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Old 16-03-2017, 09:47 PM
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BarneyMaroon (Tony)
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Advice on set-up

I swore I would not get into AP, but loving photography and astronomy it did not take that long for me to buy a T-ring. I have not gone into boots-and-all, and am just using gear that I have.

Travelling scope Skywatcher 400mm focal length ST80. 2xBarlow (so the moon is full shot), extender tube (to achieve focus).
Used as prime focus lens on Olympus EM5 Micro 4/3
I took the attached shot. 1/320 and ISO400.

I would appreciate some advice on the following questions. Thanks in advance to helpful folk on iceinspace.

1. If I wanted to make it sharper would I by an ED80 or start taking more images and stacking them together.?


2. I tried prime focus on my Meade 8'' (about 1 hour after moon rise), and frankly it was not any sharper. It was poor seeing. Should I expect sharper moon shots from the Meade?

3. I bought a tube while allows me to put an EP between the camera and scope. I have tried these with the SW ST80 and not been super impressed (possibly no better than cropping a prime focus shot). In this case I would have used Vixen LV 15mm and 25mm EPs. Is this because it is basically a dumb idea? Or I need a different set-up to do this? Or should I keep trying?

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  #2  
Old 16-03-2017, 09:59 PM
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Shiraz (Ray)
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sorry, you're hooked

that result is good. In good seeing the 8 inch will be better.

with either scope, you will be able to get better resolution by taking numerous short exposure images and stacking them in AS!2 or Registax.

with that camera you should aim for up to f20 in really good conditions and to get as close-up as possible, so the Meade with your Barlow would be about optimum for maximum resolution. You will quickly run out of resolution with any 80mm scope, so an ED may not be much advantage if you want close-ups.
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Old 17-03-2017, 08:36 AM
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ZeroID (Brent)
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Lunar and planetary are usually shot in movie mode, many frames stacked to get over the seeing turbulence. Planets and the moon of course are quite bright objects so no need for long exposure imaging. High frame rates grab those instances of stable air and in stacking you can reject poor images and stack the best to get good pix. 500 + frames is good normally.
Check air stability by watching the moon at high mag through your scope, it wobbles like a jelly sometimes.

Oh Yeh, and sorry, you're hooked as Ray says ... no going back now.
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Old 17-03-2017, 09:53 AM
glend (Glen)
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The ST80 is an achromat type refractor, and has significant chromatic aberation (CA). This results in an offset or fringing of some colours. So yes a scope like an ED80, which gives truer colour rendition will appear sharper as the colors are aligned so to speak.
Secondly, an AZ mount is ok for very short exposures of bright objects like the Moon, but for long exposure photos you will eventually need a tracking mount, like an equatorial (EQ).
Stacking and processing are another aspect of astrophotography but i would suggest you concentrate on getting some good well focused single exposures before you get into the complexities. Focusing is important, and if your camera has Liveview this helps, but a focus mask guves you a prismatic pattern that allows you to get it perfect.
Have fun.
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Old 17-03-2017, 01:35 PM
Mickoid (Michael)
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Tony, nothing really wrong with your moon shot. Considering it is a single shot , you just have to be lucky to capture an image while the atmospheric turbulence is minimal. That's why, as suggested, you capture some video footage which enables a choice of frames during a period of better seeing. The free software you can download will sort out the best video frames and stack them. After adjustments to the stacked image you will get a sharper result. I expect the fact you shot the moon at a lower altitude with the 8 inch Meade explains why it looked no better than the ST80. It should give better results than the refractor, provided it is well collminated. The CA on the ST80 isn't too bad really, I see a hint of purple fringing on the edges but it's quite acceptable. I have the 100mm version of this scope and have done some nice lunar photography with it but that was using the video feature of my camera. I have even done some planetary work with it using the eyepiece projection method. Just keep trying and experimenting, read lots and research the details used for other people's astrophotos and you will soon shoot great photos yourself. Good luck.
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Old 17-03-2017, 04:17 PM
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BarneyMaroon (Tony)
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Thanks

Thanks for your comments everyone. Good to hear I can do a fair bit of useful work before I need to head out and buy an ed80 and/or an Eq mount.

I have taken some cool pictures of Kookaburra's sitting on distant poles as well. Some photographers seem to use the set up (with triplets and ed80's) to take some razor sharp pics of birds as well.

I have some poor but enticing images of the Great Orion Nebula - learning that is hard to get the colour nebula and not have star trails. Surely need to track to do this.

I have tried once to polar align the alt-az Meade. Terrible job first go, but I will have a crack at drift alignment. I bought the scope with a home made fixed wedge (set for the Gold Coast), so I suspect I won't get super long exposures in Brisbane on it.
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Old 21-03-2017, 11:04 AM
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ZeroID (Brent)
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Another option is to get some Baader Solar film, make up a front filter for the scope and try some sunspot pix. The film will make the scope monochromatic regardless so fringing ain't a problem. Movie mode again for solar imaging. You won't see flares etc, you need to spend heaps on etalons and stuff for that but sunspots is good target and you can still get a good nights sleep !!
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