Webcam or DSLR?

[Avocette]

I know the information I am seeking will be elsewhere on SGL already, but here goes with a few statements I have gathered in my reading and some initial conclusions - please point out my errors!

• The best webcams for astro modification which used CCD sensors such as the famous Sony ICX098BQ 640x480 pixels (the whole Philips series from the ToUcam Pro (740k) to the SPC990NC etc.) are no longer produced and so available only second hand.
• If you buy a newer webcam it will have a CMOS sensor  which is much less sensitive to low light levels.
• DSLRs use CMOS sensors but of many different overall physical sizes (n-Megapixels) and different individual pixel dimensions.
• You can use a DSLR on a tracking mount scope controlled by PC for long exposure captures. With a webcam you would need to make a Long eXposure modification to do this.
• With some DSLR models (e.g.Canon EOS 550D) you can use part of the CMOS sensor for 640x480 capture of m frames per second to make an AVI file.

So  I might as well just get on and use a DSLR for my early attempts at imaging and accept that astrophotography has moved on from the modified webcam. If/when I want to do better I will need to get a dedicated modern CCD astro imaging camera. Even if I could get hold of an old-school CCD Webcam at an acceptable price, I wouldn't get much benefit over a DSLR for the sort of objects it's capable of capturing (the Moon using a matrix of exposures, a few planets, and maybe one or two small DSOs). Of course to make full use of a DSLR for DSOs I should astromod it to remove the IR filter installed during manufacture.

Am I making sense?

Thanks for your corrections!

[Langy]

From what I know about it the webcam will only be used for Lunar and Planetary images only as they are shooting video.

A DSLR is fine for the Lunar as is, but for DSO you will need some very good tracking as there will be lengthy exposures in minutes. Not sure how a standard compares to a modded one, obviously not so well.

I think if you are after DSO then you have to pay some serious money if you want to do it through the scope.

[Leveye]

CCD for Planetary stuff and a DSLR for prime focus DSO stuff and some projection work.

[Pete Presland]

not totally true regarding ccd not cmos for planetary.

the latest zwo asi120mm uses cmos sensor-based unit featuring an Aptina MT9M034 chip and this is a fantastic imaging unit.

The QHY5v is equipped with CMOS Micron MT9V032 sensor and also does a very good job. cmos sensor are getting better all the time and the 2 cameras above both double up as guide cameras.

[Avocette]

not totally true regarding ccd not cmos for planetary.

the latest zwo asi120mm uses cmos sensor-based unit featuring an Aptina MT9M034 chip and this is a fantastic imaging unit.

The QHY5v is equipped with CMOS Micron MT9V032 sensor and also does a very good job. cmos sensor are getting better all the time and the 2 cameras above both double up as guide cameras.

Thanks for this....so are DSLR CMOS sensors starting to approach the sensitivity of the Sony webcam CCD or is there still a significant difference?

[Avocette]

By the way I note that the Orion StarShoot imager has a CMOS sensor.

[Luke]

I currently use a CCD webcam (mostly for solar, lunar, and a dabble with planets), but my impression is that CMOS sensors are improving, and those ASI's look to me like good bang for buck going by some images taken with them, but I haven't used one myself.

There is a ton of info on the newer webcams - CMOS and CCD - from Riklaunim, who might comment if he sees this thread, here:

http://www.rkblog.rk.edu.pl/w/p/astrophotography-and-observations/

Check out the planetary cameras section.

I found that info useful when researching for a webcam. Thanks, Riklaunim, if you're out there!

[michaeldurban]

I just received a webcam with instructions on how to modify it for my dob.

It's a Life Cam HD-3000, with CMOS.

Attached is a link how to modify the cam for telescopic use.

http://astrophotovideo.wordpress.com/adapting-a-webcam-to-a-telescope/

[RogerTheDodger]

I started imaging with a long exposure modified webcam (see sig for link) and was amazed how much easier it was with a DSLR... 

[Avocette]

I started imaging with a long exposure modified webcam (see sig for link) and was amazed how much easier it was with a DSLR...

By the looks of your (somewhat difficult to read) signature you have one of every kind of imaging device! Are there still times and objects for which you would take out your SPC900 as your first choice camera?

[StuartJPP]

A DSLR that has got live view capture via USB in my opinion is way more versatile than any webcam though there are of course caveats. One advantage of a webcam is that some of them can take more than 30fps which you won't get with a DSLR via live view, though I normally average 18-20fps on a 1GHz netbook. You need to make sure that you can reach focus with a DSLR with your kit.

This image was taken with a Canon 7D + Canon 500mm f/4 L IS + 1.4x Teleconverter + 2x Teleconverter (equivalent to 1400mm FL) using 5x live view USB record (BackyardEOS) and stacked in Registax. I'd suspect that a webcam (with no barlow) will produce a similar FOV.

Xmas Jupiter with Great Red Spot + Io, Europa and Ganymede by StuartJPP, on Flickr

[Langy]

Wow that has some detail in it.

I'm guessing that was recorded as a video rather than stills? At what resolution does the video record? Only asking because if it was a RAW image the resolution would be much higher allowing for a much larger image.

Just better add, I know that recording the video will give you more frames than the time you would need to sit there for stills.

[frugal]

Wow that has some detail in it.

I'm guessing that was recorded as a video rather than stills? At what resolution does the video record? Only asking because if it was a RAW image the resolution would be much higher allowing for a much larger image.

Just better add, I know that recording the video will give you more frames than the time you would need to sit there for stills.

I do not know about the 7D that was used to produce the image, but my 60D will do stills at 5184x3456 and video at 1920x1080 @30fps  with the same field of view.

[wxsatuser]

I do not know about the 7D that was used to produce the image, but my 60D will do stills at 5184x3456 and video at 1920x1080 @30fps  with the same field of view.

The 60D will also do crop mode movies at 60fps, great for moon and planets as it's 1 to 1 pixel ratio.

One of the moon

[StuartJPP]

This website has more info:

http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/Canon_One_To_One_Pixel_Resolution.HTM

You do not want to record video with the camera itself unless it has "Movie Crop" mode which is only supported on a small number of cameras (60D, 60Da, 550D).

[RogerTheDodger]

By the looks of your (somewhat difficult to read) signature you have one of every kind of imaging device! Are there still times and objects for which you would take out your SPC900 as your first choice camera?

Planetary imaging - hard to beat the SPC with the others

[Avocette]

Thanks for the interesting inputs you've made on this thread. I have lots of options to think about. As it happens I've got access to a Canon EOS 550D so I can try out 'movie crop' mode, and to a Philips Toucam Pro which has been partially astro modded, so two ideas to get on with for a start.