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Old 16-07-2010, 02:06 PM
taxman (Matt)
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Canon 135mm f2.0 prime

I am looking to put together a widefield setup for airline travel and those nights where I only have a hour or so for imaging. Basically, I want something fairly simple and self contained so I don't spend a long time setting up, checking power, drift aligning etc.

To that end, I have a Manfrotto 190XDB tripod, a Manfrotto 410 geared head (here in about a week) and my trusty unmodded 1000D along with a Williams optics RDF modified to fit into the hotshoe. When my tax return comes in, I will also be ordering a Skypatrol III.

Where I would like opinions is on the lens. I was tossing up between the 200mm f2.8 or the 135mm f2.0 and I was hoping there might be a few users who have had experience with either.

At the moment I am veering towards the 135 as the shorter f-stop means I can probably get away with 15-20 sec sub-exposures, reducing the setup time but the field is much wider than the 200mm f2.8, so I am concerned the image scale of anything interesting in the shot might be a bit small.

This will be my first camera lens >$1000 and I'd like to avoid my usual MO of getting something wildly unsuitable for the first few times so any thoughts or experiences would be appreciated.
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Old 16-07-2010, 03:48 PM
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leon
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Matt, you will not get a better and faster lens in that bracket than the 135mm, I have experienced both, and although both are fantastic lenses, I would go the 135, but that is OMHO.

Leon
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Old 17-07-2010, 10:29 PM
taxman (Matt)
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Thanks, Leon...

No one else uses either of these lenses?
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Old 17-07-2010, 10:46 PM
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How about a 70-200 L zoom in f2.8 or f4 formats? The Non-IS versions are in the ball park in terms of price (f2.8 version is a bit pricier than either of your choices though). And, f4 might be too slow for short exposures.
I love this focal length range for widefield astro work 70mm takes in the Rho complex thru to 200mm for Eta - having that zoom range is very useful.

Garyh took out the top prize in last year's Malins with a widefield image taken with the 200mm f2.8.

Have you checked out the Astrotrac drive as an alternative to the SkyPatrol?
http://www.astrotrac.com/

All the best
Doug

Last edited by dugnsuz; 17-07-2010 at 11:00 PM.
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Old 18-07-2010, 05:06 AM
luigi
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Without tracking the 135mm will be good for exposures up to 5'' aprox. So you definitevely need F2 I don't own a 135 and I don't know about Comma and CA wide open but it's a very very nice lens.
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Old 18-07-2010, 06:53 AM
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I don't know about this particular Canon lens .. but I did some study of other (older and today much cheaper) Canon lenses and some results of those investigations are posted below:
http://www.iceinspace.com.au/forum/s...ad.php?t=58629
http://www.iceinspace.com.au/forum/s...ad.php?t=39293
http://www.iceinspace.com.au/forum/s...ad.php?t=51866

Neither of those lenses work for astrophotography at full aperture (and for 200mm external aperture mask must be used). The 100mm one works best with it's own iris, but shows significant CA at corners - however this is not a problem as it is asily correctable by suitable software ( PT lens for example).

Christian Buil has done a lot of tests on Canon lenses, have a look here:
http://astrosurf.com/buil/

Also, you may consider Tair-11A, (Zenit lens) it is very sharp (but stepped down to f3.5 ~ f4) especially in the centre (at the corners it shows a bit of coma)
The other good one may be Telezenitar APO 135 F2.8.

All lenses above could be found for less that $250.. 10x cheaper but not THAT much worse

Last edited by bojan; 18-07-2010 at 07:16 AM.
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Old 18-07-2010, 07:52 PM
taxman (Matt)
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Thanks for the replies.

Doug, I had considered the Astrotrac, but (and this might sound silly), I love the look of the Tak and having had an excellent P2Z and now my even better EM11, I prefer to stick with a known quantity. As far as a zoom is concerned, I considered it, but with planned short exposures (30 sec max), I want as little glass as possible.

Luis, it is certainly hard to find a bad thing written about the 135, or the 200 for that matter, and the 135 seems to be the one people are most passionate about.

Bojan, thanks for those links, but in all the Australian photography forums I have googled, there is very little activity on the buy/sell sections. I did have a look at ebay, but it is just such a risk buying from there - nearly every time I have gotten something second-hand from ebay there has been a problem somewhere.
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Old 18-07-2010, 09:04 PM
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Astrotrac is too expensive gadget, for what it is and what it does...

The alternative is simple eq3-class mount, my example described here:
http://www.iceinspace.com.au/forum/s...ad.php?t=45079

I am sorry for your bad experience re purchase on internet .. I bought all my lenses via ebay and I had a problem only once, with one UK vendor. But this dispute was also resolved quickly.

Last edited by bojan; 18-07-2010 at 09:23 PM.
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