Star abberations

[robindurant]

Just tried out a 10mm Sigma Lens on my Canon 700D. I shot 3 minute subs f4.5 iso 800, on the Milky Way.   I am alarmed at the bad star abberations at the top left and bottom corners. Is there anything I can do to prevent this or even lessen it, will stopping the f No. down help?

[D4N]

Images with camera lenses can often be improved with an external aperture mask, this prevents light hitting the iris and being diffracted (obviously you need to have the iris fully open and make the aperture mask smaller than it).

It depends on what the specific aberration is but stopping down often helps.

I don't have that particular lens though so it is possible someone who does may be able to help further.

[The Admiral]

That said, a 10mm lens is an extreme wide angle lens and I would guess getting perfect aberration correction in the design will be difficult, or else very expensive. Probably the best you will be able to do is to crop the image, which I imagine is not what you'd want to do otherwise you wouldn't have wanted such a wide angle in the first place.

Ian

[SilverAstro]

11 hours ago, robindurant said:

at the top left and bottom corners.

If it is only the top left and bottom left? and not top and bottom right then something is tilted in the lens ? (not in the camera else it would happen with your other lenses, check under high magnification that this is the case and that longer lenses are not masking the effect )

If it is both bottom corners  but not top right then tilt could still be a candidate ? or something is not centered

 

[The Admiral]

Is the 10mm a fish-eye lens? If so, perhaps you are expecting too much?

Ian

[robindurant]

No its not a Fish Eye