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Meade 7" Maksutov

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#1 donadani

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Posted 18 December 2017 - 01:32 PM

Hi guys,

 

what do you think is actually a good price for the OTA? and is that conus-thing around the secondary that increases the CO really needed? wouldn´t it possible to just put it away to reduce CO? (maybe with adding a separate dewcap to reduce straylight...).

 

cs

Chris 



#2 rmollise

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Posted 18 December 2017 - 01:59 PM

Several considerations here.

 

The _baffle_ around the secondary might be dispensed with if you plan on using an adequate dew shield all the time to block stray light. I'm guessing you wouldn't notice that much performance difference, however.

 

How about the weight in the rear cell? If there was one, and many of the OTAs, even those sold as OTAs only had it, has it been removed? If not, it's not uncommon for these telescope to NEVER cool down. Think "Questar 7.",

 

Unless it's at a really good price--say 400 bucks or so, you'd probably be happier with one of the current Chinese 180mm MCTs.


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#3 donadani

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Posted 18 December 2017 - 03:06 PM

Hi Rod - thanks for your input!

 

Well I read that baffle increases the CO from about 25% to 38% - I think the difference should be seeable on faintest details but was not sure if it only has that function to keep straylight away or maybe any other?

 

The counterweight was just removed and price is about what you mentioned - optics should be great as intra- / extrafocal image was sayed to be the same... 

 

I had a ETX90 and ETX125 before and if the optics is as good as they were this scope is a real bargain! I mean an Intes 715 is about three or four times that price just on the used market.

 

...very exciting...



#4 Mitrovarr

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Posted 18 December 2017 - 03:27 PM

The 7" meade maks have a great reputation. I would absolutely go for one at that price. Do keep in mind that if it's been de-counterweighted, the whole thing was probably tore down and it might need re-alignment.
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#5 jgraham

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Posted 18 December 2017 - 03:50 PM

I have two Mak 7's; one from LX50 production and the other from LX200 production. Both have had the weight removed and both give the sharpest image that I have ever seen in a production scope. Given the exceptional image quality I'd be hesitant to fiddle with the secondary baffle. If nothing else it keeps light from entering the primary baffle from around the secondary. If it t'ain't broke...

 

A Mak 7 in good condition for $400ish is very attractive. I paid a fair amount more than that for mine 'cause I wanted one. I ended up with two so that I could configure one for visual and the other for imaging.

 

My baby....

 

LX90 Mak 7 (7-23-2017)-1.jpg

 

...an LX200 Mak 7 on an LX90 configured for visual. With the weight removed the built-in fan acclimates the scope very quickly.

 

Good luck!

 


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#6 mvas

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Posted 18 December 2017 - 03:51 PM

Hi guys,

 

what do you think is actually a good price for the OTA? and is that conus-thing around the secondary that increases the CO really needed? wouldn´t it possible to just put it away to reduce CO? (maybe with adding a separate dewcap to reduce straylight...).

 

cs

Chris 

Yes, the Secondary Baffle is really needed.

It is part of the required baffling for this Maksutav.

And, no a Dew Shield is not a substitute for the Baffle around the secondary.


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#7 donadani

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Posted 18 December 2017 - 04:14 PM

Hi John,

 

great pic - thanks! 

 

Looking forward to check it out! I don´t really needed it but my parents were looking for a present and this one was for sale - so adding a little bit by myself and it fitted ;) This thing will arrive just at them and lands directly under the tree ;)

 

It´s from an LX200 with EMC coating and was removed from the forkmount - so the tube as some little scratches from what I know but everything else should be fine - and btw. it´s the OTA only.

 

Now I organized some rings - rail and SC visual back I just have here from an earlier scope :) Next to that back I have Baader SC adapter to work with a prism - what would you prefere for the scope mirror or prism?

 

@mvas: mmmhhh... - why? ;)

 

cs

Chris



#8 freestar8n

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Posted 18 December 2017 - 05:33 PM

As mvas says, the baffle is important for blocking light nearly on axis. It may be ok without it for deep sky work, but lunar and planetary and daytime work would be affected. And those are the cases you want highest resolution.

