Clarification and tips please?

[Screwdriverone (Chris)]

Hi,

After seeing Gary's amazing shot of Saturn with his 6" scope, I wanted to ask some questions to clarify my situation please.

I currently use a digital camera adapter to "look" into my eyepiece and the results on the planets are not too flash. Certainly nowhere near what I would consider worthwhile. Especially with the amount of time it takes to get everything lined up.

I would like to get bigger shots with more resolution and I understand that by using a camera in "prime focus" the telescope becomes the camera's lens.

Does this mean that I have to have a camera that does not have a lens on it, ie an DSLR, or a webcam that is adapted or screwed into a dummy eyepiece/adapter so that the normal point of focussing is directly onto the CCD sensor of the camera?

If so, will this allow finer resolution of images or am I just barking mad to think I can get any better than some of the planet shots I already see?

With the afocal technique, things should be bigger by using the 3x optical zoom of the camera into the FOV, but it seems that I am blurring things by doing so. When I DONT use the zoom, the image I capture is SO small that no details can be made out?

When at the "house of temptation" (Andrews) I noticed a 32mm camera projection lens, would this help? I thought a 32mm lens would only then mean that with a 2.5x barlow, the magnification from my scope would be a measly 78x and people are saying I should try 200x and up for planets.

Any ideas on what to try to improve things with what I have? I cannot set any exposures above 4 secs on both cameras, and the only camera I have with a thread is the 37mm ring outside the zoom lens on the Kodak and I cant find anything as yet to fit this to something. The Kodak only has a dodgy 320X240 video mode as well

My scope is a catadioptric Newtonian which Lee Andrews told me effectively has a built in 2x barlow so that it can double the FL of the scope as it only has a 500mm length tube. Is this whats degrading my images at high mag?

PS. I dont have a laptop currently but I do have an old webcam I can "mod", but nothing as yet to plug it into. I am also computer literate so dont worry about getting too technical. Also, I have pretty much used all funds available buying silly things, at the moment so shopping is a bit out of the question for anything over $50.

Any tips great or small would be appreciated, sorry for the essay, I am yet to find a short way to ask a long question.

Thanks

Chris

[joshman (Josh)]

i personally haven't done any planetary imaging, but i understand that the secret is that because the object is so bright, you need a relatively short exposure time (shutter speed) on your camera. as i understand it, insanely large focal lengths (2300mm and the like) and coupled with a webcam, as well as good seeing and spot on focusing, are pretty much necessary for producing the stunning images that can be found around these forums. that being said, if you can somehow set your camera to have a shutter speed of around 1/60 to 1/200 of a second, then taking lots (and i mean lots!) of photos then stacking them in registax or similar program, yo might have some success.

so that gives you something to work towards, i hope,in the mean time, see what you can achieve with what you have! after all, necessity breeds invention!

good luck mate.

[[1ponders] (Paul)]

Chris you can do solar imaging (with suitable filter) and luna imaging and planetary imaging with your normal digital camera with afocal, though being able to remove the lens with a DSLR opens up a whole new world of digital possibilities. However even a DSLR is not really the best option for planetary imaging. See if you can find an old ToUcam 840 or 900 from somewhere and get the appropriate adapter. They will leave any still camera shot for dead once an avi is processed! With the ToUcam and 1.25" adapter you can then use your 2.5x barlow to increase your magnification. With Jupiter on a good night you could even try a 5x powermate though that might be pushing your scopes resolution just a bit.

Careful though. Once you enter the slippery road of successful astroimaging there is no going back

[sheeny (Al)]

G'Day Chris,

Originally Posted by Screwdriverone

Hi,

After seeing Gary's amazing shot of Saturn with his 6" scope, I wanted to ask some questions to clarify my situation please.

I currently use a digital camera adapter to "look" into my eyepiece and the results on the planets are not too flash. Certainly nowhere near what I would consider worthwhile. Especially with the amount of time it takes to get everything lined up.

I would like to get bigger shots with more resolution and I understand that by using a camera in "prime focus" the telescope becomes the camera's lens.

Does this mean that I have to have a camera that does not have a lens on it, ie an DSLR, or a webcam that is adapted or screwed into a dummy eyepiece/adapter so that the normal point of focussing is directly onto the CCD sensor of the camera?

Correct you will need a DSLR, astro camera or webcam with an EP adapter to do prime focus photography.

Prime focus will not necessarily be larger scale than what you achieve afocally. The scale at prime focus will be fixed dependign on your scope focal length and your camera's sensor size/pixel size. Afocally, you can increase scale by using a shorter FL EP, or using the zoom on your camera. I would recommend a shorter FL EP first.

Originally Posted by Screwdriverone

If so, will this allow finer resolution of images or am I just barking mad to think I can get any better than some of the planet shots I already see?

With the afocal technique, things should be bigger by using the 3x optical zoom of the camera into the FOV, but it seems that I am blurring things by doing so. When I DONT use the zoom, the image I capture is SO small that no details can be made out?

Ultimately the resolution of your images will depend on the pixel size of your camera for low magnifications, and the diameter of your scope at high magnifications. The aim in planetary imaging is usually to get the largest scale sharp image of the subject as possible so you aim for a magnification based on your scope's diameter so that the camera resolution and the scope are pretty much maxed out. Do a search on Dawes Limit and Raleigh Limit.

The problem with your zoom focus may be due to how your camera is focussing. If you can use manual focus on you camera, focus on infinity with manual focus, then do your final focus adjustments with the scope's focusser.

Originally Posted by Screwdriverone

When at the "house of temptation" (Andrews) I noticed a 32mm camera projection lens, would this help? I thought a 32mm lens would only then mean that with a 2.5x barlow, the magnification from my scope would be a measly 78x and people are saying I should try 200x and up for planets.

Yep. You will need shorter FL EP(s) and a good barlow/powermate.

Originally Posted by Screwdriverone

Any ideas on what to try to improve things with what I have? I cannot set any exposures above 4 secs on both cameras, and the only camera I have with a thread is the 37mm ring outside the zoom lens on the Kodak and I cant find anything as yet to fit this to something. The Kodak only has a dodgy 320X240 video mode as well

If your camera will capture AVI files, then keep playing, and process the AVI's in registax. There's plenty to learn just from that exercise. As you get better cameras, EPs and barlows, etc then your results will step up accordingly.

Originally Posted by Screwdriverone

My scope is a catadioptric Newtonian which Lee Andrews told me effectively has a built in 2x barlow so that it can double the FL of the scope as it only has a 500mm length tube. Is this whats degrading my images at high mag?

No.

Collimation is critical for hi-res imaging, as is focus. Mastering those is critical.

Originally Posted by Screwdriverone

PS. I dont have a laptop currently but I do have an old webcam I can "mod", but nothing as yet to plug it into. I am also computer literate so dont worry about getting too technical. Also, I have pretty much used all funds available buying silly things, at the moment so shopping is a bit out of the question for anything over $50.

Any tips great or small would be appreciated, sorry for the essay, I am yet to find a short way to ask a long question.

Thanks

Chris

Hope this helps.

Al.

[Screwdriverone (Chris)]

To Josh, Paul and Al,

Thanks guys, this gives me a lot to think about.

I may have to check the collimation on my scope, something in my images of the moon tells me there could be something wrong here.

A 32mm camera projection EP may be something I can play with as I have trouble lining up the image at high mag. This way I should be able to get in a bit closer with the zoom and preserve some sharp details. I will also try doing some stills rather than avi as I get 7MP with the stills and have seen better results that I should be able to stack. I am getting the hang of the stacking process too.

I will do some testing and hopefully post some better quality planet shots soon.

Thanks again.