DSLR autofocus AID

[George]

http://tinyurl.com/2n9a83

Seems this little gem will help in focusing in manual mode

[cygnusx1]

Of course this is only for M42 mount lenses, so won't help with prime focus focusing.

[Jamie]

You don't need this type of thing for imaging with an AF lens on the Canon cameras as they

have a "beep" function that tells you when you are in focus.

As for your statement about M42 lenses you are quite wrong there Kevin.(well 50% anyway)

It can be used with M42 mount lenses like you say, but it can also be used for prime focus too.

As many will already know (but i will explain for them that don't) the term M42 is directed at

the thread that is on the inside of a T adapter or in this case the inside thread of the gizmo

that Upgrader posted about.

To achieve "prime focus" with this setup all you have to do is screw on a 1.25 or 2" adapter onto the M42 thread and you are ready to image using prime focus.

I have one that i bought from a place in Canada a while back and have used it in "prime focus" mode.

[George]

I was thinking of screwing the 2'' nosepiece directly into this so prime focus imaging is not an issue

[blinky]

Jamie,

Does it well when used in a prime focus setup?

[Kaptain Klevtsov]

Well as M42 isn't T thread, you ought to use an adapter. OVL do one so Steve should be able to sort you out.

Kaptain Klevtsov

[Jamie]

Craig i have only used it a couple of times and i found it to be something that will get easier to use with practice....

Basically you just focus on the brightest star within the field of view you want to image.

Once you get the "beep" you are focused..

KK

I was under the impression that because the diameter of the inner thread of a T adapter was 42mm this was why it was referred to as an M42 thread.

If i have my information wrong as to why it is named so i apologise, but the thread is 42mm in diameter on a T adapter/ring/mount.

[Kaptain Klevtsov]

The thread pitch is slightly different, though from memory I couldn't say which is the coarser. One is 1.5mm, the other 1.75 ISTR.

You get the adapter free with the Tal 200K as it has a native M42 thread on the focuser and the adapter lets you use T thread accessories on it.

Kaptain Klevtsov

[brendant]

I have used one of these for some time on my 400D and TAL-2 scope.

Just to clear a few things up, this adaptor is for M42 lenses so the thread is M42 x 1.0mm pitch, a normal T-Mount is M42 x 0.75mm pitch so they are not the same thing, fortunately the thread on the focuser of my TAL scope is M42 x 1 so it fits correctly without an adaptor. If your scope has a T-thread mount it will not. Because it is lower profile than a normal T-Mount you can gain valuable distance on a Newtonian scope which may be the difference between achieving focus and not - certainly the case on my scope.

Focusing, this is a lot more difficult than it sounds, the star must be placed on the centre focus spot for focus confirmation, very difficult if not impossible unless you have a driven mount and electric focuser, one of the reasons I fitted an electric focuser otherwise it works well.

Re using it for prime focus, yes it is possible (use it all the time) and can be used regardless of what is connected, be it the telescope or a manual M42 lens, extension tubes etc..

Brendan

[beamish]

Just had a look on fleabay uk and there's a uk supplier 18.00 in total ! and probably a tad quicker.

http://search.ebay.co.uk/_W0QQsassZphotobits42

just found the adapter ring too on astro-engineering site 16.99

[jarbi]

Hi,

I just saw this thread , very interesting findings ! For me it is too late, because already invested in this one:

http://www.kwtelescope.com/FotoSharp_page.htm

Works pretty well, but much more expensive than the solution here.

On the positive side, it looks like a standard T-ring, so no additional special piece needed to use it.

cheers,

Janos

[beamer3.6m]

You don't need this type of thing for imaging with an AF lens on the Canon cameras as they

have a "beep" function that tells you when you are in focus.

I have never heard the "beep" on my camera - how do you get this function to work.

[Jamie]

You don't need this type of thing for imaging with an AF lens on the Canon cameras as they

have a "beep" function that tells you when you are in focus.

I have never heard the "beep" on my camera - how do you get this function to work.

On the 350D when you switch the camera on and push the menu button the beep function

is the bottom of the list that appears on the rear screen.