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The poor, deluded people (camera lenses versus scopes)

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#1 RichA

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Posted 11 April 2021 - 03:31 AM

Should I point out on that group that using a $15,000 camera lens and teleconverters to do the job of a $1000 refractor is...nuts? 

Camera people are just getting their feet wet with telescopes thanks to "landscape" Milky Way images, but despite the fact

that the Leica is a great lens and the video was taken in quite good seeing (you can tell by the relatively calm air), it's still a PALE representation of what is possible with a decent telescope.

 

https://www.dpreview...400mm-f2-8-lens

 

 



#2 Jon Isaacs

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Posted 11 April 2021 - 03:41 AM

https://www.cloudyni...128-cassegrain/

 

 

https://www.flickr.c...tetaken-public/

 

Jon



#3 WadeH237

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Posted 11 April 2021 - 04:27 AM

I guess that somebody should tell these folks that they are doing it wrong...


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#4 luxo II

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Posted 11 April 2021 - 04:53 AM

Oh it is an impossible mission. I’m aware of a photo forum where someone is convinced his little superzoom compact camera resolved Saturn and rings - handheld. Not through a scope.

Needless to say all he shot was an out of focus blob of something that happened to be egg-shaped. The argument raged for 400+ posts... and he never conceded that’s not possible.

Edited by luxo II, 11 April 2021 - 05:08 AM.


#5 Mark9473

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Posted 11 April 2021 - 07:03 AM

Should I point out on that group that using a $15,000 camera lens and teleconverters to do the job of a $1000 refractor is...nuts? 

Camera people are just getting their feet wet with telescopes thanks to "landscape" Milky Way images, but despite the fact

that the Leica is a great lens and the video was taken in quite good seeing (you can tell by the relatively calm air), it's still a PALE representation of what is possible with a decent telescope.

I agree it's not the best tool for the job, but it's still just a video.

With the usual frame stacking and image processing the end result as a still image would not be a "pale representation" of what a telescope of similar size would achieve.



#6 Mark9473

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Posted 11 April 2021 - 07:05 AM

Jon, any reason why you're comparing results from telescopes with 400 mm aperture, to that camera lens having 400 mm focal length?



#7 Jon Isaacs

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Posted 11 April 2021 - 07:34 AM

Jon, any reason why you're comparing results from telescopes with 400 mm aperture, to that camera lens having 400 mm focal length?

 

I can think of at least two reasons:

 

- To show what is possible, what a hi res image of the moon actually looks like.

 

- To show that it's not necessary to spend $15,000 on optics... and that's used.

 

I wonder if they were operating the camera at F/2.8 or if it was stopped down?

 

The Dawes limit for an F/2.8 lens with a 400 mm focal length is 0.81".. I wonder how this lens would do...

 

Jon



#8 doole

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Posted 11 April 2021 - 11:46 AM

Should I point out on that group that using a $15,000 camera lens and teleconverters to do the job of a $1000 refractor is...nuts?

No. Undoubtedly that's not all they're using it for.



#9 teashea

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Posted 11 April 2021 - 08:26 PM

Should I point out on that group that using a $15,000 camera lens and teleconverters to do the job of a $1000 refractor is...nuts? 

Camera people are just getting their feet wet with telescopes thanks to "landscape" Milky Way images, but despite the fact

that the Leica is a great lens and the video was taken in quite good seeing (you can tell by the relatively calm air), it's still a PALE representation of what is possible with a decent telescope.

 

https://www.dpreview...400mm-f2-8-lens

Some people already own the camera lenses.



#10 alan.dang

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Posted 11 April 2021 - 08:49 PM

The Leica APO Telyt R is very impressive.  It’s sharper than the Canon 400/2.8 and comes from an era when Leica melted their own glass. 
 

Canon strehl is 0.8
https://arxiv.org/pdf/1401.5473.pdf

And that is 16 elements 12 groups.

 

The APO Telyt R is 10 elements in 8 groups but is really an air spaced triplet with a flattener and a focus and telephoto group.  It was corrected into IR.

 

Canon Optron makes the optics in Takahashi scopes so it’s not as if camera lens manufacturers are unable to produce premium optics.  We just don’t see them apply their technology toward premium optics.  
 

My copy of the Canon FD 800/5.6 has a figure that compares favorably against the Astro-Physics 130EDF6 even though it doesn’t have anywhere close to the same color correction.  

 

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