18 or 20 mm prime lens.

I have tried 2 Sony 16-35 f/4 ZA OSS lenses and did send both back because of the poor image quality. The first was very decentered and the second was unsharp on the sides/corners even at f/8. I am shooting with a Sony a7rII.

Not going to get another Sony 16-25 f/4 ZA OSS but instead looking for a 18 or 20 mm prime lens. Un fortunately my pockets are not real deep and my budget is €700 max. So it will be a used lens, but i don't have a problem with that. Will be using the lens for landscape and exterieur architecture.

Suggestion based on owning or having owned a 18 or 20mm lens would be very welcome.

For a number of years, I was using the Sigma 20mm F1.4 ‘Art’ lens, and it was pretty decent in terms of IQ.

Also fairly bulky and somewhat heavy (as is the case with quite a few of Sigma's offerings). The optical design was based on SLR registration distance, which was probably a factor.

If you can cope with the size and weight, it would at least be an option that falls within your budget.

Another one to consider would be the 18mm Batis. However I'm not sure how easily you'd find one for ≤ €700. If so, it would be a good option, as they're optically quite nice (at least in the sharpness and contrast departments) IMO.

Maybe the Samyang AF 18mm f/2.8 would work for you. I don't have the 18mm, but I do have the AF 12mm for APS-C and really like it. I took a quick look on Flickr, and it looks the 18mm has very good IQ.

I have the Samyang 18mm since 2 years and like it very much for its light weight and compactness, image quality is good to excellent on a7r3 and a74.
For a recent Norway stay I got a SONY 20mm F1.8, it's superb, but up to a DIN A3 print you won't see the difference. So in your shoes, i'd buy the SAMYANG or wait and save money....

I am waiting for the new Sigma 17mm f/4 that has been rumored for next month, otherwise I'm considering the Samyang 18mm

Apologies. I am using this thread as a bit of a test as to how things work. I recommend the Samyang 18mm 2.8. It's hard to beat when considering $/size/weight.
It is easy to carry it in your bag as the wa you occasionally need.

Thanks all for your time to answer my question. The Samyang is around €329 new here in The Netherlands, the Sony 20mm and the Zeiss Batis 18mm are new way out of my budget, even second hand they are well over it. The new Sigma 17mm lens is supposed to be announced on April 3rd, no idea what it will cost here, but will have a look on Monday. I also am considering the Tamron 20mm f/2.8.

I have a Tamron 20mm f/2.8 on an A7RIV; as mostly a landscaper I judge a lens primarily by its corner sharpness at f/5.6, where I do many of my images. IMO the Tamron 20mm is very good, but not perfect, no surprise. Given its low price, light weight, and decent quality I think it's an excellent bargain.

One caveat: if you're shooting something with straight lines, this lens does have distortion. I don't care, as PhotoLab does very good lens corrections on raw files. How it does with SOOC JPEGs, I don't know about; I'd suggest reading some online reviews for that.

I shoot raw, so no experience with sooc jpegs. the lens will be used for landscape but mostly for architecture. it is one of the lenses on the list. In the next week i will do some further investigation on the pros and cons of the different lenses.

I am very pleased with my Samyang 18mm f2.8, which I got new for around $300 to complement my 24-105 for walkabout use shooting landscapes in daylight and my bag of primes for event use (venue shots on a tripod) indoors. In both cases, I stop it down for DoF, so it doesn't matter if it's not tack-sharp wide-open. On my a7RIII, I've found it to be quite sharp at f5.6 and f8 all the way to the edges of the frame. I bought it instead of an UWA zoom because 1) it cost a lot less, 2) even some pretty good UWA zooms suffer more edge softness than I wanted, and 3) it's quite small and lightweight.

Note that I process my RAWs with DxO PhotoLab, which has a custom profile for this lens and does a terrific job of lens sharpening and other optical corrections.

I am using lightroom and as far as i know there is no profile for the Samyang 18mm f/2.8 lens, it does have one for the Samyang 35mm FE f/1.8 AF lens that i own.

Found a used Samyang 18mm f/2.8 listed as good as new for €279 and could not resist it and bought it. Should be arriving Tuesday.

If you want a zoo, what about a Tamron 17-28 or Sigma 16-28 ?

I do have to say I like my Samyang 18mm 2.8 but it is a touch soft at 2.8 and has quite strong vignetting. I think it would be fine for your use cases.

I have decided to move away from zoom lenses and go with primes. I will keep my Sony 24-70 f/4 OSS ZA lens, it is a good copy. Also have the Samyang 35mm f/1.8 AF lens and for macro i got the Laowa 100mm f/2.8 macro lens.

Just make sure to test it for decentering. I ordered one direct from Samyang and it had multiple issues, so I returned it. I would love to get their 14mm lens, but I don't look forward to having to extensively qc the lens. I do have one of their 12mm Cine aps-c lenses and it has been great, so if you get a good one you will be fine. Their reputation is getting better, but they are taking a while to get their production qc together. I ended up trying an inexpensive Sigma 20mm f2 dg dn, which was fine, but I ended up selling it and getting a used Sony 20mm f1.8, which is even better. I much prefer the declicked aperture ring.

The Sigma 20f2 is a very nice lens. But I am surprised that both copies of the Zony 16-35 f4 you have tested came out bad. My copy is very sharp across the frame from 4.

A friend who lives 4 houses from me has also got the Sony 16-35 f/4 and his lens is sharp from corner to corner, even at f/4. I also found it strange that i happen to receive two copies with sharpness problems. Both where used lenses, so i can not tell what happened to them before i got them. I asked the shop if they do test the lenses for decentering and sharpness but the did not do that. Only looked if the glass was good, if everything on the lens works and how the condition of the lens is.

i also had a look at the sigma 20mm f/2, if the Samyang turns out to be nog good then i might get that one. new they are €699 here, used very hard to find.

I will test it for decentering and sharpness. I always do that with all lenses i buy. I also have the Samyang 35mm f/1.8 AF and that is a good copy, sharp from corner to corner.

I had the FE 16-35 f/4 for a number of years (eventually sold it to get the f/2.8 GM) and it was an excellent lens. Like your friend's, it was sharp across the frame, so I think your experience is either bad luck or the vagaries of the second-hand market (e.g. people may be more likely to part with copies of lenses that aren't performing well).

I purchased mine new, and tested it when I received it, as you do. There was never any question about sending it back, as it was great. I'd encourage you not to give up, as there are definitely good ones out there.