lets get this sorted!

[teoria_del_big_bang]

1 minute ago, Rustang said:

I'm still very much learning a lot of things so in the same boat as you and that's well into my 3rd year of doing this. The dark corners have been a bit of an issue especially with details and nebulosity that I would like to keep in the corners but it is what it is. In regards to compatability, i.e camera sensor size to scope apature/fl what would it need to be to gain the correct compatibility if that makes sense? Bigger apature? Smaller focal length!? 

Very similar to myself, I think I have been doing astronomy for 4 years and AP for 3, so maybe a bit longer than yourself. Unfortunately mostly due to weather and no obsy I do not get as much practice as I would like as the imaging sessions are few and far between.
But I think I have gained a pretty good overall understanding of what to do but still I know a lot to learn.
So as I say please take my observations with a pinch of salt as in a way I am asking the rest of SGL as well 🙂 

Steve

[teoria_del_big_bang]

I think we both would gain a great deal with a trip to Olly's place in France 🙂 
Something else thats been on my wish list for a while.

Steve

[Rustang]

19 minutes ago, teoria_del_big_bang said:

I do not have a permanent setup either - on my wish list as it has been last few years. But I do keep all my imaging train, including FW and camera set up permantly. I have a sturdy handle on top of the rig and take the whole rig off that is sat on the dovetail and store it in a cupboard.
I am a bit of a fussy sod so I still take flats after each session, with a flat field panel really does not take long, for each filter I have used after each session. There has been a few instances this did not happen for what ever reasons but so long as the camera and image train has not moved I can pretty safely use the last set of flats. Yes a few more bits of dust may have settled or moved but generally it is better to use the last flats than not use any I have found.

Steve

I'm hoping as time goes on I can get a little more permanent, I'm considering some upgrades in a couple of months so will see how it all goes but I'm thankful and grateful for what I can currently achieve. 

[The Lazy Astronomer]

2 hours ago, Rustang said:

I'm still very much learning a lot of things so in the same boat as you and that's well into my 3rd year of doing this. The dark corners have been a bit of an issue especially with details and nebulosity that I would like to keep in the corners but it is what it is. In regards to compatability, i.e camera sensor size to scope apature/fl what would it need to be to gain the correct compatibility if that makes sense? Bigger apature? Smaller focal length!? 

In terms of equipment compatibility, there are 2 points to consider: the sampling rate and the scopes imaging circle size.

Your current sampling rate is 2.3"/px, which is probably about right for typical sky conditions.

I tried to look up the imaging circle of your scope but couldn't seem find it, however you sensor diagonal is 22.5mm, so l would be surprised if the scope was not able to fully illuminate the sensor. There does seem to be some hard vignetting though - what size filters do you use, and how far from the sensor are they?

[Rustang]

10 minutes ago, The Lazy Astronomer said:

In terms of equipment compatibility, there are 2 points to consider: the sampling rate and the scopes imaging circle size.

Your current sampling rate is 2.3"/px, which is probably about right for typical sky conditions.

I tried to look up the imaging circle of your scope but couldn't seem find it, however you sensor diagonal is 22.5mm, so l would be surprised if the scope was not able to fully illuminate the sensor. There does seem to be some hard vignetting though - what size filters do you use, and how far from the sensor are they?

they are 1.25 filters in a filter wheel straight onto the camera then i have the 0.8x reducer, i think there is a spacer between the reducer and filter wheel

[newbie alert]

With a reducer your image circle of your scope gets smaller

I try to have my filters as close to the sensor as poss, so if it needs a spacer then I have it on the other side

[The Lazy Astronomer]

14 minutes ago, Rustang said:

they are 1.25 filters in a filter wheel straight onto the camera then i have the 0.8x reducer, i think there is a spacer between the reducer and filter wheel

Assuming your filters have a clear aperture of 26mm, then they could be up to 27.5mm from the sensor without causing issues (in theory). Is it possible your sensor is slightly offset such that it doesn't sit in the centre of the filter? Or maybe your filter's clear apertures are <26mm (my ZWO ones are ~24mm, my Astronomik ones are ~27mm, so they do differ).

