Very basic imaging advice

[Starflyer]

Hello,

I would like to try a bit of imaging and have a bunch of questions. My scope is Skywatcher 130pm 650mm f5, I have a Toucam II Pro on the way.

I've been looking at adaptors and found two I think are suitable;

http://www.astro-engineering.com/Adaptors/adaptorsforteles.html

AC624 or AC378, which of these would be best suited to my setup? I understand that some scopes have limited inward focus but can I use the shorter (cheaper) one, and are there any disadvantages over buying the longer one?

I think I'll be starting out trying some Lunar and maybe Solar images, I'm currently making a filter holder for the Baader solar film, it fits on the offset hole thingy in the cap (what's that called by the way?) I'll post some pics of my DIY attempt when it's finished - it's away being anodised at the moment. Do I need to add a UV / IR blocking filter to my shopping list for Solar / Lunar imaging? I have a Meade N96 Moon filter already.

Can someone explain how magnification works using a webcam? Does the cam fit into the focuser tube with or without a lens / barlow?

It's this last bit that's confusing me, from what I can see the adaptor will only fit into the focuser or a barlow.

I have a laptop, K3CCD, registrax, and the information / primers on here are excellent. It's just the very basic: put this in here and this in here and this is how it focuses and this is what magnification you'll get, sort of stuff that I can't get to grips with.

Thanks, and apologies for all the noob questions

Cheers,

Ian

[Andrew*]

Can someone explain how magnification works using a webcam? Does the cam fit into the focuser tube with or without a lens / barlow?

It's this last bit that's confusing me, from what I can see the adaptor will only fit into the focuser or a barlow.

If you use the webcam afocally, the webcam goes into the focuser and gives you a similar field of view (more correct than "magnification" in imaging) as a 6mm eyepiece. This is quite a small field of view, so it isn't ideal for large DSOs such as M31, but is good for planets. You can use a barlow to get even less FOV or a focal reducer to increase FOV.

The other type of imaging is eyepiece projection and it's basically taking a picture through the eyepiece as if your eye were there

HTH

Andrew

[psychobabbler]

Hi Star Flyer

Your borther dogfish said you were on SGL. I'm David (psychobabbler), the guy he works with and great to have you on. He tells me you are an absolute wizard in all things enginneering so i feal a bit of a fraud giving you any advice that you have not already worked out yourself.

All i can tell you is of my experience with the successor to the toucam - the sp900c. I got a webcam adaptor no bother from Telescope house who do ones for specific webcams. Also got a cheaper baader ir filter from FLO as these are supposed to be essential (but i have heard people go without). This leaves a nice all in one system. I should have told you you needto prise off the top of the webcam first.

The only lense you seem able to use is a barlow. The rest i suspect you already know and as you say Martin's primer on registax is very good and tells you all you need to know. Please email me if you would like to get a sense of what to expect - i have a couple of pictures i can send to you on Saturn, moon, and jupiter - david.craig50@ntlworld.com

All the very best

PB

[blinky]

I think I have the 378, you unscrew the lens from the ToUCam and screw this in. You can then use the Webcam in place of an Eyepiece. It gives around the same field of view as a 5mm EP, this as Andrew says can be magnified with Barlow lenses or use a focal reducer to increase the field of view.

An unmodified webcam can be used for the moon and planets and can produce some great results. I bought an IR filter but to be honest I cannot see a lot of diffrence with/without it. It is good though to protect the CCD from dust etc as removing the lens means there is nothing in between! The IR filter is there as infra red light comes to focus slightly diffrently from 'normal' light and since your webcam is sensitive to IR light this can cause out of focus areas.

[legion48]

Hi Ian, you need the ac378. That's the one I used with the scope and I had no in focus problems at all - except when using a focal reducer.

[blinky]

Actually thats a good point, I have heard that you canot focus a newt with a focul reducer.

[daz]

Hi Ian

Yep, its the AC378 you need. I'm really sorry I didn't have a spare one to give you

The lens on the camera unscrews and the AC378 screws in, in its place. This then slots into the focuser.

A focal reducer will not work in your Newt - there is insufficient focus travel, but a barlow will. Barlows increase the magnification but decrease the field of fov (and the object brightness). At f/5 the image scale will not be huge, but here is a trick. Don't slide the AC378 all the way in the focuser. You'll need to play and find where the focus limit is, but this is a cheat to increase the size of the planet in the webcam FOV.

The hole in the dust cover is, in technical parlance, the holey-thing-in-the-dust-cover!!!

An IR filter would be a good investment, but don't panic about it.

A very good investment is an illuminated cross-hair reticule for centering the object in the eyepiece. The chip is really quite small and getting an object on the chip is the most frustrating thing ever. This will be the best money you can spend!!

Focus is another pain the bum bit, so here's what you do:

1) Get a bright object on the camera - i.e. the moon or a bright star.

2) Focus it on screen

3) Carefully remove the camera - WITHOUT MOVING THE FOCUS

4) Insert an eyepiece (a cheapo one will be just fine for this) and slide it up and down the focuser until it focuses.

5) Mark the barrel of the eyepiece in some way.

6) Then, next time you come to use the camera, use the eyepiece to focus the object and the camera will be there or there abouts! Most people that use this method use a par-focal ring.

In fact, I have a spare ring that I will dig out and send to you - some compensation for not having the adapter for you!!

