Thank you for your little investigation! And as always, very nice photos! A great inspiration to take a camera and go out!

First time I noticed focus shift was on a Canon 50mm 1.4 FD manual lens. As Matti said sharp wide open, sharp at 5.6, but everything in between hit a different focal point than the subject. It was worst at full length portraits and group shot distances, where faces would be soft. Asking around people denied their copy did it, but those who cared to repeat the experiment found their lens also shifted. I use the same lens on a Lumix and it's fine if you view at the shooting aperture.

Good work, and the tips are always welcome. Did you made this test with the latest firmware update for this lens? Can't wait for your next video, keep it up !

Thank you for this video sir!

ive had some great shots from the 25mm Some nice street and even some basic macro with + 2 macro filters . as always great information

I have used the 25mm a lot and often at f4, I never noticed a problem with focussing. I have been very happy with this lens, such great value. Thanks for the video but I do not think I will lose any sleep over this.

Thanks! I use mine at F1.7 for close up and street plus internal low light architecture. It has been a BIG problem for me. I even used Electronic Shutter instead of Mechanical, no change... It will be going back to the Seller! Helped me so much.

Great honest video as usual. Can you pleas give us your opinion about the 42.5 1.7 and the updated panaleica 25mm 1.4 II? Thanks.

Hi, I have a question, When adjusting apertures at 5:40 how did you compensate so fast for the exposure ? Was the camera set on Aperture priority maybe ? Also did you use autofocus ?

Good video Matti. For $150 for a fine fast lens, I might put up with some focus shift. Personally, I like / own the 20mm, but it does cost $100+ more.

I don't have any problems with my 25mm, I use it mainly for portraits, it works very well

Make a shots at winter time, with gloves, and hendheld is epic :) Proper way if you set it on tripod and control apertire remotly with app or so, to elimitane any motion. Comparing heldheld even with IBIS is not very reliable I think.

Does this problem exist if constant preview is on and manual focus is used? thank you

This lens restored my admiration for micro 4/3 in low light

I shoot videos and photos so I have the Constant Preview on and in manual mode so the focus shift hasn’t been a problem. Like what has already been mentioned, as long as you know it has this problem at F4 then you can work around the focus shift. For the money it is still good value for money.

excellent video as always, but I do have a point to raise. If you focus once with the aperture set wide open, and then lock it prior to shooting the sequence with varying apertures, does the camera think it's going to shoot the entire sequence wide open and 'fine tune' itself accordingly? In other words, would the results be any different if the camera was set to f/4 before focussing? Obviously it would still focus wide open, but would it then compensate knowing it's going to shoot at f/4 instead of f/1.7? Modern cameras are VERY clever pieces of kit, and it wouldn't surprise me for a moment if the camera were to compensate for each aperture.

at least finally acknowledged the issue,but I feel it's more prevalent than stated here .but as said glad it's finally acknowledged.i feel your diminishing the issue tbh,it it there,it is an issue ,and all the lenses suffer from it not just isolated builds.

Matti, you might try a quick 4k test as described in my last comment. You might find it interesting and a more revealing test. Also, can you ask Panasonic to fix this is a firmware update as I described in my prior comment? :) I know they won't fix it but it doesn't hurt to ask :) As always. thanks for the video!

I guess my question is that if you changed aperture, and then forced the camera to refocus on whatever point you set, at the new aperture, does it still shift in some way or is it mainly if you don't refocus (or let the camera refocus) and you simply change the aperture (ie. you don't let up and then half press again or use BBF to force the camera to refocus in between changes of aperture)? Wouldn't focus shift be more of an issue with the camera than the lens though, or possibly a discrepancy (say "miscommunication") between the lens and the body (ie. the body things the lens is focused say on the center point, when in fact it may be off slightly)?

Does the focus shift occur while shooting video when focus is set up manually by touching the screen? Thanks

Hi Matti! Will you do an episode on the new upcoming firmware?

