Glasspusher

Amazing images, well done!

John

Excellent images, well done!

Thanks for that explanation of your technique David.

John

Very interesting post David.  I have never attempted a Schmidt corrector plate, you make it sound very straight forward.

John

Nice images, good to see you posting again Neil.

Hi Graham, nice image. Bear in mind that most glass lenses absorb in the UV, so not ideal for imaging Venus in the UV.

John

The telescope was hired from Athos, La Palma.  Try a google search! Hope you mange to find something that meets your requirements.

Sadly, my last imaging session with the cpc 9.25 here on La Palma, could not resist a stab at Uranus, not too much details to report!!!!

John

Sadly, my last imaging session with the cpc 9.25 here on La Palma. After some poor seeing things improved a little this morning. Best 30% of 180 sec video at F20 with ASI244 colour camera. Been a good few years since I did planetary imaging, I feel like a beginner again!!

John

Thanks for the advice and comments, appreciated!

Thanks Craig. Been here a few days now and the seeing is very variable, last night was particularly bad so no imaging possible. Winjupos is something I need to catch up with, I am just coming back to planetary imaging after a break!

Re-posted the image so it can be seen without having to download!

Thanks Craig

Not sure why the image is not showing and needs to be downloaded to view! Can anyone enlighten me please? Thanks.

Another from La Palma.  Celestron CPC 9.25, ASI244 camera best 30% from 180 sec video. Processed with Astrostakkert and Registax. I have learned that using an altaz mount for planetary imaging is not without its problems, nonetheless quite pleased with the result!

Jupiter 091122.bmp

Neil, your wonderful planetary images have inspired me to have a go!

Lucky enough to be on holiday in La Palma and hired a Celestron CPC 9.25. Here is Saturn from last night at around F30! Been a good while since I did any planetary imaging so back on the learning curve and enjoying it!

John

saturn crop.bmp

Thanks for that, I will add this during my next update.

John

Thanks for that. Hopefully the changes I have made will enable those documents to be seen by all.

John

OK, hopefully that problem is now fixed and the site should be visible. Please let me know if you can see it now, thanks.

John

Sorry about the 404 error, not sure what is going on. I will look into it.

John

Back in 2011 I set up a web site to raise awareness about the great British telescope making firm of Sir Howard Grubb Parsons and Co., usually referred to simply as Grubbs. David Sinden was the last chief optician at the firm, and went on to set up his own business, the Sinden Optical company. My web site covers the work of both Grubbs and David Sinden. The original site was setup using Google sites. Since then Google have seen fit to improve there online web site  facilities. Web sites produced using the old format would be done away with unless migrated to the new format sites. Unfortunately during the migration of my site some information was lost. I am working to re-build the web site and add new information.

Those interested in the work of Grubbs and David Sinden can find the web site here: https://sites.google.com/site/grubbparsons/home

If any body has any relevant memories or information which they would like to include on the web site it would be most welcome.

Thanks for looking.

John

When using a sub-diameter tool for fine grinding it is normal to work the tool off-centre in order to give an even grind. From the video it looks like your stroke is through the centre which will give preferential grinding to the central regions at the expense of the edge. The tool also looks a little small,  the standard is around 75-80% the diameter of the main mirror.

Hope this helps.

John

Thanks for posting the video, interesting. From what I can see the tool is not free to rotate during the grinding process which it should be. Also to help with controlling astigmatism a larger grinding/polishing tool is advisable, probably around 80% the diameter of the mirror and best used in a 'spin' grinding mode. Hope this helps.

John

Hi Robin,

The spectrum was taken on Monday 30/11/20 at about 8.45pm. Thanks for the links, weather permitting I will take more images in the future!

John