Barlow and reducers, pushing my camera to the max ASI120mc

[oldpink]

having finally got all my [removed word] together and finally getting images I can work with
I'm wondering how far I can push my current setup

first up lunar

I got some decent shots of the moon yesterday but was surprised that with no magnification I was only seeing part of the moon
seems I over estimated the view I would have

I doubt a reducer would help as it would need to be a big reduction factor
I'm thinking I can use my main cover with the 2" hole opened to resolve this (due to weather I didn't have time to test this theory)

though I do understand I will reduce the light gathered so loose out on detail

next up

if I Barlow up using my bog standard X2 Sky watcher will I just flood the screen with light
i'm interested in close ups  to make mosaic's so I think a moon filter is in order, advice on that appreciated

next planets

I've been following a thread in the Camera discussion on the ASI120mc and seeing some stunning images
esp of Jupiter
I get a fuzzy blob in the camera, though with my 28mm & 10mm I can make out the moons and distinct bands
my Barlow brings out more detail and reasonably good viewing with the moons quite sharp
on the camera I get a bigger image but more fuzzy, I've managed to get Firecapture & sharp cap down to low ROI's and getting 100+FPS captures

with no Barlow I get an image about double my 10mm barlowed from the cam alone

but never any real clarity and even after processing they are pretty Rubbish compared to what I'm seeing from similar equipment

also am I right in thinking that every step up on Barlow changes the F setting
no Barlow on my setup = f/5 (Skywatcher 200p) if I add the supplied x2 it becomes f/10
so a x3 would would be f/15 (relevant to the thread I'm following) as some people are finding issues beyond f/15 but others go to f/25 (X5 barlow)

in effect giving me Jupiter at x5 times the size I see it with just my camera

or am I pushing it too far

I will add all my viewings are so far from a fairly light polluted area, I plan on going to Galloway forest soon to do some serious
dark sky observations to see how they match up to my current situation
 I suspect the dark sky will make a serious difference to what I can get just now, even seeing Orion's belt with the naked eye is difficult
 

I'm also interested in DSO's but plan to buy a modded canon D600 for that (50th birthday in a months time)

this has been modded to do cropping and x3 - 10 zoom at 30FPS and software override
to allow planetary work as well as the full astro mod

so many questions
appreciate any replys
 

picture took using x2 barlow edited in AS!2 and wavelets in registax

[Langy]

Can't help with much but if you use the 2" hole in the lens cap then you will reduce light not the focal length. Therefore same image size but less quality. You will need to reduce the image size with a reducer or get the chip closer to the projected image.

first up lunar

I got some decent shots of the moon yesterday but was surprised that with no magnification I was only seeing part of the moon
seems I over estimated the view I would have

I doubt a reducer would help as it would need to be a big reduction factor
I'm thinking I can use my main cover with the 2" hole opened to resolve this (due to weather I didn't have time to test this theory)

though I do understand I will reduce the light gathered so loose out on detail

On your planets you may find it's just a focusing issue, it's not easy through a camera to focus.

I'me sure the wiser people on here will correct e if wrong and certainly add to your other questions.

[JamesF]

The 200P has a focal length of one metre, so the size of the Moon at the image plane is going to be about 9.5mm across.  The 120MC sensor on the shortest side is only about 3.6mm across.  You'd need some fearsome reduction, or mosaics, or a DSLR

If you're going for mosaics, leave the barlow out for the time being.  You'll just make life more difficult for yourself.

You're correct about the f-ratio and how it changes with barlows.  f/20 to f/25 would be fine with this camera and scope.

Getting focus takes time to learn.  It's not easy.  Once you have it right what you see may still look a bit fuzzy but after stacking and sharpening a few thousand frames you'd be surprised at the improvement.  What I tend to do is set the exposure time to get the frame rate I want, then set the gain to give a histogram about 65% of the way across.  Some mucking about with the red and blue balance may also be required.  It's all about practice though.  Expect to throw a huge amount of data away before you feel as though you're really getting somewhere.  It is not easy.

James

[oldpink]

jamesF I really appreciate your input

your pictures are the ones I was talking about
I'd be interested to know what software you use and at what settings
I tend to go with low exposure and high frame rate with a narrow ROI

when it comes to post editing I have just found autostak as well as using it in conjunction with registack
so have a big learning curve
I'm more interested in the capture settings as I feel that is where I am loosing out on capturing detail

[jambouk]

That image us far from just a fuzzy blob, it is quite good and an excellent starting point.

JamesF is your man.

I agree with the advice he's given you so far.

The two things i'd add in are focus and seeing.