I guess you could take it off and replace it as needed with a mask in front that covered beyond the secondary.

Frank

#9 carolinaskies

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Posted 18 December 2017 - 07:12 PM

I've never heard of a 7" Mak Meade being bad optically.  Most often it was simply the fork mount not allowing the tube to swing down for parking making it an absolute unweildy thing for packing out for short nights.   At $400 that is a steal if it's in great shape.  



#10 jgraham

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Posted 18 December 2017 - 09:54 PM

The Mak 7 does great on a rail as well...

 

Atlas LX50 Mak 7 (11-3-2017)-1.jpg

 

This is my Mak 7 from LX50 production fitted with a Losmandy rail riding on my Atlas.

 

Wonderful scope!

 


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#11 vahe

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Posted 19 December 2017 - 09:35 AM

"As mvas says, the baffle is important for blocking light nearly on axis. It may be ok without it for deep sky work, but lunar and planetary and daytime work would be affected. And those are the cases you want highest resolution.
I guess you could take it off and replace it as needed with a mask in front that covered beyond the secondary."


 

That is exactly what Astro-Physics did with their 10” Mak, very similar to Meade as both are Gregory variant and both have about the same focal ratio, the AP Mak has a 23% co, but there is a catch to it, the 23% co. is undersized for this Mak, it will block stray light from entering the eyepiece if the eyepiece field lens is small, for a physically large eyepieces or any superwide with very large field lens AP offers a +/-30% mask that goes in front of the meniscus and blocks stray light from entering the larger eyepiece.

.
The AP design assumes that for high power planetary observation where high contrast is important usually a small eyepiece is used, for example a 12mm Ortho has a 10mm field lens, it would be safe with 23% obstruction, but if you insert a big low power Nagler or one of the current grenade sized superwides the use of larger mask would definitely be required, again the design assumes that for low power applications any loss of contrast due to the larger co. is of no serious consequence.

.

The size of opening at the front of center baffle is also an important variable in determining the overall secondary baffle size for blocking stray light.

My guess is that the Meade would work in a similar fashion, the original secondary baffle supplied with this scope is a one size fits all simplified approach to blocking the stray light intended for the worst case scenario, personally I would not be scared of experimenting with the baffle.

.

It is very easy to do a reverse engineering experiment to find out at what point stray light enters the center baffle, just install a 1.25” canister in the focuser. Drill a hole the size of your planetary eyepiece field lens, 10mm in diameter for example, hold a light bulb right at the back of the hole and then observe the results from the front of the scope, if the light bulb is not visible that means there is no stray light issue with or without the secondary baffle for that particular sized eyepiece.

.

And finally stray light entering the eyepiece while viewing planets does not have much effect on the overall view but would be a minor disaster if stray light enters the eyepiece while viewing the Moon, as for daytime work a 7” Mak is a bit too large to offer a satisfactory results, for daytime use a Maksutov like 3,5 Questar or its many less expensive copies would be an ideal instrument.

.

I am a Mak fanatic and have three MC’s.

.

Vahe


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#12 donadani

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Posted 19 December 2017 - 02:15 PM

Scope is on the way now - looking the days to come :)

 

Thanks vahe! - hmm let me guess - one of the three is from AP - isn´t it ;)

 

So did I get you right? if looking at smal fields the baffle is NOT needed - but for big fields it is??? isn´t that just the other way round then Frank said? well it´s late maybe I have to read your pos again ;)

 

...got the rings today too - hope the tube fits in... 

 

cs

Chris



#13 rmollise

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Posted 19 December 2017 - 02:53 PM

Hi Rod - thanks for your input!

 

Well I read that baffle increases the CO from about 25% to 38% - I think the difference should be seeable on faintest details but was not sure if it only has that function to keep straylight away or maybe any other?

 

The counterweight was just removed and price is about what you mentioned - optics should be great as intra- / extrafocal image was sayed to be the same... 

 

I had a ETX90 and ETX125 before and if the optics is as good as they were this scope is a real bargain! I mean an Intes 715 is about three or four times that price just on the used market.

