Quark and ZWO Newton's rings and bands - problem solved !!!

[Dave Smith]

Just over a week ago I asked a question about getting banding across my images on a then new camera (ZWO ASI174MM) with a Quark.

That topic can be found here http://stargazerslounge.com/topic/246932-zwo-asi174mm-bands-on-image-normal-or-a-problem/?hl=%2Bbands+%2Bquark#entry2687056

As a result it was suggested to me (Thanks David Smith) that 1parsec had made a home-brew tilt adapter and that I should contact him to see how he had done it.

I did contact 1parsec who it turned out to be Dave Rose of Rowan Astronomy. He explained that it had been made in his workshop and it was unlikely that I could make my own. He did however offer to loan me his to try out, to see if it solved my problem especially on the large chip of the 174. I was happy to accept his kind offer.

Here first of all is a flat taken before fitting the tilt adapter, using the full frame of the 174.

The Newon's rings and the broader horizontal banding, as well as some dust bunnies can clearly be seen.

When the adapter was fitted it seemed to be initially set at around 3 degrees and it removed the NRs and bands effectively. When I reduced the angle to approx 1 degree the rings were absent but the bands were showing, so I reset it at 2 degrees and they were gone. Here is a flat at 2 degrees.

No bands or rings but the illumination has changed as I had to remove the adapter to make the changes.

Here is an image taken with the adapter in place but no flat.

and then with a flat.

Both videos had the same treatment and identical process in Imppg but no further treatment.

I find that the rings and bands can be removed using a flat but in my opinion it is far better if they are not there in the first place, similarly with the dust bunnies which I have since removed.

There is also the situation where you have run off a video to find the clouds roll in before a flat can be taken.

The good news is that Rowan Astronomy are going to produce a batch of these tilt adapters in 4 - 5 weeks. I can't wait to get my hands on one.

It seems that a few folk have tried using the tilt corrector from TS but have had to modify it.

This makes an interesting read on that subject. http://www.davidcortner.com/slowblog/20130513s.php

So, many thanks to Dave Rose (1parsec) for loaning me his prototype tilt adapter. I am looking forward to receiving one from the first batch in due course.

Dave

PS I should say that my method of measuring the angle was very crude, so not reliable figures.

[JamesF]

That's quite impressive.  Thank you for taking the time to post the different images.

James

[Dave Smith]

A related problem I had this week is that for a short time, without the tilt adapter, I couldn't remove the NRs or bands using flats. What had changed from before I tested the tilt adapter was that the camera was attached almost next to the quark. When I changed back to the camera being a 2" nose piece on the camera and a 2" adapter on the quark, the NRs and bands were still there but were removed by flats. I do not understand at all why??? With the camera directly linked to the Quark the flats corrected the general illumination but made the NRs much worse???  This will not be a problem with the tilt adapter in place.

Dave

[Dave Smith]

Correction: It is Rowan Engineering or Rowan Astronomy.

Dave

[michael.h.f.wilkinson]

Very nice solution

[Davey-T]

Glad you've sorted it Dave, bit confusing with everybody called Dave and some even called Dave Smith, perhaps you could be David Essex or has that already been done 

Dave

[JamesF]

Interesting that the rings look more elliptical than circular, too.

James

[Freddie]

Interesting, thanks for posting. I too get some shots where the flats don't work but nothing has changed in the set-up, most frustrating.

[JamesF]

If Dave Rose doesn't mind, would it be possible to post a couple of pictures of the tilt unit?  It would be useful to have a think about how I might need to modify my setup to use one.

James

[Dave Smith]

Unfortunately I have had to return it. It is not that unsimilar to the TS version but is capable of larger angles. It has two T2 threads, one side male and the other side female. I fitted it directly to the camera that has a T2 thread and to the quark via an adapter (T2 to Quark)..

Dave

[JamesF]

Ah fair enough.  To work with my modded PST I think I might need to make a shorter extension than the one I currently use for a camera.  I could however make it with a T2 thread on the tail end.  I think I might need to have one in my possession before I could work out exactly what to do.  Something to ponder on in a few weeks when I have a bit less on my plate, perhaps.

James

[Dave Smith]

There is a picture on here see http://stargazerslounge.com/topic/245433-quark-ha-30-5-15/

The adapter has black tape around it to prevent light getting in.

Dave

[JamesF]

That definitely looks like I'd need to shorten my existing system otherwise I'll run out of focus travel.

James

[Luke]

That's good news, Dave, I had imagined the chip was too large to tilt and you might have areas out of focus. I hope to get my hands on one of these adapters.

[David Smith]

Glad you found a solution Dave.

[Zakalwe]

Very interesting. I have pretty bad NR with my combination too, so I am interested in finding a solution.

[Pete Presland]

Excellent end result!

[AstroEd]

I recently bought the TS tilt adapter but only had one chance to use it so far with no luck, how do you know which screws to adjust to remove the rings? Using a Lunt 80mm and asi174mm with a 2.5x powermate, was hoping to get the 4x and 5x but am scared the rings will be worse.

[Zakalwe]

It looks like yours has even worse banding than mine, and I thought that mine was pretty bad!

I just experimented with mine to find an optimal tilt. I did attach the adapter to the camera so the tilt is parallel to the long axis of the sensor.

In this picture, the socket screws are the pivot point and the grub screws adjust the tilt:

In terms of amount of tilt- 1.5mm difference between the high and low side clears the vast majority of banding and NR for me. There is a very faint amount left, but I chose to keep the amount of tilt to a minimum to prevent problems with focus across the chip.

[Dave Smith]

Hi Ed,

It was the Rowan Astronomy Tilt adapter that I have used. I don't know about the TS adapter which is really designed to correct for tilt rather than add tilt intentionally.

Here is my arrangement.

Dave