Panasonic could easily fix this in firmware. They could put an option to either focus wide open always (the default way it is now) or an option to focus only at the set aperture. Simple. There is a much easier way to test for focus shift. I have this lens brand new that I got from B and H. I tested it and it has a real problem for me. What I did was set it to 4k. All full manual settings. Find a very detailed subject, set the aperture to 1.7. Touch to focus or manually focus (just make sure the auto focus is off). Now as it is recording, just change the aperture and stop it down 1 click at a time. You will have to bump up the ISO as you stop down of course. On my copy, by the time I got to 5.6, it was quite dramatic and out of focus enough that it would ruin my shot. You could see it in real time going out of focus as I stopped down the lens in the 4k video. I made this focus mistake at a few concerts indoors when I focused at 1.7 aperture then later stopped it down to 2.5 or so as it was recording and never re-focused. The footage was very soft! What I have to do with this lens is make sure to focus every time I change the aperture when shooting 4k! It took me a long time to figure out and be aware of focus shift. Back then I wasn't aware of it. It isn't that big a deal shooting 4k with this lens as long as you know this. But taking photos is another story. There is a work around to get it to focus at the set aperture when taking photos but it isn't pretty. Years ago I found a great video that covers how to do this on a lumix camera. To all that's interested, do a youtube search for "What is focus shift and why every photographer should be aware of it" the channel name is Camerahoarders. Then skip to 7.15 for the directions on how to do it!

im a classical musician getting into videography and i got a good deal on a g9 with this lens. i've made a few test videos and they look really good to me, but what do i know haha. does this "problem" present itself when shooting video?

If I want to use F4 with the lens, what about doing manual focus? Does the problem still exist then?

Thank you for your review. I use this lens on a Lumix G100. The focus shift is visible at f4 exactly as you said it and to a smaller extend at f2.8 and f5.6. To avoid it I think there are two other possibilities, with which you can use f4 and with which you can avoid to go into manual mode. (1) When taking the picture set the focus point a little bit behind the desired object, 1.5 to 2 % at f2.8/5.6 and 3 - 4 % at f4. But maybe this is a stupid idea for a professional, therefore: (2) With Function Buttom Fn6 (can easily be remaped to Fn4) you can set the camera in the "Preview Mode", which according to the manual is used "to check the effects of aperture on the recording screen by physically closing the aperture blades of the lens to the value set for actual recording". When you press Fn4 the next single shot is focused in the desired aperture, e.g. f4 and the picture is more sharp. This works in all modes and you don't have to switch to manual mode. I tried it with the G100 and it it worked well.

This was the first add-on lens that I bought for my G85 (came with the 12-60 kit lens) and I love it -- I had not noticed a focus shift issue, though I have noticed the imperfect autofocus of the camera with this lens when shooting wide open or close to it and hoping for a narrow depth of field. And it's the camera, not the lens -- the AF just isn't always fast enough to "lock on" when I see a quick shot that I want to take, and my habit now is to shoot like 5 shots in a row as the AF settles down. But thank you for this info -- you are always educating me! Any tips on how to get the best AF performance (for "quick" still shots) from my G85??? THANKS!!!

I am wondering if the results are reliable, because no tripod was used. My concern is that the movement of your hand during the shots causes more shift than closing the aperture.

I discover this video very late, having already owned and then sold that lens for that very reason. The severity of the problem is also subject dependent, and it bit me hard as I love keeping memories of street art pieces I come across. Most of the time, street art is either painted on a wall or made of paper posters glued onto concrete. What I find fascinating is the impact of the underlying texture on the art itself. Sadly the focusing shift is more aggressive than what your test suggests on more urban settings. It slowly worsens after f/2.0, peaks at f/4.0 and enters the DoF zone past f/5.6. Even if the picture looks sharp~ish, the effect on the textures I want to keep is disastrous. It muddles the details and faults that I'm interested in because they make each art piece unique even when the same poster is mass produced. The workaround on Olympus cameras is to switch the depth of field tester to a flip/flop instead of being active only when the button is pressed (one of the 100+ options in the menu system). Then, a short press on the DoF tester switches the camera to AF at shooting aperture *in all modes*. This shift taken into account, the lens is almost as sharp as the fabled 20/1.7 (which I owned too at some point), and that's saying something. Otherwise, it's a good average lens. Finally I got fed up of pampering the lens and sold it. I've bought the 25/1.8 from Olympus instead, and never looked back.

i just got my lens in used. when i was shooting at 1.7 it was too soft for me to use. i assumed it was an issue cause everyone else was saying how sharp it was. it was usable at 2.8 and up but under 2.8 it was unusable. glad i sent it in for an exchange! hopefully the next copy wont have this issue

It might not be a pure optical problem. Because there are mechanical things happening in the lens (opening and stopping down the aperture), it is possible that it is caused by or made worse by such things. Working manually would get rid of a lot of such problems.

