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Do you need a DSLR Camera?


lw2689

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Sounds silly really but is there a cheaper alternative? If i was to buy a DSLR doubt i would use it for anything other than with my scope. Ive seen imagers, which to me look like webcams...but are a fraction of the price. Anyone recommend any?

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I have a 350d which is quite old and am looking to purchase a new Canon DSLR as I have a host of lenses to fit system. Having never thought about imaging, rather than have the 350 redundant, what exactly would I need in order to take a few images assuming I order my 127 Mak as my first scope? are they, or is there a standard adaptor?

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A dslr has a relatively massive sensor. A webcam has a very small sensor. The bigger the sensor, the larger the target you can aim for. Type "field of view calculator" into google and click on the link to 12strings... Plug in all your variables and look at how the different sensor types impact on the size ofninage you can capture.

Most webcams are rapid frame rate, so any exposure longer than a few seconds will be quite noisy. A dslr will have less noise. The cheaper the dslr, the more noise it will have.

Ypu can use a dslr to image the sky without a telescope, do star trails from a static tripod, or capture aurora, or pictures of the moon. Can mount a dslr woth a camera lens on an astronomical mount and take lovely widefield images of the night sky. Can't do this as easily with a webcam.

If you plump for a cooled ccd (most webcams are cmos, you'll have to look up the difference between cmos and ccd) camera, it will have less noise, but the chip will still be small. It will be expensive too. To get a cooled ccd camera which has a sensor the same size as a dslr's sensor, it will cost in the order of £800 i suspect.

Then you need to start thinking about mono verses colour sensors (all sensors are essentially mono, the dslr just has a mateix infront of it (again you need to reader about the bayer matrix and astrophotography).

Then there is light pollution, and light pollution filters. And computers - a dslr is a stand alone device, whereas most webcams and ccd cameras need to be connected to a computer to function.

What sort of mount and scope do you have?

It's all very complicated!

If you want to inage DSOs, I'd say ditch the webcam idea. Either get a dalr or save up for a cooled ccd with as big a chip as you can afford.

James

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You could need a canon eos t-ring, which clips into the camera body where the lens normally clips, replacing the lens. The other side of this ring is a T2 thread. You'd need to find out if the scope has a T2 thread on the back, otherwise you need a t2 threaded nose piece.

James

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A dslr has a relatively massive sensor. A webcam has a very small sensor. The bigger the sensor, the larger the target you can aim for. Type "field of view calculator" into google and click on the link to 12strings... Plug in all your variables and look at how the different sensor types impact on the size ofninage you can capture.

Most webcams are rapid frame rate, so any exposure longer than a few seconds will be quite noisy. A dslr will have less noise. The cheaper the dslr, the more noise it will have.

Ypu can use a dslr to image the sky without a telescope, do star trails from a static tripod, or capture aurora, or pictures of the moon. Can mount a dslr woth a camera lens on an astronomical mount and take lovely widefield images of the night sky. Can't do this as easily with a webcam.

If you plump for a cooled ccd (most webcams are cmos, you'll have to look up the difference between cmos and ccd) camera, it will have less noise, but the chip will still be small. It will be expensive too. To get a cooled ccd camera which has a sensor the same size as a dslr's sensor, it will cost in the order of £800 i suspect.

Then you need to start thinking about mono verses colour sensors (all sensors are essentially mono, the dslr just has a mateix infront of it (again you need to reader about the bayer matrix and astrophotography).

Then there is light pollution, and light pollution filters. And computers - a dslr is a stand alone device, whereas most webcams and ccd cameras need to be connected to a computer to function.

What sort of mount and scope do you have?

It's all very complicated!

If you want to inage DSOs, I'd say ditch the webcam idea. Either get a dalr or save up for a cooled ccd with as big a chip as you can afford.

James

Currently i have a 4" reflector, but i am looking to buy the Celestron Nexstar Evolution 6. Alt/Az mount, which i know isnt ideal for photography, but that scope seems the most portable/practical for my needs. i am more interested in visual viewing rather than imaging but it would be good for me to be able to do both (if thats possible) i am not looking for anything serious with photography, just personal pictures to mostly show my grandad as he cant really use the scope with him being old and shaky.

