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mislav

Diference in mak 127 and mak 150

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How big would be difference in mak127 and mak 150? (Specialy for planetary and moon)? Is diference noticable or just slightly?? Diference in price is very noticable.... Important ia that i live in red zone.... How priblematic is cooldown ib maks???

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It is always desirable to have slightly more aperture, but in the case of Maksutovs, a 150mm would be quite heavier, bulkier, and would take longer to acclimate to the outdoor conditions, and all for an extra 30mm.  I say "30mm" because a Synta(Sky-Watcher, Celestron, Orion) 127mm Maksutov is in reality a 120mm.  Despite that, a 127mm Maksutov is the sweet-spot among the varying apertures; not too small, nor too large, just right rather.  I have a Celestron C90, a 90mm Maksutov, here in the household, but I'll be forever wanting a 127mm until I finally get one.  But I'm in no hurry, as I want to see if the aperture is ever increased to an actual 127mm.

Edited by Alan64
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1 hour ago, Alan64 said:

It is always desirable to have slightly more aperture, but in the case of Maksutovs, a 150mm would be quite heavier, bulkier, and would take longer to acclimate to the outdoor conditions, and all for an extra 30mm.  I say "30mm" because a Synta(Sky-Watcher, Celestron, Orion) 127mm Maksutov is in reality a 120mm.  Despite that, a 127mm Maksutov is the sweet-spot among the varying apertures; not too small, nor too large, just right rather.  I have a Celestron C90, a 90mm Maksutov, here in the household, but I'll be forever wanting a 127mm until I finally get one.  But I'm in no hurry, as I want to see if the aperture is ever increased to an actual 127mm.

I've seen a few mentions on internet that Mak127 is somehow stopped to ~122mm, but I wonder why / how this is done?

Is it stopped at focuser side, or is primary smaller than it should be, or perhaps secondary?

As far as I know, with maks, primary needs to be a bit larger than corrector plate? Is this the case that both corrector plate and primary mirror are of the same diameter?

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I imagine it's some manufacturing necessity.  Let's just hope that they find a better way, and up to the 127mm advertised.

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Just reading CN thread about measurements, and indeed it's related to the fact that both corrector plate and primary mirror are both 127mm - but corrector plate spreads light out and not all light that goes into corrector lands on primary mirror - so effective aperture is something like 119mm.

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Take that up with the manufacturer at the next conference, and if they fix it, I'll buy one.

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5 minutes ago, vlaiv said:

Just reading CN thread about measurements, and indeed it's related to the fact that both corrector plate and primary mirror are both 127mm - but corrector plate spreads light out and not all light that goes into corrector lands on primary mirror - so effective aperture is something like 119mm.

Thats my understanding as well. To achieve a full 127mm aperture the primary of a mak-cassegrain should be a little oversized. Neil English mentions this in his report on the Synta Mak-cass 180 which seems to have an effective operating aperture of 170mm.

 

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3 minutes ago, John said:

Thats my understanding as well. To achieve a full 127mm aperture the primary of a mak-cassegrain should be a little oversized. Neil English mentions this in his report on the Synta Mak-cass 180 which seems to have an effective operating aperture of 170mm.

 

Yes, it looks like all Synta maks have this issue - and it should be evident from tube design - as long as it's flat - corrector is the same aperture as primary mirror, so primary is effectively "smaller" than physical size.

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It might be worth a look at the Bresser 127 which is reviewed here, http://www.astrotest.it/test-reports/compound-systems/maksutov-gregory-bresser-127-1900/  you will have to get Google to translate the page. Also the scope may have had some minor changes since then but the reviewer claims the aperture is exactly as stated in comparison to SW127. Longer focal length as well which may help with planets, doubles etc. I don`t know if anyone on here has actually got one, if they have would be interesting to hear how they are.

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Over the years I've had a few MAKs, sw 80,90 3x127, 150 and an Orion OMC140 1/6th wave. What do I have now, a 127. 

I set the OMC140 against a sw127 and expected the sw to be trounced, it wasn't so sold the 140

I tried a sw150, lovely scope but much bigger and heavier than a 127. So much so that you might as well have a 8" sct and the portability side is diminished. 

I think the 127 mak gives the best price/performace/portability set up. 

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I would stick with the 127mm Mak for portability purposes.  If you want much better planetary performance, get an 8" Dob and replace the secondary with a 20% or less by diameter mirror.  Planets look way better in my optimized 8" Dob than in my 127mm Mak.  They are more stable, higher in contrast, and sharper in details.  Saturn looks etched against the sky with the rings sharp and clear with no false color at the edges.  The Mak by comparison doesn't show the gaps sharply, edges in general are less distinct, and there is some misalignment of colors at the edges.  Folks describe Saturn as looking fake because it is so sharp and free of aberrations.  Those same folks describe the Mak views as very good, but clearly a telescopic view.  The Dob gets out of the way while the Mak reminds you that you are looking through a telescope.  It's very much the same difference as between looking through a premium eyepiece priced like a whole OTA and a bargain Plossl.  The former gets out of the way while the latter does the job, but keeps reminding you you're looking through an eyepiece.

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It is worth adding that the reduced aperture issue mentioned above (127/150/180 Maks) has been discussed in (laborious) detail on "another forum", and that current 150 and 180 Maks have effectively the full aperture I believe, but not the 127 Mak.

Measurements with my 180 Mak (3 years old) indicate an effective aperture of 179-180 mm, and this matches observations from other users, whereas my 127 Mak measures at 119mm.

I would agree with others though that the 127 Mak is a very good performer with near diffraction limit resolution, and very portable - it is now my grab 'n go scope of choice.

Chris

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