-
Welcome to the new forums! Please read this first. For known issues we are working to resolve, click here.
I tested the new SIGMA 14/1.4 DG DN Art for Astroscape
- Thread starter Digitaliz
- Start date
grsnovi
Veteran Member
Yesterday I ordered a 24/2.8 for the 7R3 to give me a wider field than I can get with the 50/1.7. I also ordered a Bahtinov mask.
I'm hoping to do more astro this summer. Our skies here actually do get dark. I was in your area in the June of 2009 so I understand that you won't see really dark skies until winter.
My plan is to see how much I get out this summer with my cameras and my 2 existing scopes (a 25 year-old 8" Celestron and a 30 year-old 90mm Meade) before I spend any more money on scopes, mounts and related gear.
I watched Nico's video on shooting Andromeda with 1000 one-second exposures yesterday and have to say that there is a lot of work taking flats, darks and bias exposures and all of the subsequent stretching that goes on in post.
Seems like it will give me something to do besides shooting birds.
- Gary
I'm hoping to do more astro this summer. Our skies here actually do get dark. I was in your area in the June of 2009 so I understand that you won't see really dark skies until winter.
My plan is to see how much I get out this summer with my cameras and my 2 existing scopes (a 25 year-old 8" Celestron and a 30 year-old 90mm Meade) before I spend any more money on scopes, mounts and related gear.
I watched Nico's video on shooting Andromeda with 1000 one-second exposures yesterday and have to say that there is a lot of work taking flats, darks and bias exposures and all of the subsequent stretching that goes on in post.
Seems like it will give me something to do besides shooting birds.
- Gary
DavidWright2010
Senior Member
In the review you show field curvature to be very pronounced, but in the summary bullet points you don’t mention it.
and why wasn’t it visible in the aberration tests?
David
the field curvature test was added afterwards and tested at finite distance. It didnt show up in my earlier tests. So for Astroscape, the summary stands.
mermaidkiller
Senior Member
Should be a great lens !
But why did you test it in summer in the (sub-)arctic region ? Not the best location, central Europe would be much better ...
And bulky and heavy. Some images are very distorted in the corners. The image
"I drove to another location and found this rock in bit out in the water."
shows Cygnus very distorted in the top left.
I have a lightweight Canon RF 16mm f/2.8 which performs well, despite having only 25% of brightness of this lens. But when I disable automatic correction and correct only vignette, coma and CA manually, it is actually 14mm while not correcting the strong barrel distortion which keeps constellations far less distorted.
I got the lens a week before the relelase. Quite hard to travel then. If SIGMA would have payed me to do that, I would. But this is an independant review.
It is indeed bulky, but so is my DSO equipment too. Still I prefer real telescope rather than lighter telphoto lenses.
My own 14mm is a Samyang 14/2.4 XP. It is not much lighter or smaller than this beast.
25% of the light is like night and day. If f/2.8 is ok for you then stick with it. It would be sad to buy a fast lens and not use it to it's fully potential.
I can say if your 16mm has a FoV of a true 14mm. 2mm extra in the those FL are very huge. Strange the camera crops out 2mm to fix the distorsion.
/Stefan
Last edited:
primeshooter
Veteran Member
Nice review. It seems it is loaded with FV as your crops suggested. Still a very interesting lens. Hope they bring it to Z mount.
nighthiker
Senior Member
Hi!
Thanks for the detailed test!
I'm probably a little bit more critical with this new Sigma lens for astro photography. I agree that the fast opening of f/1.4 is the main point for astro images, but I find the coma a little bit on the high side and the field curvature is also a little bit heavy. I'm also a user of the Samyang XP 14/2.4 and my images have less coma. The downside of the Samyang XP is the - much - lower speed and the quality control. I have several copies and even the XP lenses have a wide tolerance.
I agree that the preferences (e.g. speed versus coma) are individual and that the new Sigma is an interesting (astro) lens, but the coma .....
I'm still dreaming of a 14mm lens with low coma (like Samyang), quality control like Canon and a decent speed (f/2.0 or faster). In such a case the price is debatable ;-)
Thanks for the detailed test!
I'm probably a little bit more critical with this new Sigma lens for astro photography. I agree that the fast opening of f/1.4 is the main point for astro images, but I find the coma a little bit on the high side and the field curvature is also a little bit heavy. I'm also a user of the Samyang XP 14/2.4 and my images have less coma. The downside of the Samyang XP is the - much - lower speed and the quality control. I have several copies and even the XP lenses have a wide tolerance.
I agree that the preferences (e.g. speed versus coma) are individual and that the new Sigma is an interesting (astro) lens, but the coma .....
I'm still dreaming of a 14mm lens with low coma (like Samyang), quality control like Canon and a decent speed (f/2.0 or faster). In such a case the price is debatable ;-)
Astrophotographer 10
Forum Pro
- Messages
- 13,956
- Solutions
- 11
- Reaction score
- 6,160
What's FV stand for?
Greg.
Greg.
primeshooter
Veteran Member
I meant to write FC, Field Curvature.
Just to clarify further, when you say field curvature are you referring to geometric distortion? Because in optics, field curvature almost always refers to curvature of the field of focus from ideal flatness, not geometric distortion.
primeshooter
Veteran Member
No. I'm referring to the lens not having a flat focus field. It's very curved. It is less than ideal, you cannot focus in the centre and expect the corner to be anywhere near good. Often it's a compromise and one requires to focus somewhere between the centre and corner to get a balance when FC is so high ala this lens. This is especially true wide open (obviously).
Last edited:
Got you. I have encountered a lot of people who don't use the term "field curvature" correctly so sometimes I have to ask. (The lens does also exhibit significant geometric distortion, which isn't really a surprise in a 14mm lens. Stefan calls it "light" but I would not use that word myself given what his images show.)
It's a pity this lens fails so miserably in respect to uniformity of focus. That amount of focus variation between the corners and center isn't even good enough for general daytime photography IMO, unless you never intend to use it at f/1.8. (But Stefan didn't specify what aperture he used for that particular test, did he? I'm just assuming it was done at f/1.8.)
As Stefan says, I hope that every copy does not exhibit that amount of field curvature. But since the lens was lent to him by Sigma for his review, I'll bet that the copy he tested meets Sigma's specifications.
I have Sigma's 18-35mm f/1.8 zoom for APS-C. Not nearly as wide and not nearly as fast, but for my purposes much more practical. From my star tests, my copy of that lens has negligible focus variation throughout the field even at f/1.8. Admittedly, that's much easier to accomplish over an APS-C field at f/1.8 and 18+mm than over full frame at f/1.4 and 14mm.
Last edited:
primeshooter
Veteran Member
I notice this too. Im aware of the differences though. The 14mm 1.8 art which I still own has similar traits. Maybe slightly less bad but you cannot focus in the centre. If you pull focus on a central star at 1.8 the corner is a mess. Still we have to remember we are at 14mm and wide open and these are not telescopes! I recon if sigma went back to the drawing board and went all out and just designed this again specifically for z mount they could beat this by a long way. The z mount is the largest 35mm mount and has the shortest flange. E mount is tiny so you are compromising some optical goodness bringing those light rays into that mount. Despite this though Sony has brought some good lenses to the table.
Last edited:
Keyboard shortcuts
- f
- Forum