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World's first 200mm F/4 APO Flat-Field Astro Camera Lens will be released in this month

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#51 photobookie

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Posted 02 September 2020 - 10:28 AM

There is electronic focusing for telescopes with astrocameras and computers.  (Amy Astro has videos about it.)  You could do that with this lens if its 55 mm of back focus is sufficient.  (I don't know how much room the apparatus takes up.)  

Yes, here's one for a Space Cat that sits on top and doesn't take up back focus.  https://deepskydad.com

Trying to automate things with ASIAir Pro and thus none of these aftermarket ones that I've found work with the ZWO focusing motor. May just have to use my FSQ106 on my little GEM45 mount as it has a rack and pinion focuser but really want a wider field of view that the 200mm Askar provides. ZWO has an adapter for the FSQ that can be used with their EAF autofocuser. 


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#52 the Elf

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Posted 07 September 2020 - 01:38 AM

https://www.astrobin...?q=Askar ACL200

 

Most are by Mr. Ransburg, owner of Teleskop Service, taken with a nebula filter (Idas LPS D2). That keeps the deep blues out and may or may not have been done to hide halos. He does not explicitly say the aperture was full open but I can't see any diffraction spikes, so I guess it was.

The other images are processed to white button stars, may or may not be for the same reason. I hope someone comes up with true broad band images where the stars are not saturated and stretched far enough that some Ha nebulosity shows up. This is probably what most user will do.



#53 Joe Bruessow

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Posted 08 September 2020 - 05:39 PM

I just ordered one of these from Agena Astro for EAA.  Can't wait to try it out for wide field work using an asi294mc pro.  Maybe an asi2600mc is in my future!  I'll report once I have tried it out.


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#54 Astrojedi

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Posted 23 September 2020 - 12:55 PM

You can see my thread on this scope and first light here: https://www.cloudyni...phy-lens-scope/



#55 the Elf

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Posted 23 September 2020 - 01:51 PM

Finally I ordered the Askar FM180. Find my article here:

https://www.cloudyni...ph-first-light/

Another image here:

https://www.cloudyni...ion-wide-field/


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#56 Ensurf

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Posted 14 October 2020 - 09:21 AM

Hello,

I got a brand new Askar ACL200. I noticed that the backfocus is very important and may not be 55mm but 54,5mm because the T adapter for Nikon that I did receive with is 8mm only and a classic Nikon is 46,5mm. I tried a QSI 583WSG but could not have good FWHM in the corners despite relatively big pixels for this focal length. I think that it is because the QSI was to far and I had to largly exceed the infinite position (more than infinite...) on the focus ring. So I could focus but to far from optimal position of the optical train I assume. Did somebody experience this issue?

@Sharpstar team: I will design a special adapter for the QSI to shorten the distance. What is the external (not internal which is M48) thread dimension of the outter ring?

Clear Skies



#57 Ensurf

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Posted 14 October 2020 - 09:40 AM

Here is attached the position of the thread dimension I am looking for smile.gif

Thks 

Attached Thumbnails

  • Outter ring.png


#58 Michael Covington

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Posted 14 October 2020 - 08:02 PM

The back focus as tested with a DSLR is perfectly standard (55mm flange to sensor).  Note that you can move the lens quite a bit to allow for filters, etc.  

I do not think this lens has floating elements -- does it?  Doesn't it all move together?  Or not?



#59 Ensurf

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Posted 19 October 2020 - 09:10 AM

Hello,

Sorry for late reply. I looked carefully the travel of the fine focus ring and the coarse focus ring: they have the same effect: they move all the optical train. So I assume that there is no tricky floating elecment or "internal focus" like photo lens. I assume I was not in focus in my last test. I will try when weather is OK but for sure the pixels of the KAF83 (old timer) are "big" compared to the focal lens... CLS


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#60 jessebear

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Posted 30 November 2020 - 03:10 PM

Any more updates or pictures with this? Seems like an interesting lens. I'm looking at small APO scopes and lenses for wide field AP.

For fun I'd love to pit it against an old Soviet 200mm/F4 lens I have (Jupiter-21M).

#61 Michael Covington

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Posted 30 November 2020 - 05:57 PM

I am getting great results with it, with a Nikon D5500.

 

http://www.covington...caNeb-20x2m.jpg
http://www.covington...ephei-16x2m.jpg
http://www.covington...Orion-20x2m.jpg
http://www.covington...eme-stretch.jpg


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