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02-21-2021, 08:11 AM - 1 Like   #1
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star field of What?
Lens: dfa*50 Camera: k50 Photo Location: home ISO: 1250 Shutter Speed: 1/2s Aperture: F1.4 

Hello all. This was taken as an HDR 3 image and resolved in camera. Tripod mounted, 3 second timer, no filter, focus to infinity, I had the 3/4 (give or take) moon just off screen. and of course a lot of other light from being just a few miles from Atlanta, my neighbors porch light etc. I had the hood on which seemed to be absolutely necessary.

The image came out with a not so dark sky. I turned the contrast up and maybe the shadows down. I really just thought to make more contrast. Obviously Im not an expert.

The image is take facing somewhat south so South is at the bottom of the screen (my best recollection). I think the Pleides were to the right (east) but in some tree limbs. I tried to get a pic of just sky. In hindsight I will likey include those at the edge so i have an anchor, next time. Im not sure if just my inexperience but I thought the central object was Arigua. However, now that I cannot currently go out and look again - until tonight (fingers crossed)- It is a mystery to me what I took a photo of. I have been looking at star charts and I don't get them to match. So my bet is that I am so wrong that this is not going to help you help me.

So far as the image, I see the edges of the photo the stars sort of double up, which Im guessing is due to the 3 image composite and different colors/wave lengths so some should probably be cropped . But I did not crop so y'all might be able to give more advice for when the next semi clear sky appears. I think we have been overcast for a couple of months until last eve.

I was staying with f1.4 and keeping the ISO 3200 or below on Auto ISO. I tried 2 sec and 1.6 1.3 1.0 .8 .6 .5. This is the one that came out best. Given a better game plan I would like to try shots at f1.4 1.8 up to 2.8 to see if sharpness improves.

Yes I am looking for critical advice. I do not have a astro device currently. Perhaps that would help. The tripod has a 2.5 lb weight hanging and is on concrete. This to say its about as stable as I can think to make it.

My other lens options for primes are the 70 limited 2.4 and the 40 limited 2.8. I have a Tamron 70-200 2.8 from back when it had the macro moniker so that lens might be an option. I have slower lenses but without tracking etc. I think I need to stay below 2 seconds shutter.

Fire Away!

Oh Yes and Thank You all for Your comments ahead of time! I am looking forward to the help.

Risx

2 20 21 star field.jpg | Kenneth Jones | Flickr

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02-26-2021, 04:46 AM - 1 Like   #2
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One option which may help is to download Stellarium. You can feed in your location and roll the time back to when the photo was taken to get a view of the sky at that time. You may be able to work out what you were seeing.

You may be better taking several photos and using deep sky stacker (DSS) to stack them rather than doing it as HDR.
I am also no expert but am looking to have a go at this once we get some clear skies.
02-27-2021, 07:31 AM   #3
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Abstract star field of What?

Thank You Stevejo.

Thank You for responding.

I will try that site.

Yes, I want to try stacking. This was a bit impromptu. I think the lens will work for this very well. I am afraid the k50 has more noise than the KP level cameras especially after 400 iso. I was looking at protons to photos and the iso/noise charts (Input-referred Read Noise versus ISO Setting) and apparently in addition to the lower MP count and 12 bit, one of the real differences is in noise attributed to using higher ISO in low light - of course to me that is exactly why i would use higher ISO. So I notice I said 3 sec exposure in the OP. I meant to say 3 frames at .6 sec. The stars appear to be round. This at 1250 iso. I should probably have tried to stay at 400 iso. I believe this would have produced lines instead of dots as the shutter could go over 1.5 seconds. Also the 3 shot hdr would be around 4 .5 seconds in that case. I tried several shutter speeds and admittedly the focus was the best in this case but as the times got longer I saw more lines. Of course the interface between the OVF and the shutter button is not an extremely sharp tool and I may just be going at it wrong. My thinking was f1.4 fastest lens I have and sharpest. Slow shutter speed. I actually started at 2 sec shutter and worked up to .5 sec. ISO was on auto although the limit was at 1600. It was afterward I found the p2p site and realized why(i think) the sky is so blotchy.

Next chance I get I will try setting up f1.4, Step the ISO down to 800, 600, 560, 400, and set the shutter speed accordingly. Somewhere in there should be a happier medium.

It is a hobby and I am enjoying it immensely,

I look forward to seeing your pictures of the sky.

Thank You again for responding.


Risxsoul
Ken
02-27-2021, 09:20 AM - 1 Like   #4
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I am surprised that no-one else has pitched in. There is quite a lot of good info on this site . It mainly concentrates on the Milky Way but has good general info for starters too.

02-27-2021, 05:29 PM - 1 Like   #5
kwb
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QuoteOriginally posted by Risxsoul Quote
The image is take facing somewhat south so South is at the bottom of the screen (my best recollection). I think the Pleides were to the right (east) but in some tree limbs.
Hi Risxsoul, the quickest way to determine is to submit it to an astrometry.net.
Astrometry.net
Click upload, select your photo, submit, and it will automagically calculate and identify the stars. You can do it anonymously if you like without creating an account.
02-27-2021, 07:20 PM - 1 Like   #6
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A first guess would need date and time of exposure to nail down a starfield.
02-27-2021, 08:18 PM   #7
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oh I wondered if there was a site that would do this
many thanks.

thanks kwb

oh your correct jbinpg. I see my date is correct but the time is 12 hours off. Should be just before 9 pm ET. I hate that the date needs to be set every time there is a battery change. I have many pics taken on 1/1/2013. Ah well.

---------- Post added 02-27-21 at 08:49 PM ----------

The obect near the middle is Procyon which is one of the two stars in Canis Minor. according to nova.astrometry.net.
That was fun.
Thanks again
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