RedCat 51 first image - Oh No!

[symmetal]

Took my first image with my new RedCat-51 this evening. Bahtinov focusing was very precise and easy. I used the ASI1600MM with filter wheel and took this 45 sec L sub centred on the Christmas Tree Cluster. Look at the bottom of frame particularly Bottom Left, out of focus smeary stars.  I took three more subs rotating the camera through 90 deg each time and the horrible stars corners rotated 90 deg each time so looks like the fault is with the scope. I've included two CCD Inspector images of the 0 and 90 deg images which shows it clearly.

I thought Petzval scopes were meant to save you having to bother with spacing and tilt troubles. Do you agree it has to go back? 

Alan

 

[Davey-T]

Little fan shapes reminiscent of coma, where did you buy it ?

Dave

[symmetal]

1 minute ago, Davey-T said:

Little fan shapes reminiscent of coma, where did you buy it ?

Dave

FLO. Have you tested yours from FLO yet Dave?

Edited March 24, 2019 by symmetal

[Davey-T]

Just now, symmetal said:

FLO

That's all right then, still waiting for mine.

Dave

[symmetal]

You do agree it's a fault with the scope then Dave and needs returning. 

Alan 

Edited March 24, 2019 by symmetal

[Davey-T]

I think so, let's hope the RC doesn't go the way of the Star71 Mk1 because WO can't maintain the QC at that price point.

Dave

[symmetal]

Yes it's a real pity Dave having waited so long. Now writing email to FLO. It's back to using the WO-61 then for the ASI1600. At least it's now much better once I got the tilt sorted out.

Alan

[Davey-T]

I've studied the corners of a few RC images online and they've all looked good.

Dave

[symmetal]

Thanks Dave, Clear Outside shows 5 green nights coming up so I thought I got the RC just in time. 

Alan

[Buzzard75]

I'm fairly new to CCD/CMOS imaging here so I'm probably going to show my ignorance. Just trying to understand what I'm looking at. Assuming the bottom of the first distortion pattern is parallel to the ground. You rotate the camera 90 degrees counter clock wise so now the left edge of the sensor is parallel to the ground. Hence, the distortion pattern shifts sides of the sensor.

Had the distortion remained on the same edge of the sensor pattern after rotation, you could then assume your sensor was off a bit and had some induced tilt on the camera.

Correct?

[symmetal]

Yes, that's correct Buzzard75. 

Alan

[Davey-T]

Well just had a look at some of Wei Hoo Wangs RedCat images on Astrobin and he appears to have one dodgy corner showing up on blue stars particularly..

Dave

[symmetal]

Ooh! that's a bit worrying Dave. I wonder if FLO can send them to Es Reid for checking/fixing like the other WO scopes.

Alan

[FLO]

12 hours ago, symmetal said:

Do you agree it has to go back? 

Yes. It should be returned. We have just reopened after the weekend so I will find your email this morning then will reply again to arrange collection. 

William Optics are struggling to keep up with demand at the moment so it will be some time before we can provide a replacement but because yours is the first RedCat to be returned we will happily send it to Es Reid for checking / adjustment. The RedCat is a new model so he is probably itching to have one on the bench. 

HTH, 

Steve 

[symmetal]

FLO have just received a delivery or white RedCats so offered to send one for delivery tomorrow at the same time as they collect the Red one for return. I was debating whether to wait for Es Reid to fix the bad one when you know you'll get a good scope back or get a new white one tomorrow. In the end I opted for a new white one as it's meant to be good weather for the rest of the week. Fingers crossed hoping it's a good one. 

Great service FLO as ever. 

Alan

[Adam J]

18 hours ago, symmetal said:

Took my first image with my new RedCat-51 this evening. Bahtinov focusing was very precise and easy. I used the ASI1600MM with filter wheel and took this 45 sec L sub centred on the Christmas Tree Cluster. Look at the bottom of frame particularly Bottom Left, out of focus smeary stars.  I took three more subs rotating the camera through 90 deg each time and the horrible stars corners rotated 90 deg each time so looks like the fault is with the scope. I've included two CCD Inspector images of the 0 and 90 deg images which shows it clearly.

