[Luny Tune]

Look at these MTF charts. It looks quite promising for the new Samyang 45/1.8, I think.

Samyang 45/1.8:
http://allphotolenses.com/lenses/item/c_...rettyPhoto

Sony FE 50/1.8:
http://allphotolenses.com/lenses/item/c_...rettyPhoto
(Be careful to read this one right. The think red line is not for the lens wide open, but for F8. In this chart only the green lines are for the lens wide open. I missed that at first.)

Canon EF 50/1.8 STM:
http://allphotolenses.com/lenses/item/c_...rettyPhoto

Sony Zeiss FE 55/1.8:
http://allphotolenses.com/lenses/item/c_...rettyPhoto
(Note here the difference in Lines/mm)

MTF charts are probably the most reliable way to describe the actual performance of a lens with data.

I am only just these days beginning to understand MTF charts. Am I way off in comparing the Samyang more to the Sony Zeiss, and the Sony FE more to the Canon?

[Klaus]

It is very unlikely that you can compare the MTFs between different manufacturers.
If that was the case, we could close the site ;-)

The most obvious difference between those MTFs is about the line pair baseline that is supposed to illustrate the resolution - 30lp/mm vs 40lp/mm.
Samyang uses the weaker 30lp/mm approach which is boosting the corresponding line towards the top making it seemingly look "better".

Even if the lp/mm baseline is the same, there are still enough parameters to render a cross-comparison useless.
On top of that comes the fact that these MTFs are either simulated or from an optical bench - thus ignoring any side-effects from image sensors (protection filter, micro-lenses, etc.).

[JJ_SO]

It is very likely that you can compare MTF of various lenses - if the procedure to get the numbers remains the same.

Manufacturers partly use the calculated MTF and not the real MIF and they try to let the lens look a bit better. Comparative MTF charts, wide open (and oftenonly wide open, while OL tests at various apertures) you can get over at lensrentals.com/blog
https://www.lensrentals.com/blog/2019/04/just-mtf-charts-rokinon-samyang-lenses/ (no 45/1.8 though, as Samyang appears to be too cheap to rent - people who want one, simply buy it.

In the case of Samyang, I too often read "not bad, if you get a good copy - and don't every try to get it repaired".

[Klaus]

Indeed the MTFs over at lensrentals are comparable - but this is an independent site.

[JJ_SO]

Like OL as well, Klaus . I think you were saying that each manufacturer fabricates their own kind of MTF charts?

Btw., Luny Tune: I tend to disagree about "MTF charts are probably the most reliable way to describe the actual performance of a lens with data" - as MTF results also depend of the procedure. OL uses charts, and there are some limits to these as well as the charts are first photographed, then post processed and then analyzed. Lensrentals has a very expensive measuring device which leaves the different sensors and the post process out of the equation. Both results are not directly comparable, I guess, but lemons at OL will not become shiny superglass at lensrentals - and vice versa.

There's also more to a lens than only MTF - and just because you read the MTF-numbers, it still remains an incomplete characteristic. I guess, you're still in the "what is the best lens for my camera?" state?

[Luny Tune]

I guess, you're still in the "what is the best lens for my camera?" state?

No, I'm in the "I'm not gonna lug the Sigma 50 Art around at family parties or just around the kids, so I just want a decent nifty fifty, and I hate the existing one, and I can't believe that my only other options are to adapt a Canon 50/1.8 or /1.4 which have their own considerable problems, and I'm not gonna get the 55/1.8, partly because it's overpriced, and partly because I actually would prefer something a slightly shorter than fifty, but the Tamron 45/1.8 is just as big as the Sigma 50 Art, so I really hope this Samyang will fit the bill, and resolve better further out towards the edges than the crappy Sony FE 50."-state.

