Attaching a video camera to a telescope

[Chrissyo]

Sorry everyone, but here is another topic on connecting cameras to telescopes :P

Well, the time has come. I want to update how I attach my video camera to my telescope. If you see the image I attached to this post, I think you would agree its time for an upgrade! :lol: I have attached 2 images of the front of the video camera onto this post so you can see where the thread is and how it works.

So I have been reading some of the older posts and looking around the websites of some Australian vendors. It seems I have two options: the Prime Focus method or the Eyepiece Projection method. I have been using 2" eyepieces in the past and I wish to continue using them.

What sort of adapters would I need for either method? I have been looking at some images in other threads posted by other members laying out the required equipment (such as these images by Dennis: http://www.iceinspace.com.au/forum/attachment.php?attachmentid=23310&d=1170894740 and http://www.iceinspace.com.au/forum/attachment.php?attachmentid=23309&d=1170894740). However, SRL cameras appear to be a bit different to my video camera.

Prime Focus:

From the looks of it I would need something like this...

https://secure.attl.com.au/bintelshop/Stock/7403X.jpg

Would I need a T-thread with this to fit my camera, or is it supposed to be a fairly generic thread. Too add to this, I'm not really sure what the thread size of my camera lens is. However, it has 43mm diameter written on the inside of the thread.

Eyepiece Projection:

I think this is the method I would prefer to use as it would give me a greater variety of magnifications to work with. But I have little idea at all what kind of equipment I would require. I am thinking something along the lines of a tube that connects to the outside of the 2" eyepieces that has a thread on the other end that I can screw onto the camera lens. Is this the kind of thing I should be after?

Furthermore, I have seen some products like this (http://www.myastroshop.com.au/products/details.asp?id=MAS-238) that would be good as they would simply be better built versions of what I am currently using. However, I haven't yet found one that will fit my 2" eyepieces (the one I just linked too only takes an eyepiece with an outside diameter of 45mm where as a standard GSO 2"er is at least 50mm.)

Sorry for my complete newb-iness at this! There just seems to be so much variety and I have gotten myself into a muddle with all the different threads and adapters.

[netwolf]

Chrissyo, have you tried using the firewire (i assume your minidv camera has one) to capture live images to your pc instead of recording them on Tape. I just had this thought and posted it about 2mins ago on the QHYCCD thread.

Regards
Fahim

[Chrissyo]

Yup, the thought has crossed my mind. However I don't have a firewire port on my laptop and theres no way I'd be able to shift our desktop outside at nights. Recording onto tape has worked quite well for me so far :)

[[1ponders]]

Isn't it about time you started thinking about a ToUcam Chris ;)

[iceman]

You can get firewire in your laptop by using a PCMCIA card - that's what I do for my firewire DMK21AF04.

[netwolf]

Well I got firewire built in hence all my curiosity about fire wire. Looking at buying a webcam next and am wondering what to get that will not break the bank. The QHY2 looks good saw it listed on the American distributor page for 225USD. http://ccd-labs.com/eshop.htm
Looks real nice and it has built in guiding controller. Should work nicely with the LX90.

Regards
Fahim

[Chrissyo]

Well I've been doing some searching and found this...

"DG Ring 43mm" under the 'Camera Rings and Adapters' section at this webpage:

http://72.14.253.104/search?q=cache:k2_lMbi3HeoJ:www.tel escopes-astronomy.com.au/vixen-pricelist.htm+43mm+camera+adapter+t elescope&hl=en&ct=clnk&cd=1&gl=au

Would that be the kind of adapter I am looking for for connecting to the front of my camera? I'm still not sure what that would connect to then. :P

[netwolf]

Chrissyo, I do not believe prime focus is possible using a fixed lens camera or video camera. An EP is required to project the image onto the camera lens. I to am wondering why this is not possible but so far have not seen a good explanation of it. I want to do it with my Canon A610, but as it has a fixed lens, I am told its not possible.
Why not? I hope the experts can answer this one.

