had light pollution removed and realistic colors, I branched into 3 different versions of the image to make sure that the stars, the nebulas and the dust lanes came out properly. The dust lanes needed the biggest push and I also enhanced them with the tonal contrast filter from nik-color efex. In the end I masked everything together in Photoshop.

[mttdxb]

great shot! what kind of tripod did you use? i am using a similar setup but seem to get a lot of movement and slightly blurred images.

[Guest all8]

great shot! what kind of tripod did you use? i am using a similar setup but seem to get a lot of movement and slightly blurred images.

 

 

Its a telescope mount : http://ca.skywatcher.com/_english/02_mounts/02_detail.php?sid=68

[mttdxb]

Its a telescope mount : http://ca.skywatcher.com/_english/02_mounts/02_detail.php?sid=68

sorry maybe my comment was misleading. I use the same star adventurer mount with A7R2 and the 70-200mm + teleconverter but attach it onto a standard Benro aluminum tripod. i think the tripod is the main issue to get stability into the setup i use. considering now to use a wooden tripod to get less vibrations and a more stable setup.

[Guest all8]

OK, perhaps you even feel the motor operation in the tripod legs?

 

Are you using a remote shutter release? When I was using a long lens on a tripod, no astro mount, triggered by pressing the shutter release, I noticed that it was taking more than a few seconds for the motion caused by pressing the shutter release to stop. Interesting enough, my newer and lighter RRS carbon tripod has much less vibrations than my previous aluminum mount.

 

You could, at very least, turn the mount Off and take a long exposure. If there are no vibrations then you should get very nice sharp star trails. Might help find the cause of the problem.

[Ben]

great shot! what kind of tripod did you use? i am using a similar setup but seem to get a lot of movement and slightly blurred images.

 

Thank you

 I used a lent Alta Vanguard (http://www.vanguardworld.us/photo_video_us/alta-pro-263at.html). But I haven't had any troubles getting steady shots with my old aluminum tripod either. I use the timelapse app (which disables IBIS) to capture all sub exposures and during stacking they get a score depending on how many stars were found. It is easy to remove bad frames that way. But it is mostly the first frame or the last that I have to disregard.

 

BTW, I can only recommend staying below firmware 3.3 for now. Sony enabled the low pass spacial filter a.k.a. the star eater algorithm to all exposures longer than 3.2 seconds. Prior to this update it was only a Problem in Bulb mode or other 12 bit modes.

 

See 

http://blog.kasson.com/?p=16472

 

Unfortunately I already upgraded. 

[mttdxb]

OK, perhaps you even feel the motor operation in the tripod legs?

 

Are you using a remote shutter release? When I was using a long lens on a tripod, no astro mount, triggered by pressing the shutter release, I noticed that it was taking more than a few seconds for the motion caused by pressing the shutter release to stop. Interesting enough, my newer and lighter RRS carbon tripod has much less vibrations than my previous aluminum mount.

 

You could, at very least, turn the mount Off and take a long exposure. If there are no vibrations then you should get very nice sharp star trails. Might help find the cause of the problem.

I am using the remote shutter release that comes with the MEIKE battery grip, so that shouldnt be the problem. I saw the same effect that you described before as well. seems to take at least 1-2 minutes for the system to get stable.

 

I think the weight of the setup seems to be at the limit of the Star Adventurer. The motor rotation or simply wind seems to create a "swinging effect" that goes from the mount into the legs. I cant access the pictures now but the reason why I believe that this is the problem, is an observation that the "unwanted trailing" is not consistent into one direction. Example picture one has minior trailing "north to south", picture two taken just a minute after might have trailing "east to west". Not sure if that makes any sense... will try to post samples next weekend.

[Ben]

I think the weight of the setup seems to be at the limit of the Star Adventurer. The motor rotation or simply wind seems to create a "swinging effect" that goes from the mount into the legs.

