Astro Physics 155EDF 1st Month Impressions!!!

By: Vlad Fedosov

So I “accidentally” bought an AP 155EDF on an AM auction(I picked up the scope in person and had the pleasure of meeting Herb and Paula, owners of the AM!). The scope was in a way beyond a dream scope(the AP130GT was it, and I already owned it). Anyhow I wanted to give a first impression of using the scope for both deep sky as well as the planets. If you don’t want to read the entire post, I’ll just say that it exceeded my expectations!

Double Stars:

The first couple of times I had the scope out was just to test the overall functionality of the scope just to make sure it’s in good working order. The first time I had the scope out I had it pointed at Venus(was really close to the horizon) before dark. I had my wife come out to take a look through it(to warm her up to my little unexpected purchase;). The view was nice and it was nice and color free. Later that first night I did confirm that the collimation of the scope was spot on! I did split a few easy doubles to warm up the scope. I then proceeded to observe double star λ Cygnus which it a relatively close separation of .9″. To my surprise, the seeing was good enough to push the scope to about 460x and get a nice clean split in moments of good seeing(I have notes that I suspected a split in my 178ED in the past. This time it was a certain split!). Very nice, I knew that the scope had amazing optics! Having to work the next day I called it a night confirming that the scope functions as it should!

Deep Sky:

The next real time that I used the 155EDF was on a very transparent and moonless night from my simi-dark sky driveway. I started observing a few DSO’s that I was really familiar with such as the Dumbell Nebula(m27) and the Ring Nebula(m57). I immediately noted the excellent contrast that the scope provides. This is no surprise as this is what I was used to from my experience with the AP 130GT. I was curious to see what the AP 155EDF would do on the Vail Nebula! Putting the ES 25mm 100° FOV eyepiece into the 2.7″ focuser I was able to produce a 2.4° true FOV at 41x. Certainly not wide enough to fit both sides of the nebula in one view. Unfiltered the nebula was there but honestly not very well defined. Not surprising as I knew that an O-III filter is pretty much a must for this one. Putting on an O-III I was greeted with a drastically more contrasty and defined nebula system that filled the entire FOV! 

Now before I get into what the 155EDF showed on the Vail, I’d like to give you some background on my favorite other ways of observing this nebula. This involves employing a combination of a short focal length refractor(FSQ-106) and larger dob(SpicaEyes 24″ f/3.1). This to me is the nirvana of visual observation on this nebula. The wide field scope can show the entire nebula complex all in one view so you can get a “good overview of the land”. The large dob can provide a zoomed-in perspective on any individual part of the nebula for a close-up detailed view! This combo of scopes does provide an extraordinary visual viewing experience!

Back to the 155EDF. The view that this scope provides, I’d describe as unique! You get a kind of combo of the above two scope system all in one package. The FOV is quite wide with the 155EDF, but only wide enough to show ane half of the nebula at a time. The half that is shown is in MUCH greater detail than that of just the wide field scope(FSQ-106). I do not know how to describe it but the view was one of the best I had ever seen of the nebula. I think the image scale was very nice to frame a large portion of the nebula while still providing a great amount of detail. The high contrast of the AP155EDF no doubt helped make it a very awesome view!

Having been so impressed with the view I got of the Vail Nebula I went on to checking out the Crescent and the North American nebulas. Again the detail that I saw in these nebulas was really much greater than I would expect from a 6″ telescope!!! The Crescent was particularly nice as the FOV was wide enough to fit the entire thing and at a really high level of detail. 




Testing of the ultimate 6″ refractor could not be compete without doing some planetary observing right??? I had to see what the AP 155EDF could do on the gas giants! I set up my alarm clock for 2am on a clear night. After getting out of bed I mounted the AP 155EDF on the g11 that was already setup in the backyard. I let the scope cool down for probably 20min while I gathered everything I would need to observe. I was excited as this is the first time this part of the year that I was going to observe them!

The first target that I pointed the scope at was Jupiter! At low power(~120x with Baader Zoom at 8mm) the planet looked tac sharp and displayed the main gas belts as well as some hints of finer detail. Bumping the power up to 170x(6mm Baader Classic Ortho) I sat there mesmerized by the vast amount of finer details in the two main belts! I could tell that the scope was not fully cooled though in that the view was still not quite sharp.

I next proceeded to check out Saturn. Even at the relatively low power of 170x I was greeted with one of the coolest views of the planet ever! The contrast was obviously VERY high that the 155EDF provided in that it showed a prominent belt on the planet very distinctly. The rings are also at such an angle that they cast a shadow on the entire disk of the

 planet! Very cool 3d effect! 

Once the scope was fully cooled about an hour after I brought it outside I could tell that the seeing this night was actually quite good! I pulled out my instrument of choice for serious planetary observing; the Binotron binoviewer! I like to use this thing in straight-through mode with large refractors as it’s a really cool experience sitting right under the scope looking throught it(also I feel it helps the view a bit by eliminating the diagonal and optical corrector you need to reach focus)! The eyepieces I used were the 10mm and 6mm Baader Classic Orthos. combined with the 2x setting in the Binotrons power switch this produced about 205x and 341x. 

The seeing was certainly good enough to support the 205x 100% of the time this night. Both Saturn and Jupiter looked stunning! I mean it was like looking at a picture of the planets!!!! I was sitting there like a little kid on Christmas just soaking in the view! Many fine swirls were seen(as noted in my “sketch;”). Switching out to the 6mm BCO’s I would say that the seeing was good enough about 25% of the time to use that power. Still, in the moments of steady, the detail seen on Jupiter in particular was out of this world! One notable thing was how well-defined the moons were. They were certainly little orbs(with Io I belive being visibly larger than the others). Interestingly enough I did not see the great red spot as shown in the Sky Safari??? I must say that this night of planetary observing was one of the most memorable ones that I have had!!!

Not to make this report any longer than it needs to be I will say that out of the 100’s of scopes that I have owned the AP 155EDF is one of the most impressive. In a mere month of use, it has already provided me with some of the most memorable views that any scope has provided. There really is something special about having a perfect, unobstructed telescope!