Our Beautiful Universe - Photos and Videos

[Devin-M]

focusing on the north star through bahtinov focusing mask and 6nm narrowband hydrogen alpha filter (cropped 30sec @ 25600iso test shots)

https://www.speakev.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.speakev.com/attachments/5f0e8216-b6f4-4de9-87a8-9921e69b1dad-jpeg.140546/

 

[Devin-M]

This is last night's attempt at the Wizard Nebula with the narrow band hydrogen alpha filter under heavy light pollution (bortle 6 surrounded by street lamps)... I think my effort was hampered by only getting 7 x 5 minute exposures at high iso (8063iso) resulting in significant noise remaining in the final image.

Wizard Nebula - NGC 7380 - 8500 light years
35 minute exposure - 7 x 5min - 8063iso - 600mm f/9 - Bortle 6 w/ heavy local light pollution (3/6/21)
Nikon focal 300mm f/4.5 + Nikon TC-301 2x teleconverter
Nikon D800 w/ Star Adventurer 2i Equatorial Mount
Astronomik Narrow Band (6nm) Hydrogen Alpha Filter For Nikon Full Frame DSLR
Center (RA, Dec): (341.716, 58.101)
Center (RA, hms): 22h 46m 51.916s
Center (Dec, dms): +58° 06' 03.161"
Size: 48.7 x 73 arcmin
Radius: 0.731 deg
Pixel scale: 1.68 arcsec/pixel

detail...

 

[DennisN]

This is last night's attempt at the Wizard Nebula

What's that big device mounted on a tripod on the grass?
Is it your camera gear or an anti-aircraft gun? Hard to tell...

 

[DennisN]

Here's a black thing I picked up from a store yesterday:

Finally, after years of angst deciding on a suitable camera for me, I decided to give this one a shot,
since I wanted a better low-light camera (than my LG G4 phone), combined with a decent allround camera, since I did not want to buy two cameras. I need the remaining funds for lenses, a scope and a guider.

Fellows, I'm finally getting a bit closer. :)
(though I have not decided on a decent scope and guider yet, I have had really trouble making
my mind up!)

Now, does anyone of you know which camera the above is?
The first one who guesses correctly will win a free, used lens cap from me.

Spoiler

It's the Sony A6000 mirrorless system camera (24 MP), which has a Sony APS-C sensor
with pretty good low light performance. It has also got great autotracking and pretty
decent video capabilities.

I will also buy a couple of more lenses to it (e.g. wide, ultrawide and portrait lenses),
since I intend to use it as a normal, non-astro camera too.
I already have some tele- and zoom lenses at home so I will probably get mount adapters for them.

Here are three reviews:

• Astrophotography Review of Sony A6000 by "Lonely Speck"
  (there are some very nice photos of auroras further down on that page,
  and a gorgeous clip of moving auroras!)
• Sony A6000 sensor review - Little wonder (on DXOMark)
• Review on "Digital Photography Review" (a long and very thorough review)

(and, yes, you are seeing correctly; the thing to the right of the camera is the ship
that made the Kessel Run in less than twelve parsecs. It's a model project of mine.
I haven't gotten around to paint it with airbrush yet, and put LEDs into it, which I intend)

Edit:

Oh, I forgot to say that one very cool thing is that the camera can be remotely controlled via a computer, tablet or smartphone (incl. taking photos, setting ISO, shutter speed etc).
That is a great added benefit that I had not anticipated nor even looked for.
This of course means I don't need a dedicated remote shutter control for it.

It also supports uncompressed video out via HDMI to a computer/recorder, and it's got WiFi and NFC connectivity. It is truly remarkable for the low price. I paid ca $580 for it (brand new), which included a standard lens and some minor accessories.

 

[chemisttree]

Things are going to get very interesting for you now!

 

[Devin-M]

It's the Sony A3000 mirrorless system camera (24 MP), which has a Sony APS-C sensor

Some Sony mirrorless cameras have been known to have issues with noise reduction that can't be turned off even in raw files which has led them to be referred to by some astrophotographers as "star eaters" ... hopefully you won't have the same issue.

https://petapixel.com/2018/06/08/sonys-star-eater-problem-has-been-defeated-in-the-a7-iii/

https://petapixel.com/2017/05/04/star-eater-issue-no-longer-recommend-sony-cameras-astrophotography/

https://www.lonelyspeck.com/sony-star-eater-and-how-to-fix-it/

https://www.michaelfrye.com/2017/08/06/sony-star-eater-issue/

http://www.markshelley.co.uk/Astronomy/SonyA7S/sonystareater.html

 

[chemisttree]

View attachment 279318
View attachment 279319

I like the homemade dew shield and especially the battery pack!

