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Meade 1000mm f/11

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#1 Ownthenight

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Posted 23 June 2022 - 10:09 PM

Does anyone have any experience with the 1980s American made Meade 1000mm f/11 Cass? White body, with the finder scope?

Is this scope of good quality?

#2 RichA

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Posted 24 June 2022 - 12:23 AM

Does anyone have any experience with the 1980s American made Meade 1000mm f/11 Cass? White body, with the finder scope?

Is this scope of good quality?

Not great.  Modern Maks/SCTs are better. I don't even know if the corrector was coated though it was claimed to be.  That, and the 88% reflectivity mirrors and the central obstruction means pretty mediocre light through-put, around that of a 3 inch refractor.  Some have said good examples exist, but unless you can grab it (unmounted) for $100 or less, there are better choices.  If this is the same model, the benefit of the scope is that it can be used easily as a camera lens owing to the camera-lens style focusing.  But 1000mm f/11, even with modern cameras means critical focusing and stability is a must.



#3 luxo II

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Posted 24 June 2022 - 01:03 AM

It was an offshoot from the Meade 2045 SCT. I had one in the 1980s for solar eclipses… it wasn’t particularly great with a Pentax film SLR. Not particularly sharp and transmission wasn’t great either, even then.

I had it for 20+ years and even had the mirrors recoated locally at one point, before giving it away to someone.

There’s an aspect you need to understand regarding old camera lenses - the resolution of typical films on a good day was circa 150 lines per inch and at the time spot sizes of 25 microns were considered acceptable for lenses. An awful lot of lenses are still around secondhand from that era which people remember as good or even excellent in their day, but compared to modern optics they’re pretty awful.

Edited by luxo II, 24 June 2022 - 01:12 AM.

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#4 deSitter

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Posted 24 June 2022 - 03:32 AM

I assume you mean the 90mm f/11 "mirror lens". It's OK with a low power eyepiece, e.g. a 40mm Plossl. It's WAY inferior to the optically similar 90mm f/14 ETX90. A Maksutov design should be f/12 or slower for good performance.

 

The mirror lens is very well made, so is a reasonable camera lens, although my Nikon pocket camera at high zoom is better.

 

-drl



#5 Ownthenight

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Posted 24 June 2022 - 01:58 PM

Not great. Modern Maks/SCTs are better. I don't even know if the corrector was coated though it was claimed to be. That, and the 88% reflectivity mirrors and the central obstruction means pretty mediocre light through-put, around that of a 3 inch refractor. Some have said good examples exist, but unless you can grab it (unmounted) for $100 or less, there are better choices. If this is the same model, the benefit of the scope is that it can be used easily as a camera lens owing to the camera-lens style focusing. But 1000mm f/11, even with modern cameras means critical focusing and stability is a must.



Thank you for your input...it was well taken.

#6 Ownthenight

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Posted 24 June 2022 - 01:59 PM

It was an offshoot from the Meade 2045 SCT. I had one in the 1980s for solar eclipses… it wasn’t particularly great with a Pentax film SLR. Not particularly sharp and transmission wasn’t great either, even then.

I had it for 20+ years and even had the mirrors recoated locally at one point, before giving it away to someone.

There’s an aspect you need to understand regarding old camera lenses - the resolution of typical films on a good day was circa 150 lines per inch and at the time spot sizes of 25 microns were considered acceptable for lenses. An awful lot of lenses are still around secondhand from that era which people remember as good or even excellent in their day, but compared to modern optics they’re pretty awful.


I understand this perfectly..., Thank you for taking the time...

#7 Ownthenight

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Posted 24 June 2022 - 01:59 PM

I assume you mean the 90mm f/11 "mirror lens". It's OK with a low power eyepiece, e.g. a 40mm Plossl. It's WAY inferior to the optically similar 90mm f/14 ETX90. A Maksutov design should be f/12 or slower for good performance.

The mirror lens is very well made, so is a reasonable camera lens, although my Nikon pocket camera at high zoom is better.

-drl



Thank you for that information.

#8 davidmcgo

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Posted 24 June 2022 - 06:40 PM

Meade had several 1000mm tubes in the way back.  The 4” 2040/2044/2045 tube was also sold as a spotter marked 1000mm f10 Schmidt Cassegrain.  OK to good, blue tubes.  Really really really sensitive to collimation though.

 

They also had a blue or black tube 1000mm f10 Mirror Lens marked that had a Magnin secondary, those reportedly are kind of soft.  There was also a version sold with a barrel focus like a camera lens.

 

Then there was the 97 1000mm f11 Mak.  All of those focused like a camera lens.  Mechanically they were really nicely made in contrast to the sloppy Celestron machining on the C90s but optics were pretty similar.  Ok to 100x and deteriorate rapidly above that. In the samples I have owned or used.

 

Dave


Edited by davidmcgo, 24 June 2022 - 06:41 PM.


#9 GSR

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Posted Today, 10:24 AM

I recently purchased a used D=103mm F=1000mm black tube (with focus ring not knob).  In initial checkout I came up with FWHM of PSF to be about 30 um.  But I was not set up at optimum back focus, and seeing was maybe 1-2 arcsec.  So at best 25 um FWHM - rough estimate.

 

Does anyone know the correct flange focal distance at infinity focus for this model?



#10 Ownthenight

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Posted Today, 04:30 PM

Meade had several 1000mm tubes in the way back. The 4” 2040/2044/2045 tube was also sold as a spotter marked 1000mm f10 Schmidt Cassegrain. OK to good, blue tubes. Really really really sensitive to collimation though.

They also had a blue or black tube 1000mm f10 Mirror Lens marked that had a Magnin secondary, those reportedly are kind of soft. There was also a version sold with a barrel focus like a camera lens.

Then there was the 97 1000mm f11 Mak. All of those focused like a camera lens. Mechanically they were really nicely made in contrast to the sloppy Celestron machining on the C90s but optics were pretty similar. Ok to 100x and deteriorate rapidly above that. In the samples I have owned or used.

Dave


Acknowledged. Thanks for the reply.


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