[Rustang]

14 minutes ago, The Lazy Astronomer said:

Assuming your filters have a clear aperture of 26mm, then they could be up to 27.5mm from the sensor without causing issues (in theory). Is it possible your sensor is slightly offset such that it doesn't sit in the centre of the filter? Or maybe your filter's clear apertures are <26mm (my ZWO ones are ~24mm, my Astronomik ones are ~27mm, so they do differ).

Mine are Baader filters, the filter wheel is attached directly to the camera so I cant bring the filters any closer unfortunatley. It would be a real shame if it was the filters and not the reducer/scope because I am considering a scope upgrade, something like the SW Esprit 100, WO FLT 91, SharpStar 94EDPH f/5.5 Triplet or something along those lines so bigger aperture with similar FL. I wasnt really considering a camera/filter change just yet so it could mean I would have to live with the vignetting.

 

I believe mine are these so this info could be correct https://www.rothervalleyoptics.co.uk/baader-h-alpha-7nm-ccd-narrowband-filters.html

"Special Filter Cell: Baader's special filter cell design offers unique features that enhance their reliability and usability. Though difficult to produce, the ultra-thin filter cell results in the maximum possible clear aperture, in order to minimize vignetting (1.25" Filter clear aperture is 27mm, 2" Filter aperture is 45mm). The special threading has been designed to fit a wide variety of eyepieces and accessories (there is significant variation between the 1.25" filter threading used by eyepiece and accessory manufacturers). The front 'crown' of the filter incorporates milled notches which make handling and threading the filter a more secure operation in the dark."

Edited July 31, 2021 by Rustang

[tooth_dr]

I'm going to have a look for some older flats that I would have taken with the camera and ED80 but 0.85x reducer, and compare them to yours.  I used the QHY9 with 1.25" filters down to F4.7 so I'm surprised there are issues at F6.

[Rustang]

28 minutes ago, tooth_dr said:

I'm going to have a look for some older flats that I would have taken with the camera and ED80 but 0.85x reducer, and compare them to yours.  I used the QHY9 with 1.25" filters down to F4.7 so I'm surprised there are issues at F6.

Thanks Adam, appreciate that, I'm sure we will get to the bottom of it 👍

[Clarkey]

Just come across this thread.

FWIW I use an ED80 with the 0.85 FF/ reducer with an ASI1600 which has a 22mm diagonal (so similar). Even with the 31mm unmounted filters I do get some vignetting so I suspect you may get some with the 1.25's. It is claimed that the 31mm versions are good down to F2 - but I am not convinced. What is the distance from the sensor to the filters on the QHY camera? As you are using a different reducer the image size may be smaller, but the Altair does state 38mm clear aperture so it should be enough.

There is a post about it here:

 

[Rustang]

On 04/08/2021 at 14:46, Clarkey said:

Just come across this thread.

FWIW I use an ED80 with the 0.85 FF/ reducer with an ASI1600 which has a 22mm diagonal (so similar). Even with the 31mm unmounted filters I do get some vignetting so I suspect you may get some with the 1.25's. It is claimed that the 31mm versions are good down to F2 - but I am not convinced. What is the distance from the sensor to the filters on the QHY camera? As you are using a different reducer the image size may be smaller, but the Altair does state 38mm clear aperture so it should be enough.

There is a post about it here:

 

Thanks for your reply, only just seen it. I've not measured the filter to sensor distance, the camera is directly attached to the filter wheel so I doubt I Could bring the filters any closer anyway. I'm thinking it's the filter size because I can't see it being anything else unless it could be the Altair 0.8x reducer but I doubt it. There's some talk on whether this camera needs 2inch filters which I think it probably does unless you can get the filters 1.25 ones closer to the sensor. 

I'm surprised you get vignetting with with the ASI 1600, I was looking into getting one to hopefully get rid of the vignetting and also help bring down my sample rate! But as you say with pretty much the same sensor size il probably have the same issue, I had forgotten to check that when researching. 

Edited August 7, 2021 by Rustang

[Clarkey]

5 hours ago, Rustang said:

I'm surprised you get vignetting with with the ASI 1600

It's not bad, but you can see it on the flats. Easily calibrated out though.