 

[bruha]

Hello, I attach images of Orion M42 (resp. central trapezium ) taken by my friend:

*Nikon d600 + Tamron 70-300/4-5.6
*Stacked from the 30 photos (2s, f5.6, iso 10159) in the Affnity Photo editorOndřej Brůha

Horský průvodce a fotograf
tel. +420733263858
mail ondrej.bruha@outlook.com
web www.ondrejbruha.com

 

[DennisN]

Things are going to get very interesting for you now!

Yes, and not only with respect to astrophotography, also normal photography. I've tried the camera briefly and it clearly and visibly beats my LG G4, which actually has a quite good camera on a phone.

But not all is that peachy... I'm a complete newbie when it comes to system cameras, and I had a real shock when I discovered how incredibly expensive many lenses can be. :)

I thought telescopes was rather expensive (which they can be) , but if anybody has got a ton of money to spend, go for a couple of high-tier tele- or zoom lenses, and you'll see your money disappear faster than Millennium Falcon. :)

Therefore I will go for some decent budget lenses from budget brands and/or maybe some vintage lenses with manual focus. There are a lot of interesting sites and videos with reviews on good budget lenses.

 

[DennisN]

Some Sony mirrorless cameras have been known to have issues with noise reduction that can't be turned off even in raw files which has led them to be referred to by some astrophotographers as "star eaters" ... hopefully you won't have the same issue.

Luckily the camera isn't a "wallet eater" :).
And I 've got 50 free days to test it, and I can return it if I'm dissatisfied.
And actually I consider astrophotography yet as a secondary photo hobby. I spend much more time doing normal photography. But who knows, that may change. :)

 

[Devin-M]

I thought telescopes was rather expensive (which they can be) , but if anybody has got a ton of money to spend, go for a couple of high-tier tele- or zoom lenses, and you'll see your money disappear faster than Millennium Falcon. :)

Therefore I will go for some decent budget lenses from budget brands and/or maybe some vintage lenses with manual focus. There are a lot of interesting sites and videos with reviews on good budget lenses.

If I had a heftier mount, something like this would be a surprisingly good deal for astrophotography:

Nikon Nikkor 600mm F/4 ED IF Manual Focus Lens $1400US

https://www.samys.com/p/Pre-Owned-L...--Pre-Owned/227434.html?origin=product-search

 

[Andy Resnick]

That would be a good deal! I use something similar (400/2.8 ED IF lens with optional 2x teleconverter), also purchased for not-very-much money.

 

[Andy Resnick]

...In other news, we had three clear nights in a row over the weekend, so I worked on Orion @ 105/2 (5.4 hours @ ISO 64), incomplete background correction:

The interesting bits look much better now (100% crops):

 

[chemisttree]

.View attachment 279392

View attachment 279393

18-point stars? Did you shoot this stopped down a bit or wide open?

 

[Andy Resnick]

After Orion has moved out of view, I still had an hour or two of imaging time before bed- so last night I tried imaging M51 at 800mm rather than 400mm- previously, I reasoned that the benefit of imaging at f/2.8 outweighed the benefit of higher magnification. Now that I am using AstroPixelProcessor, I am re-visiting my assumptions. I was only able to get 10 minutes (8 seconds at a time) at 800/5.6 ISO 1000, but here's 'first light' at 100%:

For comparison, here's what 4.7 hours of 400/2.8 ISO 500 looks like, scaled to 200%:

We'll see... possibly better.

 

[Andy Resnick]

18-point stars? Did you shoot this stopped down a bit or wide open?

The lens was stopped down a full stop, from f/1.4 to f/2. Nikon uses 9-bladed aperture stops, so voila- 18-point starbursts!

 

[chemisttree]

Amazing you get them with such a minor adjustment. Very nice, though.

 

[Devin-M]

I composited the Hydrogen Alpha (9 x 5min 6400iso 600mm f/9) with the RGB (60 x 2min - 12800iso 600mm f/9) and got this:

detail:

 

[DennisN]

If I had a heftier mount, something like this would be a surprisingly good deal for astrophotography:
Nikon Nikkor 600mm F/4 ED IF Manual Focus Lens $1400US

That would be a good deal! I use something similar (400/2.8 ED IF lens with optional 2x teleconverter), also purchased for not-very-much money.

I stumbled upon a very funny picture when I was on a review page about camera lens mount adapters.
This one seems to be a small and nifty allround lens, and easy to pack :

The handle on that lens is about as big as my cheap 70mm telescope.

Source: Sony a7RII Canon EF Smart Adapter Tests (Brian Smith Pictures)

 

[DennisN]

Tamron 70-300/4-5.6

One of my zoom lenses is a Tamron.

I already have some tele- and zoom lenses at home so I will probably get mount adapters for them.

