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Canon L Lenses

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#1 Mhp_sd

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Posted 15 January 2021 - 06:01 PM

As I slowly venture into EAA and AP, I am enjoying using my 6SE/reducer but am wondering about something a bit wider.  I have a Canon 135 f2L and a 300 2.8L IS (v1).  Before I put time, energy, and money (Arca Swiss adapters, ZWO camera adapter (I have a 294MC)), is it worth the effort?  Is this a recipe for frustration?  Do I just save up for a small triplet APO?

 

I know that there are examples of people doing well with lenses like these - the question is how much of a struggle is it to make them work.

 

Thank you for any insights/advice/tips/tricks.



#2 ngc7319_20

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Posted 15 January 2021 - 07:00 PM

I tried with 300/2.8L (non-IS) and a ZWO camera.  The biggest challenge was focusing.  Without power, the internal focusing stuff in the lens wont go -- not even in manual mode.  I need to use a camera body and "park" the focus at infinity.  I made some manual focuser to fit between the camera and lens.  Maybe others have found a better work around.  There may be powered adapters that can control the lens internals.  Amazingly sharp lens once its working.  Somewhat sharper at F/4 vs F/2.8.

 

EF lens controller example:

 

https://www.astromec....org/ascom.html

 

https://innssi.com/c...ASAAEgKHKfD_BwE


Edited by ngc7319_20, 15 January 2021 - 07:58 PM.


#3 T~Stew

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Posted 15 January 2021 - 08:28 PM

I have that lens little brother the 300 f/4L. I think its a great lens for some wider AP though I generally use the 400/5.6 unless I really need the wider field. I was really thinking about selling my f/4L and trying to find a used f/2.8L to get more aperture advantage and better glass but now I realize these lenses have electronic motor driven focus with encoders and wonder just how precise the focus can be. That might be quite the hassle trying to use an astro cam.

 

Do you have a dSLR? Could always give it a try, an arca plate is always handy if you have your tripods setup with them anyhow. I shoot birds and things with gimbal head with arca mount so the camera and lens go straight from birding to AP without any changing, I just slide on the guide camera and ASIair (both with arca quick release clamps.



#4 pedxing

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Posted 15 January 2021 - 10:43 PM

I use that lens (135mm) with a modified T3i on an Astrotrac and stop it down to about f3.8 with a filter step-down ring to avoid diffraction.
 
Antares Region

Orion - Sword, Belt and Loop - 2 panels


Edited by pedxing, 15 January 2021 - 10:48 PM.


#5 Paulyman

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Posted 15 January 2021 - 11:35 PM

I have the Astro Mechanics adapter for canon lenses, I have a QHY183C attached to my 70-200mm f4L and it is awesome. I have full focus and aperture control via SGP, including autofocus. I find my 70-200 needs to be stopped down a step or two to minimise any coma and chromatic aberration, which is easy with the adapter and can be done from within SGP. I keep mentioning SGP because that is what I use, it is an ASCOM driver though so will work with the likes of Sharpcap just fine.



#6 Mhp_sd

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Posted 15 January 2021 - 11:42 PM

Thank you. Looks like it is worth pursuing. Any way to make this work with the Asiair pro using the 294mc (in terms of focusing)?

 

Beautiful shots pedxing!



#7 rj144

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Posted 16 January 2021 - 12:41 AM

I'm using a zoom lens on my Nikon D750 as a start and I'm seeing what focal lengths I most like to use before I get an APO in the future.  I personally like the setup and it's working fine so far.




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