I thought Petzval scopes were meant to save you having to bother with spacing and tilt troubles. Do you agree it has to go back? 

Are you sure its not sensor tilt? The way to tell is by rotating the camera relative to the scope, if the bad stars stay in the same corner then its not the scope, its something else in your imaging chain. 

Adam

[symmetal]

49 minutes ago, Adam J said:

Are you sure its not sensor tilt? The way to tell is by rotating the camera relative to the scope, if the bad stars stay in the same corner then its not the scope, its something else in your imaging chain. 

Adam

I did that as mentioned in the paragraph you've quoted.  The CCD Inspector results I posted above  implies it's not the camera. FLO are delivering a new scope tomorrow. 

Alan

 

[Adam J]

1 hour ago, symmetal said:

I did that as mentioned in the paragraph you've quoted.  The CCD Inspector results I posted above  implies it's not the camera. FLO are delivering a new scope tomorrow. 

Alan

 

Must have skipped over while reading. One thing is apparent from my readings on such things. The more lens elements a scope has the more of a pain in the a** it has the potential to be.

Edited March 25, 2019 by Adam J

[FLO]

33 minutes ago, Adam J said:

One thing is apparent from my readings on such things. The more lens elements a scope has the more of a pain in the a** it has the potential to be.

Only if it goes wrong ?

I.e. if the elements are knocked out of alignment then resetting them can be difficult. A doublet is quite straightforward. Triplets are harder (quite a bit harder!) and the difficulty increases further with each additional element. 

HTH, 

Steve 

[Alien 13]

The number of elements shouldn't be a problem these days, camera lenses can have 19 or more and they do alright...

Alan

[FLO]

I’ll mention that to Es’ when I next see him ?

Steve 

[Alien 13]

36 minutes ago, FLO said:

I’ll mention that to Es’ when I next see him ?

Steve 

The comment was a bit tongue in cheek but have noticed that highly regarded lenses like the Samyang 135 f/2 with a measly 11 elements still manages to control collimation to a very high degree, I wonder whats their secret?

Alan

Edited March 25, 2019 by Alien 13

[symmetal]

Received the replacement white Redcat today from FLO, great service , and I'm afraid the first test image was not much different to the first scope with one bad corner. However rotating the camera orientation using the scopes rotator there was one point where the corner stars were better though still not sharp. At other rotation angles it was much worse with CCDI showing large tilt errors. I tried using a tilt adjuster to see if I could find a point where it could be cancelled out but it was too awkward. The camera had to be removed each time to adjust and you end up chasing your tail. The rotator was a lot looser to move than on the other scope so was wondering whether it was causing tilt when tightened.

You have to focus on the 'thirds' and not the centre to get the flattest field, though it's still quite curved.

I checked some photos on Astrobin using this scope and the full resolution ones are downsampled quite a bit and possibly cropped so it's hard to do a comparison. Maybe I'm expecting too much. I'll post some test samples tomorrow. Spent five hours and haven't got an image I liked. My WO-61 has much better corner stars.

I'll wait to see the results others get and what the review by RayD says.

If FLO send the returned scope to Es Reid for checking I'd be interested on what he finds. Hope I don't end up with egg on my face and caused FLO expense for nothing. 

Alan

[FLO]

On 27/03/2019 at 03:58, symmetal said:

If FLO send the returned scope to Es Reid for checking I'd be interested on what he finds. Hope I don't end up with egg on my face and caused FLO expense for nothing. 

It won't a problem either way. It has at least given us an opportunity to send one to Es' for assessment. If we had withheld one for any other reason I think we'd have been lynched! ? 

Steve 

[Nubian]

Thanks for testing Alan! Im still waiting for the RC with my name on it.

I can't deny that I'm a little concerned now. After all this hype about the "sharpest 250mm" nobody wants to read about results like yours.

I hope there will be more customer reviews soon and maybe we get feedback from Es Reid too.

Henning