 

 

This very picture was acquired with a Nikon D750 and a 50/1.5 piggy backing the same mount(shutter shock was no issue). In my experience the Star adventurer can handle up to the advertised 10 pounds, iirc. But I must add that I use the 1kg counter weight and try to balance my gear in all axis. I made up to 90 second exposures at 500mm that showed no sign of trailing on a really flimsy tripod. Maybe I have a good copy but aside from that you could try:

• checking the batteries
• balance each axis
• mind ground vibrations from streets, or walking near the tripod
• mind the wind at the spot
• sandbagging your tripod

If nothing helps and your periodic error is still visible with good polar alignment in 30 sec exposures or shorter, I would try to get a refund.

[Guest all8]

I am using the remote shutter release that comes with the MEIKE battery grip, so that shouldnt be the problem. I saw the same effect that you described before as well. seems to take at least 1-2 minutes for the system to get stable.

 

I think the weight of the setup seems to be at the limit of the Star Adventurer. The motor rotation or simply wind seems to create a "swinging effect" that goes from the mount into the legs. I cant access the pictures now but the reason why I believe that this is the problem, is an observation that the "unwanted trailing" is not consistent into one direction. Example picture one has minior trailing "north to south", picture two taken just a minute after might have trailing "east to west". Not sure if that makes any sense... will try to post samples next weekend.

 

 

Should be easy enough to test with the motor off. Also, consider if you are using the Electronic First Curtain shutter mode. At least on my A7ii the shutter is able to cause some movement too. For the second shutter its OK, since the exposure will be completed.

 

 

And and and .... make sure the stabilization is turned OFF.

[porterbasset]

Seriously beautiful shot!

Wondering now if I should take a chance on the Star Adventurer. My wife is using Nikon 800E and Nikon 750 for astrophotography, and I was worried that the Star Adventurer would be pressed to handle the load. Currently she's using a Celestron GoTo mount. (A friend made a bracket and camera mount that slides onto the Goto mount.) It works well, but requires a lot of effort to cart around and can't use the telescope at the same time. The Star Adventurer would be a lot easier to handle, that's for sure.

Disappointed to read my A7rii having ver. 3.30 firmware won't be able to take advantage of the great sensor on longer exposures. But, looks like it's worth trying anyway.

[mttdxb]

Finally had 3 hours of clear skies over the christmas weekend to take another shot at Orion. I am still far far away from Ben's image and this image is taken from JPEG, has no post-processing besides DeepSkyStacker and a bit of contrast corrections in Irfanview. At least I got most of the movement out, the remaining movement in the setup is due to quite some heavy winds that night.

 

Setup:

A7R2

Sony 70-200 GM + 2x tele @ ~340mm

Skywatcher StarAdventurer + Counterweight

100 x 30s @ 5000 ISO

 

Still have the raw files and will try to get some proper processing done, just need to find some time to do this...

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[Ben]

This looks very promising. Please post your final result once you manage to pull of a stack from raw files. The 70-200gm with the 2x extender seems to be very good for astro(at least much better than my 170€ Nikon ai 300/4.5 ed if). Did you stop down on top of the implicit 2 stop loss of the 2x extender or is this as wide open as you can go with this combination?

[mttdxb]

This looks very promising. Please post your final result once you manage to pull of a stack from raw files. The 70-200gm with the 2x extender seems to be very good for astro(at least much better than my 170€ Nikon ai 300/4.5 ed if). Did you stop down on top of the implicit 2 stop loss of the 2x extender or is this as wide open as you can go with this combination?

 

sorry forgot to include that above... this was all taken at f9. Wide open would be F5.6 with the extender. I am still in a trial and error phase to find the best settings. I think i will take the ISO a bit down next time. Definitely quite/too grainy for my taste. But will try how much I can reduce this in post processing.

 

If you are interested in the raw files to compare them to the Nikon, let me know and I can upload the 100 images in a zip file over the weekend.

[mttdxb]

work in progress... now from the raw files. better but still nowhere close. I guess the 100 exposures are just not enough to get the fine dust lanes and better contrast into the horse head... 

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