Vignetting or what?


Frogherder

Link Posted 10/08/2012 - 15:29




Ignoring the likely exposure error what is the likely cause of the apparent vignetting which is evident in the above shot.

It's an effect I've noticed on several occasions, but this is probably the clearest

Taken last night with K10D 18-55 lens (1/60, f4.5, iso100, focal length 18mm, no filter of any kind, no lens hood[also the same with a lens hood but for this shot I removed it to see if i was that])


regards
Bernard

PS new upload worked absolutely fine, but what happens to the picture if I move it to a different folder on my PC- is itlost to the forum?
Last Edited by Frogherder on 10/08/2012 - 15:31

McGregNi

Link Posted 10/08/2012 - 19:26
I think this is just a characteristic of the lens (a weakness some might say). It occurs in all shots at the widest end, but is most apparent with this type of exposure, because the contrast is very high between the brightest parts of the sky (the orange on the horizon) and the darkest at the top.

It's easily corrected, maybe with just a single click! In Pentax Digital Camera Utility (assuming you shot RAW) select the image and then click on the 'Custom' tab in the top left. Then find on the right the Lens Abberation Correction tab, and here you will see 'Marginal Lumination Compensation'. Set the focal length slider, tick 'apply', then play with the compensation slider to control the amount. Should be easily sorted.
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Pentaxophile

Link Posted 10/08/2012 - 19:47
Yep it's a feature of the kit lens, should improve as you stop down. Re the photos uploaded to the thread, once uploaded they will remain on PUs servers and it won't matter what happens to the original.
[link=https://500px.com/will_brealey/[/link]

womble

Link Posted 10/08/2012 - 20:36
I've had that problem with the kit lens too (18mm @ f/6.7):




It is a pain. K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website
Last Edited by womble on 10/08/2012 - 20:38

Frogherder

Link Posted 10/08/2012 - 20:40
Thank to both for the info, and how to solve it.

I do shoot RAW, but I don't think this shot is worth the bother, except for experimentation. I only took it as I noticed that we had quite a large number of vapour trails (right over head and on into the east) and the western ones were nicely lit.

regards
Bernard

Algernon

Link Posted 11/08/2012 - 07:46
Just do some mid grey shots of a white wall/card at different
apertures and see where it becomes acceptable. It's normal
will most lenses.

This is something like what you will get:

Grey_Exp_Test_M-35mm_f2-8




Note: Vignetting returns at f/16 and f/22 something no one
ever mentions

-
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

johnriley

Link Posted 11/08/2012 - 07:56
In many instances vignetting can be turned into a virtue. We used to add slight darkening of corners in the darkroom as it concentrates the eye towards the centre of the image, where, presumably, we want the eye to rest.

Having said that, the sky picture looks more as if an inapprpriate lenshood has been used - the vignette is too sudden and intense to be natural lens darkening.
Best regards, John

womble

Link Posted 11/08/2012 - 22:26
If you are talking about my image it was the standard hood that came supplied with the lens. K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

johnriley

Link Posted 11/08/2012 - 22:57
Kris, that doesn't look right. It looks as though the lens hood is not fully clicked into position - is this possible?
Best regards, John

Pentaxophile

Link Posted 11/08/2012 - 23:55
johnriley wrote:
In many instances vignetting can be turned into a virtue. We used to add slight darkening of corners in the darkroom as it concentrates the eye towards the centre of the image, where, presumably, we want the eye to rest.

Having said that, the sky picture looks more as if an inapprpriate lenshood has been used - the vignette is too sudden and intense to be natural lens darkening.

When it comes to Pentax, the glass is always half full, eh John? :LOL:

FWIW, vignetting is the least of my complaints with my kit lens. It's funny, but since my original Mk1 kit lens, I haven't had a copy I've been happy with.
[link=https://500px.com/will_brealey/[/link]

johnriley

Link Posted 12/08/2012 - 00:03
Nothing to do with Pentax, Pentaxophile, but everything to do with lenses having quirks of their own. This is something that is rarely touched on by testers, but lenses have character.

The thing is to find what suits you and find what defects (if we can call them that) we can use. The classic example is the 1970s photographer David hamilton, who made a fortune out of his favourite, flare-ridden, rubbish 50mm lens.

Just recently I have found a use in my chapels series for the purple fringing that can be induced in the 12-24mm in some circumstances. It is a defect, but there are times when it can become a virtue.
Best regards, John

Smeggypants

Link Posted 12/08/2012 - 02:21
I often add vignetting in Lightroom precisely for the effect john describes "as it concentrates the eye towards the centre of the image"


It's particularly good for street people shots when there's some distracting stuff in the periphery, which cropping out would spoil the composition.
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Snootchies

Link Posted 12/08/2012 - 09:57
Smeggypants wrote:
I often add vignetting in Lightroom precisely for the effect john describes "as it concentrates the eye towards the centre of the image"

Absolutely - I have done the same myself.
Bob

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