Rokinon fisheye Milky Way pic

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While planning this shot, I didn't find as much info as I would of liked as far as astro stuff with the Samyang / Rokinon fisheye, so I figured I would post an example of what worked for me. This pic was taken with a 25-second exposure at ISO 2000 with an E-PM2. I bumped up the exposure, contrast and clarity in LR, and added a small amount of sharpening and noise reduction. I went with this shot because of the meteor visible at about the one o'clock position of the frame. The math calls for a 30 second exposure, but in my case I liked 25 seconds (and even 20) better. As this was my first attempt at this sort of thing, I wonder if the shorter exposure worked because I was in a truly remote area- just outside the Strawberry Mountain Wilderness in Eastern Oregon last week while bowhunting.

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shutterduster

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With the 7.5mm, wouldn't have thought of that. What aperture and focus method did you use?

By the way it is a great shot for first attempt.

Dave T
 
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Thanks, All. I'm a little embarrassed to admit that I don't remember the aperture- I think it was f8 for sharpness, but it could have been bigger. Pretty sure it wasn't wide open. I have the vf4, so I prefocused on a fairly distant tree before dark.
 

physicsdude

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I would have thought that just setting the focus ring to infinity would have been enough to get the focus right..
I was planning to get some night shots as well, but didnt think about my 7.5mm. Thanks to you I will try that one too!
 

RobWatson

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Infinity is not infinity (focus by wire lenses doubly so) and hyperfocal does not really work so well.

Closing the aperture down is more to control aberrations than focus. This is a real pain as one wants the largest aperture to capture the most of the faint light but generally the larger apertures and faster lenses have worse aberrations!

Even if you could focus on the moon the stars will not be in focus (one might imagine moon is close to infinity).

Stars are unforgiving targets.

I always consider it a success if one returns home (with any images) unravaged by the beasts of the wild ... one time this pesky family of raccoons made a mockery of me. Go ahead and laugh if you must but a 15-20 pound momma raccoon is a force not to be considered lightly.
 

tradesmith45

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Good start underwater! Not sure what else you tried but here's some suggestions for further exploration.

When looking at the potential of a lens for wide-field astro, I go over to LensTips to get their review. I pay particular attention to CA, fringing, astigmatism & coma - these turn stars into little bow ties or shooting stars. The Rok 7.5 looks excellent even wide open. So there's absolutely no reason to stop it down & lots of reasons not to. The dark MW gas clouds are barely visible in your shot so it needs lots more exposure to get that detail.

To focus - a critical step, find the brightest star you can & focus using 10-14x mag. assist. Or focus on anything bright & far away before you start & tape the focus ring in place. Or note the true infinity focus location on the focus scale during the day & set the lens to that at night.

The rule of 250 says you could use a 33" SS (250/7.5=33.33) w/o creating star trails. The more light the better if you want to see the fine structure of the MW.

Set WB in the 3500-4000K range. The night sky is actually weakly yellow-greenish if you could see it w/ the eye. So even using the lower WB, you'll likely still have some adjustment to do in PP to get a black-really dark gray sky.

No ISO info but judging by what you got @ f8 & 20", it must have been high. Good. I use ISO 3200-5000 on my E-M5 w/ f2. Extended range starts a ISO 6400 so I try to avoid it.

Do a search of YouTube for MW photo processing tutorials & you'll find several good ideas about how to post process these.

I'm really liking DXO Optics Pro particularly for MW RAW development, NR (using their very powerful Prime tool), CA & fringing corrections. Be aware however that Prime takes a ton of processor power so it will take awhile to run - 2 min./per capture on my 2012 3.4GHz i7 iMac.

Being able to shot the night sky opens up so many possibilities its addicting! No more sleeping on camping trips to wonderful places like the Strawberrys.
 

RobWatson

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One thing to note when shooting raw and working with low light levels is adobe camera raw does a terrible job preserving low light levels and sharpness. Use Olympus Viewer to convert the raw into tiff then import into LR (or where ever).

Believe me or not it is simple enough to verify for ones self the camera raw cannot compete with olympus viewer when converting raw images from olympus cameras - particularly in the low signal regime.

No point going to all the trouble to collect those precious few photons to then lose them with substandard raw conversion.
 

tradesmith45

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Hey Rob, I'd like to do a comparison of just this question using OV3, Aperture & DXO. But I've used OV3 so little that I'm worried I'll not be able to get the best from it. I assume OV3 has some settings for ORF to RAW conversion & .tiff export. For example does OV3 apply any NR during development?

Any suggestion about how to do this comparison?
 

tradesmith45

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OK, I think I've done this test correctly. Here's a comparison of RAW development+NR by DXO w/o NR but w/ distortion correction, OV3, DXO w/ Prime + lens corrections & Aperture w/ NIK Define. I'll show both ISO 6400 & 3200. All shot w/ the M.Z12mm @ f2 & 24".

I found that OV3 default setting clearly apply NR to these & I couldn't find a way to turn that off so I used the other NR tools for the comparisons. Also, Since I turned on the DXO Vignette correction when I applied Prime, I used Apertures Devignette tool @ max for the others. Note even at max, there is still some vignetting left compared to the DXO results. All images had the same WB, tone curve & contrast corrections applied but no clarity, sharpening or color adjustments. Vignetting is a major problem w/ most M43 lenses because of the push to keep them small.

Summary of results: OV3 does a terrific job w/ NR given that its free but other corrections are still needed. DXO applies a stronger devignette & distortion correction than the other 2. Even though no highlight protection tools were turned on in DXO, it did not yield blown highlights but the other 2 did. This is likely the result of NR. From all my tests, every NR tool also changes image tone & contrast & sometimes color in some way. DXO produced the least noise & sharpest stars when you pixel peep. But the overall images from all of them can produce usable results that would become very pleasing w/ additional PP.

Hope this is helpful, it was for me. OV3 might help me out of another PP jam I'm in w/ a full moon pano in Monument Valley.

ISO 6400 results:
DXO w/o NR + distortion & Aperture Devignette
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[/url]_8270053_DxO by tradesmith45, on Flickr[/IMG]

OV3
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[/url]_8270053-OV3 by tradesmith45, on Flickr[/IMG]

DXO w/ Prime & Lens Corrections (CA, PF, Distortion, Vignette)
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[/url]_8270053_DxO wPrime by tradesmith45, on Flickr[/IMG]

Aperture+NIK Define 2
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[/url]_8270053 Aperture+Define by tradesmith45, on Flickr[/IMG]

Now Same Order for ISO 3200

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[/url]_8270031_DxO by tradesmith45, on Flickr[/IMG]

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[/url]_8270031-OV3 by tradesmith45, on Flickr[/IMG]

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[/url]_8270031_DxO wPrime by tradesmith45, on Flickr[/IMG]

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[/url]_8270031-Aperture+Define by tradesmith45, on Flickr[/IMG]
 

RobWatson

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Sorry for being tardy ... not ignoring you just too danged busy lately.

OV3 has the same controls as in camera so so noise filtering can be turned off (not the long exposure correction as that is already applied to raw data anyway).

Exporting as 16 bit tiff preserves all the signal range not lost under non-linear adjustments (like color temperature, etc).

There are a couple of older threads with images, etc on this topic.
 
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