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07-11-2015, 02:03 PM   #76
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QuoteOriginally posted by ZeGaby Quote
Some pics from my last session :

Look !


Starry Car
Impressive. I would love to shoot stars in the summer but the sun never sets fully here in the north...

07-11-2015, 04:18 PM   #77
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The second picture is very, very good. No movement, no traces of coma anywhere (what lens is this, 18mm f1.8?), a very clear Andromeda, and the Milky Way, ... Superb!!
07-12-2015, 10:39 AM - 2 Likes   #78
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Thanks for your comments !
QuoteOriginally posted by Tjompen1968 Quote
Impressive. I would love to shoot stars in the summer but the sun never sets fully here in the north...
But you've got some aurora borealis

QuoteOriginally posted by JimmyDranox Quote
The second picture is very, very good. No movement, no traces of coma anywhere (what lens is this, 18mm f1.8?), a very clear Andromeda, and the Milky Way, ... Superb!!
It's the Sigma 18-35mm f/1.8 Art (i love this lense ! )

I've try a new way to enhance Milky Way on my two last pictures :

Look ! V2


Starry Car V2


And a new picture from my session

The blue Hour


Just before the night....
you can see when the stars appear (the smooth is natural, it's not an effect)
07-12-2015, 06:00 PM   #79
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Very nice this Blue hour. And I like the name too.

About V1 vs V2, I like V1 more.

About ''Look''. It is something interesting in that picture. You have an aircraft at the left, and a satellite, at extreme left, just around the edge. Up, you have three satellites, with long and thin traces, and a very slow moving target. Much to slow to be satellite or aircraft, especially that is quite high in the sky, maybe 40-50 degrees. Ovni? Also, a slow target at the right, at a low angle. Again, a good choice of name for this picture.

07-14-2015, 12:58 AM - 1 Like   #80
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QuoteOriginally posted by JimmyDranox Quote
Very nice this Blue hour. And I like the name too.

About V1 vs V2, I like V1 more.

About ''Look''. It is something interesting in that picture. You have an aircraft at the left, and a satellite, at extreme left, just around the edge. Up, you have three satellites, with long and thin traces, and a very slow moving target. Much to slow to be satellite or aircraft, especially that is quite high in the sky, maybe 40-50 degrees. Ovni? Also, a slow target at the right, at a low angle. Again, a good choice of name for this picture.
Thanks

Milky Way
I use the O-GPS1 module, Sigma 18-35mm @ 18mm f/2.0 Iso800 60sec

07-14-2015, 08:51 AM   #81
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great work, ZeGaby!
08-09-2015, 04:29 AM - 2 Likes   #82
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New pictures made with the Sigma 18-35mm f/1.8 and the O-GPS1 module

Sending from Andromeda


Iso 1600


Up above Moivre


Iso 800
08-11-2015, 12:40 PM   #83
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Up above - Panorama

A new version of "Up above Moivre" ! Made of 3 pictures, stich with AutoPano.
Made with OGPS-1 50s with the Sigma 18-35mm @ 18mm f/2.0 iso800



08-11-2015, 09:06 PM   #84
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I'd have a question for you astrophotos litterates:
in this link, they promote the usage of a SMC Pentax K 135mm f2.5 for astro photo, as one of the best lens...

The Best Telephoto Lenses for Astrophotography - Articles - Articles - Articles - Cloudy Nights

However, when they mention: "When the aperture is stopped down to 37mm using step-down filter rings, this lens produces incredibly tiny pinpoint star images from edge to edge."

I don't understand why they refer aperture in mm ???

Is this a typo or Am I missing something ?

Thanks in advance
08-11-2015, 11:02 PM   #85
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QuoteOriginally posted by Weevil Quote
I'd have a question for you astrophotos litterates:
in this link, they promote the usage of a SMC Pentax K 135mm f2.5 for astro photo, as one of the best lens...

