Jump to content


- - - - -

Denkmeier 2” IVB Star Diagonal with Power X Switch

Discuss this article in our forums

Denkmeier 2” IVB (Interlocking Visual Back) Star Diagonal with Power X Switch

by Kevin Vaught

Back in October, I reviewed the Denkmeier 2” IVB (Interlocking Visual Back) Star Diagonal. This is a continuation of that review along with the Power X Switch that I added to the IVB in November. I had meant to get this written much sooner but decided that more time should be spent with the unit evaluating its use and performance. I will also explain how to install the Power X Switch (PXS) as I purchased the PXS as an add-on to the IVB. The entire unit (2”IVB with PXS) can be purchased as a complete system but I did not have the funds available at the time to buy the entire setup. Russ Lederman with Denkmeier Optical spoke with me at length several times during the process of my purchasing the parts and subsequent installation of the PXS. He was very helpful and very patient with me as he explained the procedure of installing the PXS on my 2” IVB Star Diagonal. The installation was not difficult at all with his expert guidance. So let’s get to the installation of the Power X Switch onto the Denkmeier 2” IVB (Interlocking Visual Back) Star Diagonal.

First a little bit about the IVB star diagonal. This is a high quality machined 2” dielectric mirror star diagonal that is available for SCT and refractor type telescopes. It is advertised to be 99% reflective in its light transmission with a 1/10th wave flat substrate Quartz mirror. I can definitely say that the images of all types of objects viewed are bright and crisp and with plenty of contrast.  I will expound on more of the optical merits latter, so for now, we will concentrate on the installation of the PXS. The picture below shows the unit that I received without the Power X switch installed. In this picture the telescope side is to the right and eye piece side the left.

(All of the pictures of the installation of the PXS to the IVB star diagonal are oriented in this fashion unless otherwise noted.)

In order to install the Power X Switch onto the diagonal, one needs to remove the barrel on the telescope side of the diagonal. This is simply a matter of unscrewing the barrel in a counter clockwise rotation until the barrel comes off.

In the picture above, I have removed the barrel from the IVB and am now ready to install the Power X Switch (PXS). If you will look closely at the picture above, you will notice a small set screw on the side of the diagonal with the logo printed on it. The set screw is located to the right of the logo and in between the two Philips head screws. This set screw is used to lock down the barrel once it is screwed into the body of the diagonal. Russ told me about this set screw and advised that I may need to loosen it in order to remove the barrel. In my case I did not need to do this, however, this set screw will be used once the PXS is installed.

The following picture is of the Power X Switch before I installed it. This is the side of the PXS that will face the observer. Notice the nice large white letters on each end and the knurled sliders below each letter. Also note the threaded barrel protruding from the opening of the middle of the housing. This is the part that threads into the diagonal where the barrel we just removed threaded into.


The next picture shows the PXS threaded on the body of the diagonal. This procedure was incredibly simple and straight forward. The machining of the parts is first rate and they go together extremely smoothly. As a matter fact, this is so well designed that the threads start to get tight at the point where the PXS is oriented in the proper position without having to over tighten the two pieces. I will also state again about that set screw. After I threaded the PXS onto the diagonal I merely tightened up that set screw to prevent any rotation of the PXS on the diagonal body.

The picture above is the barrel that we removed in the first step attached to the PXS threaded portion that you can see in the picture above that. Again, this piece threads very easily into the PXS and all I did was snug it up hand tight. Also notice the “teeth” on the silver colored part. This is one half of the IVB descriptor.

The picture above shows the completed installation of the PXS onto the Denkmeier 2” IVB star diagonal. Also notice that the black barrel with the 2 thumb screws mates to the teeth of the silver part. This is the other half of the IVB descriptor. I explain what this is and how it works in greater detail in the article/review that I wrote in October of 2013 that is posted on this website.

Now, wasn’t that easy? At this point we would attach the completed assembly to the back of the telescope using either the rear cell or, in my case, a micro focuser such as the JMI EVH motorized focuser.

