Lenses for astro/nightscape photography.

spraynpray

@kenadams: Where I lived in France, I used to walk my dogs down the lane last thing at night and when it was clear the milky way was right over head running along the length of the lane. It was truly majestic. When I have polished my technique locally, I will return to capture it.

The images above also include light painting and so look extra dramatic.

spraynpray

I'm going out to give the 20/1.8 a workout tomorrow night on stars and milky way. I have been disappointed so far, so if I don't get acceptable results from it, I will be sending it back in exchange probably for a sigma 35/1.4. The 35/1.4 is a narrower field of view than I wanted, but it seems that from 24 and wider has too many aberrations to cut the mustard at nightscapes. It's fine during the day, but I am buying it for nightscapes.

I will post a result from it for you to see although if it is no good, I will not PP it much.

WestEndFoto

I'm going out to give the 20/1.8 a workout tomorrow night on stars and milky way. I have been disappointed so far, so if I don't get acceptable results from it, I will be sending it back in exchange probably for a sigma 35/1.4. The 35/1.4 is a narrower field of view than I wanted, but it seems that from 24 and wider has too many aberrations to cut the mustard at nightscapes. It's fine during the day, but I am buying it for nightscapes.

I will post a result from it for you to see although if it is no good, I will not PP it much.

Spraynpray, coma tends to be more of an edge and corner issue then a centre frame issue. If you are willing to contemplate a longer focal length, then you should crop your 20mm test image to the same focal length as the Sigma and compare that to the Sigma. That might be an excellent comparison in favour of the Nikon as the Nikon may have no coma in that cropped field while the Sigma will likely have some.

You will lose some resolution by cropping, but you have not have to crop by that much and resolution will likely be less critical for night sky photography.

spraynpray

@WestEndPhoto: That has of course occurred to me but the only reason I bought the 20 was because of it being 'coma free' which it isn't. If I were to crop it to about 35mm I would get the worst of all worlds. To expand on that - it doesn't have the centre performance of the 35, it doesn't have the clear aperture diameter of the 35 and I wouldn't get the resolution that I would with the 35. The clear aperture is a huge deal and although I was prepared to put up with that if the 20 had been coma free, I am not if it isn't. I now realise that there are no wide lenses that are coma free, it is just a question of how much and whether you get a good one. The other way to reduce coma is to stop the 20 down to f2.8 but I would rather not have to do that either as light on the sensor is king.

Come on Nikon, you gave us the D810a, how about some wide lenses with no spherical aberrations? For sure the AFS 35/f1.4 is expensive enough to not have any!

WestEndFoto

Or the 24 1.4. Both are older (for a bread and butter lens) lenses, so perhaps on the next update.

spraynpray

I reckon it would give them quite an edge because there isn't anything in the 14-24 range that can be called free of coma in reality. If the lenstip test results are accurate, I am going to be happy with the Siggy 35/1.4 in terms of coma and because it will be more useful to me for general photography than the 20 would have been.

As usual, I will update on my findings in case it saves somebody else the a$$ache I've had. :P

Beso

I have to ask what may seem like a stupid question - can a scene like the above actually be seen with the naked eye?? Because I sure as hell know I've never seen anything like that despite having travelled, lived and stayed in fairly dark, non-urban areas at times..

The short answer is no. In a good dark sky location one can make out the Milky Way and many peripheral stars with the unaided eye but not to the extent a good camera can produce. The reason is pretty simple. The camera sensor is typically exposed for 15 to 30 seconds, so it can gather light that the human eye/brain will not see because the human eye/brain processes visual images far too rapidly. Similarly, the foreground will appear much lighter than the unaided eye/brain sees for the same reason. Often a photographer will "light paint" the foreground to bring it to a visible level. The best dark sky locations simply do not have enough extraneous light to make the foreground visible at a level which enhances the overall image.

WestEndFoto

That said, you will be wowed even with your naked eye if you can find a truly dark sky location at high altitude with dry air and no moon.

In my opinion, the best photography often shows us what we can see but is still there.

spraynpray

Well guys, just thought I would update y'all on my progress on this subject. I bought the Siggy 35 Art and found it to be a really good lens in decent light - stunningly sharp with great colours - BUT, I tried it at a low light party and found the focus to be unreliable. I then tried it for night sky and although it captured LOTS of stars, the tangential and sagittal astigmatism were really disappointing so I took it back.

Today, I took my laptop to a UK dealers and tested another Sigma (exactly the same results as the first copy), a Nikon 35mm f1.8 (absolutely horrendous abberations) and a Samyang 24mm f1.4 (even though I had bought a Bower 24mm f1.4 (same lens exactly as the Samyang) and rejected that one as not good enough) but this copy was GREAT. That means that I had a refund of £200 burning a hole in my pocket which I put towards a 60mm f2.8G to test against my old 'D' for my macro shooting.

Happy at last and can't wait to get out on the next clear night to shoot the milky way.

Here is a shot from the Sigma, five stitched shots:



Fortunately most of the aberrations were cut off during the stitching process.

I will post a shot from the new lens when I have a one.

WestEndFoto

If you are willing to stitch, more possibilities are opened up.

spraynpray

If you are willing to stitch, more possibilities are opened up.

That's true to an extent, but then the wider the lens, the less images you use for a given field of view while (usually) the worst of any aberrations are cut off so wider is still better. I will still stitch 'special' views, but stitched shots with foreground interest focussed are a pain when shooting a mosaic. Ideally you still need a fast low aberration wide angle lens with proper manual focus (270 degrees of focus ring rotation and a hard infinity stop).

