Whale galaxy with TS off-axis guider

[PortableAstronomer]

Hi there,

I've been experimenting with the TS ultra-low-profile OAG, with my 190MN Maksutov-Newtonian.

I chose to try off-axis guiding because of mounting problems with my guide scope, the extra weight & setup, portability, and having less elements to require dew heater strips. Also the off-axis sharpness of the 190MN scope is superb, having very little coma, so I thought this would be better-suited to OAG than classic Newtonian scopes.

Below is what my imaging train looks like.

Further down I'll show some results from my very light-polluted location.

[SteveL]

The TS-OAG makes a hell of a difference, doesnt it! No more flex, less weight...

[PortableAstronomer]

(continued from 1st paragraph)

I wanted an OAG that's slim enough so I could put the autoguider before the filters, and have space for a filter drawer between the autoguider pick-off prism and the main imaging ccd.

In my case I have a QHY8 as the imaging camera, and a QHY5 as the autoguider.

The QHY5 (guider) is a very high noise camera, especially compared with something like a Lodestar, but less than half the price. It was clear that this was going to be a challenge.

As you can see, the light pollution here is quite bad. I put an IDAS filter behind the pick-off prism, in a Gerd Neumann filter drawer behind the OAG , and before the QHY8.

[PortableAstronomer]

Finding a guide star has not been a problem so-far, with the limited number of objects that I've targeted.

I usually centre the object in the main imaging camera, then rotate the entire imaging train in the 2" eyepiece holder of the telescope, until the autoguider picks up any speckles of stars.

The noise from my QHY5 has to be seen to be believed. I had less noise with my modified SPC900NC webcam.

Quite often I found that Maxim or PHD would lose the star because the SN ration was so appaling, it was like trying to find a white ball in a snowstorm!

Anyway, here's the results of 40 mins under my urban sky; 8x5min exposures with the QHY8, Gain=1, then simply stretched in the histogram. It shows a familiar sight of a very bright background from the sodium lamps.

[PortableAstronomer]

And finally, after a few minutes processing using PixInsight.

I am always blown away on just how powerful this program is.

I performed

- Dynamic background subtraction

- Histogram stretch

- Colour adjustment/ neutralisation

- Deconvolution

- Noise reduction

- 2nd round of Dynamic background extraction

- Further slight histogram stretch.

- Colour saturation boost

[PortableAstronomer]

Thanks again to Harry's AstroShed for the videos on how get some good results using PixInsight.

[Keiran]

That does look absolutly brilliant.

[harry page]

Hi

All looks great to me

And it look like you have a handle on pixinsight now

Harry

[Tim]

Hi,

You use pretty much the same combination as me I love the fact that it is possible to take the camera(s) arrangement out of the MN190 and drop it into a 'frac, or SCT.

Nice result on the whale and Hockey stick there, captured the colours in spite of the LP.

TJ

[barkis]

It's wonderful what you can do with processing tools.

Your LP seems fairly bad, but you have succeeded in producing a really good Image in spite of the difficulties. Well done Indeed.

It will inspire others with bad Light interference.

I'm almost Identical in setup to you too, except I will be using a Meade DSI as a guide Cam. I had toyed with getting a QHY5 as a guide C., but your revelation on the SN has put me right off that notion.

I will follow your progeress with interest.

Ron.

[zhgutas]

Lovely image, and can I say a huge thank you for such a vast amount of imaging/processing detail! Very useful indeed.

Marius

[PortableAstronomer]

Thanks for the comments. Much appreciated.

Many of you noticed the LP. That was quite a good night.

This is what my street looks like on a *cloudy* night.

[PortableAstronomer]

Got to replace the QHY5 with something that's less noisy than a de-tuned TV receiver. Saving those pennies for a Lodestar I think. :-)

[Coco]

Thats a wonderful image.. and interesting workflow..

Cheers

Guy

[BlueAstra]

Where do you get the attachment that projects the constallations on the sky?

[PortableAstronomer]

- "Where do you get the attachment that projects the constallations on the sky?"

I saved the photo as a .jpg then opened it up in Windows Paint (mspaint.exe).

Then I drew the lines manually on the sky, and saved the picture.

The LP is quite bad so only Arcturus and one other star was visible in that part of the sky.

[PortableAstronomer]

When I get a spare moment I'll try to write a proper equipment review on the TS off-axis-guider, having owned a couple of other OAGs and various other scopes.

But for a quickie, here goes:

Pros: the 9mm ultra low profile, means it will theoretically fit into most Newtonians. Also the T-thread guider attachment puts the guider sensor close to the imaging path, minimising the back focus required to the main imaging chip.

Cons: on top of the usual off-axis drawbacks, the TS unit is quite flimsy, prone to the side-tube/guide turret movement, flimsy thumb screws to hold it still, clumsy OAG focus mechanism, the unit can let in stray light into the imaging path.