Omegon 90mm vs. SkyWatcher StarTravel 102?

[jjohnson3803]

I recently sold my f7 102ED refractor - a bit too big and bulky for my uses - and I'm considering getting an achro in the 90-100mm range.  I'm trying to decide between an Omegon 90mm refractor and a SW ST102.  I want to keep things as light and portable as possible for grab-n-go and travel.

Aside from the extra 10mm, any thoughts or experiences?  

Thanks.

 

[Louis D]

For GnG, I would get a 102mm or 127mm Mak.  They are very sharp on solar system objects and good for DSOs under 1 degree in size.  They are rugged, compact, lightweight for their aperture, and hold collimation very well even after being roughly transported multiple times.

If you insist on a refractor for GnG, I would recommend a 70mm or 72mm ED.  They are quite compact, and yet will show larger DSOs and solar system objects quite well.  If you want the best high power performance, spring for an FPL-53 version.

90mm to 102mm achromatic short tube refractors are still going to be big and bulky, just somewhat lighter than their ED/APO counterparts due to lighter weight construction.  However, the color on solar system objects and brighter DSOs will probably displease you since you've been using an ED refractor for some time.  I've been tinkering with filters to subdue the false color, but you end up with a yellow or green image for brighter objects to get a sharp image.  The unfiltered false color doesn't intrude much below about mag 2 to mag 4, depending on your sensitivity to violet light.  Thus, if you're only into faint DSOs, it might not matter much to you.

Another option might be a Heritage Newtonian in either the 130mm or 150mm size, but mounted on an alt-az setup using the dovetail.  I don't have experience with them, but they seem to be well regarded here on SGL and elsewhere.  Just be aware that the helical focuser can be a bit of a work in progress and doesn't play nice with zooms.

I did buy a 6" f/5 GSO Newtonian with dual speed focuser, and I can say that they are hands down a far better all around performer than a 6" short tube KUO refractor which I also bought for comparison.  That, and the Newt is about half the weight and is much easier to mount and use standing thanks to the eyepiece being at the top of the tube.

I suppose if you dropped down to a smaller diameter Newtonian like the SW 130P-DS it might be compact enough for GnG without sacrificing the dual speed focuser.

[jjohnson3803]

Yes, I have a 72ED.  I was thinking of upping the aperture a bit, albeit in a non-ED scope.

 

[Gonariu]

I have a acromatic refractor 80/400 whose I am content, a Konus Vista-80 which I put on a photographic tripod, at my car (a Fiat Panda) I haven't problems of space with the other luggages when I go to Cagliari for the week-end. I put a link in italian where there is a test of thise scope: https://www.dark-star.it/astronomia-articoli-e-test/test-strumentali/omegon-90-500-acro/

[andrew63]

If you like refractors and want easy to mount and compact, the 100mm F5 are very good. It's a different animal compared to the ED F7 ones and probably lighter than your ED72.  I use mine along with the 80 version on a Manfrotto tripod, but any small alt az will work. Obviously best for wide field deep sky, I've seen mag. 10 comets with it.

[jjohnson3803]

Ahhh, now that pic (and your comment about the weight relative to a 72ED) is compelling for me.  I have an AZ5 and a ScopeTech Zero and I'd probably use it most on the very lightweight Zero.

[jjohnson3803]

On 19/05/2023 at 13:37, andrew63 said:

 

Could you tell me what the length of the OTA is with the focuser racked in, no diagonal on?  I've seen some strange (to me) numbers quoted.  Thanks!