Flat question

[rockinrome]

Hello all

I'm having some (recent) difficulty with my flat frames and wondered if anyone can help?

I haved just moved to the 150P Quattro with a 533C ProTec camera (cooled to -10c).

The image here is my stretched flat to highlight my 2 questions:
(1) Does this look like a "normal" flat frame to you all
(2) Does the position of the light cone suggest I need to tilt-adjust my camera, focuser, etc.

As always, thanks for any advice.

 

Edited July 1 by rockinrome

[Vroobel]

Hi,

Here is how PixInsight sees your flat, definitely something should be corrected. The red circle marks roughly the brightest area.

 

[Clarkey]

Yes, the collimation does look a little out, but I would be more concerned about the number of virtually identical dust motes. The number here is excessive.

[rockinrome]

Thanks @Vroobel @Clarkey

Indeed re. dust moats. There is no way there is THAT much dust on any mirror/camera sensor in the image train.
I will deffo check my collimation though as you suggest - it does look more of an alignment issue rather than tilt, i.e. the image could do with simply moving up and right a little.

Thanks again

 

Edited July 1 by rockinrome

[Oddsocks]

Looks as though you have two separate sources of focal path artefacts.

A large mass of ice crystals on the right hand side of the image that are on the cover glass of the sensor, time to renew the desiccant, and a large distribution of particles on the window of the camera, possibly Birch pollen which gets everywhere on open optical tubes at this time of year and being translucent are difficult to correct with flats unless the flats light-source is an exact spectral match for the night sky due to the selective wavelength absorption and transmission that are characteristic of pollen grains.

[rockinrome]

Right. Thanks @Oddsocks, much appreciated.

I forgot about those "pixel" artifacts too - that explains a whole lot.

OK, so two fold I see - some camera maintenance and a tweaked alignment.

Just another quick question also - when I use the cheshire collimator (laser collimator shows as collimated) I see the secondary a slightly elongated. Should I see this as circular?
I didn't know whether this is a "feature" of this type of scope.

I think I may need to collimate on a star eh?

Thank you

 

Edited July 1 by rockinrome

[Oddsocks]

On 03/06/2024 at 09:41, rockinrome said:

Just another quick question also - when I use the cheshire collimator (laser collimator shows as collimated) I see the secondary a slightly elongated. Should I see this as circular?
I didn't know whether this is a "feature" of this type of scope.

It's many years (probably ten or more) since I last collimated a fast newt with a combination of Cheshire and  CatsEye Auto Collimator,  using the "New Method" as outlined in Vic Menards booklet "New Perspectives on Newtonian Collimation", sadly out of stock everywhere in the UK now, although it might still be available on direct import from the USA.

I wouldn't feel comfortable trying to guide you through the steps to collimate a fast newt, too many years have gone by.

For specific help with collimation of a fast newt you'll probably attract more replies by opening a new topic under the forum section "Discussions - Scopes / Whole setups" than in this "Beginners - Getting Started With Imaging" section of the forum, although this time of the year such topics will always be slow to gather replies as many observers/imagers have packed up until astronomical darkness returns.

[rockinrome]

13 minutes ago, Oddsocks said:

It's many years (probably ten or more) since I last collimated a fast newt with a combination of Cheshire and  CatsEye Auto Collimator,  using the "New Method" as outlined in Vic Menards booklet "New Perspectives on Newtonian Collimation", sadly out of stock everywhere in the UK now, although it might still be available on direct import from the USA.

I wouldn't feel comfortable trying to guide you through the steps to collimate a fast newt, too many years have gone by.

For specific help with collimation of a fast newt you'll probably attract more replies by opening a new topic under the forum section "Discussions - Scopes / Whole setups" than in this "Beginners - Getting Started With Imaging" section of the forum, although this time of the year such topics will always be slow to gather replies as many observers/imagers have packed up until astronomical darkness returns.

Thanks for the advice, much appreciated.

[alacant]

On 02/06/2024 at 16:57, rockinrome said:

I'm having some (recent) difficulty with my flat frame

Hi

What difficulty are you having?

With regard to your questions, the Quattro is unlikely to hold either focus or collimation unless, as with any low end Newtonian, certain modifications have been made. These include upgrading the springs, removing the flexible parts of the focuser, fixing the mirror in the cell...etc. None are particularly difficult, but really need attending to if you want to bring it up to imaging standard.

If you want to go the whole journey...

Cheers 

Edited June 4 by alacant

[rockinrome]

Seen as I asked the question and you were kind enough to answer, I thought I'd update with my findings.
Thank you all for your input - recently @alacant - with regard to the upgrades - yes Cuiv gave me the bug and I upgraded the focuser, spider and mirror mask a while back.

I did find this very useful post on Cloudy nights (which was exactly what I was trying to describe, i.e. the elongated secondary) - https://www.cloudynights.com/topic/635284-collimation-of-a-fast-newtonian/page-2

Also my issue kinda looks like it's been sorted after using a simple collimation cap. I will also do a finer collimation on a star - Lukomatico has a good tutorial on this also - 

 

Kind regards, clear skies (yeh right!)

Edited July 1 by rockinrome

[Clarkey]

1 hour ago, alacant said:

With regard to your questions, the Quattro is unlikely to hold either focus or collimation unless, as with any low end Newtonian, certain modifications have been made. These include upgrading the springs, removing the flexible parts of the focuser, fixing the mirror in the cell...etc. None are particularly difficult, but really need attending to if you want to bring it up to imaging standard.

Or save yourself the hassle and buy a decent imaging scope to start with.... I was lucky, I picked up a 10" Quattro Carbon Fibre with the 'good' focuser for £450. I have done quite a few mods anyway - just need a new spider.

[rockinrome]

On 04/06/2024 at 21:14, Clarkey said:

Or save yourself the hassle and buy a decent imaging scope to start with.... I was lucky, I picked up a 10" Quattro Carbon Fibre with the 'good' focuser for £450. I have done quite a few mods anyway - just need a new spider.

Hi @Clarkey

I did not go into this blind and was fully aware what I needed to do when I bought it. The included coma corrector was also a big plus.

As Cuiv points out in his many posts - the scope goes from budget to a real performer with not that much more spend. We all know this hobby is a money pit anyway!

Regards

Edited July 1 by rockinrome

[Clarkey]

14 minutes ago, rockinrome said:

The included coma corrector was also a big plus.

To be honest with the coma corrector the Quattro 150 is a bit of bargain for a widefield scope. Also, being relatively small, the amount of flex is minimal. I have a TS f4 Photon newtonian, but by the time I added a coma corrector and new focuser it cost nearly £1000. Unfortunately, I had horrendous reflections from the filters so I couldn't use it...

[alacant]

The other consideration is quality control. It took us three attempts to find a q150p with mirrors which were usable. The first two from the last batch delivered to Germany gave stars like this. Yes, that's without the mirror clips; similar result with an aperture mask. The third-time-lucky example was from the the Paris importer, alas with the dreadful two speed non-reinforced focuser. But hey, decent stars over aps-c, even with the mirror clips in place.

Don't forget that as well as the cuiv modifications, you'll also need to prevent the 1º from slipping. The double sided silicone pads are ideal. This may explain your off-centre flat image.

With the replacement focuser, spider and primary cell upgrades,  the total outlay is well on its way to that of a TS UNC; the latter being the closest we've come to finding a Newtonian which just works.

 

Cheers 

Edited June 9 by alacant
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