Cameras Again

[yuklop]

Dear All

I'm sure this kind of question has been asked before as I have read loads of threads somewhat along this line but technology progresses so I ask again for opinions on cameras.

I use a 150mm, f5 refractor and I like imaging. I have a modified MS Studio webcam which I attempt to use for lunar and as a guide-cam when it can see a star nearby. I also have an unmodified Nikon D50. My primary interest is DSO for which both of the cameras have drawbacks. The webcam is impossible as there are no long exposure (quite a large drawback) and the nikon is hard to focus and has IR filter but does work.

I could get another DSLR body, probably a canon 450d or 1000d and modify it.

I could also get a dedicated astronomy cam which is the route I prefer at the moment. I have a budget of up to 500 quid.

There are so many options here it becomes tough. For example are the cooled cameras that much better than to non-cooled ones. Is there a big drawback to small sensors. I ask as the ICX618ALA sensors seem to get good reviews but I am unaware of larger sensors eg. 1/3 or 1/2'' equivalents.

There is this cooled ICX618ALA camera here for a reasonable price. Any experiences?

Actually in this topic too much reading around becomes pretty confusing as there is simply so many different choices!

Enough from me! Any thoughts or experiences would be gratefully received.

[yuklop]

So choosing CCD's is far from simple. I have spent a few too many hours trying to decide what to get as a dedicated astro camera.

The principles of operation and what to look for can be learnt and there is an excellent sticky to that effect by narrowbandpaul on this forum.

What is trickier to decide is what to actually spend the money when it comes to it and to that end I will try and sumarize my experience here in the hope that I may save some other confused soul hours of "research".

The simple and unhelpful answer is you get what you pay for. A QHY 8L or ATIK314 range are surely great ccds however they cost around thousand quid give or take a bit. I can't justify a 1000 pound spend sadly and I suspect there are many that feel this way. However let me use these two as an example of perhaps the most important desicion that needs to be made and will cut the research time required from the off.

What kind of field of view (FOV) are you after. This relates directly to the size of the CCD sensor and the pixel dimensions and the focal length of your scope. There is a truely excellent little program for free which will show you what certain objects will look like using any telescope and any ccd. Its here.

Objects that appear small will be framed better by a smaller chip. This is planets, and some distant or small galaxies / clusters. Extended objects like nebulae or large/close objects will be better served by a large chip as to image them completely in one exposure. Look at the QHY 8L. It has a DSLR sized sensor whereas the ATIK314 range have a much smaller chips and as such these cameras should find different application.

Once you have decided on a field of view you still have some options.

1. Large field of view. Requires large sensor. The best value large dedicated astro CCD is perhaps the QHY8L. It is cooled (cooling reduces the noise, obviously a good thing). It is 16-bit enabling it to pick out very subtle changes in brightness. However it is very expensive. The other way to get a large sensor but without spending so much cash is a DSLR. Second hand DSLRs can be picked up very resonably priced, certainly less than half the price of the QHY8L. When looking for a DSLR try to get live-view (helps with focusing), 14-bit (gives good brightness sensitivity), mirror-lock-up (allows DSLR to take short exposures without wobble from moving mirrow) and consider support. In the astro community this means getting a Canon. I would recommend a 450d as it has all the above features and is very well priced. Other options are an 1100d (no mirror lock up) or 40d (a bit heavier and perhaps slightly noisier according to some reports?) a 500d (lower noise, more expensive see this to see if you think its worth the extra), 550d or 600d which should all do the trick but are more expensive. Risky especially since you will want to modify it. This means reomving the aggressive IR filter that allows the camera to photograph as we see. There are plenty of articles on that.

See here for instructions

2. Small field of view or "planetery camera". The ATIK Titan would be a good choice as an entry level, cooled, dedicated planetary camera costing about 400 pounds. The alternative is using a modified webcam. There are loads of articles and cheap bits and pieces to buy for this. The usual route is the Philips Toucam range which can be got for as little as a tenner! The nice thing about these is that they can be "long exposure" modded to help them act as a guide cam for autoguiding. Another one for consideration are the Microsoft Lifecam series. The Studio is particularly noteworthy for having very high resolution and a very sensitve chip. It cannot be "long exposure modded" as yet but the exposure controls can be adjusted from the software to some pre-set maximum (which is still short by astro standards).

3. Something in the middle would be pleasant. Here the ATIK314L+ is noteworthy but expensive. Not really a simple cheap alternative here. The MS Lifecam studio gives a slightly larger FOV than other webcams or

this

which should be suitable although I cannot find any reviews or people with experience of this thing! The FOV is still smaller than the ATIK and its 14 not 16-bit but it is also ~half the price.

So I decided in the end to go for a Microsoft Lifecam studio as a planetary camera. It works well on the moon, pretty well on the planets and can catch brighter stars for guiding. The modification is relatively simple and the sensor is excellent for the relatively small outlay. The hope is that one day someone will crack the long exposure mod for this camera and then it'll be fantastic value. I will acompany that with a second hand DSLR which I will modify. These two between them give the ability to capture most objects. Great things can be done with DSLRs and my skill is way short of the capability of a DSLR camera. Total outly here is less than the price of the ATIK Titan. Then I can get good, save up the pennies and think of a dedicated cooled astro ccd in the future.

Thanks for reading and I hope it help someone!