200D - with Samyang 14mm - strange star shapes

[brenski]

the UK Service team Intro2020 were (at best) ineffective and (at worst) woeful.
here's the saga of the lens
♦ i send lens to them, after two days they reply deeming it "beyond economical repair" and offering me a shiny new Mk2 14mm for a greatly reduced price.
♦ mk2 arrives - complete with focus lock, but displays the same symptoms as the original
♦ i return the mk2 to them and Intro2020 refund me and return my original lens
♦ original lens returns and they've not even bothered to restore it to the condition it was when it left here
focus ring is way out of line - infinity stop is hit around 0.4m!
♦ Intro2020 were unhelpful saying they could do nothing - even though i could prove - from markings on the grip, that they'd had it open and tinkered with it
♦ i've now adjusted it back myself

thanks John for your suggestion - next clear night, i'll retest with disabled "in-camera lens corrections" and see how i go

[John Liddle]

Hi Brenski - any progress?

It just occurred to me that in-camera lens corrections might have something to do with the problem.

You could check if this is so by recording both RAW and jpg copies of an image - the corrections are only applied to the jpg version.

[brenski]

Samyang's UK Servcie Dept have come back to me - I've just emailed them more information

[John Liddle]

tested the Canon 18-55mm kit lens - it produces nice round solid stars @ F/3.5.

Then I suspect that you have 2 defective Samyang lenses.

[brenski]

tested the Canon 18-55mm kit lens - it produces nice round solid stars @ F/3.5.

[brenski]

will be trying the kit lens again tonight

[John Liddle]

Hi John

I wish. no - the crops are taken from (almost) centre of image.

Oh dear!

What were the results like from the kit lens?

[brenski]

Hi John

I wish. no - the crops are taken from (almost) centre of image.

[John Liddle]

Brenski - are the images you have shown from the edge of the field of view?

If so, then surely this is just the coma that almost all lenses suffer from to some degree.

https://photographylife.com/what-is-coma

[brenski]

samyang star shapes.jpg

seems that even stopped down to F/4 there's still something going on.

am wondering if any of the following Canon 200d settings are likely to help, and if so, what should i opt for?

♦ Mirror Lock
♦ Lens Electronic MF
♦ Lens aberration correction ► Peripheral illum / Chromatic aberr / Distortion / Diffraction
♦ White Balance
♦ Colorspace
♦ Auto Lighting Optimizer
♦ Long Exp Noise Reduction
♦ High Speed ISO NR

or anything else "on camera" that may help?

[Trev B]

To far, if you had been local to me I would have let you have a body for a night.

PS. Camera that is

[brenski]

worcestershire

[Trev B]

Where do you live

[brenski]

unfortunately, i don't.

[antoeknee]

i don't have a different camera body to try. which is why i went for the lens option

Ahh, that does make a difference. Do you know another Canon user who could help?