The Best Telephoto Lenses for Astrophotography - Articles - Articles - Articles - Cloudy Nights

However, when they mention: "When the aperture is stopped down to 37mm using step-down filter rings, this lens produces incredibly tiny pinpoint star images from edge to edge."

I don't understand why they refer aperture in mm ???

Is this a typo or Am I missing something ?

Thanks in advance


I remember having read in some forum that it was commendable to stop down lenses at the front end using step-down filter rings instead of using the diaphragm of the lens. It said that keeping the rear aperture wide open and reducing diameter at the front end avoids/reduces diffraction patterns occurring at bright stars. Have not tried it.
08-12-2015, 12:24 AM   #86
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QuoteOriginally posted by Weevil Quote
I'd have a question for you astrophotos litterates:
in this link, they promote the usage of a SMC Pentax K 135mm f2.5 for astro photo, as one of the best lens...

The Best Telephoto Lenses for Astrophotography - Articles - Articles - Articles - Cloudy Nights

However, when they mention: "When the aperture is stopped down to 37mm using step-down filter rings, this lens produces incredibly tiny pinpoint star images from edge to edge."

I don't understand why they refer aperture in mm ???

Is this a typo or Am I missing something ?

Thanks in advance
Because in astronomy 'aperture' means the diameter of the frontal element of the lens or telescope.
08-12-2015, 05:13 AM   #87
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My Understanding

My math: 135mm / 37mm = f/3.6 where f is the focal length. So they are using step down rings to build a funnel that is screwed onto the front of the lens with a 37mm diameter opening to get the desired aperture? I guess this prevents using light from the edges of the lens; sort of a light tunnel passing through the center of the elements.

I'm new to astrophotography (My K-3II is being delivered today!!), so I'm trying to summarize what I understood from this thread. Thanks,

Lee
08-12-2015, 11:57 AM   #88
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QuoteOriginally posted by Quirky Quote
My math: 135mm / 37mm = f/3.6 where f is the focal length. So they are using step down rings to build a funnel that is screwed onto the front of the lens with a 37mm diameter opening to get the desired aperture? I guess this prevents using light from the edges of the lens; sort of a light tunnel passing through the center of the elements.

I'm new to astrophotography (My K-3II is being delivered today!!), so I'm trying to summarize what I understood from this thread. Thanks,

Lee
This is correct, but not the full answer.

The step-down rings (having a completely round hole) PRIMARILY avoid the diffraction spikes that the regular diaphragm (non-round blades) would cause for imaging stars. These spikes are rarely visible for daytime photographs, but are quite prominent on brighter stars, which are pinpoints of light on a totally black background. Think of the "starbursts" so desired on the SMC (vs HD) DA 15mm ltd for nighttime and sunrise/sunset shots.
08-12-2015, 12:39 PM   #89
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Quick question .... I'm hoping to set my K-3 out tonight with the Rokinon 14 or maybe Samyang 8mm fisheye and try to get some Perseid shots. I thought maybe I'd set the interval shooting and let it go for as long as the battery lasts or the card fills up. But then I got to thinking ... what about dew?

If I put a couple handwarmers around the lens, will that keep dew off? And in your experience, will there be enough dew to damage the camera -- since neither of those lenses is weather sealed??

Thanks!
08-12-2015, 01:48 PM - 1 Like   #90
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QuoteOriginally posted by loco Quote
Quick question .... I'm hoping to set my K-3 out tonight with the Rokinon 14 or maybe Samyang 8mm fisheye and try to get some Perseid shots. I thought maybe I'd set the interval shooting and let it go for as long as the battery lasts or the card fills up. But then I got to thinking ... what about dew?

If I put a couple handwarmers around the lens, will that keep dew off? And in your experience, will there be enough dew to damage the camera -- since neither of those lenses is weather sealed??

Thanks!
Dew won't damage your camera since the lens is attached but the visibility could affacted by water drops on the lens.

This article may also help you.

Dew Heaters for Night Sky Photography | Phil Hart
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