I thought I'd write a quick and dirty review between these 2 scopes.
I have an AP140 and also an AP155TCC which is the reducer/corrector that gives F5.7 and will handle the largest chips around.
I also have a TEC180fluorite and flattener and it will also handle the largest chips.
Pictures speak louder than words - so the saying goes. So here are 2 images, taken with the same camera (Apogee U16M) at the same location (my dark site observatory in NSW) and around the same exposure time and not sure if it was the same night or the next night now.
http://www.pbase.com/gregbradley/image/115775756 TEC180
http://www.pbase.com/gregbradley/image/115775760 AP 140
The AP140 was using a Tak 4 inch flattener which luckily worked really well on the AP. The TEC used the TEC flattener designed for the scope.
Neither show any coma so the flattener is out of the equation.
As you can see they look much the same but the TEC shows a more close up image (longer focal length) and a bit more detail in the blue neb area (as expected from the larger aperture and capable of greater resolution).
But as far as sharpness, chromatic aberration, no coma etc there are very much the same.
The TEC is F7, the AP is F7.5.
They are both oiled triplets. The AP is ED glass (FPL53 presumably) and the TEC is ED glass plus a fluorite centre lens.
Mechanically the AP is slightly better but heavier for aperture. The focuser is really solid and smooth and the feathertouch microfocuser is a delight. I like the compression ring system AP uses which is solid and secure yet easy to fit. The TEC has a slightly awkward screw on ring to fit the flattener which takes a bit to get the thread to take. The AP focuser is better than the feathertouch focuser but the TEC feathertouch has to be described as very nice. I only say that the AP is better as it is stronger.
My AP140 needs something corrected in the sliding dewshield where it scrapes the black inside paint. Something AP are willing to fix when I get around to it. My TEC sliding dewshield is nice but you can slightly see the weld line where they made a joint and ground it back mostly but not all the way.
The 180 is manhandleable and is heavier than the 140 but the 140 is quite heavy for its size and quite a bit heavier than a Tak FS152 I had once.
Visually the AP140 is amazingly sharp. Part of that is the smaller image scale from focal length of about 950mm. The TEC is 1260mm focal length so you get a more close up view. Both are fabulous visually. The AP perhaps more a of a wow because the stars are such tiny pinponts but I think that is mainly the focal length difference giving a widerfield view.
Absolutely no chromatic aberration is visible with either visually or photographically.
The AP rings are superb. They are slightly stiff so they don't fall together with gravity and they have a great locking knob. The AP is really mechanical perfection and I couldn't fault it (apart from the dewshield which I will get fixed). They sell a nice quick release finder scope attachment as well. The reducer/corrector is a stunning piece of optical work. Really something.
The TEC flattener works perfectly as well. The TEC rings are different to others and I give them only 7 out of 10. They have a snap lock system which means you have to open them to slide the scope to get balance. If the scope were way off balance the scope could fall out at that point.
They also have a concave inside face with a recessed rubber insert.
The point here is if you are not careful you can scratch the scope lifting in and out of the rings as the edges of the rings are metal. Not a good design and I have seen comments from owners having scratched their scopes from this.
I have a set of APM German made rings for it which are ridiculously strong and probably over the top in strength but are the standard type with felt inserts and more like AP rings but stronger and thicker and super well made. The hole pattern though does not match my AP dovetail plates - grrrr.
The TEC 180 has given me many fine images and has considerable resolution and is a lifetime scope. The AP140 is a smaller scope but at the top of its class. It is more flexible than the TEC 140 in that you can get this marvellous reducer (no reducers are made by TEC), has better rings, a slightly better focuser (also it is 4 inch rather than 3.5 inch not a problem now but what about the 100 megapixel cameras of 5-10 years from now??).
Both are very similar scopes in optical performance. Both are sensational instruments. The TEC is my favourite as aperture rules and the comments above about slight mechanical preferences are minor indeed and it is extremely well made. I also have a thing about flourite. It is often said on the net there is no difference between FPL53 and fluorite. FPL53 is predominantly fluorite anyway. But there is a small factor of light dispersion that a laser test shows up. The fluorite does not disperse light hardly at all whereas glasses do to some extent. It is measureable.
Does it make a difference visually or imagingwise? Probably subtley only and hard to quantify and other factors dominate, but it is there.
Greg.