Author Topic: Milkyway  (Read 1816 times)

jackyes

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Milkyway
« on: March 02, 2017, 10:30:22 AM »
Hi all,
i'm a long time ML user but never posted before. Thank you and congratulations to the entire dev team for their awesome work!

i'm planning to make some Milky way photo (astrolandscape).
I'm a bit confused on the use of ETTR in this case, some people say it's good when there is high light pollution, other says it's pointless (or a bad practice).
It's good to stack more ETTR photo (all previusly edited in exposure)? it is usefull even with a skytracker?
What do you think about this? previus experience?

In the case that ETTR is usefull, how to set AETTR (highlight %, Mid S/n, shadow S/n, ecc)?

thank in advance!




BBA

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Re: Milkyway
« Reply #1 on: March 03, 2017, 11:45:39 AM »
Wait for the gurus' good ideas....

Meanwhile, I can share some raw pictures with the ML community (they are published under ML licence if it makes sense)
so that each one can figure out :
 - what's wrong with them and
 - what else could be done to get better results
and...
 to challenge each one's image-editing skills....

They were taken from the "platform" near the "Gornergrat observatory" in the Swiss Alps (Zermatt) during the night 8th-9th of July 2016 (see EXIF data).
https://www.dropbox.com/s/ewfz2hyhy6ux6ct/_GOR0542.CR2?dl=0
https://www.dropbox.com/s/v3rj7womjjvxhgh/_GOR0599.CR2?dl=0
https://www.dropbox.com/s/dww6opt1f3gyykd/_GOR0610.CR2?dl=0
https://www.dropbox.com/s/jy186kk07sj6t70/_GOR0712.CR2?dl=0
https://www.dropbox.com/s/nsduxvhl5jbf7xo/_GOR0858.CR2?dl=0
https://www.dropbox.com/s/b0f2v2xfv6z4yt3/_GOR0769.CR2?dl=0
https://www.dropbox.com/s/r8o8jrtesx5kwyk/_GOR0721.CR2?dl=0
https://www.dropbox.com/s/seejz6i9ax9co2q/_GOR0560.CR2?dl=0
https://www.dropbox.com/s/frz00ej2rj9yoxc/_GOR0678.CR2?dl=0


jackyes

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Re: Milkyway
« Reply #2 on: March 03, 2017, 04:15:13 PM »
Good shot BBA! 

i read a lot on this topic (ETTR),
i suppose (but i can be totaly wrong):
-it can be very good using a skytracker (will buy in the next days  8) ) with low iso and very long exposure. Making many shoot and stack them to reduce the noise from the long exposure.
-Use iso as low as possible. Increase the iso to Expose on the right lead to decrase the DR and a consequent loss of detail.
-Expose on the right over the "analog ISO" is pointless.
can someone confirm my assumptions?


Levas

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Re: Milkyway
« Reply #3 on: March 05, 2017, 07:23:22 PM »
Not an expert on this, but have shot the milky way a few times.
Most of the times your only variable is the iso setting.
Exposure time is restricted by star movement, so your maximum exposure time is about 15 seconds (on wide angle lenses 14-24mm)
(with a sky tracker you can go longer than 15 seconds exposure, but not if you want some visible horizon in you photo's with mountains/trees and stuff  :P)
With a 15mm fisheye you can use about 30 seconds exposure before seeing star movement in the photo.
Aperture is most of the times wide open, since stars are at infinity you don't need much depth of field  :P plus you need all the light there is  :D

So that leaves you with iso setting to play with to get the exposure as much to the right as possible, which depending on where you live is probably iso 3200 or 6400 (with 15 seconds exposure and F2.8 )

I'd liked the first picture of the Zermatt serie, this is the result of a quick edit in Lightroom:
http://drive.google.com/open?id=0B1BxGc3dfMDacHFPcnlWTnBmLW8

jackyes

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Re: Milkyway
« Reply #4 on: March 05, 2017, 07:39:59 PM »
Obviusly, with a sky tracker you make a separate shot to proprely expose the foreground and merge it with the tracked (and stacked) of the sky, so the ISO can be low (<800 and) with an exposure time much more long than 30 sec  ;D...

BBA

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Re: Milkyway
« Reply #5 on: March 06, 2017, 09:06:22 PM »
@Jackyes
I met a swiss pro photographer using a small tracker on his tripod and looking for "polaris" with his smartphone to initialize it.
He told me he used to take "black pictures" to remove some of the noise.

@Levas
A quick edit makes a big difference with great skills. Beautiful work (white balance, colors, lighting of the mountains, low noise, very limited light noise from behind the mountains) !