I'll miss the Sigma Art, but not for its manual focus, auto focus, aberrations or field of view.

spraynpray

Y'know, if I didn't have bad luck, I'd have no luck at all (as the saying goes). I had a chance to use the Samyang 24/1.4 last night, and it has a problem in that it has no hard stop at infinity - it rotates about 5 mm past infinity before it hits the stop. Because of the wide field of view (tiny stars) and the HUGE amount of noise in live view, trying to focus even using a loop was impossible so the shots were scrap. I know this is not uncommon with these lenses, but I figure that at $750 (£500), it should be right.

Doh! :-w

Ironheart

You need a brighter/larger object like a planet or moons of a planet to obtain critical/infinity focus, or a really bright star such as Sirius. None of the Samy's have a hard stop infinity because of thermal expansion it wouldn't always be correct even if you do set it.
I have this problem every time I go out at night. Usually spend the first 10-15 min getting and checking critical focus regardless of lens. None of the G lenses have a hard stop infinity either.

spraynpray

Sure, if it was an AF lens, I would accept no hard stop (along with the smaller angle of rotation of the focus ring), but it is MF. I have to disagree with you there @Ironheart, because if you remember back in the day, all lenses had hard stops and I seem to remember it got quite hot in the summer and cold in the winter then too. :P I had the 14mm f2.8 Samyang recently and that had a hard stop? I have always thought that AF lenses have no hard stop because they don't know they are at infinity until they pass it and then come back to it. I could be wrong there that it is the way closed loop servo systems work.

Have any of you noticed how ridiculously noisy the rear screen gets when zoomed in 100% to manual focus on a dark night? You cannot see the stars it is so noisy. I haven't read about this, but it seems the camera 'boosts the ISO' on the rear screen when it gets darker and as there is no way to stop that, live view focussing on my D750 is virtually impossible. I say 'on my D750' because live view focussing at 100% zoom when using my D7100 is easier because it is LESS noisy. @-)

My A.D.D. is starting to kick in now.

Ironheart

No, it is ridiculously noisy at 100% on every camera I have too. The technique I use is to 1) locate the brightest object I can 2) focus through the viewfinder first to get it "in the ballpark" 3) switch to live-view and set fine focus there 4) take a test shot and confirm

spraynpray

I think I should take a tablet (and I don't mean medication!) and review the shots on screen because I don't have a problem getting it close, but I do have a problem getting it perfect which I need a better screen to see. Sounds like a plan to me.

Thanks for getting me thinking.

I have spoken to the distributor of Samyang lenses here (they are very helpful) and they are going to speak to South Korea to see if the lens should have a hard stop at infinity and if it should can it be adjusted. I had a nasty thought - given that the lens is MF, the only reason for making it have a hard stop after infinity would be to cut costs by not putting all the paraphernalia in the lens and the steps in the production line to adjust it. That way they would never have manufacturing tolerances add up and result in a lens where infinity can't be reached. If that turns out to be the case and it can't be adjusted to coincide, it would be very disappointing. I'll let you all know.

Ironheart

They are easy to adjust, it's just that your infinity would be different than anyone else's, and it might move depending on temp. Film was much more forgiving.

Some folks mark the lens like this:



If you want to get adventurous you can adjust it yourself (this is for 14mm, 24mm would be similar):

Ironheart

This is the best writeup I've seen on live-view focusing. Even with the level of detail here, this article makes it seem easier than it is. It is more art than science and every lens/camera combo is slightly different:
http://www.astropix.com/HTML/I_ASTROP/FOCUS/Live_View_Focusing.HTM

Another interesting article about critical focus on a telescope, but lots of detail. Some of the coma in the corner of the lens can be reduced with proper focusing:

http://www.steveluce.com/astro/focus.html

autofocus

I just picked up the Rokinon 12mm 2.8 Fisheye and so far I'm impressed with the lens. Anybody else tried it yet?

spraynpray

@Ironheart,

Those are interesting links on focusing, although nothing new for me there.

The focus adjustment vid was interesting, and strangely easier to follow in Portuguese than an English version I found the other day! If I'd bought mine used I would have had a go at it but as it is new and within the return period, I can't touch it.

Strange how they don't even mention the hideous noise when zoomed in 100% in live view. :-?

@autofocus,

That is an interesting lens. I would be VERY interested in a night sky shot wide open for 1 to 2 seconds at ISO 3200 if you have a mind to?

autofocus

@spraynpray will do tonight and post here.

spraynpray

Good man!

autofocus

@spranpray - Here is a photo I took last night as a test shot. Sorry the clouds are covering so much of the sky. D810, ISO 3200, 8 seconds, f2.8, Rokinon 12mm 2.8 Fisheye Lens. This is a JPEG right out of camera. Full size on Flickr. I can do a 2 second exposure tonight if you like. At least the sky is clear now.

spraynpray

If you could upload it full res and make it sky edge to edge please, that would be great. It's the edges that matter you see.

If you have to adjust the exposure, use ISO not shutter speed. Longer than 2 secs will give slotting at full res. Thanks.

autofocus

@spraynpray, I'll do it tonight and post here. The one above is full res in Flickr. I'll shoot straight up at the sky as best I can with the trees and such ensuring you have sky/stars out to the edges.