Prime focus is possible with SLR's where you can remove the lens and directly mount the camera without lens (using the adapters you have found) to the telescope.

Regards

[Chrissyo]

Well I guess that narrows my options down a bit. Thanks for the info!:)

[bojan]

Cameras with fixed lens can not be used at prime focus of the telescope.
This is because the lens prevents focusing. The lens of the camera can focus on objects that are relatively far away (from infinity down to 1/2 metres or to macro distance, 10cm or so). The telescope objective (lens or mirror) forms the image of celestial objects at the focus point, and in order to focus to that you have to move away with your camera at least 1/2 metres (or, to the distance for macro mode). This will seriously reduce the field of view to the point of uselessness, and the loss of available light is also huge (due to only a central part of the light cone entering the camera lens... in case of newtonian because of the secondary there would be no light for the camera at all.

It is not correct to say that eyepiece projects the image onto the camera lens.
In case of fixed lens camera or eye, eyepiece effectively creates the virtual image of the focal image in infinity, so the camera (or eye) can focus on that.
In case of the eyepiece projection on the screen or film or CCD sensor, eyepiece projects the image of the focal image to that screen.

To use the prime focus, one must bring the CCD (or film, or screen) of the camera into the focus of the telescope.

Now, most likely it is not possible to remove the lens form the fixed lens camera and retain the basic functionality of the camera because camera software actively communicates with the lens hardware (lens position, iris etc), and it expects feedback, and to find focus among other things. With some models, not finding the focus may even prevent taking pictures (I used to have one such camera and it was sometimes very frustrating taking terestial pictures, after 1/2 seconds of focusing, camera would simply refuse to go further because correct exposure and/or focus was not found).

B

[Chrissyo]

Ok, so I've done some snooping and I think I've found what I need for my camera for eyepiece projection.

It seems I would use this (http://www.astronomyonline.com.au/Default.aspx?tabid=52&ProductID=2184&cid=2798) to attach to the filter thread on the front of my camera, which would then thread into this (https://secure.attl.com.au/bintelshop/Stock/5488.jpg). Does this look right? (I just dont want to check I'm not thinking about the wrong items:P).

I guess its not a huge problem, but the meade camera adapter I just linked too only accepts 1.25" eyepieces. Does anybody know of any Variable Projection Camera Adapters that accept 2" eyepieces?

Thanks :D

[Gama]

And if Bojans explanation still doesnt register, then think like this..

Lets say the camera with its lens is focused for infinity, your telescope mirror or lens without and eyepiece is NOT. If your eye is focused at infinity and you look into a telescope without an eyepiece, what do you see ?... Krapola. This is what the camera will see too. But placing an eyepiece in produces an image at infinity (If focused correctly), then your eye or camera will see the image correctly and in focus.

[Chrissyo]

Ok, so prime focus is out.

So at the moment it looks like I'm set for a Meade Variable Projection Camera Adapter and a Hyperion T-Adaptor M43/T-2. I've drawn a quick diagram that I added below and I wondered if someone would quickly have a look and just double check that I've not messed up. I'm not 100% sure that the hyperion T-adaptor is designed for connecting to a variable projection camera adapter.:help:

The sections in blue mark where something is getting threaded INTO and the sections in red mark what is getting threaded IN. (Red is male thread, blue is female thread?)

Anyway, thanks in advance:D

[bojan]

Chrissyo,
You have to make sure your camera lens is as close as possible to eyepiece, ideally the lens should be where exit pupil is (that depends on eyepiece design, those with greater eye relief are better because the exit pupil is farther away.... as in case of visual observation, you have to come close to the eyepiece with your eye, right?).

So, you should have some sort of eyepiece extender involved, to bring the eyepiece inside projection adapter, almost, but not touching the camera lens. The whole thing must be of course brought closer to the objective, to achieve focus.
You can check for this by watching through the eyepiece, of course, then the camera will see the same thing you are seeing.

