Celestron Mak C90

[flanker]

Hey folks

Has anyone here used a Celestron Mak C90 scope for astronomy? I recently bought one as it was the best portable scope in my budget. I was looking for a scope portable enough to be used with bicycle tourism, rather than in an automobile.

It has a 90mm aperture and 1250mm FL. The FOV is supposed to be 1.6 degrees with the supplied 32mm Plossl. Would a 80mm achromat with 900mm FL do really better than this?

Thanks

Hari

[flanker]

And would it make real sense to get an 80 or 90mm achromat to complement this when I'm not on the bike?

[rowan46]

Like everything else there is a trade off . It it will beat a 80mm achro on portability and colour correction but that narrow fov is a killer on anything less than planets. A small pair of binoculars  8x42 may be a good way to offset this. Don't get me wrong a cat can be used to great effect on dso's  its just  that with this small an apparture dso's isn't something that this scope does well  90mm and less is better for  bright objects hence most  better astro scopes are optimised for wide field at this sort of apparture. Optically this scope will be up there with best of them at this apparture  except for fov and the quality of the mount will make a difference as to how useful it is for astro work.

[flanker]

Okay. So a 10x50 binoculars will be a better addition to my inventory than a 80-90mm achromat?

[NGC 1502]

I think a short tube achromat refractor like the popular Skywatcher 80mm diameter objective and 400mm focal length would complement your C90 very well.  

Both of those scopes will do things the other will not - the C90 will be better corrected for the medium to higher magnification views, but won't do low power wide field that the short tube refractor will be great for.

Both are nicely portable.  You could get many happy years of portable astronomy from those two.

Edit - something like this would be good http://www.firstlightoptics.com/startravel/skywatcher-startravel-80-az3.html also available without the mount.

Regards, Ed.

[flanker]

Oh okay! I'l go for that then! Thanks!

[rowan46]

I think a short tube achromat refractor like the popular Skywatcher 80mm diameter objective and 400mm focal length would complement your C90 very well.  

Both of those scopes will do things the other will not - the C90 will be better corrected for the medium to higher magnification views, but won't do low power wide field that the short tube refractor will be great for.

Both are nicely portable.  You could get many happy years of portable astronomy from those two.

Edit - something like this would be good http://www.firstlightoptics.com/startravel/skywatcher-startravel-80-az3.html also available without the mount.

Regards, Ed.

I disagree but no problems with that my opinion is as likely to be wrong as anybody's. i just think that for bicycle tourism some wide 8x42 binoculars will be easier to pack, less fragile ad will thus compliment the mak better an 80mm short achro is a wide field scope your mak will give better magnification and the bins will give a nice wide field.

[flanker]

Would a TravelScope 70 be good? I will be able to pack it along with the Mak and a tripod in a backpack.

Would a 10x50 binocs beat the TS70 for wide field?

[Alfian]

Hi Hari, I have the Skywatcher 102 Mak (1300mm) which is similar. The little Maks pack a big punch for their size and providing you have a decent finder need not limit you to lunar/planetary observation. Regarding the 900/90 achromat idea - a 900mm scope would give 28x with a 52 degree/32mm plossl which amounts to 1.8 degree fov. Whether the extra half a degree of fov is worth it is a personal choice. A faster shorter achromat (90/500?) would make a low power wide field of view option and would be very portable - but at the cost of increased chromatic abberation.

A pair of 10x50 (or perhaps 15x70) binos would make a good alternative to give you the wider sweep of view from which you can then home in on an object using the C90.

[Andy Mitchell]

I own a very similar Skywatcher 90mm Maksutov with the same 1250mm focal length. I believe both companies products come out on Synta's factory. Its an excellent design and short of buying a very expensive APO you are probably not going to get a better quality image, but.....

1250mm is a long focal length, and that means you will need a solid mount. I tried mine with my photo-tripod, very wobbly with the 25mm eyepiece I had at the time. On the EQ1 mine came with its much less wobbly, but still not ideal. So to use it expect to carry about a good weight of tripod/telescope mount.
 

A shorter focal length will make the mount less of an issue, binoculars or a widefield travel telescope would probably be more practical.

[Alfian]

Hi Hari, apologies for missing your comments on the travelscope (posted together) - the Travelscope (which I also have) in terms of the OTA is not a bad little scope - but let down by what comes with it. With a moderately priced star diagonal, a couple of plossl EPs, and a better tripod it works quite well. All of those improvements (although as Andy comments, the tripod needs to be fairly sturdy) can be also used with the C90.

As to comparing the travelscope with binos, yes a pair of 10x50s will almost certainly give a wider fov and binos are always handy to have around. That said, so much depends on quality. I love my binos but they cost a lot more than the travelscope.

[jonathan]

The StarTravel 80 on EQ1 is a nice scope, the EQ1 is sufficient for it for some basic visual astronomy, you'll be able to see plenty of clusters, the Orion nebula, Andromeda galaxy (though I think binoculars are better for this), some doubles, just don't expect to be searching for those distant galaxies or splitting double doubles with it.  Planets will still be coloured dots, you may see a bit of a disc for Jupiter (possibility of some indistinct cloud bands) and Saturn (oval shaped if the rings are showing).  Clusters will be visible as grey smudges, fuzzy groups of dots, or beautiful bright pin points, depending on which ones you look at.  It's a scope for the boot of a car or to carry out into the garden from the house / garage, you wouldn't want to walk very far with it.  Best used for wide field views, asterisms, open clusters, large targets.  Good on the moon but will suffer with colour fringing, a moon filter is a must.

15x70 binoculars are too heavy to sweep the sky with in my opinion, they are really for tripod mounting (with an L bracket) though will give excellent views of the moon and wide field.  A smaller pair such as 8x42 or 10x50 are better suited to finding objects, they can be held up to your eyes for longer and steadier by hand, that is not to say you couldn't also mount them on a tripod with the same L bracket, tripod-mounted moon watching or Orion Nebula viewing can be great fun through a reasonably good pair of binoculars.  I paid about £135 for my 8x42 binoculars, they are very nice and compact.

[flanker]

Thanks a lot for the advice, folks (esp Alfian)! So I got an Olympus 10x50 and will also use the 32mm eyepiece with the TravelScope 70.

[Alfian]

Enjoy your binos Hari. I've used my 32mm on the travelscope which gives 12.5x, way below what most people would consider useful - but as the scope is an 5.7 it gives an OK (ish)exit pupil of 5.6mm (which for my older eyes I admit is pushing it a little)  and a 4 degree fov. This virtually makes the not very good finder on travelscope redundant.

[nicks90]

Enjoy your binos Hari. I've used my 32mm on the travelscope which gives 12.5x, way below what most people would consider useful - but as the scope is an 5.7 it gives an OK (ish)exit pupil of 5.6mm (which for my older eyes I admit is pushing it a little)  and a 4 degree fov. This virtually makes the not very gold finder on travelscope redundant.

I also use a 32mm ep in my 70mm f5 giving x11 mag - amazing widefield views! Also doubles up as a mega finder for my 12" dob