whats wrong with my lens?

[daine042 (Daine)]

just got back from a weekend at Wiruna and was going through all the photos i had taken with my D90 and tamron 17-50mm lens combo all of the images seem to be focused on one side but not the other im really happy with the performance of the lens during daylight and hadnt done much during the dark heres an image from last night everything to the right of the emus head seems pretty focused but to the left is plain crap what could it be? oh the exif data may help f3.5 @ 17mm ISO 1600 exp. 20sec shot in raw

[LewisM]

Wasn't dew or frost perhaps? Or condensation BEHIND the front element? (had that happen a few times with Tamron, hence why I won't use them apart from my 70-200 f/2.8 these days, which STILL does it anyway).I also use to have the kit plastic body lenses form condensation internally also - and they take AGES to equalise out.

Apart from that, it looks like a lens tilting issue (?)

[daine042 (Daine)]

Wasnt foggy at all on the lens at the time altough it did for over later in the night i took this batch its like this on images from both nights is there a way of correcting lens tilt it only seems to show up in low light on friday night i was shooting at f2.8 so i tried stopping down last night and it made no differance at first i thought it was just the stars trailing but at that focal lenght on that point of the sky for that exposure they shouldnt appear like they do

[rogerco (Roger)]

Suggest you create a lens test chart and take some photos during the day to see what is happening. If it seems ok close up, find a big enough flat wall (brick is good) and set up directly perpendicular to it from thirty metres of so away and use it as a test chart.

[gregbradley]

Bad lens. Decentred lens elements. The lens is also vignetting very badly.

I got a new Samyang 24mm F1.4 and it was like that. Not as bad as that but sharp on the right and out of focus on the left. I sent it back for a replacement and the replacement was good.

Tamron is an economy brand so lens variability quality control may be an issue. I read on the net a lot about Sigmas and Tamrons and QC issues. Sigma has an art series now that are at the highest levels of performance. So they are lifting their game but the old saying you get what you pay for applies.

An old Nikon 28mm F28 AIS lens costs very little and is a very high quality lens. Try some of the older Nikons - there's some real bargains to be had.

Samyang 14mm F2.8 is a popular lens but again be prepared to return it to get a decent copy. Samyang QC is a bit sus too.

Greg.

[BakerStreet (Allan)]

A lot of new lens for auto focus have problems with alignment because they have to make the bodies very loose so the small motors can drive them. It becomes more obvious when you have the aperture full open.

I use a collection of old lens for serious work because they are much more stable. My favourite is a Carl Zeiss Jena from the 60's with a screw mount that I use with an adapter to mount to my DSLRs. It is 135mm in a solid aluminium body and only two elements.

For happy snaps I use the auto focus lens that came with the cameras.