CL/TL2 sensor for milky way photos?

[kalifornier]

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Hello All,

Has anyone tried milky way photos with either CL or TL2?

Thanks,

Abhi

[pocholin]

I did, but I was completely using the wrong F!!!! I went F10, or so, thinking that was better for the overall sharpness, then I read I should've gone 3.5!

I've only had an opportunity to take a few pictures of stars where the milky way is visible on a clear night, sadly, it was an over casted weekend so no milky way was visible, here's an example of some of those stars with the CL + Sigma 16mm @ F1.4

CL is capable, for sure, it just needs to be in more experienced hands than mine

 

 

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Edited December 13, 2020 by pocholin
Correction of F in first sentence.

[pocholin]

Here's one, on the night that I could see the milky way (in center going from bottom to top of this pic) with CL + Leica 18-56, F10! 😕

 

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Edited December 13, 2020 by pocholin

[kalifornier]

Thanks for sharing your experience @pocholin. Much appreciated. Once the Milky Way season starts again in few months, I', going to try the Sigma 16/1.4 as well. 

[Rac1ngsnak3]

It’s not the easiest. The sensor is a bit primitive and you need fast glass. It is possible under ideal conditions. This was using my TL2 with 11–23 at 11 mm and f3.5 for 30 sec. This was taken near the town of Woodside, CA and the light from the town blew out that left lower corner.

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Edited December 14, 2020 by Rac1ngsnak3

[kalifornier]

1 hour ago, Rac1ngsnak3 said:

It’s not the easiest. The sensor is a bit primitive and you need fast glass. It is possible under ideal conditions. This was using my TL2 with 11–23 at 11 mm and f3.5 for 30 sec. This was taken near the town of Woodside, CA and the light from the town blew out that left lower corner.

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Thank you! I'm thinking the f1.4 of the Sigma 16mm might help. 

[bcorton]

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Hi. I believe I've posted some of these elsewhere on the Forum, but I'll post them again here for easy reference. They are all unguided photos of the Milky Way taken with the TL2.

First, with the Sigma f/2.8 14-24.

 

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Edited December 20, 2020 by bcorton

[bcorton]

Here, with the Leica f/2 23mm Summicron-TL. Not quite in focus, but you get the idea of what the TL2 sensor can do.

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Edited December 20, 2020 by bcorton

[bcorton]

This is with the 50mm Summicron-M

 

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[bcorton]

Again with 23mm Summicron-TL

 

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[bcorton]

I recently acquired the Sigma 16mm, f/1.4 but haven't had a chance to try it out on the stars. Anyone who has, please share.

[kalifornier]

Many thanks @bcorton. The example with Sigma 14-24 looks pretty good! 

[bcorton]

I finally got to take the Sigma 1.4s (16mm, 30mm, and 56mm) out last night to try out on Orion (et. al) with a nearly first quarter moon. 

So here are some renderings of the night's efforts. It wasn't a perfect session: there was some speck of dust on the sensor, and my post processing was quick and dirty, but I wanted to let you see what I got. Camera is the TL2.

First, the Sigma 16mm at f/1.4, 13 seconds, ISO 1600. I used the snow on the mountains for color balance. This is the only one of the three lenses to be recognized by Affinity Photo so far. It exhibits (as does the 30mm) a good deal of color purple fringing around brighter stars. Defringing creates a bull's eye of a dark circle around the stars, but this disappears into the darkness of the sky when the sky values are brought down to night-looking levels. So I guess it isn't an insurmountable problem. The stars seemed somewhat tighter, and the colors better at f/2.0, but since I didn't adjust the shutter speed to compensate, it could simply be that at f/1.4 the stars were getting twice as much light. Anyway, f/1.4 is quite usable. I wouldn't hesitate. Do note that there is some coma showing at the far off-axis at f/1.4; gone by f/2.0.

(Edit) Here is the image. It got lots flatter once uploaded. Boh!

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Edited January 20, 2021 by bcorton

[bcorton]

Here's the 30mm. The purple-fringiest lens of all. But, as with the 16mm it can be fixed in post. 

f/1.4, 8 seconds, ISO 3200.

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[bcorton]

And finally, the 56mm at f/1.4. This lens was the biggest surprise. I wasn't expecting much at f/1.4, but the lens proved me wrong. f/1.4 is quite usable. Also there was no fringing to speak of with this lens. Stars are mostly pinpoint, even wide open, although there is some coma at the very extreme edges and corners. Still, nothing to sneeze at. I've seen far worse in slower lenses. I was really jazzed to see the lens's rendering of the Orion Nebula and the Flame Nebula—although the subtleties don't really show in this quickly-processed and resized version. 

f/1.4, 4 seconds, ISO 3200

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Edited January 20, 2021 by bcorton

[Mr.Prime]

If I remember my physics properly...

 

For stars only, which are a point source, your light sensitivity (ability to record feint stars) depends primarily on the actual physical aperture rather than f-number.

For nebula and other diffuse objects (non point source) your light sensitivity depends on the f-number

[bcorton]

You are correct that in astronomy and astrophotography aperture is king. But the physics should be the same for point-source objects and extended objects. That is, a larger aperture telescope will show fainter stars than one of a smaller aperture—but it will also show fainter detail in extended objects. The only meaningful difference between observing point source versus extended objects is that one cannot magnify a point source object. And that's physics too. (Note: some few stars are close enough and large enough that they do subtend a measurable angle in really large aperture telescopes, eg., Betelgeuse. So the "point source" thing is a nod to a practical rather than a theoretical truth. If we had telescopes large enough, we could theoretically see the girth of all stars.)

Since f-number expresses a ratio (focal length divided by aperture), bringing f-number into the discussion can get tricky—especially for people with a photographic background. Say you have two telescopes or lenses of equal aperture: one is f/5, the other f/22. If we use eyepieces to equalize the magnification at output of each lens, the brightness of the image in each will be identical. Visually, f-stop doesn't matter. If we attach a camera to each (instead of the eypieces), in an attempt to photograph, say, a dim nebula, then the image of the nebula in the f/5 might require a shorter exposure. However, the nebula will be smaller, less magnified. The f/22 lens, because it has a longer focal length, will magnify the nebula more—spread the same amount of light gathered by the aperture of the objective over a larger area—but the amount of light gathered from the nebula will be identical in each instrument. 

Does that make sense?

Edited January 21, 2021 by bcorton

[Mr.Prime]

yes, that makes sense, it all comes down to how many photons you can collect at the input - the aperture, and what density of photons end up at the sensor. I’ve never tried astrophotography [1] but I remember reading some advice that optimally you want to arrange for the diffraction limited image of a star to fit onto one sensor pixel, rather than spread over several.

 

[1] around 25 years ago I took an SLR with HP5, pushed, and hand held a long exposure of some stars. The idea was to look at the spidery star trails to get a sense for camera shake. We were thinking about rudimentary IBIS at the time in conversations with the guru CCD designer from TI (Jerry was quite a character).

[kalifornier]

Thank you for sharing these images @bcorton. Much appreciated. The 56/1.4 indeed looks very good. I might have to consider multi-row stitching. And it would make a  great portrait lens as well. Hmm, very tempting! 

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Hallo,

Look here: Leica L-Mount

[pocholin]

I went to Big Bend National Park a week ago and took some beautiful pictures, so, yes, the CL is a capable camera. Used a Ttartisans 11mm f2.8 for the first pic and a Sigma 16mm f1.4 for the second for twilight 

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