Astrophotography - Rokinon 24mm 1.4 vs upcoming Sigma 24mm 1.4 Art (or other ideas)

pigeyejacksn

Confirmed 16mm/3200/f4/30 seconds. In hindsight I guess I should have gone 6400 and 15 seconds hmmm

Thanks

spraynpray

With those settings and that lens I would say you have slitty stars and coma in all the corners?

sevencrossing

I would say you have slitty stars

I am tempted to make a comment about the Duke of Edinburgh.:)

spraynpray

heartyfisher

NASA Just Released The Largest Picture Ever Taken

Koru

Okay. Feeling small, here.

CallMeAl

Hi Folks, just thought I'd chime in with first hand experience of using the Sigma Art 24mm f/1.4 for Astrophotography, specifically shooting the Milky Way.

THE GOOD
I was in awe at how much light and detail the lens captured - I was using exposure settings of f/1.4, 20sec at 1600 ISO on a Nikon D810. I latter bumped the ISO up to 3200 for even better results. However, based on my own personal thresholds for what's acceptable, I won't push beyond 3200, I found 5000 to be un-printable for my own tastes - but it would look fine for web publishing. People have reported that the D810's "Sweet spot" is ISO 5000 but I made a 32 inch print of a shot at ISO 5000, with in camera and post production noise reduction (dark frames etc) and was still too noisy for my likings.

THE BAD
COMA, and lots of it. While sharpness was spectacular at the centre, you should expect "gull wing" like coma on the edges, unless you stop down to at least f/2.8. This renders any "single shots" unusable at f1.4 and I had to resort to shooting panoramas, with lots of masking and cropping to ensure coma affected areas weren't kept in the stitch.

From field and post processing experience (rather than lab based tests, because I'll never use my camera in a lab ) I found that the 24mm at f2.8 performs about the same as the Sigma ART 50mm at f/1.4.

THE BEST?
I also have the Sigma 35mm ART f1.4 and beats both of the above lenses for astrophotography in terms of combined sharpness, contrast and coma (or there lack of). It's practically coma free around the edges at f/1.4 and retains all the detail you need/want. If you think 35mm is too narrow of a FOV, take three steps back and you'll get what is reasonably the same FOV as a 24mm.

However, I really enjoy shooting at the wider spectrum (14mm) and the Samyang 14mm 2.8 was a letdown (can't complain really, as it only cost me $300). So I'll be saving my pennies for a Nikon 14-24mm 2.8. Yes filters are an issue for general photography but I'll be keeping the Sigma A 24mm, 35mm and 50mm for that work.

Spy_Black

@spraynpray: " I would like to start by saying what lens to NOT buy; the Rokinon/Samyang 14mm f2.8...It has tragic coma."

Did you try more than one sample? A problem I've seen with third-party (and probably OEMS) is inconsistency from sample to sample. Everyone raves about the Tamron 24-70 f/2.8, but the sample I bought had "tragic coma", yet everyone says it's as sharp or sharper than the Nikon and Canon counterparts.

So although you may need to sell your copy because it doesn't serve your needs (unless you bought it recently, in which case you should just return it), consider renting the same lens from, say, LensRentals and see if their copy is also as bad, or if it should live up to it's hype.

"The exposure calculator is too simple - there is more to it than that..."
Do you have a reference to a more detailed approach to exposure calculations? That calculator doesn't strike ma as that bad a starting reference.

Spy_Black

@pigeyejacksn: If you have a copy of Photoshop, you can try the process outlined in this video link below. Personally I wouldn't bother with ProFoto or ZIP as he outlines, but that's just my personal decision. I also would not be as sloppy with my masking. ;-) You camera body should have an intervalometer option if I'm not mistaken.

The advantage here is that it allows you to shoot at, say, 6400 and still be able to get a good quality image. You can even stop down a stop if you're getting some image smearing at the edges.

spraynpray

@CallMeAl: Thanks indeed, good experience shared. I hope somebody here can do a similar post on the Sigma 24mm f1.4 as for me, a 24mm f1.4 will always beat a 35 f1.4. It's not the field of view, it is the number of stars you get wide open due to the clear aperture diameter.

@Spy_Black: Didn't try more than one example and bought it used in perfect condition. Nearly every exposure indicator on the internet is wrong (for me) because they all get slitting. They may tell you 9 seconds for example before slitting, but if you look at the speed of the fastest star in the frame and consider the time that a pixel is within its diameter, the time is about 5. These 20-30 second shots everybody does are OK viewed tiny, but if your aim is to print large, you have to aim higher with your equipment, technique and processing.

Ironheart

@SnP, you need an attitude adjustment. I mean latitude ;-) Seriously, you either need to 1) loosen up 2) aim more at the North Star, or 3) get an equatorial mount.

spraynpray

Cmon Ironheart, you of all people must be able to see that holding the shutter open for longer than 5 seconds at 24mm only gives you slits not brighter stars? Also, as I shoot nightscapes not astrophotography, an equatorial mount will not help me. a latitude adjustment would help me though as I would like to get some northern likes.

Surprisingly good results can be got if you get the right lens/shutterspeed/ISO/PP balance. I am going to be at the learning stage for a while yet, but if anybody thinks they have it all sorted with 20 second exposures and cranking clarity, NR and sharpness in PP, they are mistaken. I look at my first nightscape images and cringe!

I have decided I am going to hire the 24mm Siggy and if it is the answer to my prayers for coma, I will flog my Rokinon 14, Bower 24 and Tokina 11-16 to fund it.

proudgeek

^^Have you considered the 20mm f/1.8? Or maybe even the the 14mm f/2.8? Question for the mathematicians: which allows for longer exposure times, the 20mm f/1.8 or the 24mm f/1.4? Assume for a moment that all other quality issues are equal.

spraynpray

The 20mm 1.8 is interesting, it is down to coma in the end. My Rokinon 14mm is 2.8 but it has poor coma. I think the Nikon 14mm f2.8 is similar for coma.

Spy_Black

@spraynpray :"...you of all people must be able to see that holding the shutter open for longer than 5 seconds at 24mm only gives you slits not brighter stars?"

You know, with such a small amount motion blur, an effective correction is probably within the reach of the new anti-blur tool in Photoshop CC. It is a further addition to image deconvolving, on a relatively simplified level.

You can also use a full-blown astronomical deconvolver, but their controls settings are not for the faint of heart.

Ironheart

@sprayandpray, I was pulling your leg a bit :-) I am interested in your analysis of the siggy 24mm for astro. From what I've seen so far, it does have coma on the edges.