Digital photography

[Mike]

Preferably a better telescope, but perhaps yours will be ok for the above.

Carol the scope and mount you have at the moment will be perfectly fine for doing the Moon and planets. All you would need to add to Fay's list would be a good quality Barlow of at least x3. As the moon and planets only require very short exposures and lots of them, guiding isn't necessary. A good level mount that is polar aligned accurately will do the trick adn the optics on the ETX are very good for planetary stuff, particularly the moon. This would be the cheapest option. Webcams are around £40 and a new laptop is around £300. Second hand laptops can be purchased on eBay for around £100 that would do the trick. Then you just need a decent Barlow (about £100) and perhaps a neutral density filter for the moon (£20).

[Ian]

I agree with wot Fay and Mike say, but to clarify...

You can add USB ports to a laptop with a reasonably priced card, and you will probably only need one to begin with. I agree with USB2, but toucams are USB1 and they are still the best bet for astro work...

As you're currently using a catadioptric scope, which has a lens in the image path it's advisable to use an infra-red block filter. Webcams have them as standard but they're usually built into the lens that you'll be removing to attach to the scope. Just order one to fit the adaptor for camera and scope you'll inevitably have to buy. Planetary imaging is usually done with a barlow too, as they're tiny, which makes an IR filter a must.

Do you have a wedge for your ETX? That might help with alignment and tracking (if aligned well, only one motor needs to run to track the planet).

I've never used an ND filter on the moon, I don't think the ETX will give an image that bright. The webcam's electronic shutters are fast enough to cope...

If you get an older laptop with a duff battery, they can be run off a car battery (bearing in mind you'll have to carry it around, which I know is Fay's concern) and 3 hours is quite an ask even for a new laptop if you're imaging. The laptop can't power down the hard drive, you'll be writing to it all the time and after the screen backlight that accounts for a major portion of the power useage. A small car battery will power a laptop all night, and probably your scope too.

I would use K3CCDTools v1 which is free. It's good enough to start, and as Fay said £25 for the latest version won't be your most expensive purchase.

[Fay]

Yes, I was only giving Carole a very basic list, to start with, did not want to scare her off, with batteries etc. I would think she would first practise in the garden & would use the mains.
I forgot about the Barlow.

Fay

[Rocket Pooch]

Just to confuse everyone here, that ETX Cat has a central obstruction of about 20% and an exit diameter of about 9mm, this is going to make it quite useless for a SLR

Sorry just a thought.

[Ian]

the cat on the mead

Of course, it's better to use purpose designed counterweights. Our feline friends have a habit of jumping off scopes at inconvenient moments. Particularly if Space Dog barks.

[Carole]

You've now all overwhelmed me with so much information (and many thanks) that I am now thinking I need to put this off until after I've retired so I have more time to get my head around it all and read up before I make a purchase/decision.  I'm retiring end of 2008.  In the mean time I will try to do some reading and follow what Miriam and Delphine are doing.

In reply to you question Ian
"Do you have a wedge for your ETX?"

I don't know what a wedge is so I guess I don't have one.

Fay, just to clarify, I like deep sky just as much as planets, don't know how you formed that impression.

Carole

 

[Ian]

sorry, been a bit verbose...

The ETX is usually used as an alt-azimuth mounted scope, so the base is horizontal. This is fine for visual observing, but less good for lunar and planetary imaging, and hopeless for long exposure. This is because as the target tracks across the sky it appears to rotate in the eyepiece as it goes. The other reason is to track across the sky, an alt-az needs to use both motors.

The alternative is to align the mount with the rotation of earth which in the UK means tilting the base to an angle. If you can remember Mac's scope from DSC, he had that on a wedge that does just that. The image won't rotate and only one motor is needed to track.

If you have access to any laptop made in the last 5 to 6 years, you'll be able to do imaging with it, provided you can power it, and you're welcome to borrow one of my Toucams to have a go. I'd start with lunar, mainly because the best planets, Jupiter and Saturn are not best placed for photography at the moment. You will probably have more success if you have access to a barlow too.

I didn't mean to scare you off

[Fay]

At Herstmonceaux etc you have always been interested in the planetary observing days & I think you once said to me that they were more interesting to look at than stars.

Fay

[Delphine]

Carol

I will try to remember to bring the webcam imaging book to the next meeting so that you can have a look at it before you buy it.   

Delphine

[Carole]

Hi Ian,

I think I know what you're driving at now (excuse the pun).  I seem to recall that an ETX can be (what they call in the operating instructions) "polar aligned", where you tip up the base according to the latutide you are at.  As I have never had to use this so far I had forgotten about it, I will have to read this up.  I remember doing this on my previous telescope which was on a newtonian mount but didn't track, plus it was very difficult to take anywhere as so many fiddly bits had to come apart, which was why I bought an ETX for tracking and portability. 

I had also noticed on my ETX when I am viewing objects being tracked that they do indeed move in an arced way and thought the telescope was faulty or I had done something wrong, plus I could never really understand how Alt/Az could work accurately and now all this is making sense.

OK, so if I can borrow your webcam and bring a charged up laptop and telescope, what else do I need (i.e. software installed on lap top?) just to get started?

Which Ian are you by the way?  I am sure there are two, maybe you can "reveal yourself" to me at the next meeting.  (That will keep this thread going for some time yet!!!!)

Fay:  Yes I do seem to recall that conversion, but I was referring to stars as single item points of light which the observatory seems to point their telescopes at on public evenings which are boring on their own.  I am very interested in nebulae, supernova remnants, galaxies etc etc. 

Sorry if I misled you, I wondered why you had said this on a number of occasions before.

Carole

[Ian]

I think I was the sole Ian at DSC... Usually scruffy, with a chin full of fluff.

If you bring a laptop to next meeting, could you let me know in advance what version of windows it has on it? I'll need to know to install the camera drivers. I'll also bring a copy of K3CCDTools and other stuff with me too.

[Fay]

Don't take the request to "reveal yourself" too literally, Ian.


Fay

[Rocket Pooch]

I think I was the sole Ian at DSC... Usually scruffy, with a chin full of fluff.

Sparticas moment comming up!

[Miriam]

Hello Carole
From a mere beginner!
Delphine and I managed to get a picture of Jupiter and four moons at DSC, using a webcam, laptop and Delphine's scope. A bit hit and miss to start with, but we had plenty of advice.

Jeff and I had another attempt at photography in the garden during the following week, partly to see if we could get an image without all the expert advice. I was pleased with the basic images (just a single frame - no processing)  but acknowledge there is a lot to learn . . .

Roll on clear nights!

PS I didn't take the photo of Hale Bopp at Stonehenge (see left)

[Carole]

Ian,

I thought I had sent you a personal message but not sure if you got it.  Can you E mail me so we can discuss further, as I don't think every-one wants to read all my technical questions and learning stages.  You asked what system the laptop runs on and it is Windows Me.  It won;t connect to my broadband unfortunately as I tried this once before. 

Carole