Planetary imaging - 200P + ASi120MM + 2.5powermate or ED3x

[Fordos Moon]

I dabbled quite successfully imaging Jupiter last month with my 200P, ASi and 2.5x powermate.

Speaking to a chap in the business at the weekend he suggested a £30 ED3x barlow would be better than the powermate I paid £100 for.

Is he right?

Here are a couple of my images I managed using the powermate:

With hindsight I need to take it a little easy on my wavelets but this game is one big learning curve isnt it?!

[oldpink]

very nice images, and nicely captured moons
the colour one seems a little heavy on the reds

[Fordos Moon]

very nice images, and nicely captured moons

the colour one seems a little heavy on the reds

Couldnt agree more! Was one of the images that has made me realise my laptop screen must wash out reds as it looked well balanced on there!

[leelee970]

maybe he wanted your powermate

[Fordos Moon]

maybe he wanted your powermate

lol that made me chuckle!!

[michael.h.f.wilkinson]

Maybe he wanted more image scale (the ASI120 can take a bit more than the F/15 you are using now). A 3x Meade TeleXtender (now sold as Bresser SA Barlow 3x) is better in that case. I use my ASI120MC at F/ 20 or F/25 on Jupiter regularly (and even F/30 on Mars), so F/18 should be OK.

[Fordos Moon]

Maybe he wanted more image scale (the ASI120 can take a bit more than the F/15 you are using now). A 3x Meade TeleXtender (now sold as Bresser SA Barlow 3x) is better in that case. I use my ASI120MC at F/ 20 or F/25 on Jupiter regularly (and even F/30 on Mars), so F/18 should be OK.

Many thanks Michael, i have felt the 2.5x wasnt giving me the scale i desired and the 5x would be too much. Sounds like the Bresser SA Barlow 3x is what i need. So would i still need the powermate for anything I wonder?!

[michael.h.f.wilkinson]

Saturn takes less magnification, I find, due to the lower surface brightness. It could still be useful in that case.

[alcol620]

Can someone explain in simple terms the references to the 120MC at F/15, F/20 etc?

[Andy Milner]

I'm also a 200p owner. I'm considering buying a powermate. And was wondering if I would be okay with a 4x powermate? I'm certain the 5x maybe too high.

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[oldpink]

I tried a revelation 5X on my 200 and it was not very good, I think it was pushing the telescope past its limit
A 3 or 4X is probably better suited esp for Jupiter

alcol

the higher the F number the slower the scope becomes meaning more time / longer exposure rate needed to capture the same amount of light

though as said the ASI can be used at some high F ratio's, the scope its self is normally the limiting factor not the camera

as its only able to capture the light coming in

[alcol620]

Hi oldpink

Thanks for that. Just ordered the 120mc for use with my Celestron 8se any advice welcome regarding settings and best capture software.

Only just started this astroastronomy lark and the children are having to go hungry!!!

[oldpink]

for capture software try Firecapture or Sharpcap 2
you should also get PIPP to pre process the captures then Registax to process the images

[NGEddie]

I use both the 2.5x and 5x powermate with the 200pds. Whilst not for every occasion, the 5x can be useful. the below image was taken with the 5x and 200pds (albeit with the DMK618) earlier this year.

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[alcol620]

NGEddie

What's the secret of finding the image when switching to the camera and 5x from the initial alignment eyepiece?

Alec

[Andy Milner]

NGEddie that's awesome. Being a 200p owner do you think if I just have enough cash fir one powermate. Should I plump for the 4x, as like you say the 5x is only useful in very good conditions. Or maybe a 2.5x. I already own a SW 3 element 3x barlow. I would like to improve the clarity for imaging.

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[oldpink]

NGEddie

What's the secret of finding the image when switching to the camera and 5x from the initial alignment eyepiece?

Alec

I normally start with an eye piece and center

swap to the camera its self with no Barlow and re center then add the barlow

use max ROI with histogram on  and fine tune as needed

also knowing your focus points with different configurations is a real help

I have marked my draw tube so when I swap I can set a very reasonable focus making finding the target easier

normally I just have to adjust the exposure to find the target

[alcol620]

Oldpink

use max ROI with histogram on  and fine tune as needed?

Can you explain a bit more re the above sentence. How do you set ROI to max and where do I turn on histogram and what does this show?

Apologies for my ignorance, a relative newbie

Thanks for your help

Alec

[oldpink]

in the capture software you can set the "Region of Interest" (ROI) in firecapture there is a Max ROI tick box at the top left of the capture window
Sharp cap IIRC has a dropdown box, select the largest area

the histogram shows how much light you are seeing, in firecapture there is a histogram button in the right hand side menu

if you are off target it will be very low and to the far left
when the target appears the histogram will show you have a light source by spreading to the right and the spikes rise
so even if you can't see the target on the screen you know you are close, then I scroll the image up & down / left to right
and the target is normally visible somewhere then I use the controller to center the target

[alcol620]

Thanks oldpink, very helpful.

Is there a histogram adjustment in Sharpcap. I have looked at running firecapture, but it seems very complicated with lots of settings etc so I have continued to use Sharpcap.

[NGEddie]

Thanks for the comments. I can't comment on the 4x as I haven't used it, but ill probably hold out for the 5x. Both my 2.5x and 5x were purchased second hand on astrobuy/sell and seem to appear relatively frequently or around £100 mark.

I have to admit, with the long focal length and small sensor size, i do spend more time trying to find the object than i do actually imaging it. It certainly helps having at least a rough focus, I just ensure that my Telrad is as accurate as possible, then just move the scope (via the pc) in a scanning type way until it appears on the screen. Upping the gamma/brightness helps as you will likely see some moons first

I use firecapture.

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[oldpink]

Thanks oldpink, very helpful.

Is there a histogram adjustment in Sharpcap. I have looked at running firecapture, but it seems very complicated with lots of settings etc so I have continued to use Sharpcap.

to turn on the histogram in sharp cap there is an icon just next to the zoom setting on the top tool bar

click on that and the histogram comes up at the bottom of the screen

[alcol620]

Thanks oldpink. I see it now. Will try at next viewing, whenever that is!!

Thanks again

[oldpink]

if you use EQMod it has a spiral search mode that I use occasionally

its particularly handy if you are using a Xbox controller as I do

first get centered with a lens then swap to the camera bring up the software and turn on histogram
hit the button and the scope will move in a stepped spiral motion going out from your current center spot
just keep holding the button till the target comes in to the screen

as said turn up the gain so your target appears very bright making it easier to find, then back off the gain & exposure

till the histogram is about 75% and you should be good to go

[alcol620]

Thanks oldpink, but this gets a bit advanced for me at this stage.