 

jackyes

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Re: Milkyway
« Reply #6 on: March 06, 2017, 11:19:14 PM »
@BBA For Deep Space photography you have to take several light shot, bias, flat and dark frame. But for astrolandscape if you have a modern camera (7d,6d,5d mk3,ecc..) is not necessary. before the start of the shooting session remember to make a "manual sensor cleaning" with the cap on the lens and wait 30 sec in order to activate the hot pixel mapping function, more info can be found googling ;) 

@Levas good work but for what i understood the real color of milkyway is orange/yellow so that color are completely wrong...looks good but not true  :P

Levas

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Re: Milkyway
« Reply #7 on: March 08, 2017, 09:29:26 AM »
Who cares about realistic colors, it's photography not documentary  :P

Quote
Obviusly, with a sky tracker you make a separate shot to proprely expose the foreground and merge it with the tracked (and stacked) of the sky, so the ISO can be low (<800 and) with an exposure time much more long than 30 sec  ;D...
Photoshop is our friend here, if you can't make it, fake it  ;D

Levas

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Re: Milkyway
« Reply #8 on: March 08, 2017, 09:49:54 AM »
@Jackeyes
I'm curious how detailed the milky way can look with a sky tracker, if you have one, can you post a picture here in this forum ?

This is one of my best Milky way shots, taken on the beach in the Netherlands, Lens used -> tokina 10-17mm fisheye at 15mm and f4.0.
Fisheye makes it possible to use 30 seconds exposure.
http://drive.google.com/open?id=0B1BxGc3dfMDaekpzWnR5aFBGb2M

Boscom

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Re: Milkyway
« Reply #9 on: March 08, 2017, 01:45:48 PM »
You can stack a series of single exposures, around the 10 - 20 second length for minimal star trailing, and use either  Photoshop and/or  Deep Sky Stacker (Freeware) to process them. Plenty of tutorials around on doing this. You wont get any more details in the image, but the noise will be considerable reduced allowing the processing to be pushed further to being out the detail.

You dont necessarily need a tracker for this as long as you shoot a separate exposure for the landscape (should you choose to include any).

jackyes

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Re: Milkyway
« Reply #10 on: March 08, 2017, 02:49:32 PM »
@Levas i will buy a tracker in the next few days  ::
Very good shoot! awesome! With my canon 6d and a samyang 14 mm f 2.8 i can take 30 sec without trailing...I have also a samyang 12mm 2.8 fisheye, will try it next time ;)

@Boscom with a skytracker you can take many, more long exposure (and at less iso with higher f number), and stack  them (with DSS or IRIS or PixInsight or photoshop, etc..). The result will be much better, with more detail and less noise ;)
A skytracker is not necessary but if you want a better photo this can help a LOT ;)

we are a bit OffTopic  :D.

So anyone has some experience with (A)ETTR, skytracker and milkyway?
Maybe only with (A)ETTR and milkyway?

SpcCb

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Re: Milkyway
« Reply #11 on: March 08, 2017, 07:12:22 PM »
So anyone has some experience with (A)ETTR, skytracker and milkyway?
Maybe only with (A)ETTR and milkyway?
IMHO, ETTR is useless for this kind of subject. How the ETTR algo will know where is the right on a scene with _saturate, in all probability_ stars and very low level on 90% of the surface?
It depends of what you are looking for, but usually we try to get the maximum of signal so it meanly depends of the sky quality (background level) if you are not limited by the tracking. We can say we are 'sky limited' in this case.
Of course, if you use a simple tripod and you don't want trailing, you will be 'tripod limited', but if the sky is very illuminated.

Edit: Here is an example of Milky Way photograph with tracking under a very _very_ good sky -> https://www.instagram.com/p/BQqGnkgj_su/
(5D2mod+ML - [email protected]/4 - no filters - sideral tracking - 9*300s - isoless)

jackyes

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Re: Milkyway
« Reply #12 on: March 08, 2017, 11:00:39 PM »
Thank you SpcCb!

How you chose the correct exposure with a tracker? Do you have a rule of thumb for a beginner? ;)

SpcCb

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Re: Milkyway
« Reply #13 on: March 09, 2017, 03:35:50 AM »
(...)
How you chose the correct exposure with a tracker? Do you have a rule of thumb for a beginner? ;)
There's some rules, however the mean issue will be the sky darkness if you have a tracking device I as said. Even with special filters to reduce the light pollution.
If you live in a big city, there's nothing to do. If you live in a country side, it's limited. You have to go in a dark wild place to fully exploit tracking capabilities.

To begin, start to learn how this device work (you have to make precise alignment, well balance all the gear, find the adapted mobile energy source, etc.), then make tries with short exposures wide open with a 'relatively high ISO' (with a digital camera it's easy to get results in a couple of second @1600~3200ISO), and if all is good increase the exposure time. If something wrong, go back to the beginning and try to figure what is wrong. Like that you can make progress, step by step.
Beside, if you have an astronomy club in your country, it could be a big help to meet and speak with people passionate by that.