 

...very exciting...

 

For that price, I'd say "full speed ahead." Don't expect miracles, of course. It's a nice enough telescope.



#14 rmollise

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Posted 19 December 2017 - 02:54 PM

I've never heard of a 7" Mak Meade being bad optically.  Most often it was simply the fork mount not allowing the tube to swing down for parking making it an absolute unweildy thing for packing out for short nights.   At $400 that is a steal if it's in great shape.  

 

Oh, there were some distinctly average ones, that's for sure. I've run across a couple, unfortunately, which would indicate there are more than a few out there. Most are quite good, however, once the cooldown issue is addressed. I would not say quite as good as Intes/Intes Micro, however.



#15 jjack's

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Posted 19 December 2017 - 06:34 PM

I had one. Good but no miracle here. The laws of optics are what they are. 38%obstruction is prety high and decrease contrast on planetary views. I have seen a 200/1000 skywatcher newton giving more detailled views on Jupiter.

More : take care if you want to take off the secondary baffle to reduce obstruction : the hole into the primary mirror can be greater than the secondary spot ! Other than that it is a nice scope. Mine was textbook perfect. The f/6.3 reducer for sct fits perfectly and give a nice f/10 scope with larger field.


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#16 vahe

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Posted 19 December 2017 - 06:36 PM

 "hmm let me guess - one of the three is from AP - isn´t it wink.gif"

 

 

No, all three are TEC.

.

Vahe


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#17 Live_Steam_Mad

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Posted 19 December 2017 - 06:43 PM

I had one. Good but no miracle here. The laws of optics are what they are. 38%obstruction is prety high and decrease contrast on planetary views. I have seen a 200/1000 skywatcher newton giving more detailled views on Jupiter.

More : take care if you want to take off the secondary baffle to reduce obstruction : the hole into the primary mirror can be greater than the secondary spot ! Other than that it is a nice scope. Mine was textbook perfect. The f/6.3 reducer for sct fits perfectly and give a nice f/10 scope with larger field.

Interesting. My 7" Meade Mak has also got the most perfect optics I have ever seen in any telescope, with crisp clean Airy Discs at high magnifications. Pity about the 39 per cent (as I measured it) obstruction that I found when I disassembled it whilst taking the internal 3Kg cast iron weight out! Also a pity that Meade never bothered to overcoat protect the secondary, and as a result my secondary coating is blue and cloudy (that's why it was 100 GBP when I bought mine, amongst other reasons).

 

I am quite familiar with it's peformance on Mars and Jupiter, and will try my new-to-me (old!) second hand SkyWatcher 200P F5 Newtonian that I bought from a local friend, on Jupiter next time I get the chance, and compare them.

 

I find it fairly easy to collimate the 7" Meade Mak at 666x in focus with 8mm TeleVue Radian and 2x Barlow, despite what I have read. The 200P is more challenging to collimate at 250x with the same eyepiece and Barlow but I managed it, can't wait to try it out on Mars also.

 

Regards,

Alistair G.


Edited by Live_Steam_Mad, 19 December 2017 - 06:46 PM.


#18 jjack's

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Posted 19 December 2017 - 06:51 PM

Waiting for your review live steam man. Be objective ! wink.gif



#19 Asbytec

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Posted 19 December 2017 - 07:14 PM

It is very easy to do a reverse engineering experiment to find out at what point stray light enters the center baffle, just install a 1.25” canister in the focuser. Drill a hole the size of your planetary eyepiece field lens, 10mm in diameter for example, hold a light bulb right at the back of the hole and then observe the results from the front of the scope, if the light bulb is not visible that means there is no stray light issue with or without the secondary baffle for that particular sized eyepiece.

