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Old 22-03-2009, 08:47 PM
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Anyone used a Canon TE1.4x Converter for astro imaging with a telescope?

I've been wondering about this the past few days.. I've seen many examples of the TE1.4x extenders being used in conjunction with Canon L glass, and I've seen teleconverters being used for lunar shots through scopes...

I was considering a way to increase the imaging FL a little bit without vignetting the field too much..

The new GSO RC should be here early/mid next week, and Im waiting on word from Eric regarding a modded DSLR for "easy" colour imaging.. I was considering getting a TE1.4x extender to increase the focal length to 2270mm Although this would result in the scope being F/11 or there abouts, It would give me a nice field of view..

Just wondering if its been done? and if so, does it cause vignetting? I would imagine not, as generally speaking the longer the focal ratio, the less light falloff you tend to experience.. In any case.. Im open to suggestions, comments on this idea..

Alex.
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Old 22-03-2009, 10:45 PM
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scarper (Mart)
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I tried to use one the other day, but got an error on the camera. I think you need to cover 2 of the pins on the converter to make it work without a lens attached.

Havent tried since.
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Old 23-03-2009, 05:49 AM
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I just got the 2x from this site second hand and love it.
I am using it with 70-200mm
Phil
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Old 23-03-2009, 08:10 AM
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RB (Andrew)
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You will get errors unless you cover the pins like 'scarper' mentioned.
This is what I was told too when I inquired about it because the chip inside the teleconv communicates with the body.

I haven't tried it yet but intend on trying it with the TAK some time.
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Old 05-04-2009, 11:30 AM
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is this basically a barlow for the dslr?
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Old 05-04-2009, 11:37 AM
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essentially yes... Its a canon tele-extender that has a male bayonet mount on the back to attach to the camera like a lense, and at the front it has female bayonet mount to attach either a lens, or T-ring for astrophotography. The one in question, the TE1.4x multiplies the lenses focal length by 1.4, so a 200mm F/4 becomes a 280mm F/5.6 or a 8" F/8 telescope @ 1624mm becomes 2273mm F/~11.7 or there abouts. Would be very useful in some situations to gain the nesscasary magnification on some targets like M104...
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Old 05-04-2009, 11:39 AM
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Going down to CraigL's next week to try my Canon 1.4x extender on his Tak Sky 90 - will keep this thread in mind.
What is the best way to cover the pins without getting adhesive from the tape on them!? Do you use tape!!??
Doug
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Old 05-04-2009, 11:54 AM
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I dunno how you would go about it without having to permanently modify the extender Doug... I've been considering blutac? but that too could get messy... In the end I'll probably just buy a 2nd one and have an astro-extender and one for my lenses..
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Old 05-04-2009, 12:55 PM
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??? And, is it the pins on the scope/lens/t-ring or camera side that need to be covered!?
Doug
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Old 05-04-2009, 01:00 PM
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I have absolutely no idea mate... But Im sure google has the answers..
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Old 05-04-2009, 01:52 PM
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Quote:
Originally Posted by dugnsuz View Post
??? And, is it the pins on the scope/lens/t-ring or camera side that need to be covered!?
Doug
Just put some sticky tape over the pins on the tele-extender, the side that mates to the camera body so the extender can`t communicate to the camera and the camera doesn`t know it is there and will operate as if using it prime focus..
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Old 05-04-2009, 03:16 PM
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10 points to Gary! That will definitely work..

The answer was so simple yet it eluded me.. I think I need a steak... mmmm fooood
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Old 05-04-2009, 05:01 PM
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Has anyone had trouble achieving focus using one of these?
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Old 05-04-2009, 05:09 PM
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JJJ, Much like a barlow, this will cause your critical focus point (CFP) to move inwards.. Most imaging systems as you know require extension tubes to get the camera back to the CFP.. I dont forsee any focus issues when using one with a telescope..
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Old 06-04-2009, 03:26 AM
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I've been using a 1.4x TC on my scope for taking bird shots. I found the easiest way to get around the error message was to use a short macro tube. The really cheap ones on eBay have no pass though for the electronics. A quick click-click and you're good to go.
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Old 06-04-2009, 05:47 AM
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I've used a Nikon 2x TC-300 teleconverter with great success. The optics are FAR better than an average barlow, so unless you have top-end TeleVue or something, a decent (Nikon, Canon, et al) TC is a good choice.

Sharpness? How's this...
Attached Thumbnails
Click for full-size image (moon_appenine_range.jpg)
189.8 KB45 views

Last edited by Omaroo; 06-04-2009 at 06:52 AM.
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Old 06-04-2009, 06:38 AM
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That's sharp.
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Old 06-04-2009, 06:51 AM
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Quote:
Originally Posted by Omaroo View Post
I've used a Nikon 2x TC-300 teleconverter with great success. The optics are FAR better than an average barlow, so unless you have top-end TeleVue or something, a TC is a good choice.

Sharpness? How's this...
That looks great Chris!
I have been using a cheap Kenko 2x with the scope but find it shows coma CA etc and wouldn`t recommend a cheap substitute brand. But have heard the Sigma ones are pretty good as well.
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Old 06-04-2009, 07:07 AM
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I've a cheapy 2x too.
Be interesting to see how well it works.
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Old 09-04-2009, 10:41 AM
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Follow Up...
Met up with CraigL last night, successfully used the 1.4x Extender on his Tak Sky 90.

Covered the pins on the camera side of the extender to defeat the error message with no problems.

There was enough clearance to allow the protruding part of the extender to even be used with a filter on the T-ring also.

Only downside was the slightly longer time we took to achieve focus. Either side of the focus sweet spot showed obvious colour aberrations, so being very critical in focusing is a must. (When isn't it!!??)

Our test subject was Eta under a full moon.
Will post images soon so you can appraise the differences in image scale, sharpness etc.

Doug
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