Prime focus AP with lenses?

[billw]

How is this done? I have read somewhere in passing that you can get lenses that fit inside the T-ring/adapter housing, but I can't see any of these lenses on FLO, and can't workout what to google for (my attempts get no results useful). If I wanted to do, for instance, a close up of a DSO or planet, how would I do it? Basically how can I change my FOV while using prime focus technique?

Also on a related note:

Has anyone used this: http://www.telescopeadapters.com/index.htm?true2_eos.htm? Is it as good as it seems?

I am worried about using a Canon 350D with my 130P Explorer because I read that it may be impossible to focus due to the length of the focuser. This would appear to solve that problem... Would I be able to mount lenses in it?

Yes many questions as I am about to be expending a fair chunk of money, thanks for reading!

[Capricorn]

If you put a lens in the path then you are not doing prime focus photography.

So you cannot by definition have a lens for it, as if there is a lens then it isn't prime focus.

This could be why you cannot locate anything.

The field of view is fixed for prime focus, it is whatever the objective of the system delivers.

I suspect you mean the technique of putting a barlow into the optical path to get a larger image of planets, but that is not prime focus.

Do not try it on DSO's they are far to faint to be magnified and then get a meaningful image.

Might be simplistic but isn't the link just another form of a T-ring but bigger ?

What mount is the 130P on, if it is the EQ2 that it is advertised with the astrophotography will I think be close to impossible with that scope and a DSLR on it. If it is on the Synscan AZ then the mount is wrong.

[billw]

Ah okay that explains it then.

The adapter in the link connects a Canon EOS camera directly to a 2" focuser without needing a separate T-ring and camera adapter. Also it is only one I have seen that is 2" rather than 1.25 which would seem to be a big bonus when trying to attach to my 130P as it should stop me getting the problem of not being able to in-focus enough (as I can remove the 2" to 1.25" adaptor from the focuser and connect directly).

I am getting a HEQ5 Syntrek + ASCOM + bits for the mount. I am going to make another post when I have worked out my final equipment list so I can hopefully have help checking it over, but first I need to ask a few of these newbie questions to work out what I am doing!

So if I understand correctly it just simply isn't really possible to adjust the FOV when attaching my camera using a T-ring adapter? Except maybe using a Barlow lens..

[atmenterprises]

I think what you're wanting to do is called eyepiece projection. If you search for that term you may find more hits that are in line with your thinking.

[umadog]

Eyepiece projection is also known as afocal photography, since collimated light comes out of the back of the eyepiece you don't have an image-forming condition. Instead, you need another lens before the detector. Cornea+lens then retina or SLR lens then CCD.

[atmenterprises]

Eyepiece projection is also known as afocal photography, since collimated light comes out of the back of the eyepiece you don't have an image-forming condition. Instead, you need another lens before the detector. Cornea+lens then retina or SLR lens then CCD.

Huh. I'd read on here that eyepiece projection and afocal were different things altogether.

http://stargazerslounge.com/topic/126072-afocal-vs-projection-vs-prime-focus/

Is that not right? Not trying to stir the pot - I want to make sure I don't spread misinformation.

[billw]

http://stargazerslounge.com/topic/126072-afocal-vs-projection-vs-prime-focus/#entry1250268

If that is the correct definitions then it looks like what I want is eye-piece projection photography. I don't want to buy a camera lens, I want to take advantage of all the lenses I already bought for my telescope, to allow me to photograph exactly what I am seeing, and also use long exposures to pick up on things I can't see.

Can anyone tell me how to attach the camera when doing eye-piece projection (or if this is definitely what I want)? I have seen something called the Orion SteadyPix Universal Camera Mount, but it is difficult to find in the UK (well, neither amazon nor FLO sell it as far as I can see). How come this isn't a really common piece of kit? It seems like it would be the first stop for AP...

Thanks for the info so far!

[billw]

(this forum doesn't allow editing posts?!)

http://www.scopesnskies.com/prod/60.html

So here we go, this looks like what I was originally talking about.

[Cornelius Varley]

(this forum doesn't allow editing posts?!)

http://www.scopesnskies.com/prod/60.html

So here we go, this looks like what I was originally talking about.

That's the piece of kit you need. Your eyepiece drops into the tube and the camera body attaches to the tube via a t thread. The limitation of the tube is that it will only allow you to use only certain eyepieces, the eyepiece has to be smaller than the tube for it to go into the tube. A more sophisticated version is this one http://www.telescopehouse.com/acatalog/Meade_Variable_Projection_Camera_Adaptor.html which allows you to vary the distance between the eyepiece and the sensor, adjusting this distance allows you to vary the magnification of the eyepiece.

Peter

[Tinker1947]

Pentax XW and Baader Hyperion EP's have a 43mm thread to take a adapter that allows a DSLR to be attached, so you place the EP in the focus tube as per normal, with the DSLR on the EP, results can be good if you have a EQ mount and good PA as a extreme this is Mizar using a Pentax XW 5mm with the DSLR on the end.....

Canon attached to a Pentax XW....

This Mizar with its Binary (not Alcor) look it up in Stellarium and get the FOV down to 0.00100 or there abouts, that's what this image is......thats Pentax WX 5mm with the Cannon 1100D attached...

[billw]

That is awesome! So I think what I will do to start with is get one of http://www.telescopeadapters.com/index.htm?true2_eos.htm (to ensure I can do some form of imaging, without the not-enough-in-focus problem), and a T-ring camera adapater + one of http://www.scopesnskies.com/prod/60.html, which will work with the cheapo lenses that came with my Explorer 130P. And then save up for the Baader Hyperion lenses!

Thanks a lot for the help everyone!

[StuW]

The Baader Zoom MK3 also has the thread+adapter ability making framing a little easier.

Sent from my HTC One X using Tapatalk 2

[Hightower]

Billw - how did you get on with this? Any images you can share?