Can you comment or make a video on the G9 firmware update?

My G80 let me preview the dept of field in Program mode too! So, problem solved, as this is the mode I usually use. Thanks for your excellent videos, Martin

What is the difference between panasonic 25mm H-H025k and H- H025E-K

I know this is an old video, but I watched it again since this issue seems to have resurfaced in December 2022. I have this lens, but have not used it much, preferring other prime focal lengths. No complaints with shots taken with it, however. I tend to use 5.6 in good light, wide open or close in low light, so rarely F4. I sometimes wonder whether these issues are a bit esoteric, but once they surface on social media, take on a life of their own. Review sources I trust give the lens high marks. I also trust your straightforward, fair perspectives. But at the end of the day, am I happy with the images I get from this lens? Yes I am. So I'll keep it, and continue to use it, internet opinions notwithstanding, until such time as I personally experience dissatisfaction with my image results.

I use Panasonic G 20 f/1.7 on Olympus bodies and my favourite apertures 3.2..4.0 but I haven't seen any issues with this lens. But I saw this kind of issue on some old manual lenses in the past, especially fast and wide angle lenses like 24 f/2.0.

I don't have this lens, I bought the f/1.4, but if anything goes wrong with mine, I will probably replace it with this lens. Here in the US it it sells for less than what I spend on coffee in a month. I have seen so many great pictures taken with it I wouldn't hesitate.

Yep, I experienced this problem with this lens. I may sell it and buy the Olympus 25 mm f1.8 instead.

You can solve this by turning on Constant Preview and using autofocus OR set your focus first, aperature 2nd and then take your shot

I feel really stupid but... if you change the aperture, would you not just double check your focus afterward and adjust it accordingly? I'm genuinely asking because I don't know the answer.

same issue with my 20mm 1.7

This is one of my very favourite lenses. If I didn't watch this video I wouldn't ever know about this issue 😄

Lumix G95 user, I have been using it for portraits and I can confirm it exists. It's so bad 😞

I owned the Panasonic 25mm f1.7 and my sample was weirdly out of focus in only one corner. I assumed it would be two, opposite corners - that an out-of-alignment element, for example, would create a symmetrical focus error. Nope, just one corner was bad. I tested it twice; once with focus charts, once against a brick wall. Both tests also included the Olympus 25mm f1.8. My copy of the Panasonic 25mm definitely had problems. I wouldn't say it's so bad it was "barely usable" in real world use, although sometimes I do put subjects in the corner. Both the Panasonic and the Olympus are otherwise plenty sharp. The Panasonic 25mm is slightly longer than the Olympus and for that reason I liked the Panny better, but I feel the smaller sensor format calls for glass that is really really good. So, despite the Panasonic's incredible value, I dumped it. I was late in testing the lens thoroughly, and so both the return period and the warranty had expired. I took it to a shop and traded it for store credit. The Olympus 25mm is better with video AF on the E-M1 Mark II, has a metal lens mount, and I feel it's just a prettier lens, which were other reasons to switch. Go ahead and try the Panasonic 25mm f1.7 if you need an inexpensive, fast prime, but test it a lot before the store return policy expires!

Mine is fine. Nice and sharp and fairly cheap.

Hi ... so I watched the video again, and yes you said it at least twice: you focus once then take a series of shots at different apertures. This is a thing I never do, it's a video recording technique, I guess. I'm now relieved to know I can safely shoot at f/4 after focusing at f/4.

Apparently, I have a rather good copy of this lens. I can't get mine to shoot out of focus.

