ISS over Gloucester



Leland33
Joined: 02 Apr 2011, 03:07

15 Jul 2017, 14:17 #243

Exposures recommended for the Aurora:
f/ratio 400 ISO 800 ISO 1600 ISO
2.......15 sec..... 07 sec...... 04 sec
2.8.: 30 sec...... 15 sec...... 07 sec
4.:... 60 sec...... 30 sec...:: 15 sec



==========================

Here's something that 99.99% of people with cameras don't know:

An f/stop is merely an index mathematically related to the diameter of the aperture and the focal length of the lens - for a 50mm
go a length at f2.0 the aperture is 25mm likewise moving UP ONE STOP TO f2.8 50/2.8 = 17.9mm.

Now, Area of aperture =
(pi = 3.14) x r x r
For f2.0: 3.14 x (25/2) x (25/2) = 490

Up one stop to f2.8
3.14 x (17.9) x (17.9) = 245

So, that interesting isn't it???? As you go up in f/stop index the area of light in the aperture is halved (490 vs 245). This math relationship is true for all f/stops (1.4, 2.0, 2.8, 4.0, 5.6, 8.0, 11.0, 16.0, 22.0 ....)

The relationship of exposure duration and ISO is straight forward. If you look at look at the exposures for the Aurora f2.0 @ 15 sec = f2.8 @ 30sec and the same is true for ISO. So all exposures in the Aurora chart are the same amount of light on the film plane or digital sensor.

Bracketing is selecting an f/stop above and below what you are shooting. But it's also a good idea to shoot everything the same, maybe change composition then bracket.
Last edited by Leland33 on 16 Jul 2017, 03:32, edited 1 time in total.
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Fortune Cookie
Joined: 13 Nov 2010, 17:37

15 Jul 2017, 14:30 #244

I think anyone who is serious about photography understands that -- and that a one-stop difference, whether achieved by changing the aperture or by changing the shutter speed -- is a two-fold change in the amount of light reaching the exposure surface.
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Leland33
Joined: 02 Apr 2011, 03:07

15 Jul 2017, 15:47 #245

Fortune Cookie wrote:
I think anyone who is serious about photography understands that -- and that a one-stop difference, whether achieved by changing the aperture or by changing the shutter speed -- is a two-fold change in the amount of light reaching the exposure surface.
I think we're both right - aren't we? Going up each stop of the f/stop scale the light is halved going down the scale it's two-fold. But I do think most people with a camera don't know the derivation of f/stop = lens focal length vs aperture area. But most know the relationship between f/stop, shutter and ISO/ASA.
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Leland33
Joined: 02 Apr 2011, 03:07

15 Jul 2017, 15:51 #246

Thank you Karly and Cathy for pointing out the Aurora might be seen this weekend.
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Cathy (Admin)
Joined: 13 Aug 2005, 09:30

15 Jul 2017, 21:30 #247

UPDATE 1: NOAA Expects the significant activity to begin towards the middle of the storm watch: between the 12th and 24th hour of the watch.


When does the Aurora storm watch begin?  The storm watch begins Saturday at 8:00:00 PM


The storm watch starts at the above time and continues for 48 hours.


http://www.softservenews.com/en/aurora- ... 00142.html
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Leland33
Joined: 02 Apr 2011, 03:07

16 Jul 2017, 02:03 #248

It looks like Gloucrster is going to have clear skies tonight starting at 11PM thru sunrise.

I read that recording video is not as effective on the Aurora but instead using built in time-lapse or do it manually and then edit a sequence with many images (e.g. 10 sec = 250 images or so.)
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Leland33
Joined: 02 Apr 2011, 03:07

16 Jul 2017, 15:44 #249

Just after sunset last night the sky had a blue-green sheen to it. Throughout the morning I drove around the cape to several northern exposed sites .. but nothing ... despite it being fairly clear. There was a very vivid green-blue sky at dawn than the blue-green I saw earlier.

I think that was predicted, per Cathy's posts especially the vivid green blue kind of fit time wise 8-24 hours after the start 8PM last night.

So, is tonight the night???
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Cathy (Admin)
Joined: 13 Aug 2005, 09:30

16 Jul 2017, 18:03 #250

The activity level was at kp 7+ an hour or so ago and has been steadily declining since then.  Not sure if that was the height of the storm for this one or if there is still a chance that the activity will increase.


Trying to decide whether or not I should take a nap so I can pull an all-nighter on storm watch, lol.


Play the video on the Northern Hemisphere at this NOAA site - it is pretty cool.


http://www.swpc.noaa.gov/products/auror ... e-forecast
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Leland33
Joined: 02 Apr 2011, 03:07

16 Jul 2017, 19:46 #251

Around 3:30AM there was a raspberry burst that filled the entire night sky. It looked like activity was NE of Lanes Cove. As I made it around 127 past Halibut the sky was greenish blue. Granite Pier it was dusk with greenish blue to the NE and darkness to the SE. So I was seeing the Auroral Borealis not directly but on a bounce.

The videos are very helpful. I was watching the former video while on site. On the latest video I noticed a huge increase at about dawn which is what I saw on a bounce. If sunrise was more like 7 or 8AM, it probably would have been a real show!
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Fortune Cookie
Joined: 13 Nov 2010, 17:37

17 Jul 2017, 03:15 #252

Heavy rain and lightning here.

Guess it's a bust for me.
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Leland33
Joined: 02 Apr 2011, 03:07

17 Jul 2017, 03:24 #253

Aurora update - About ten cars lined up on Granite Pier tonight like birds on a telephone wire - all facing east. Waiting for the Eastern Lights due at 5:20AM.

Nothing much but a tad brighter in North both at Granite Pier and Lane's Cove.

Wow, total flame-out in Washington State - lucky guys!
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Cathy (Admin)
Joined: 13 Aug 2005, 09:30

18 Jul 2017, 00:51 #254

I was at Old Garden Beach.  The aurora forecasts were showing continued weakening, so I packed it in around midnight.  Another miss, lol.
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Dun Fudgin
Joined: 21 Jun 2007, 03:54

18 Jul 2017, 01:54 #255

All we have over Cape Ann lately is contrails!
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Leland33
Joined: 02 Apr 2011, 03:07

18 Jul 2017, 02:36 #256

Cape Ann Web wrote:
I was at Old Garden Beach.  The aurora forecasts were showing continued weakening, so I packed it in around midnight.  Another miss, lol.
I packed it in about then too. I spent two evening with much needed bonding with my camera. For a SONY product there are some oversights. No remote max time exposure 30 sec. (RX-100i). I really should have worked with the 4AM green sky In Rockport - instead of moving to Bearskin I headed to Gloucester and the green sky had faded.
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DM3194
Joined: 07 Feb 2008, 22:54

23 Jul 2017, 23:11 #257

Hasn't been this high in the sky for a while!
....and a horizon-to-horizon 6-minute pass.

Time: Sun Jul 23 9:58 PM, Visible: 6 min, Max Height: 83°, Appears: 10° above WSW, Disappears: 10° above NE
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Karly
Joined: 20 Feb 2010, 02:12

24 Jul 2017, 02:05 #258

Very cloudy so not our best sighting of it but we saw it and first time for one of my kids...thanks for the heads up.
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Fortune Cookie
Joined: 13 Nov 2010, 17:37

22 Aug 2017, 00:33 #260

On the evening news, I saw a series of 7 images of the eclipse that NASA released that included the ISS photobomb. I wish I could find that one. 
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