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DSO Imaging on a budget


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This is a very old post so inevitably has become somewhat out of date.  8 bit modified webcams are obsolete although there is no reason why a cheap guide camera can't be used for basic deep sky imaging.  I believe K3CCDTools is still available but newer software such as SharpCap and FireCap may now be a better bet.  Older highly capable DSLRs are now incredibly cheap second hand.  Short focal length achromatic refractors in conjunction with a colour filter continue to be a very cost effective way to get into deep sky imaging.  For image processing on a budget Gimp is the goto choice, it has all the features you need with lots of support available online.

Hartmann masks have now been replaced by Bahtinov masks

Otherwise, I believe that most of what is written below remains relevant today.

MartinB 04/02/2021

 

With the starting price of decent CCDs at over £1000, apo refractors, mounts the price of a small car, not to mention a micosoft office block's worth of software it is easy to think Astroimaging is for the wealthy, the reckless or quite probably both. Well it isn't!!!

The expensive kit is definitely pushing the boundaries of what can be achieved by amateurs but excellent results can be achieved with very reasonably priced kit. The trouble is that imaging is hard, there's just no getting away from it. It's one thing placing a camera at the eyepiece, focussing and producing an image of M42 (great fun though that is), quite another to produce detailed images with good signal to noise ratio. This requires an understanding of the target, the equipment, capturing techniques and processing.

The fact is that very few people reach the limit of what their existing equipment is capable of. Have a look at Roger Warner's (Celescope) Atik 2HS images. Admittedly these were taken on a very nice Nexstar GPS scope but similar results can be achieved with a small refractor on a relatively light motorised mount. Roger worked and worked on capturing and processing these images, learning to squeeze out every last photon from that camera.

If you have a scope which can be brought to a focal length of 1000 or less and a motorised mount with enough weight to carry it you are laughing. You then need either a DSLR or a modded webcam such as an SC3/atik 2HS etc. Afocal imaging (through the EP) is always going to be fraught with problems and adds a whole lot of extra difficulty. OK for 1st images but not recommended long term A laptop is necessary for a web cam and desirable for DSLR - but they certainly don't need to be state of the art. A cheap second hand model will do. Goto is a luxury you can manage without.

Here is a cheap set up which will provide great results on a budget. An achromat short focal length 80mm refractor (around F6 say - £50 second hand). To avoid chromatic aberration you need a green filter - this will remove light pollution as well but does increase exposure time slightly (but you have a fast scope). You can pay more of course and get a second hand ED80 which will deliver some improvements (£200 second hand). A motorised EQ3 will do, again second hand but better still would be a second hand CG5 or even better, one of the Vixen Polaris mounts. At the lower end of the range you should be able to find something for around £150.

If you have a DSLR you are away. Although there must be a lovely sense of freedom with a DSLR being freed from the need to link up with a laptop, my impression is that ultimately a laptop and some capture sofware will make the whole process easier. There is some excellent software available at around £100 but that might be out of budget at the mo.

The alternative to a DSLR is a modded web cam. These have a much smaller chip and need a laptop. However they work with some great free software called K3CCDtools, the chip is very sensitive and has small pixels providing excellent resolution. You can use focal reducers without introducing vignetting which can give you 2 or 3 scopes in one. For around £25 you can pick up a 0.5 reducer designed specially for web cams. You can often find a second hand Atik 2HS for around £200 and are highly recommended.

The beauty of a light, short focal length refractor with a modded web cam is that you have a wide field view which is great for a small chip, there is little weight on the mount, it is very forgiving of tracking and other errors allowing long, unguided exposures.

K3CCDTools will stack your images or DSLR users can use Deep Sky Stacker which is also free. Registax also does a good job. You don't need to pay a fortune for processing software. Many of the budget packages will do a good job for you. Ideally you should have something with the "curves" tool to allow proper stretching of the histogram. Unfortunately this isn't provided in photoshop elements but others do have it I believe.

You will then need the usual extras - a red dot finder gets you in the right area and a nice wide field EP will often work better than a finder scope with a small refractor. Later on you can build your system as finances permit - you might want to collect some RGB filters and maybe a narrow band Ha filter for emission nebulae.

Do your homework - get slicker with your set up esp a good polar alignment routine, make sure your mount is performing at it's best - strip down and regrease if necessary. Understand the characteristics of you mount and how long it can go without tracking errors appearing. Work hard on your focussing skills - you might want to make a hartmann mask.

