[Quark (Trevor)]

Originally Posted by Dennis

Hi Trevor

Excellent experimentation and what results! The image scale certainly is huge and it will be interesting to see what you get when the seeing is better. Good luck with chasing down those infuriating spots – so many optical surfaces to check!

Cheers

Dennis

Thanks Dennis, looks like it may be to much image scale, it created a lot of problems with processing. I was unable to use ninox which caused further problems for Registax.

Originally Posted by Lester

Wow Trevor, that is huge. The second image is showing a slight improvement in seeing, being sharper than the other two.

Its been so long since I have been able to get Jupiter, so thanks for the update with your images.

Yes, this has been the worst run with the weather that we have had for a long time. Not sure if the 5x powermate will be a viable proposition for my scope and imaging setup.

Originally Posted by bird

Trevor, I replied to your message directly. I think you're trying for too large an image scale here. It's worth working out how many pixels per arc second there are in these images, somewhere around 10 pixels per arc second should be fine, so a 40" Jupiter that measures 400 pixels across the equator should be ok.

At a guess I'd say your image here is about 550 pixels across the equator, so to get Jupiter at about 400 pixels across you'd need to be using a 5x instead.

Of course, that's a difficult value for you to reach, a 4x powermate loses power slightly as you get further away from it, so it can never get to 5x, and the 5x that you're using now almost invariably ends up at least 6x or 6.5x even if you get as close to it as possible.

Just a thought, but maybe try to add a 1.3 or 1.5x focal reducer in train with the 5x powermate, that could get you a bit closer to a 400 pixel size. A smaller jupiter also means it's brighter, so you can use shorter exposures and pick up more detail :-)

Or you could change cameras, and get one with 7.4u pixels like my Dragonfly2 :-)

cheers, Bird

Thanks for the advice Anthony, I am following up on another option that may better optimize my system. Have been looking at the spec's graph for the Televue 3x Barlow. I am stuck with the distance provided by my filter wheel to the chip in my DMK being 70mm, I have very accurately measured this. I note that the Televue 3x Barlow will give me 4.5X with the 70mm of my setup and if I extend that another 30mm it will give me 5x. What are your thoughts on this?

Originally Posted by Paul Haese

Have to agree with Anthony here, your image scale is a bit too large. I have tried this several times myself with a 3x instead of the trusty 2 x on the C14. Although Anthony you got it wrong about the 4x powermate. It actually increases but very slightly. See below

http://www.televue.com/engine/page.asp?ID=42

Thanks Paul, wondered also, what your thoughts are on going to the 3x Televue Barlow, given that it will work at 4.5x with my setup and with a 30mm extension would go to 5x?

Originally Posted by bird

oh yeah, I was thinking of the 2.5x. Anyhow, I remembered that the 4x doesn't change much...

cheers, Bird

I was aware of the spec's for the 4x Powermate, initially that is what I ordered but I changed my mind and got the 5x instead, probably the wrong decision.