William Optics RedCat 51 APO

[MushroomBill]

Redcat arrived yesterday. 

Feared the worst with the weather changing but very amazed that the sky suddenly cleared at 1am.  Set everything up in record time and managed to get 4 subs before clouded out again.  Not often you get first light on day one of ownership though.  Sadly no time to run through the rest of the filters.

Elephants Trunk, 4 x 10m, Baader Ha filter with Atik One.  Stacked in DSS and adjusted the levels a bit.

Andy

[R3tr0]

@Jkulin - A heads up to anyone using a Sony Alpha camera and the Redcat 51 (I'm using the Sony Alpha A7R3) the train I purchased wont work, it is a little long.

- M48 Female to T2 Male Adaptor 6mm Optical Length

 - T-Mount for Sony Alpha

I have the official sony alpha adapter from WO now and that is perfect for the job - https://williamoptics.com/48mm-t-mount-for-sony-e-red

 

 

Edited May 8, 2019 by R3tr0

[R3tr0]

First test with Redcat - 

Taken lastnight 30 x 90s and 12 darks.

Astronomic CLS.

Heavy crop from Sony A7R3.

 

[Davey-T]

Stars look OK, could you post an uncropped one ?

Dave

[symmetal]

Also with less jpeg compression if possible as all the stars are hard edge clipped making their true shape difficult.

Alan

[R3tr0]

21 hours ago, Davey-T said:

Stars look OK, could you post an uncropped one ?

Dave

Here you go (DNG), I am quite new to astro and any advice is appreciated, hard to get rid of colour cast from bottom left to top right.

No crop, edges of cls are visible, a little edit. 

A7R3 + Redcat 51 (moon half full)

Bode-s Gal-3.dng

[Davey-T]

Looks a bit strange on the left hand side, stars misshapen and black areas in the corners with no stars ?

Gradient could be removed with Gradient Exterminator.

Dave

[Jkulin]

I've had a good look and to be truthful, your stars are really out of shape, this was from the middle: -

And this from the left hand bottom corner: -

It looks like it is coma, but can't be 100%, I don't think it is guiding as the right hand side of the stars are flattened.

Personally I would return it for a full refund as I would never accept that for a brand new OTA.

[Davey-T]

34 minutes ago, Jkulin said:

And this from the left hand bottom corner: -

Have a look at the full frame image John it's really strange.

Dave

[Jkulin]

I have Dave and there really is some weird stars shapes, I know R3tr0 has the correct back focus as I have had a chat with him on that and all seems good, but you are right the stars are bad all over the image, if it was tilt it would be in one corner predominately.

Personally after reading so much about bad star shapes and not flat fields for this new OTA, I think WO needs to recall them all and get them checked before selling any more.

Its looks a lovely OTA and is a good FL for travelling, but I would rather use my cameras 200mm F4 focal length than have stars like that.

Edited May 17, 2019 by Jkulin

[Astroscot2]

I personally think we are looking at processing artifacts and slight trailing across the image and not lens aberrations . The image to me has been grossly over sharpened and dark point clipped in this representation, Or It could just be the image compression?

Difficult to evaluate optical quality with this image in my opinion.

Mark

[Davey-T]

8 minutes ago, Astroscot2 said:

I personally think we are looking at processing artifacts and slight trailing across the image and not lens aberrations

Did you download the full image and look at it ?

Not sure what's going on here but corners are black ?

Dave

Edited May 17, 2019 by Davey-T

[Davey-T]

3 hours ago, R3tr0 said:

Here you go (DNG), I am quite new to astro and any advice is appreciated, hard to get rid of colour cast from bottom left to top right.

No crop, edges of cls are visible, a little edit. 

A7R3 + Redcat 51 (moon half full)

Bode-s Gal-3.dng 176.41 MB · 10 downloads

Is that a single frame ? if not could you post one unprocessed.

Dave

Edited May 17, 2019 by Davey-T

[Astroscot2]

In unable to download the full image , the CLS filter is causing some issues here by the look of it, ignoring the colour cast the dark corners could be the filter holder in the light path, There are also strange fan tails on a few of the stars which point in different directions , not sure that that's about, again could be the filter.   Overall I would say the stars looks quite good to me.  Id like to see a a single frame without the CLS in place and go from there.

Mark

Edited May 17, 2019 by Astroscot2

[Jonk]

9 hours ago, R3tr0 said:

Here you go (DNG), I am quite new to astro and any advice is appreciated, hard to get rid of colour cast from bottom left to top right.

No crop, edges of cls are visible, a little edit. 

A7R3 + Redcat 51 (moon half full)

Bode-s Gal-3.dng 176.41 MB · 13 downloads

For what it's worth, here is the CCD curvature plot, which is showing major tilt.

[symmetal]

CCDI ignores clipped stars which excludes most of the stars in R3tro's image as the image has been stretched. Only dim indistinct stars are left and CCDI only found 807 of them with the bulk of these being towards the bottom of the image hence the implication (by omission) that the top 2/3 of the image is good. Those near the bottom do show some distortion which is coma like but is not distinct enough to say for sure.  CCDI reports it as tilt as that's its goto option when one side is worse than the other. A flat field with one side showing coma will be reported as having tilt.

For CCDI analysis short exposures of 10 to 20s are best to avoid many clipped stars and image trailing from alignment/periodic error. Also no processing, and no need for calibration.

Alan

[R3tr0]

18 hours ago, Davey-T said:

Is that a single frame ? if not could you post one unprocessed.

Dave

Ill post one later unprocessed, the black corners are the Internal cls edges.

[R3tr0]

Sorry for the long delay but here is the promised image from the redcat straight from the camera *.ARW file. examine away.

This is with Sony A7R3 in cropped mode, single 50 sec, no filter, using a Skywatcher Star Adventurer.

DSC07172.ARW

[Jkulin]

I just had a look and whilst the centres were reasonable this is from the Top left, horrendous star shapes: -

Bottom Left: -

Bottom Right

Top Right

Middle

Sorry Scott, but I really think you have got a real problem with that OTA and I woudln't waste any more time with it.

I will most definitely not be buying one until I see some consistency with the quality

[Davey-T]

Dodgy  stars in all corners looks like it just hasn't been assembled properly 😟

I get the impression that the QC consists of taking the odd one off the assembly line to test once a week maybe.

Dave

[Jkulin]

Here's your CCD Inspector images: -

Yep I think you are right Dave, especially after looking at the CCD Inspector images.

[Davey-T]

I think mine takes the prize for worst sample so far.

Coma across entire image these are centre of images.

Dave

[Adam J]

6 minutes ago, Davey-T said:

I think mine takes the prize for worst sample so far.

Coma across entire image these are centre of images.

Dave

yes that is horrible.

[geordie85]

44 minutes ago, Davey-T said:

I think mine takes the prize for worst sample so far.

Coma across entire image these are centre of images.

Dave

Ouch

[JimothyC]

10 hours ago, Davey-T said:

I think mine takes the prize for worst sample so far.

Coma across entire image these are centre of images.

Dave

What was your spacing to the sensor on these shots? I had some pretty dodgy stars in mine, but I've now seen this diagram (this wasn't included in the quick start guide supplied with the scope)

 

 

It looks like spacing should be 59.7mm rather than the normal 55mm. My test shots were taken at 56mm using the zwo recommended setup for a filter wheel and asi1600. I'm not sure how to achieve 59.7mm using any commercially available adaptors.