I only shoot wide open with it... So... No problems for me. lol

Fyi..Nov 19th, 2019 Lumix became release update Firmware for S1,S1H,G9,etc..so please check the website. No one perfect in the World include our gear,lens,camera,etc. So I am keep going with my lens 25mm F1.7

The lens IQ is very good. Just got it last week. Using it with the Panny G7. I found that in manual focus you turn the focus wheel, the damn lens focus for different lengths for the same turn depending on speed with which you turn, so its completely unreliable for manual focusing itself. I attached a focus lever onto the wheel for accuracy. 12pm position focus on my wall painting. Turn the lever to 3pm position and then back to 12pm (its supposed to be focused on the wall painting) and its not focused on the painting. Its totally de-focused. Again go to 3pm position now its somewhere else from the last 3pm focus it achieved. So a rotate from 12pm to 3pm will never get you the same focus rack. I turned focus assist on, which shows you the focus direction from macro to landscape, and it confirms this, i can see that as i move the focus lever (lens ring) slow, the focus is not moving at all, then suddenly the marker jumps towards the landscape icon. Then i attempt again and this time same quarter turn and the line has moved to a different spot. SO then i make the same quarter turn in full speed, but same turn. The damn marker jumps to the landscape end. So the wheel is completely latency laden and responds with a bad delay and is speed responsive so you can never get a marked focus pull. Can someone confirm its the same for them ?

My 25mm 1.7 has real serious problems!

Just a PSA here: Send me those worthless lenses and I will see to it that they are properly disposed of ....I'm here to help. You're welcome.

This lens is fantastic, one of the best for MFT and at £150 its a steal. This is a perfect example of a little knowledge is a dangerous thing and the result of people who havent a clue doing common sense experiments. I watched that ridiculous and corrosive video and for about 4 weeks became dissatisfied with my 25mm lens. I was looking through my annual folder next month and what struck me was that the images from my Lumix 25mm were about the best that year in folder containing photos from Olympus 17mm and 45mm f1.8 primes and an APS Leica 23mm f1.7 Summilux. The 25mm photos were tack sharp; even those taken about f4. Well I thought, I am an Experimental Physicist with an international reputation so what is going on here. First this stupid focus shift experiment; yes it is stupid!!! He was focussing on printing on an A4 sheet. This means the focus was very close; no extremely close. Well all lenses have focus shift; the question is how much is too much? What are the tolerances; every physical measurement comes with a tolerance. The fact is once you go to extreme close up you are pushing tolerances to the maximum. No other MFT 25mm lens will fail this test. Why? Because no other 25mm lens will focus this close (shall I talk instead about the chromatic aberrations of the Leica 25mm f1.4? No? Didn't think you wanted to hear about that, its the reason I use the f1.7 instead). So having discredited that bit of video, lets cut to the chase and discuss normal usage. So lets assume the focus shit is considerable, what then is the tolerance? Its a 25mm lens, the DoF is huge; at f4 an entire room will be acceptable sharp right to to the back wall and beyond. . I have never ever had any substandard photos from this lens at any aperture; you better trust that as I have run two of the worlds best analysis labs and my standards of requirement are critical. So what of your results? So what? Have you compared the worst result of this lens with another lens? No you have compared it with itself. Its softest at f4 instead of teh usual wide open, still looked good to me; what you are describing is a poor spot just as most lenses have a sweet spot at f5.6; do you not use these lenses wide open? Well do you? No this lens is a stella performance, any focus shift is mostly well within DoF (BTW that is what DoF means, the region of acceptable sharpness not the sharpest). THis lens is acceptably sharp at ALL apertures and yes you can find it sharper but that is true of all lenses. Hope that makes sense. You should love this lens, its just about my favourite and I can afford any lens; even Leica primes - winks

Is lumix 25mm f1.7 made in china? Cuz i saw made in china mark on some lens. Comment plz

I found a way to solve this problem..................... I SOLD it and bought the 20mm 1.7..............

Hi, it is nice you spent the time to look into this issue. But really I think you would need to be really pedantic. Tell these people to take another photo or change aperture. Some people complain about everything.

you get what you paid for, this lens is not sharp at all but for the price is good, you wil never find a pro photographer using cheap glass