 

waytogo.gif

 

I removed the secondary baffle from my Orion 150, then tested is from all angles. I find the silvered spot is plenty large to prevent light from directly entering the eyepiece field lens (which cannot be seen looking through the meniscus). Looking down the primary baffle, and using a laser, I can hardly see the end of the mechanical path at the end of the OTA. Add a diagonal and it's impossible to see the edge of the eyepiece barrel. There may be some reflections internally along the primary baffle wall, but they seem well attenuated especially with flocking paper on the primary baffle interior. I found the baffle system in the (older) Orion was too tight, so much so it was vignetting the full aperture. 

 

Best Small.jpg



#20 Phil Barker

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Posted 19 December 2017 - 10:48 PM

 

Hi guys,

 

what do you think is actually a good price for the OTA? and is that conus-thing around the secondary that increases the CO really needed? wouldn´t it possible to just put it away to reduce CO? (maybe with adding a separate dewcap to reduce straylight...).

 

cs

Chris 

Yes, the Secondary Baffle is really needed.

It is part of the required baffling for this Maksutav.

And, no a Dew Shield is not a substitute for the Baffle around the secondary.

 

Skyflooding will ruin the views without the baffle on wider fields.  May not occur for planets or high power work.  A compromise would be to reduce it to baffle say a 20mm field.

 

I would point out the corrector actually cause the light to diverge or go outwards and so effective obstruction is  less than the physical width of the baffle.  The primary is larger than 7 inches for this reason also.

 

The 2 inch wide field views in those maks are superb from my experience and the baffling is effective in reducing stray light over a large field.  I owned an intes micro 715 that was hopeless with 2 inch eyepieces (skyflooding and vignetting) but superb on planets (smaller obstruction).

 

Maybe reducing the secondary baffle in the meade 7 will allow this?   



#21 donadani

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Posted 20 December 2017 - 12:53 AM

Will use it for high mag planet views only - for widefield a cheap refraktor will do much better.

 

Had an Orion UK OMC140 before - it was a Rumak design too and I cant remember it had any baffle - will test the socpe just as it is first but maybe later remove that baffle and just check it out...



#22 freestar8n

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Posted 20 December 2017 - 02:27 AM

"As mvas says, the baffle is important for blocking light nearly on axis. It may be ok without it for deep sky work, but lunar and planetary and daytime work would be affected. And those are the cases you want highest resolution.
I guess you could take it off and replace it as needed with a mask in front that covered beyond the secondary."


 
That is exactly what Astro-Physics did with their 10” Mak, very similar to Meade as both are Gregory variant and both have about the same focal ratio, the AP Mak has a 23% co, but there is a catch to it, the 23% co. is undersized for this Mak, it will block stray light from entering the eyepiece if the eyepiece field lens is small, for a physically large eyepieces or any superwide with very large field lens AP offers a +/-30% mask that goes in front of the meniscus and blocks stray light from entering the larger eyepiece.
.


Cool - I had no idea AP did it with their mak. It does make sense.

I have a meade mak7 at a remote location from an old lx50 - and I had the spot re-coated, then I re-attached the baffle.  I haven't been able to collimate it and try it out - but should be able to eventually.

 

Frank



#23 jgraham

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Posted 20 December 2017 - 08:42 AM

Although it's not my largest scope by a long shot, my Mak 7 has become my favorite deepsky scope. No, it doesn't break the Laws of Physics, but the sharp, high contrast image is simply woderful. Something magical happens when all of the light goes where it is supposed to go. As far as the field of view, UWA eyepieces were made for this scope! There are few objects that don't fit nicely into the field of the 30mm UWA, and I do most of my star-hopping with a 20mm UWA. For the moon and planets I like to use my binoviewers fitted with my trusty old Meade 20mm RG Erfles. I have also been using my imaging Mak 7 for deepsky imaging; the flat, coma free field is really nice to work with. Imaging at f/15 isn't for everyone, but it can be a lot of fun!


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#24 donadani

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Posted 20 December 2017 - 11:53 AM

Wanna have it now!!! - the two smaler Meade Maks I had before had outstanding optics! would be too great if that 7" is on the same level... laugh.gif



#25 Starman27

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Posted 20 December 2017 - 11:27 PM

Just wanted to share my Meade 7 inch LX200. Excellent performer. Since it was observatory mounted, it was always ready to go.

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