The ccd does sound like an option, but a dslr does sound like a cheaper and more cost effective option. Ive set aside a budget for my next scope, mount, acessories etc of £2,000. But i dont want to get an amazing camera and not use it much. However wide feild images of the sky does sound like something i would like to progress into.

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You wouldn't go far wrong to get a copy of "Making Every Photon Count" which will give you a much more complete account of imaging techniques and equipment required. It's easy to read, covers all angles, and will save you a lot of money in the long run. Hth :)

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For widefield all you need is a cheap body and a 18-55mm kit lens.

Depending on how much you want to spend, you could get these for around £100/120.

Take a look on MPB there are loads of bargains.

These would get you going and you could mount the whole thing on your new scope.

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Short answer is that webcams won't work in long exposure (unless they have been modified), so are not suitable for deep sky imaging.  A DSLR is the cheapest way to get into imaging.  But for long exposure there are a whole lot more accessories you are going to need.

Moon and planets can be done with a webcam and you won't need all the extra bits.

Carole 

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^0 seconds will be unachievable for lots of the sky with an alt-azimuth mouth. At the zenith exposures of 5-10 seconds maximum as field rotation there is the quickest. Just above the horizon east and west is the best, but then you are looking through the thickest part of the atmosphere and encountering all sorts of other problems.

Luckily, Google has two pages in one of my favourite astro-imaging books available for free:

https://books.google.co.uk/books?id=Agho6QnsrzsC&pg=PA112&lpg=PA112&dq=bill+keicher+field+rotation&source=bl&ots=GjWqaY0cJy&sig=Q6QHpKq8r_bRdu50tvdVcNN4qKU&hl=en&sa=X&ved=0CDMQ6AEwA2oVChMIpPfsru3fxwIVBo_bCh36wwia#v=onepage&q=bill%20keicher%20field%20rotation&f=false

For me the bottom line is, if you want to image DSOs, use a tracking equatorial mount.

Good luck.

James

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Thank James and Peter. I think an Equatorial mount is a must then. Just to find the scope now.

Could you recommend any DSLR cameras? i would like to get into wide field photography i think, the thought of being able to take my own picture of the milkway is such a great thought. Plenty of practise im sure though!

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I would recommend a Canon DSLR - one with live view. Get one that supported by Backyard EOS if you can - its a great piece of software. I have an unmodded 550d which is great and also a modded 1200d which is good for nebula. Used Canons can be picked up quite cheaply but always check the shutter count before you buy. There is on-line info about shutter counts of Canons and what to look for. You should find one under £200.

Also consider a short refractor like an ED80 for DSOs. It all gets a bit expensive this astrophotography lark. :sad:

Peter

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Currently i have a 4" reflector, but i am looking to buy the Celestron Nexstar Evolution 6. Alt/Az mount, which i know isnt ideal for photography, but that scope seems the most portable/practical for my needs. i am more interested in visual viewing rather than imaging but it would be good for me to be able to do both (if thats possible) i am not looking for anything serious with photography, just personal pictures to mostly show my grandad as he cant really use the scope with him being old and shaky.

The ccd does sound like an option, but a dslr does sound like a cheaper and more cost effective option. Ive set aside a budget for my next scope, mount, acessories etc of £2,000. But i dont want to get an amazing camera and not use it much. However wide feild images of the sky does sound like something i would like to progress into.

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Hmm  The nexstar has a focal length of f10 and you are on an alt/az mount.  I'm a long way from an expert but I think you'll struggle to get any pics other than solar system objects.  I've just ordered a beginners set-up from FLO.  Heq5 mount, Skywatcher ed 80 and reducer, skywatcher skytravel guidescope and lodestar x2 autoguider plus dew heater and various bits and bobs.  Total came to £2100.  The lodestar can be used as planetary camera and apparently can do deep sky objects too (although I'm not getting my hopes up)  I already have a second hand unmodded canon 450dslr which I got for £100.  I have done some widefield shots just using the camera on a static tripod and got some rather pleasing results.

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