Edit:
The diagram you attached previously would be OK for projection onto screen, film or CCD, without camera lens involved.
With the camera lens, it would not work properly (very small field of view, just to name a most obvious problem)
Have a look at the attached diagram I modified. Eyepiece extender is missing from the drawing, but the correct position of the eyepiece is indicated.

[netwolf]

Scopetronicx and other manufacture specialy designed Eyepices and adapters for this purpose. You particular video camera is not listed however other panasonic video cameras are listed. I would email them to check if there is an adapter for yours. There is another UK company that also makes the same adapters http://www.astro-engineering.com/.

I think this is the best one for you.
http://www.astro-engineering.com/Camera%20Mountings/Resources/digita7.jpeg

Myastroshop did have these i think listed on there site at one point.

Regards
Fahim

[Chrissyo]

Thanks for the company names, I've been looking around them this evening and found a few items that would work. However, only one of the options would work on my 2" eyepieces (and would cost more than $100 AU not including postage!).

So I've done a bit more snooping and found something that looks like a winner on Ebay. Large F-adapter (http://cgi.ebay.com.au/Large-F-adapter-for-digiscoping-digiscope-birdwatching_W0QQitemZ230091342082Q QihZ013QQcategoryZ30066QQcmdZViewIt em)

I had a quick search of the forum to see if anyone else had had any experience with these and it seems someone else also sucessfully bought one on Ebay (I'm presuming from the same person as only one 'store' seems to be selling them). Here (http://www.iceinspace.com.au/forum/showthread.php?t=12376&highlight=F-adapter) is the link for that thread.

Anyway, it seems like a simple thing which is what I was after, $50 au for the actual item, +$5 for a stepper ring to my cameras 43mm thread (I just emailed the guy to see if he had that size available. If not I can get one from ebay for about $15 anyway) + $10 shipping. So all up $65 au. So much better than the $100+ for the other sites.

Anyway, I'll wait for a reply from the guy then decide what to do.:D

[bojan]

Large F-adapter looks promising in terms of distances of individual optical components etc, however there may be a problem with the weigth of the camera it can support, those lock screws and (metal?) tape used to hold the whole thing in place look a bit suspicous to me, you may damage your eyepiece while trying to tighten it. Eyepieces are NOT designed to hold any weigth (especially not those plastic ones, often supplied with telescopes recently)
B

[bojan]

I had another look at the ad on ebay, it seems that adaptor can be attached to the focuser itself, leaving the eyepiece free, In this case, the weigth support may not be the problem, but the focussing may be impossible.
You may need some sort of extension to ovecome this problem...
Perhaps you should consider something else.
Why don't you use the wooden adaptor you already have? You just have to attach it to the focusser outer barrel somehow and the problem solved, without a penny :-)

[Chrissyo]

The eyepiece should be able to take the weight just fine. The wooden bracket I've been using for 2+ years now has always hung off the eyepiece, which has never shown any hints of damage. Also the total weight hanging off the eyepiece with the F-adapter would be considerably less than with the wooden bracket I've been using because it only has to hold the camera. With my old bracket the eyepiece had to hold the weight of the camera AND two blocks of wood. So judging by past experience, it should be just fine.:)

To save from possible dents or scratches from the F-adapter to the eyepiece by the three screws, I'm thinking about maybe getting some cloth or plastic and wrapping it around the eyepiece beforehand. Maybe I could even run some masking tape around a few times as a bit of padding. From what I've seen on the eyepieces, they shouldn't be damaged by it.



I found an oldish webcamera (one of those logitec quickcams I think) no one wanted the other day, so I've taken the lens off, rigged up a quick adapter from an old film canister (those things are so useful!) and I'm waiting for some clear sky. Obviously it wont perform as well as a ToUcam, but I'm thinking it will give me a bit of an indication of what I could expect from one.:thumbsup: