[Dawson]

Thanks both. Helpful comments and insight.

James

[Dawson]

Martin, thanks for that link. It is interesting, depending where you look, the transmission data varies… Surely the colour IMX585 should have a near identical transmission profile whatever camera it is in? Here are three plots, one from your link, one from the ZWO website (https://www.zwoastro.com/product/asi585mc-mm-pro/) and one from the PlayerOne website (https://player-one-astronomy.com/product/uranus-c-usb3-0-color-camera-imx585/).

James

Attachments:

1. 

   585MC-1.png
   

[Dawson]

Martin, thank you.

Yes, poor Chris Hooker has been helping me, dragging me along really as I’m not that bright when it comes to solar physics, magnetospheres, energy states, wavelengths etc…! But good fun for me anyway. I’ve just seen there is a 585 mono camera which appears to have a QE of just under 90% at 589nm. I may have to do some overtime. The binning is an interesting idea I’d not thought of.

Regards

James

[Dawson]

Thanks David.

James

[Dawson]

Thanks David. Do you know when Martin gave this talk?

Regards

James

[Dawson]

We are going to try and live stream from Nottingham too in white light, and Ha if the clouds permit. Live stream should go live just before 10am.

https://youtube.com/@nottinghamastronomicalsociety?si=niCKwEgSv8w_qnWi

James Dawson
Nottingham Astronomical Society

[Dawson]

We got it in Nottingham too on the all sky camera and both meteor cameras:

https://youtu.be/Pm4pqW7jNaY?si=zqSEIPv6M1a9R0kZ

[Dawson]

I’ve just seen your image and am REALLY impressed. Looking forward to seeing what else you achieve with it. Congrats too.

[Dawson]

Looking forward to it. I am bringing a load of second-hand books to try and sell on behalf of the Society for the History of Astronomy.

See you in a few weeks.

James

[Dawson]

It is dust and dirt in the optical path somewhere. Things directly on the sensor can appear nearly focussed, things on the lens of a refractor can appear grossly out of focus. These things look to be between the two. Are you using any filters near the sensor?

[Dawson]

Thanks to Denis I now have a complete set of these. The numbering is odd (and incorrect) and is as follows:

Spring 1994, Vol 1, number 1 (“Premier issue”)
Summer 1994, 1, 2
Fall 1994, 1, 3
Winter 1995, 2, 1
Spring 1995, 2, 1 (it should be 2, 2 but presumably misprinted)
Summer 1995, 2, 3
Fall 1995, 2, 4
Winter 1996, 3, 1
Spring 1996, 3, 2
Summer 1996, 3, 3
Fall 1996, 3, 4
Winter 1997, 4, 1 (final edition)

Thanks also to Jeremy Shears for giving me the original copies a few years ago.

James

[Dawson]

Yes, the Mayor emailed me to see if she could come to the observatory tonight for the spectacle.

[Dawson]

Denis, thank you. I’ll email you my address.

If anyone else has copies, I’ll still need:

Winter 1994
Spring 1997
Summer 1997
Fall 1997

James

[Dawson]

Given the site the tank ended up is known, is all this information used to refine the models for predicting where actual metoerites land?

[Dawson]

Pick up by our two meteor cameras in Nottignham, and if it is the same lump which landed in poland, this is a rough ground track (no scientific data used for this, just me and Microsoft Paint).

Attachments:

1. 

   Poland.png
   

[Dawson]

Thanks Robin. Indeed with a dedicated planetary camera, one minute of video is typically in excess of 3GB. I am just writing a talk for my local society and showing them how Registax and AS!4 both handle a 10GB video file… AS!4 does all the processing in 2 minutes, whilst RegiStax has only aligned 7% of the frames at 25 minutes, and has yet to limit them, and stack them…

I will have to look what the file size is for the lowest compression DSLR video at 60fps.

James

[Dawson]

Alex, yes, a number of stills in RAW with the added dynamic range is also a good option. Thanks.

[Dawson]

I learnt that Canon has a live chat function. I asked them. This is the answer I got:

“In general when changing resolutions the camera uses the data from the sensor to interpolate the resolution, this is done by merging and binning pixels to record lower resolutions on the camera so it will still show the same aspect ratio at different resolutions”

If it is binning, with the sensor 5184×3456 (18MP) to get 1920×1280 (Full HD), there would be roughly 3×3 binning (effective pixel size 12.9um), for 1280×720 (HD) there would be roughly 4×4 binning (effective pixel size 17.2um), and to get 640×480 (SD) would be roughly 7×7 binning (effective pixel size 30um).

Maximum fps for video is 30fps for Full HD and SD, and 60fps for HD.

Therefore, using a 2x Powermate on his C11 with his 700D camera in 1280×720 mode with least compression, that gives him 0.63″ per [effective] pixel amd 60 fps. Sounds reasonable. Given the compression, he’s likely better off with a dedicated planetary camera, but interesting exercise to figure out what the DSLR does.

James

[Dawson]

An interesting film. Thank you.

[Dawson]

I’ve had a useful email conversation with a technical person at Lunt. This is a summary of their suggestions which I have yet to try asI’ve not had time nor a clear day! It has a new blue filter in which I replcaed before the April 2024 total solar eclipse.

Now, may I ask with the double stack removed, do you also experience such views? It is certainly true that a double stack can really make your image extra special but if not tuned correctly, can also consistently be at odds with the primary etalon.

What I might recommend here, might seem like a step backwards. When I test double stack units, for the LS50THa or otherwise, I of course start with my scope in single stack mode. I tune and adjust until I am at the best point, and then I introduce the double stack. From there, I make sure my double stack is at rest (that is, no tilt introduced through the tuning wheel) and begin to tune from there. There are times when double stacks need a little something else. If I was testing your LS50THa, with this LS50c, the first thing I might do is go through the entire range on the LS50c that is attached and find my absolute best view while tuning that (after having tuned the primary without the double stack attached). If my field is much like your picture, my next thing I do, is to attempt to retune the primary etalon. At times, a little adjustment on the primary can really go a long way to making the double stack image what I would like it to be. From there, I would lastly try rotation of the double stack unit itself. This may seem the most precarious, but of course you have multiple threads securing it, and you wont need to during any more rotation than the initial 360 degrees, as anything past the first complete turn will put you at the same physical position in terms of lens tilt, but with just less thread to hold the filter onto the telescope.

Very often, customers who are experiencing a lack in quality views with their double stacks will find some relief between these suggestions.

Lastly, I am uncertain how old your telescope may be- but have you checked the BG (Blue glass) optic in your blocking filter as of late? This would be the blue glass element found under the nose tube that is introduced into your focuser. It should be perfectly clear, and without occlusion. Some of our older scopes have an uncoated version of the BG, while the new ones have a coated version. In either case, it should be 100% clear.

[Author]

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