Jupiter, Saturn, Mars 13/14th September

[Tommohawk]

First proper go at planetary imaging with my experimental scope. Its and F4 Quatro 250mm mirror mounted in a Flextube  with camera at prime focus - pic below. I think I will probably abandon this design because focusing is a nightmare. Almost impossible to motor focus, and manually focusing the helical focuser at the business end at F20 is challenging to put it mildly. I ended up using a Bahtinov with the powermate in place and then starhopping to the targets, correcting the position as I went. Bad pointing possibly due to cone error or maybe dodgy PA. Anyhow...

Jupiter and Saturn I can only see for about 30 mins when already somewhat past maximum elevation, so wasn't expecting too much. Jupiter was so woolly I reduced the image to 80%. Somehow seem to have captured Callisto shadow, though Stellarium shows Callisto itself in that position - puzzling. Mars I was quite happy with for a first effort, though hopefully there is more to come. Had work next day, so captured quite early at 36 deg. 

Seeing was amazing, even on Jupiter and Saturn. Omegon Velox 385C captured with Toupsky, 5x powermate, PIPP, AS3, bit of PS. Happy for any comments!

 

 

 

[CraigT82]

These are great Tom, I love the Mars especially. What an intereesting OTA, what prompted you to get rid of the secondary? 

[David J H]

I think your photos are very good. The clear skies yesterday gave excellent views of Jupiter, Saturn and Mars. I was able to identify Mars' polar icecap, using a 5mm eyepiece in a Vixen SP102M 4" refractor, and your photograph is very similar to what I was seeing. I was also able to identify Uranus (close to Mars) and Neptune (between Mars and Saturn) for the first time, although they were very small objects. 

[Tommohawk]

1 hour ago, CraigT82 said:

These are great Tom, I love the Mars especially. What an intereesting OTA, what prompted you to get rid of the secondary? 

Thanks Craig.

What I had in mind with this design was a wide aperture but short travel scope - this requires a fast mirror, and in turn that typically requires a larger secondary. Because planetary cameras are now relativity small - the Omegon has a diameter of 42mm I believe -  mounting one in place of the secondary is perfectly possible. Ultimately I was hoping for a 300mm aperture, maybe with a conic mirror, with some kind of truss or other dismantleable construction. Another plus with this design is that collimation is much simper. 

This scope has had the primary adapted so the collimation screws are linked via a toothed belt - the idea was to use this a focusing mechanism. It works, but because of tiny variations in the screw pitches, the target wanders too much off centre when focusing. So I fitted a helical focuser ... which  works but is impractical as I can find a way to motorize it. 

I think we discussed this sometime back on another thread, and the conclusion I came to is that although the principle is sound, the aberrations on a commercially available fast mirror are such that any advantage in the small CO is probably lost.  In addition, focusing is tricky. 

If anyone has any ideas on focuser design improvements I'm all ears! 

1 hour ago, David J H said:

I think your photos are very good. The clear skies yesterday gave excellent views of Jupiter, Saturn and Mars. I was able to identify Mars' polar icecap, using a 5mm eyepiece in a Vixen SP102M 4" refractor, and your photograph is very similar to what I was seeing. I was also able to identify Uranus (close to Mars) and Neptune (between Mars and Saturn) for the first time, although they were very small objects. 

Thanks David. I was too tired after the previous night at the scope and a day at work to have another late night last night! Good to  hear your observations match. I'll have another go when I'm not working next day.

[Aussie Dave]

Very nice Tom, that Mars is particularly good. I'd be very happy getting a result like that here in Australia.
I'll be tackling Mars in a couple of weeks, I haven't had a lot of luck with it.

[Tommohawk]

2 hours ago, Aussie Dave said:

Very nice Tom, that Mars is particularly good. I'd be very happy getting a result like that here in Australia.
I'll be tackling Mars in a couple of weeks, I haven't had a lot of luck with it.

Thanks Dave. My previous efforts at Mars have been pretty dismal, not sure what's different this time.

Good luck when you have a go!

 

Edited September 15, 2020 by Tommohawk

[morimarty]

A lovely set of images Tom and a very interesting scope set up you have too.