I just looked at the tele- and zoom lenses I've got, and they are these:

• Chinon 135mm f/2.8 (according to reviews I've seen, people say it is a very sharp lens)
• Tamron 55-200mm f/4-5.6
• Optomax 300mm f/5.6

I bought them some years ago at a second hand store for about $30 to $50 each. I would need two lens mount adapters for them in order to use them with the Sony A6000, and I'm considering Fotodiox M42 to Sony E and Fotodiox Canon EF to Sony E.

I've also been looking at the Olympus Teleconverter 1.7x, since I've seen it recommended many times.
If anybody has any other teleconverter to recommend, please do!

If I've got my maths* correct that teleconverter (TC) will yield the following possible magnifications with the vintage lenses above (on an APS-C sensor):

• Chinon 135mm:
  4x (default)
  7x (with TC)
• Tamron 55-200mm:
  1.6x - 6x (default)
  2.8x - 10x (with TC)
• Optomax 300mm:
  9x (default)
  15x (with TC)

(*)

Magnification = Focal length * Sensor crop factor / 50 mm
(50 mm is human eye equivalent, right?)

The sensor crop factor for APS-C is 1.5x, so

Magnification = Focal length * 1.5 / 50 mm = Focal length * 0.03

Adding a teleconverter (TC) means

Magnification = Focal length * TC magnification * crop factor / 50 mm

and for a Teleconverter 1.7x and an APS-C sensor this means

Magnification = Focal length * 1.7 * 0.03 = Focal length * 0,051 = (ca) Focal length / 20

 

[Devin-M]

If you download stellarium to your computer/laptop, it will simulate the night sky, and you can input different focal lengths and sensor sizes and it can preview the framing you will get on various astronomical objects. There is a phone version but many of the features are missing and the framing function is harder to use.

 

[Devin-M]

(50 mm is human eye equivalent, right?)

50mm on a crop sensor is about 26 degree horizontal field of view, human eye is about 210 degrees horizontal field of view.
https://www.nikonians.org/reviews/fov-tables

Subjectively it could be argued 50mm lens on a full frame sensor shows the part of your vision which you pay most attention to and has a natural appearance. Those 50mm lenses usually have large aperatures (f/1.4) for enhanced bokeh and artistic effect, which also makes them the best option for low light photography as well since the large aperature let's in the most light.

 

[Andy Resnick]

I stumbled upon a very funny picture when I was on a review page about camera lens mount adapters.
This one seems to be a small and nifty allround lens, and easy to pack :

View attachment 279440

The handle on that lens is about as big as my cheap 70mm telescope.

Source: Sony a7RII Canon EF Smart Adapter Tests (Brian Smith Pictures)

Heh- how about these lenses?

https://img.kentfaith.de/cache/catalog/lense/2248-canon-tv-5200mm-f-14-800x800.jpg

http://www.mir.com.my/rb/photograph...sources/reflex/ReflexNikkor2000mmf11_Side.jpg

 

[Devin-M]

possible magnifications

Usually when I’ve heard “magnification” discussed in terms of photography it relates to the size of the object being photographed versus the size of the image of the object projected on the sensor. For example in macro photography it’s useful to achieve a 1:1 magnification ratio meaning whatever you photograph has the same dimensions projected on the sensor as its size in real life. For example, the nikon 105mm f/2.8 achieves 1:1 magnification for macro photography, and when used with a 2x teleconverter it will achieve 2:1 magnification. A big factor in this is how closely you can be to the subject and still be in focus. It so happens with the 105mm f/2.8 you can be just a couple of inches away and be in focus. Other lenses, particularly telephotos, have much longer close focus distances and as a result can’t achieve as much magnification. I have a 500mm f/5 mirror lens made by nikon in the late 60’s but you have to be over 60 feet from the subject to be in focus, so it has a lower magnification ratio than the 105mm f/2.8.

 

[Andy Resnick]

(50 mm is human eye equivalent, right?)

Pretty close- I have seen specs ranging around 40-50mm. You can verify for yourself by keeping both eyes open and looking with one eye through your camera (w/ 50mm lens)- your visual field is basically undisturbed.

 

[Andy Resnick]

Usually when I’ve heard “magnification” discussed in terms of photography it relates to the size of the object being photographed versus the size of the image of the object projected on the sensor. For example in macro photography it’s useful to achieve a 1:1 magnification ratio meaning whatever you photograph has the same dimensions projected on the sensor as its size in real life. For example, the nikon 105mm f/2.8 achieves 1:1 magnification for macro photography, and when used with a 2x teleconverter it will achieve 2:1 magnification. A big factor in this is how closely you can be to the subject and still be in focus. It so happens with the 105mm f/2.8 you can be just a couple of inches away and be in focus. Other lenses, particularly telephotos, have much longer close focus distances and as a result can’y achieve as much magnification. I have a 500mm f/5 mirror lens made by nikon in the late 60’s but you have to be over 60 feet from the subject to be in focus, so it has a lower magnification ratio than the 105mm f/2.8.

