Tring and barlow confusion

[Timbo32]

Hi All

just a quick question!!....  

                                       i am getting abit confused with all the different thread size's!

This is the barlow that i have in the link below

http://www.amazon.co.uk/Celestron-Telescope-Camera-Adapter-Barlow/dp/B00009X3UV/ref=sr_1_1?ie=UTF8&qid=1389299671&sr=8-1&keywords=celestron+barlow+t+adapter

What Kind or size of T ring do i need for my Canon 600d?

would this one work?

http://www.amazon.co.uk/Canon-EOS-T-Ring-Revelation/dp/B0039ZHWYK/ref=sr_1_2?ie=UTF8&qid=1389299824&sr=8-2&keywords=canon+t+ring+t

i am planning to connect my 600d to my scope via the barlow that can be removed if needed to take a few pic's of the moon:)

Thanks in advance

Tim

[Leveye]

If you look the correct t-ring for your canon and celestron are in the package deal just below the barlow listing on the amazon page to the left.

http://www.amazon.co.uk/Celestron-T-Ring-Adapter-Digital-Cameras/dp/B000237C9M/ref=pd_bxgy_ph_img_y

[ronin]

You can cause real confusion with that title. :eek:

Tring is not that far away and there is an astro shop there. :grin:

Trying to figure out what a possible relation between Tring and a Barlow was from the title really is difficult. :rolleyes:

[Leveye]

Prime focus may be an issue but using an eyepiece holder for your canon might work. You might want to work those numbers before you purchase. Try holding the camera over the focuser with the barlow installed to see where it does come to focus using liveview if you can. If you can't get it to focus by moving the camera back and forth then the mirror needs to be moved. Personally if it's a firstscope you're using try a webcam instead.

[Leveye]

http://www.optcorp.com/open-box-orion-steadypix-deluxe-camera-mount-05338-7018.html

[Timbo32]

i am more confused now

[Oddsocks]

Hi Tim,

The Canon "T" adaptor that you linked to on Amazon is the correct one for use with your existing Celestron Universal Barlow and "T" adaptor and your Canon 600d.

The male "T" thread at the end of the Barlow's 1-1/4 eyepiece fitting will screw directly into the female "T" thread on the Canon "T" adaptor.

According to the blurb on the Celestron site: ( http://www.celestron.com/astronomy/celestron-t-adapter-with-barlow-universal-1-25-in.html ) it will, with the Barlow attached to the 1-1/4" eyepiece fitting,  move the telescopes focal point out far enough to allow your DSLR to reach focus although this is not specifically stated as being applicable to the First Scope model. I did find a couple of web link comments at Amazon to other First Scope users that had been successful using your Barlow and a DSLR camera on Moon images.

There are a couple of issues that may affect your intended use: 

1. Trying to use your DSLR for "prime focus" photography (without the Barlow part attached for none-magnified images).

The Celestron blurb does state that some telescopes do not have enough "back focus" available when the Barlow part is removed to allow the camera to reach focus and helpfully they do not list which of their scope models this applies to but given the short travel focuser fitted to the First Scope I would suspect this might be the case, you would have to e-mail Celestron support and ask them to confirm that prime focus photography can be carried out with a DSLR and the First Scope model.

2. Balancing the telescope with the camera attached.

You will need to find some way of preventing the telescope tube from dropping under the weight of the camera when the Dec lock is released or a smashed tube and camera may be the result.

The other SGL posters have recommended using a webcam instead of your Canon DSLR because these don't need so much in the way of back focal length, many of them fit completely inside the focuser's draw tube so you know they will reach "prime focus" without any problem plus they only weigh a few grammes/ ounces and pose no balance problems.

The other option linked to was a clamp-on camera holder, this clamps around the focuser body and holds the DSLR in line with the focuser.

It can be used for both "Prime-Focus" photography with your DSLR lens removed or it holds your DSLR in-line with whatever eyepiece is in the draw tube, and produces an image by eyepiece projection just the same as you would see looking through the eyepiece with your own eye, again you would have problems with balance and it might not be possible to reach focus with your particular eyepiece(s).

You can carry out a simple test to find out where the "prime-Focus" point is with your First Scope, fit your Barlow's eyepiece tube to the focuser with the Barlow lens removed and no eyepiece fitted, wind the focuser all the way in towards the telescope body, look through the focuser and align the telescope on the moon, hold a piece of white card over the focuser's opening and gradually move the card away from the focuser draw tube until the image of the moon is sharply focussed on the card, the distance between the flat threaded end of the Barlow's 1-1/4" body and the card has to be equal or greater than 55mm, if so then you will be able to carry out "Prime Focus" imaging, if less then it will only be possible to use the DSLR with the Barlow lens fitted or by eyepiece projection.

HTH

William.

[Timbo32]

Thank you William your a Star thats exactly what i wanted to know, all the "blurb" can be confusing and overwhelming at times when you are unfamiler with the kit!!

this will give me plenty to fiddle with for a while along with th widefield fixed tripod photography which i am experimenting in!!

Thanks again william

Clear Skies Tim