Captured 33 avi's between midnight and 3:30 am CST.
This was the first time I have used my new 5x Powermate and the image scale is incredible. With my filter wheel in place the distance between the top of the powermate and the surface of the CCD chip in my DMK results in the powermate working at 7x.
The relative image scale produced by my 16" F4.5 Newt is generally very good and in this instance, enormous. Jupiter will not fit on the CCD chip with both of the poles slightly clipped.
This was trial and error to work out what settings worked best with this setup. My raw data looked promising, although the seeing would have to be very good to do justice to this much magnification.
These images were captured with the seeing being fair about 5 to 6 / 10 and are pretty ordinary but I can see the potential of this setup.
I cannot wait to have a crack at Saturn next year and Mars later this year.
There are some spots in these images that, initially, I thought was dust on my CCD. Before packing up this morning I gently rotated the DMK and as the image rotated the spots stayed in the same places on my screen. The spots are on all of my avi's and in the same positions regardless of which filter is in position, so there cannot be on the CCD or on the filters in the filter wheel. I am thinking they must be on the powermate, but it is brand new and looks clean as.
As this really was just a test of my setup and as the image fills the frame, I have not labeled them. However South is up and West is to the right.
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!
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 :-)
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
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.
Quote:
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.
Quote:
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?
Quote:
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
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?
Quote:
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.
Last edited by Quark; 08-07-2009 at 11:45 AM.
Reason: grammer
Yep 3x is more likely the best solution to this problem. I use the 2x regularly, with the filter wheel acting as an extension and this gives me very large image scales. The 3x with your native focal length would be fine and get you up to near 4x meaning a focal length of 7315mm. With a small extension you could get it up near 10,000mm. I could loan you a 3x to see if this will work and it not at least you would know without spend more money than necessary.
Yep 3x is more likely the best solution to this problem. I use the 2x regularly, with the filter wheel acting as an extension and this gives me very large image scales. The 3x with your native focal length would be fine and get you up to near 4x meaning a focal length of 7315mm. With a small extension you could get it up near 10,000mm. I could loan you a 3x to see if this will work and it not at least you would know without spend more money than necessary.
Thanks very much for the offer Paul, I really do appreciate it, however this afternoon I rang Micheal at Bintel and he is quite willing to let me change the 5x powermate for a 3x TV barlow. Looking at the Televue data graph for the 3x at 70mm from the top surface of the barlow it is producing 4.5x add another 30mm and it delivers 5x. My filter wheel and DMK give me spot on 70mm from the chip to the top surface of the barlow. The FL of my scope is 1,827mm, with my DMK and filter wheel on the 3x TV barlow at 4.5x my FL would become 8,221mm and if I turn up a 30mm extension with my lathe, at 5x my FL would be 9,135mm. It looks like this will be the best way to optimize the DMK for my optical system.
I see on the TV that the Clayton weir is being built. When completed we will be able to cruise down to Clayton with our boat which hasn't been out of the storage shed at The Marina H. I. since Oct 2007. Will have to catch up with you some time.
Quote:
Originally Posted by bird
Trevor, the 3x TV sounds like a good option if you can get it up to 4.5x.
I think it's also a 3 element barlow (from memory) so one less lens than the 4 element powermates, a slight plus.
cheers, Bird
Thanks Anthony, checking the data sheet for the TV barlows it seems there are only 2 elements in them, have attached the Televue data graph, the 3x TV does seem to offer the best solution for my needs. It would be great to upgrade my CCD but the upgrade is not really within my means at this stage. I wonder why Al Nagler has not put out a 3x Powermate.