And the MTF charts I linked to reflect e-x-a-c-t-l-y what I've experienced with these lenses. And they also reflect the exact behaviour in Christopher Frost's reviews, in that the drop off from barely leaving the center of the frame towards the edges with the Sony 50 is not a smooth gradual drop off, but it picks up again just before the very edge. The review of the Samyang shows better resolution much further out and then with a quick drop off at the very edge, where the Sony in comparison weirdly appears to be sharper somewhere at a point. That's perfectly reflected in the charts. The charts also reflects the smoother bokeh.

I do get that these charts are not telling the whole story, but on the other hand, they are close enough to quite precisely show what I'm experiencing. Like they reflect my experience with the Canon 50/1.8 being more even in it's performance. It may not be as sharp in the middle, but the results are more predictable and even, and thus easier to work with. Alas, that's not quite enough for me either. I want a better option, and I'm hoping the Samyang 45/1.8 is it.

I'm just an impatient 12 year old kid in a 53 year old guy's body, so I'm analyzing on every little bit of info I'm finding. Hoping that the search is over, because if not, I could have spent the time searching for something else.

---

I'll be happy to demonstrate the quite visible drop off in quality even just slightly away from the center wide open, if anyone is interested.(?) I got suspicious during a small improvised shoot with my sister in law last summer, and I can post the 100% crop examples.

[JJ_SO]

That's quite a mouthful, long-story-state, Luny Tune.

Good luck wi it. The Tamron 45/1.8 was nothing to care about, as in "too big and heavy"?

[Luny Tune]

That's quite a mouthful, long-story-state, Luny Tune.

Good luck wi it. The Tamron 45/1.8 was nothing to care about, as in "too big and heavy"?

I know. 

I totally get the need and reason for the big high end glass, but there's neither need nor reason for producing crappy cheap glass. If we could easily do with lenses that only resolves decently in the very middle, then what's the point of having focus points right out to the edges? I get that edge to edge sharpness isn't gonna happen with an $80 lens, but at twice the price of cheapest Canon, Sony should be able to come up with a better lens. Using the same optical formula as in the Canon, it's not like they spent a lot of money on R&D. Couldn't they at least have ripped off a better design? There's not much prestige in the cheaper lenses, I know, but it's sooo practical to have these "throw around" lenses. If you outgrow your nifty fifty, you pass it on to a new photographer, if you like it, you buy a second one and keep it as a backup, in your other bag or something. They gave us a (then) $250 lens that nobody wants. I'm sure that had it produced decent images, we could all live with it's other quirks, but let's not go there.

I love what I've seen from the Tamron 45, but it's only slightly smaller than the Sigma Art. It suffers som from CA, but once that's removed/mitigated in post, it makes some great images. The imperfect bokeh, I could live with, also for serious work. I was contemplating that lens, but having the Sigma already, I'm not gonna get the Tamron.

I want the "nifty fourtyfive", and I sooo hope that I'll be able to use it for serious work whenever I jjjjust can't back off far enough with the Sigma 50 Art. That happens to me a lot for some reason. I often find myself holding the camera almost against a back wall, juuust being able to look at the back screen and frame the shot.

[JJ_SO]

I also own the 50 mm Art - and it's in rather good condition because I usually decide to go lighter and smaller with the 35 mm Art. I know it's not as good as the 50 mm, but the 50 mm is not as good as the 40 mm I recently tried. And I'm on the same page - I really like the quality coming out of these glass colossuses, it just don't saves that much weight. The 40 mm Art is only 200 grams lighter than the 50 and 35 together. I haven't seen a comparison between the Nikon 5/1.8 S (currently around 500.- because of instant rebates) for the Z series and the 40 mm Art (or the 35/1.8 S).

Right now, I stopped buying into more Z glass as there's not much interesting FLs available which I haven't covered by other lenses. Yes, the Sigma 14-24 is much heavier than the 14-30/4 S - but when it comes to distortion, I prefer to carry more weight and need less software correction. I can use the Sigmas on all cameras I own while Z glass might be lost investment.

That was my reason to point out MTFs are not everything. No need to wait for lens correction profiles has also it's value.

[Luny Tune]

https://youtu.be/SpZ_aD4qCD4