If when you look at Jupiter it looks like you are looking over the top of a hot radiator and there is lots of ripples in the air/image, then the seeing is poor; often caused i think by the jet stream being over head (http://www.netweather.tv/index.cgi?action=jetstream;sess%3D), or by more local factors such as looking out over a neighbours roof which is poorly insulated and the heating is flooding out of it through the air you are looking through. This will make your final image poorer than if the air in all layers of the atmosphere is more steady. Even on the clearest of clear nights the seeing can be awful.

Focus - this is hard to get right. But as jamesf suggests it takes time to sort out and if your data is out of focus, just bin it and learn from it. Different ways to focus are: use a bahtinov mask on a near by star; try and get the moons of jupiter as small and as sharp as possible; just try and focus on the body of jupiter.

With the moon, if you are unable to get it all on the sensor in one go, using a barlow will just make it worse. You could make a 9 pane mosaic of the moon from the sounds of things. Nine video captures making sure there is sufficient overlap; stack each, then crop off the black edges and load them all into microsoft ICE - hey presto, a pretty detailed lunar picture.

Good luck

Jd

[JamesF]

jamesF I really appreciate your input

your pictures are the ones I was talking about

I'd be interested to know what software you use and at what settings

I tend to go with low exposure and high frame rate with a narrow ROI

when it comes to post editing I have just found autostak as well as using it in conjunction with registack

so have a big learning curve

I'm more interested in the capture settings as I feel that is where I am loosing out on capturing detail

I use FireCapture (or my own capture program on Linux) for capture, then AutoStakkert and Registax.  I also have a motorised focuser which helps enormously.

The scopes I use for planetary imaging are very different from a 200P so I'm not at all sure the settings that I use would work for you.  What I'd do to start with is to set the exposure so you get, say, 30fps or thereabouts.  Then raise set the gain so the histogram is about 65% to 70% of the way across.  If that means the gain is very high then I'd go for longer exposures and lower gain.  It's a balancing act really.  Short exposures/high frame rate give dimmer images that are less affected by seeing, but increasing the gain to compensate for the shorter exposure time increases the amount of noise.

Keeping the ROI small will help with throughput, but can make tracking more difficult.

James

[oldpink]

thanks for the input
thats basically what I've been doing, I think I just need better viewing conditions

[JamesF]

The seeing down this end of the country has certainly been pretty poor this winter

James

[oldpink]

yeah been pretty Rubbish up here the last couple of weeks
I may try tonight just after sunset, I'll have the moon at a nice angle due south

weather is saying partly cloudy till 9 then cloudy

[Langy]

It's a very high haze out there now when the lower clouds clear.

[oldpink]

well in mixed viewing conditions and scope way off align as nothing to lock on to I got some results
even through cloud (low & high)

and getting better results as I get my head around the software and settings
I'm a sound engineer so I under stand a lot of principals of filters (light is just an extension of the frequency range to me)
I also work with lasers so I know about light frequency's

I'm finding mixing software and settings I can pull out some good results from what seems like a fuzz
so a lot of shooting images and trial and error seem to be the order of the day
and scrapping a lot of exposures when the cloud gets too much to deal with

anyway a couple from a very overcast Scotland tonight

basically the same file at two different settings to see what worked best

the moon shot was my S3 over the eyepiece on x28

[Langy]

The small Jupiter and moon are great images, especially with the conditions you have faced.

I'd be happy to get a good image like that in good conditions. Thanks for sharing.

[jambouk]

Yes the moon is very good.

Jd

[Pete Presland]

the seeing has been pretty shocking so far this year, keep persevering it will get better!

[JamesF]

The Moon image is looking good.  I think you might be struggling with the seeing for Jupiter.  Perhaps some time soon we'll get some nights with decent seeing.

James

[oldpink]

thanks for the encouraging words folks
yes seeing was way off last night but as long as I can see even a faint glimmer of light I'm out the door

hopefully some clear skies soon (well we can always live in hope)

[Macavity]

The asymmetry (egg-shaped-ness) of some of the Jupiter images should give more *hope*

than despondency? Was there some... source of "vibration" of the scope, during imaging?

Weather (WIND!) seems hardly conducive to planetary imaging? A lot of my time is / was spent battling poor focus and backlash (random wandering!) of my mount. Much of this is now FIXED? There is of course still the (astronomical) "Seeing"...

BUT we will see (sic)! Frankly a *lot* of things to get right? So many, I have been seduced (away from mono VIDEO astronomy) by the challenge of this camera (Save one for me!)... Jupiter... Planetary Imaging... etc.

Give me a month or so... Still buying [minor expletive] cables and interfaces for my "remote astronomy" project. <sigh> Jupiter should still be "there" though! Spring might have (gently) Sprung etc. etc.