If you want to be serious about imaging you have to be serious about exposure times. 7x30 seconds = grainy images without much detail. You should be aiming for at least an hour on most targets. With the above set up you should be able to track unguided for 1 minute so 60 sub exposures should give you something to be proud of.

If you buy wisely second hand you can be up and running for under £500. You also have a modest visual set up for grab and go.

Like I said, it's not easy but it doesn't have to be that expensive. Be warned though, you can get hooked very easily. Then your idea of how much spending is justified changes quickly, welcome to the club!!

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That is a great post Martin, and I am sure it will give inspiration to quite a few "would like to partake" potentials.

Some people down the line are going to be grateful to you for writing those words.

Ron. :D

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  • 1 month later...
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  • 1 year later...

I'm afraid I can't offer any advice on DSLRs since I've never used one. It does need updating a little since budget astro cams have moved on from modded web cams. I could certainly point out that there is a lot of support packages out there for DSLRs.

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  • 7 months later...

Nice post Martin, what's your impression, or anyone else for that matter on the Meade LPI ccd imager for around £80 for someone who wants to start off cheap and progress to a more expensive ccd later? or is it in fact a glorified web cam with some additional controlling software?

Regards

Keithp

Edited by Keithp
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Just to add a couple of pennies worth to this.. You can, using a short tube Achro mounted on something teeny like a NexStar SLT mount, and be willing to capture enough subs, produce some good results. I've had tracking up to 2 minutes in AltAz but didn't commonly go that long.

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  • 1 year later...

KeithP - I've had much fun with my Meade LPI for lunar and Saturn images. It is what it says though - a lunar planetary imager. All but useless for Deep Sky imaging with a maximum exposure time of 15 seconds and very noisy subs at that.

I'm now most definately down the DSLR route. As much as I'd like a dedicated Astro CCD the price is far too rich for me. My Canon 1000D cost £400 inclusing the 18-55mm lense. I've not had it modded. A useful point to add to MartinB's excellent thread is that the more recent Canons including the 1000D come with excellent bundled software which is perfectly good for DSO work. The live preview is useful when getting focus and the software can be set to take a chosen number of images at a chosen exposure length. Most settings can be adjusted on the camera from within the software.

I've put my rig together over the last 18 months for DSO work and I reckon it probably cost about £1500 in total. This is for an 8" newt, CG5 GT mount, Skywatcher 80mm Star travel, Canon 1000D, power tank, LP clip filter and laptop computer plus various cables and bits and pieces. Hunting round for second hand stuff will cut this price tag down considerably.

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  • 4 months later...

The post is showing it's age a little with it's focus on 8bit webcam images but is still relevant given that people often start on solar system imaging and may want to extend use of their camera into DSO work. Not everyone has a DSLR!

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Martin, maybe worth adding to it now, as the older DSLR's are getting seriously cheap and definitely offer a budget route into DSO imaging. With a little patience, it's possible to pickup a 300D for the price most people are asking for a SPC900NC.

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Good info thanks

As a "Daylight photographer" night work has always been interesting, a whole new field of picture to take. SLR & DSLR several lenses, a study tripod, whole buckets of patience (well sometimes not) has produced some nice images (sometimes NOT).

Next step - Telescope, but as with any new field of gagetry lots of reading first before the wallet comes out.

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Astro imaging (like any other part of astronomy) can be as cheap or as expensive as you can afford.

The main thing with all aspects of astronomy (or ANY hobby) is no matter what budget you have that you enjoy it and are proud of what you achieve......be it visual or imaging.

Never forget that some GREAT images have been captured by very low cost methods.

Make the most of the gear you have. Do not try to "keep up with the Jones'" just for the sake of it.

Exploit your gear to the MAX.

If then you are still not happy...............by all means upgrade.

Edited by LukeSkywatcher
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  • 1 month later...

I bet a good start is getting a mount and putting a DSLR on it and only later you buy a scope you like. That would be the cheapest way in. I was almost taking this path but found a deal on scope I couldnt resist :)

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Well, if you will work hard you can even catch exoplanet transiting a star with a DMK and a 60 mm refractor. And you don't have to use "serious" exposure times to catch a lot of DS objects. 8-bit planetary/lunary cameras have insane gain compared to 16-bit DS cameras and allow catching DS objects at short exposures. If you catch a lot of frames - then the image won't be bad... but you will also have to process the image more (educating imaging :D)

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