S50 Pro Sensor Tilt

tcsmith

I received my S50 Pro on the 4th of September 2026 and since have watched YouTube videos from "Curtis" regarding the sensor tilt in the S50 Pro. I tested mine in ASTAP Image Inspector and find it is 79% (Extreme) tilted. I also have an S50 and ran an ASTAP tilt test on it and it was reported as mild. Have others done the same tests on your S50 Pro and have you gotten an extreme tilt reading? A friend of mine got his S50 Pro the same day as mine and he also has an extreme tilt reported.

Is there a plan from ZWO to address this issue? Replacement unit? Return for modification? Or anything?

AstroDave1958

tcsmith My Seestar S50 Pro had a sensor tilt measured by ASTAP to be 120% (Extreme). I have returned it to the seller, together with FIT Files as evidence, and they are now going to replace it asap... My worry is that the S50 Pro sensor tilt is a design issue as the amount of flex appears to be dependent on the orientation of the 'Pro' in relation to the object in the sky. If this is the case, it is possible that ZWO may expect to see a substantial amount of returns (for either replacement or refund) within the warranty period. I am also concerned with how much the degree of sensor tilt, reported in S50 Pro's, will affect the accuracy of the new Photometry feature in the Seestar App.

Support@Seestar

Could you please send the original image in FITS format to our technical support email address? You can contact us via this link. Thank you.

3AC9bx99

Support@Seestar This doesn't appear to be an isolated incident and should not be treated as such. There are several reports on the internet regarding tilt problems with the new S50 Pro. There needs to be a statement put out by ZWO regarding this.

Support@Seestar

3AC9bx99 I have reported this issue.

Gulyas K

The FB is full of reports about the S50 Pro sensor tilt. Mostly the lower 1/3 of the FOV is defocused and/or shows elongated stars.
My S50 Pro has a tilt between 12-18% in ASTAP. Actually it decreased by the time. I measured my very first photos with it and the tilt was over 35%, sometimes 40%. The fresh raw fits made 3 days ago. The tilt is much better, sometimes below 10%. Maybe the usage helped? I don't know. Actually I do not care too much, because BlurXterminator can fix it.
My first S50 about 2 years ago had a serious sensor tilt. Some users said that I could fix it by switch to scenery mode, choose manual focus and go throught the entire range from the minimum to the maximum 3-4 times. It did not help, so I sent the device back to my supplier. He replaced it and the new one was almost perfect. I measured it now in ASTAP and it's below 8%. I am still using it aside the S50 Pro.

YF5I3f19

The tilt problem seems to be affecting quite many Seestar units, mine showed a 66% tilt and is presently in the replacement process. I really do hope I'll get a better one, fingers crossed.

francescoCh

Checked my images and there's great variability. Some are way off, most though are in the 0-10% range. I think it might have something to do with the tripod and the polar alignment accuracy.

For instance Omicron persei got 20-30% on 22 and 27 September.
For Helix nebula 0% (but few stars, due to light pollution from south)
On the same night on NGC1893 the tilt was arond 5%

For M45 on the 24th it started in the 20% range and went down to 9% by 3:00 CET, then to 5% on 4:00. Seems to depend on the orientation, but not always. Anyway the final image is available in astroimg and it didn't look bad.

Gulyas K

francescoCh Well, I thought the same at first. But the affected part is only the lower part of the FOV. Polar alignment or tripod issue causes star trails all way across the FOV. I use my S50 Pro on a very stable concrete pillar. Polar alignment is 0.0 on both axis due to the the app, but I tried NINA as well, same result, 0.0. And the lower 1/3 part of the FOV is affected. Whatever I do, always the lower 1/3, especially the right corner. It does not matter whether I use 10s, 20s, 30s or 60s exposures the affected area always looks the same, which rules out the polar alignment error.
However I process my subs in Siril and I use BlurXterminator which can correct all these aberrations.