Levas

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Re: Milkyway
« Reply #14 on: March 09, 2017, 09:33:14 AM »
@SpcCb
Wow, great pic of the milky way :)

9 exposures of 300 seconds  :o

What is the mod on your 5d2, did you remove UV/IR filters in it ?

jackyes

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Re: Milkyway
« Reply #15 on: March 09, 2017, 03:01:42 PM »
@SpcCb
 I will buy an Ioptron SkyTracker V2, it can handle 300mm @ 150 sec well (i'm mainly interessed in astrolandscape, i don't need such precision :P ), can be powered by 4 AA battery ([email protected]) and is LIGHTWEIGHT (i love to go on the mountains). And it is cheap ~300€.
Do you have some hint on a good Skytracker?

SpcCb

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Re: Milkyway
« Reply #16 on: March 10, 2017, 06:44:35 AM »
@SpcCb
Wow, great pic of the milky way :)

9 exposures of 300 seconds  :o

What is the mod on your 5d2, did you remove UV/IR filters in it ?
Thanks Levas ;)
Yes, 9*300s; a moderate (number of frame)/(exposure time) ratio, I already did more on Milky Way :)
This 5D2 is not full spectrum, there's an Astrodon Inside filter in place of the Canon IR-cut filter who gives 400>700nm @99% with fluorite substrate, very nice product.


@SpcCb
 I will buy an Ioptron SkyTracker V2, it can handle 300mm @ 150 sec well (i'm mainly interessed in astrolandscape, i don't need such precision :P ), can be powered by 4 AA battery ([email protected]) and is LIGHTWEIGHT (i love to go on the mountains). And it is cheap ~300€.
Do you have some hint on a good Skytracker?
You know, 150s @300mm with this kind of device is 'marketing'. I think you could use up to a 80mm, more you will see stars trails because the device has ~40" of periodic error in tracking. <50mm it will be easier, specially at the beginning. But <=80mm will be far enough for Milky Way, look at my previous link where it was 50mm.

For the power source, with AA batteries maybe it will be enough for a couple of hours but it could be expensive (?). An other solution could be to use a external source (9~12V, 500mA), like from a car lighter if you have your car close to you.

In the same budget there's the Skywatcher Star Adventurer travel mount, two times heavier but stronger and more precise. Plus you could use an auto-guiding system, later. It depends if you want a very light device or not, for 300€ and 0.5kg the Ioptron is the one on the market I think.

jackyes

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Re: Milkyway
« Reply #17 on: March 10, 2017, 08:37:47 AM »
My mistake, at 200mm (as some user review) the skytracker can't go longer than 1 min  :-[
But i'm mainly interested in Wide field space, but will try some Deep space (with the limitation of the skytracker...).
Lightweight is a must for me. I plan to walk for hours before camping and start shooting ;)

I think i will buy the iOptron  :-\

SpcCb

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Re: Milkyway
« Reply #18 on: March 10, 2017, 07:00:46 PM »
My mistake, at 200mm (as some user review) the skytracker can't go longer than 1 min  :-[
Mhmm.. If you use a 200mm with big aperture (200f/2.8?) + camera body, I think it will be a lot for the device for a question of weight/balance. It's a supposition, it needs to be tested, however I'm very perplex. And if you use a lightweight 200mm (plastic body 200f/4.5||5.6?), with 60s exposures you will not see many things on images. :/ Sorry to say that, but forget to use this startracker with a focal over 80mm, you will be disappointed. As I said, see what you can get with a cool 50mm, and 35/24/14/etc. on Milky Way or wide field, the Ioptron is made for that. ;)

But i'm mainly interested in Wide field space, but will try some Deep space (with the limitation of the skytracker...).
Lightweight is a must for me. I plan to walk for hours before camping and start shooting ;)

I think i will buy the iOptron  :-\
Ok, I see, I did it too ;) So my 2ct advice would be to take a look on Li-ion AA batteries and a flexible solar panel with a charging module to charge batteries on your backpack during hikes by day.

jackyes

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Re: Milkyway
« Reply #19 on: March 10, 2017, 07:59:49 PM »
i found some shoot at 300mm with the ioptron:
http://www.cloudynights.com/topic/480574-surprising-what-a-300mm-lens-ioptron-skytracker-can-do/

but for me that will be a plus, not necessary ;) the important part is the wide field part.
i have a 70-200 F4 L (not the IS version wich is more heavier)and i will try also with it.

Thank you i wil buy the ioptron, no more doubts!

jackyes

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Re: Milkyway
« Reply #20 on: May 29, 2017, 04:14:31 PM »
@Jackeyes
I'm curious how detailed the milky way can look with a sky tracker, if you have one, can you post a picture here in this forum ?

https://drive.google.com/open?id=0B8RCIZlBGQ5wMWQwWi1zOW5Ya2s

This is one of my first shoot with the iOptron Skytracker V2. (Processed, but i'm not good with photoshop,lightroom,etc ;) )
Taken in a higly light polluted zone  :'( ( Radiance point: 19 accordingly to lightpollutionmap.com wich is probably 4-5 in the bortle scale).

Canon EOS 6D, Samyang 14mm, 105", f5.6, iso 1600.
 
Next time i will try in a more good sky.  :D