6-inch Mak?

[pakarinen]

In the random churning of my idle brain, I’ve been thinking about a 6-inch Mak. I have 80mm and 120mm ST fracs and maybe a slower Mak would be a nice addition for lunar and ???. I still have my vintage C8 but I’m going to sell or donate the OTA. I already sold off the pod, wedge, and fork. I like the idea of a Mak since collimation appears to be straightforward.

So, any thoughts? Worth it? Not worth it?

[JayTee]

Between your 120mm frac and the 150mm Mak, I don't think you'd see much of a difference. How about something large and fast?

Cheers,
JT

[notFritzArgelander]

I have had my Intes MK 66 for 16 years now and I love it. It is hard to get a Rutten Maksutov Cassegrain anymore though. The Rutten Maksutov design has a secondary that isn't just a spot on the corrector plate, it has an independent curvature. That allows a much tighter spot diagram and better correction in the optics. In addition stray light is really well controlled by knife edge baffles.

They used to cost more than Chinese spot Maks and were clearly better. Since the Putin redirected the companies that made them into defense production they have become hard to find.

Here is a link that has some Santel and Intes Micro scopes

http://www.hoo-germany.de/index.php/cat ... grain.html

https://www.teleskop-express.de/shop/in ... copes.html

I've dealt with Teleskop-Express happily.

Of course if you are budget minded the Chinese spot on the corrector Maks are the way to go. But my Rutten Maksutov Cass has really spoiled me over the years. Great contrast and terrific on small DSOs and planets.

[DeanD]

I think it is worth a go. If you could pick up an Intes like not_Fritz that would be great, but the cheaper Chinese ones should still give great contrast and be excellent for moon, planets, and a lot of dso's. The best view I have ever had of Saturn was with an ETX125... I always remember my first view of the Swan through a lowly ETX90, and it blew me away because of the clarity and contrast.

I assume your ST120 is the Orion, and is not an Apo? I think a good 6" Mak would be a big jump in planetary performance.

All the best,

Dean

[pakarinen]

Yes, it’s an Orion F5 ST.

[Baurice]

I think if the 120mm is F/5 then a 6" Mak will be a very different type of beast. I have a 127mm Skywatcher Mak (one of those Chinese ones) and am very pleased with it.

If your 120mm is an APO or longer focal length achromat, you might not get much gain.

[notFritzArgelander]

I think if the 120mm is F/5 then a 6" Mak will be a very different type of beast. I have a 127mm Skywatcher Mak (one of those Chinese ones) and am very pleased with it.

If your 120mm is an APO or longer focal length achromat, you might not get much gain.

You would gain the ability to get high magnification views of the Moon and planets that are free from chromatic aberration. Nice as a 120mm ST f5 scope is they don't take high magnification well. Whether the preferred Rutten or Gregory (spot on corrector plate) design, a Mak will open up a whole new range of observing possibilities.

[Don Quixote]

IOptron also makes the Rumak type. I would like to have one of these. :-)

iOptron 150mm Rumak Maksutov-Cassegrain OTA - 6101
https://www.highpointscientific.com/iop ... n-ota-6101

Is this the type, nFA?

[notFritzArgelander]

IOptron also makes the Rumak type. I would like to have one of these. :-)

iOptron 150mm Rumak Maksutov-Cassegrain OTA - 6101
https://www.highpointscientific.com/iop ... n-ota-6101

Is this the type, nFA?

It claims to be and might be. I'm not sure because I can't see the collimation screws on the secondary. So here's what I glean from careful examination of the photo.

At first glance it looks like it's just a silvered spot on the corrector which would make it NOT a Rumak. But if you look closely it might just be a shiny covering over the collimation screws. I can see evidence of baffles around the secondary which indicates IT IS a Rumak. So does the f12 which is a little fast for a Gregory Mak. (f13 or slower, f15 is better for them.)

There is a YouTube video that shows what my MK66 looks like.

https://www.youtube.com/watch?v=XHlpPp-nbz4

The Intes has wonderfully effective knife edge baffles that the iOptron doesn't seem to share. I'll see if I can post a pic later that shows the OTA baffling better.

My take is that if I were in the market, I'd give the iOptron a go.

[notFritzArgelander]

PS I looked and found instruction manuals.

http://www.ioptron.com/v/Manuals/6101_MAK150_Manual.pdf
http://www.ioptron.com/v/Manuals/6101_M ... mation.pdf

It is unusual for the collimation on a Rumak to be done back at the primary but not impossible.

There is also a CN review where the owner of the iOptron misidentifies the corrector as the objective but seems sure about the difference between a Rutten and a Gregory Maksutov.

https://www.cloudynights.com/topic/4743 ... -mak-cass/

[notFritzArgelander]

Well I tried to get a photo that expresses the care in the baffling of my MK66 but it just doesn't work well. You have to be there. Anyhoo FWIW here goes



I like the design on the Internet Micro baffling a little better with knife edges just behind the corrector to the tune of 6 to 7. The Intes baffling has a very long Cassegrain baffle sticking up from the center hole in the primary.Then there is a knife edge at the end of the cone. In the picture there is very large circle (the primary), then a smaller one which is a reflection of the secondary in the primary, and emerging from that down and to the right is a dark conoidal cylinder terminating in a cutoff bright circle. That last is the front end of the baffle illuminated from the visual back.

[Mandrew]

The 6” mak is a totally different beast from the ST. You will love it. I have a 7” Mak, and it is tack sharp and lots of power. You may never go back!

[coopman]

I also think that a 6" Mak would be an big improvement over the 120ST for high power viewing.

[Richard]

My 150 Mac is about the same as my 8 inch dobs on planets so for that purpose yes , not good for DSO's , can handle 250X on a very good day

[Makuser]

Hello pakarinen. I started with a SkyWatcher C90 Mak, later moved up to an Orion 127 Mak, and finally to the Orion 170 Mak. The long focal length of the Mak telescopes make it possible to reach maximum magnification with a 12mm or 9mm eyepiece, instead of a 4mm or 5mm eyepiece with a "pin hole" eye lens. Although good for splitting doubles, they are not well adapted to DSO work, due to their very narrow field of view. And, they are not too friendly with "focal reducers" as are the SCTs. However, they are lunar/planetary killers. nFA covered the difference between the Gregorian Mak and Rutten Maks. The Gregorian uses a silvered spot deposit for a secondary mirror, as the Rutten uses a center secondary mirror button, which allows the optical engineers to use a different curvature than the corrector plate (meniscus) for more correct optical correction. The down side is you now have more central obstruction, but you gain with the finer detail of objects. The Maks are noted for their excellent acutance (sharpness, as in an acute pain). Don Quixote (Mark) and I had a telephone conversation last year about the IOptron 150 Rumak telescope. And, It seems to come with lot of nice refinements and accessories, however the link states of course, that it is for the OTA only, and you would have to buy suitable mount. Having said all of this, I think the IOptron 150 Mak and your fast wide field 120ST would be a great "1-2" punch for you. I hope this helps pakarinen, and the best of wishes on your telescope decision.

[John Baars]

I think it is worth considering.
While doing that you could consider the OMC140 as well. (5.5 inch)
https://www.orionoptics.co.uk/OMC/omc140maksutovca.html
I have the normal 1/4 P/V one, but Wolfgang Rohr tested the 1/6 P/V version:
http://r2.astro-foren.com/index.php/de/ ... tografisch
On Planets it equals my 120mm Doublet APO, maybe a tad better for it has no visible CA anymore. Sensitivity to seeing is a bit worse though, if not isolated.