3AC9bx99

I imaged M39 with my new S50 Pro in EQ mode, this has a rich star field. I set 10s exposures and analysed 12 individual subs using ASTAP and got an average tilt value of 45% across all 12, on the combined stack the tilt value was 35%. Looking at the images and another image on a different target I am hard pressed to see elongated stars, nothing different to what I am used to seeing with Seestars. Perhaps if you really zoom in on the bottom left, depending on the orientation of the image, but nothing BlurXterminator cannot fix. I realise not everyone has deconvolution software. The final image looks good, but with cloudy weather I have only managed a couple of targets in these early days of ownership.

024ESI2P

Gulyas K I too use the RCAstro tools but I wouldn't want to always give the corner the extra treatment on a brand new telescope. It just doesn't feel right, imo.

024ESI2P

I just received my S50Pro recently and have severe Tilt Issues on the bottom right corner. I tried various targets on multiple Nights but the star blur remained overall no matter the fits or target. I'm going to return it as I don't want to go through all the hassle.
My trusty S50 is putting out great images for two years, ZWO should fix the internal design as it's clearly a manufacturing problem. I"ll wait until this stuff is fixed or a version 2 comes out.
Edit: I checked my fits with ASTAP and yes, I made the right choice returning it. Depending on the targets and night I had a Tilt in the corner of between 34 - 67! All where 10s exposures, everything setup even better than normally(0.0/0.1 degrees) and in EQ mode! Good luck to buyers...

Seestar_S50

Try this in landscape mode first;

Let the Seestar auto focus on an object at least 50m away, then manually adjust focus to both exterems, then auto focus again.
Next do the same in star gazing mode at night, auto focus on a known bright object then again manually wind the focus to both extrems and then auto focus again. Then check the tilt in ASTAP see if this improves the tilt.

Gulyas K

Seestar_S50 This was the "magic trick" with the S50 too. In most cases it did not work. However it's worth to try.

Lilo

Seestar_S50
So, is it your pay for? )) To run focus back and forth?
Long ago known issue, question to ZWO assembly standards and factory quality control.
And note, no word from them in this topic for 24 days.

pPl241iR

I also had to return my S50 Pro due to extreme sensor tilt. I sent it back to a shop in Germany—I’m from Belgium—and requested a refund. I’m not taking the risk of receiving another faulty unit; I’ll buy something else instead. According to ASTAP, I had tilt ranging from 32% to 63%,

9gJ0Q9O2

Add me to the list of sensor tilt Pro owners, looking at returning mine.
ASTAP reports extreme or severe tilt.
The elongation is most noticeable in the lower 3rd of the frame.
I have tested at 5s and 10s exposures and the result is the same.
My 30s exposures stack of NGC1365 shows noticeable star elongation.

braunschweiger

What many people here are writing is just ridiculous. Sensor tilt doesn’t simply change on its own. Many have absolutely no idea what it is they’re actually measuring. Sorry, but instead of just parroting what others say on social media, you’d be better off actually educating yourselves on the subject. It’s sad to see such stupidity—I honestly feel sorry for the manufacturers.

LuisFlo

Good afternoon,
I have read about and seen the issues surrounding "tiltgate" in various forums and videos. After performing several checks for this problem on my S50 Pro—which I purchased from Astroshop on August 26th and received on September 18th—I believe I will initiate a warranty claim to have it inspected. Using ASTAP, I am seeing tilt values of 37% (an extreme case) when imaging M45. For other objects, such as M27, I am seeing values starting from 21%. I think the most sensible course of action is to have it checked under warranty for peace of mind, even if it means being without the device for a while.

o238GaMH

Is there an official reply from ZWO for sensor tilt?

3AC9bx99

o238GaMH Support has reported the problem, as above, so ZWO are aware of it. Whether anything is done we will have to wait and see. If you are not happy with your Seestar you can return it but there is no guarantee any replacement will be any better. The simple fix is to use software like BlurXterminator, but I realise not everyone will have access to this.