Looking forward to seeing your results

[daz]

6mm eyepiece.

That was the one bit of info that I could not remember - 6mm!

So, in terms of magnification, the camera would get 650 (scope focal length) / 6 (camera focal length) = 108 times

[Cloudgazer]

I think I'll be starting out trying some Lunar and maybe Solar images, I'm currently making a filter holder for the Baader solar film, it fits on the offset hole thingy in the cap (what's that called by the way?)

Ian

Are you making a full aperture solar filter or are you making it to fit over the hole left in the dust cover when the removable cap has been removed?

Scott

[legion48]

Ian, have you bought a AC378 adapter yet? If not I have one I'm not using since I got my Nexstar and had to get a "shorty" adapter. Your welcome to borrow it until/unless I get another scope and need it back.

[Starflyer]

All i can tell you is of my experience with the successor to the toucam - the sp900c. I got a webcam adaptor no bother from Telescope house who do ones for specific webcams. Also got a cheaper baader ir filter from FLO as these are supposed to be essential (but i have heard people go without). This leaves a nice all in one system. I should have told you you needto prise off the top of the webcam first.

The only lense you seem able to use is a barlow. The rest i suspect you already know and as you say Martin's primer on registax is very good and tells you all you need to know. Please email me if you would like to get a sense of what to expect - i have a couple of pictures i can send to you on Saturn, moon, and jupiter - david.craig50@ntlworld.com

Hi David,

Thanks for the reply, reading through the other replies and the primer again has helped. I'm sure I'll pick it up, I'm the sort of person who learns by doing rather than reading and the cam / filter should have been delivered by now - but they were delivered to my work address and I've been away for a couple of days

Are you coming to Kielder with Martin? I'll be there from the Friday afternoon, hope to share a few beers with you and hopefully learn a bit too

What I'd really like is one or two un-processed captures of Saturn, Jupiter or the moon so I can have a play with the software. Any chance of emailing them or putting them up on some webspace if they're too big for email. Email addy in my profile is valid and from your end NTL limit emails to 10MB IIRC.

Thanks again,

Ian

[Starflyer]

Hi Ian

Yep, its the AC378 you need. I'm really sorry I didn't have a spare one to give you

Hi Daz,

No worries, I got an AC378 from Telescope House, arrived today The cam (and filters I ordered) will hopefully be waiting for me in work when I go back in on Friday

The lens on the camera unscrews and the AC378 screws in, in its place. This then slots into the focuser.

A focal reducer will not work in your Newt - there is insufficient focus travel, but a barlow will. Barlows increase the magnification but decrease the field of fov (and the object brightness). At f/5 the image scale will not be huge, but here is a trick. Don't slide the AC378 all the way in the focuser. You'll need to play and find where the focus limit is, but this is a cheat to increase the size of the planet in the webcam FOV.

Right, I think I understand that bit. Would I get a full moon image with my set-up this way?

The hole in the dust cover is, in technical parlance, the holey-thing-in-the-dust-cover!!!

Duly noted and already added to my glossary of technical terms

An IR filter would be a good investment, but don't panic about it.

A very good investment is an illuminated cross-hair reticule for centering the object in the eyepiece. The chip is really quite small and getting an object on the chip is the most frustrating thing ever. This will be the best money you can spend!!

I'll look into that, although it'll have to wait until next month now. Could I use that for drift alignment either now or in the future? I thought my polar alignment was reasonable but things still drift at high magnifications - is this just the EQ2 mount?

Focus is another pain the bum bit, so here's what you do:

1) Get a bright object on the camera - i.e. the moon or a bright star.

2) Focus it on screen

3) Carefully remove the camera - WITHOUT MOVING THE FOCUS

4) Insert an eyepiece (a cheapo one will be just fine for this) and slide it up and down the focuser until it focuses.

5) Mark the barrel of the eyepiece in some way.

6) Then, next time you come to use the camera, use the eyepiece to focus the object and the camera will be there or there abouts! Most people that use this method use a par-focal ring.

In fact, I have a spare ring that I will dig out and send to you - some compensation for not having the adapter for you!!

That's very generous Daz, thank you!

Looking forward to seeing your results

Cheers,

Ian

[Starflyer]

Are you making a full aperture solar filter or are you making it to fit over the hole left in the dust cover when the removable cap has been removed?

Hi Scott,

No not full aperture - it fits onto the holey-thing-in-the-dust-cover . Aluminium is too damn expensive at the moment and I had to make do with using a piece of 2 1/2" bar that I scrounged as a sample from one of our suppliers.

Hopefully it'll be waiting for me when I get back into work on Friday and I'll be able to fit the film and post some pics of the various stages.

Cheers,

Ian

[Starflyer]

Ian, have you bought a AC378 adapter yet? If not I have one I'm not using since I got my Nexstar and had to get a "shorty" adapter. Your welcome to borrow it until/unless I get another scope and need it back.

Hi Tony,

Thanks for the very generous offer, unfortunately I've already bought one from Telescope House.

I'm enjoying the scope - lots But at the moment either: it's cloudy or I'm knackered from the work thing or I have other commitments that mean I have to get up at a ridiculous hour and need my sleep.

Thanks again,

Ian

[Starflyer]

Thanks to everyone else who replied - all good info to get me on the way to taking some images.

I go away for a couple of days, the thread gets moved and I get loads of replies

Cheers,

Ian