IM 715 v Questar 7

enjoyed a very interesting night comparing my 715 delux to a questar 7 a friend owns in good conditions.

One of the reasons I got the 715 was i was well aware of the quality images a 7 inch mak can deliver after using the Q7 on several occasions.

We concentrated on Jupiter and both scopes showed superb resolution and contrast.

The GRS was coming round and both scopes showed impressive detail in several bands including white spots ovals festoons and the division near the GRS.

The questar was beaten but only by a whisker. The image was slightly higher in contrast and all in all a harder image in the 715.

Tyhe obstruction is 33% for the Q7 and 24% for the 715 without secondary cap in place.

In terms of brightness the 715 was clearly giving brighter images over the mid 70's Questar with standard coatings.

More colour in the grs was visible in the 715 but the Q7 is a superb performer and everything visible in the 715 could be seen with patience in the Q7.

The Q7 took longer to reach thermal stability than the 715 which had a fan that appeared to prove its worth.

In terms of darkness and light scatter the Q7 showed some stray light entering the field around Jupiter not visible in the 715 hence a blacker background.

I'm not putting the boot into the Q7 but the 715 Delux has a clear advantage even if slight.

Thanks for that comparison--one I've always wondered about. If only the Russians could match the Questar in terms of mechanical and cosmetic coolness. I love my STF 180 Mak, but of course the Questar 7 is one of those unobtainium dream scopes. Also, Questar should reduce the secondary obstructions on the scopes back to the 28% of the originals. To claim the highest performance the obstruction should be minimized and your review shows that clearly.