Unlike macro (or micro) imaging, when the object distance is much much much much larger than the lens focal length, it's usually more convenient to think in terms of 'angular magnification'- comparing the angles subtended by object and image. Angular magnification (relative to unaided vision) can be easily estimated by the ratio of camera lens to eyeball lens- 400mm is about 8x angular magnification, for example.

There is also a slight complication that lens magnification varies with object distance (except for telecentric lenses). That's called 'perspective distortion' and used to great effect with ultrawide-angle and fisheye lenses.

 

[Andy Resnick]

50mm on a crop sensor is about 26 degree horizontal field of view, human eye is about 210 degrees horizontal field of view.

That is definitely not correct- I am not able to see behind myself. A single eyeball has a (static) field of view about 30 degrees:

https://i.redd.it/5xdtk9ycnirz.jpg

Together your eyes cover a binocular field of view about 120 degrees.

 

[Devin-M]

“If the analogy of the eye's retina working as a sensor is drawn upon, the corresponding concept in human (and much of animal vision) is the visual field.[3] It is defined as "the number of degrees of visual angle during stable fixation of the eyes".[4] Note that eye movements are excluded in the definition. Different animals have different visual fields, depending, among others, on the placement of the eyes. Humans have a slightly over 210-degree forward-facing horizontal arc of their visual field,[5][6] while some birds have a complete or nearly complete 360-degree visual field.”

“For example, binocular vision, which is the basis for stereopsis and is important for depth perception, covers 114 degrees (horizontally) of the visual field in humans;[7]the remaining peripheral 40 degrees on each side have no binocular vision (because only one eye can see those parts of the visual field).”

https://en.m.wikipedia.org/wiki/Field_of_view#Humans_and_animals

 

[DennisN]

If you download stellarium to your computer/laptop, it will simulate the night sky, and you can input different focal lengths and sensor sizes and it can preview the framing you will get on various astronomical objects. There is a phone version but many of the features are missing and the framing function is harder to use.

Thank you very much, I did not know that!
I've got Stellarium but I did not know there was that kind of preview function, which is enormously helpful.
Splendid!

 

[bruha]

Hello, please do you know somebody how to adjust exp. time clone and ISO in Open Camera?
I tried by phone camera Orion Trapezium with bad (suburb) ligt condition of course and there is probably just stars Orionis A,C,D I suppose and some remote star..

Thank you and lot of succes...

 

[Andy Resnick]

“If the analogy of the eye's retina working as a sensor is drawn upon, the corresponding concept in human (and much of animal vision) is the visual field.[3] It is defined as "the number of degrees of visual angle during stable fixation of the eyes".[4] Note that eye movements are excluded in the definition. Different animals have different visual fields, depending, among others, on the placement of the eyes. Humans have a slightly over 210-degree forward-facing horizontal arc of their visual field,[5][6] while some birds have a complete or nearly complete 360-degree visual field.”

“For example, binocular vision, which is the basis for stereopsis and is important for depth perception, covers 114 degrees (horizontally) of the visual field in humans;[7]the remaining peripheral 40 degrees on each side have no binocular vision (because only one eye can see those parts of the visual field).”

https://en.m.wikipedia.org/wiki/Field_of_view#Humans_and_animals

I'm not entirely sure what we are arguing about- again, looking through a 50mm lens (35mm image format) provides a nearly perfectly matched visual field, this can be easily verified.

A really good reference for the optics of human eyes is Atchison's book:

https://www.sciencedirect.com/book/9780750637756/optics-of-the-human-eye

and a really good reference for the physiology of vision is Snowden's book:

https://www.amazon.com/dp/019957202X/?tag=pfamazon01-20

 

[Devin-M]

things may look the same size to your eye through the viewfinder with a 50mm lens fitted, but on a cropped sensor you’re only seeing a 26 degree horizontal field of view compared with the more than 180 degree field of view of human vision...

 

[Devin-M]

I just performed an experiment. I looked at a picture on the wall with one eye looking through the viewfinder and one eye just open. I was looking with a full frame nikon d800 with a 50mm lens and a 105mm lens to test. The picture looked significantly smaller through the viewfinder than to my eye with the 50mm and bigger through the viewfinder than eye with the 105mm. Probably on an 85mm lens the picture would look much closer to the same size through the viewfinder and through my eye. A 50mm lens on a 1/1.5x DX cropped sensor would look like a 75mm lens on a full frame FX sensor.

 

[chemisttree]

Ooooh! Look what came in the mail today!

Oh wait... let me check something!

 

[chemisttree]

I thought so!