Not everyone will want to do it this way, buying the two parts independent of each other. The entire unit can be purchased as a whole and then just installed on the back of your telescope. As stated earlier, I did it this way due to not having the funds available to purchase the whole shooting match at once.  The cost for the entire assembly is $498.00 plus shipping. If you decide to purchase the two pieces separately, then the only additional cost will be for shipping each piece by itself. Each part is $249.00 plus shipping. The cost for the case is $49.00. I am at this time considering purchasing the filter slider system that will also attach to this system allowing the use of filters without having to thread them onto your EP’s. Look for that write up soon (I hope).

You can go online to www.denkmeier.com to get current pricing and all the information you may need. I just can’t stress enough how helpful Russ was to me before and after my purchase. Yes, it is an expensive piece of equipment, but if you read on, I think you will see how handy this device really is in observational astronomy.

Using the Denkmeier 2” IVB Star Diagonal with Power X Switch

I have been using the IVB PXS now for a couple of months and I can tell you with no hesitation that it has made my time at the Eye Piece (EP) even more enjoyable than ever before in all my 40+ years of touring the skies above. From not having to worry about the diagonal slipping and falling over to clunk me on my head to having 1 EP turn into 3 with the slide of a switch. (You can read about the head clunking in the first review that I mentioned earlier).

Before getting the Power X Switch (PXS), in order to use my C11 in native F10, I would have to remove my diagonal, un-thread the F6.3 FR/C (Focal Reducer/Corrector) from the telescope, then reattach the diagonal. This is a time consuming affair and is a major disruption to the flow of my observing sessions, not to mention the possibility of dropping something in the dark. Of course, if I again wanted to go back to a wider FOV using the F6.3 FR/C, I would have to reverse the steps above, further disrupting my session, and again increasing the chances for a dropped EP, diagonal, etc. Prior to getting the PXS I just left my F6.3 FR/C on the telescope all the time, thus never using the scope at its native F10. I was missing out on an entire viewing option that now I can take advantage of. Not to mention the ease of going to a 2X Barlow with the same simple sliding motion.

I’ll walk you through one of the ways that I use the IVB PXS so that you can get a sense of the power that this product can impart to your observing sessions. Before proceeding with the actual procedure I need to explain some verbiage that I will be using.

RC Mode: the PXS with the F6.3 option engaged (the A side slid into the optical train)

Native Mode: nothing in the optical train. Telescope at F10 (both A and B switches in the outward position)

2X Mode: the PXS with 2X barlow option engaged (the B side slid into the optical train)

With that out of the way, here we go:

I am starting out without having an aligned mount so that it will be clear how powerful this tool can be even in the alignment process. I have a Celestron CGEM DX mount and it is mounted on a pier in my observatory. Although I don’t need to align every session, I do realign every once in a while due to having to rebalance the scope because of putting a different telescope on the mount, camera additions, guide scopes, etc. When I align, I use a 12mm Meade illuminated EP with cross hairs to make sure that I get as accurate an alignment as I possibly can. With the PXS, I start in RC mode to get as wide a FOV as I can with a 12mm EP (about 45degrees AFOV). I use this after I have centered the alignment star in the finder (in my case a Telrad) and have pressed enter on the HC or clicked on enter in NexRemote, which I use almost exclusively now. I will then center the star in the EP in RC mode, slide the A switch out of the optical path, putting me in native mode (F10), center the star again, then slide the B switch into the optical path putting the scope in the 2X mode. After centering in the 2X mode I will then press the align key or click align on the virtual hand controller (NexRemote or NR) on my laptop screen. Now please understand that this is an extreme way of performing an alignment and I don’t think I would do this same procedure if I didn’t have the Power X Switch. It would just be too time consuming and inconvenient to have to unthread and rethread the FR/C each time for each star and then have to insert a Barlow for that last high power centering of the star. And to then do this for the next alignment star and then for 4 more calibration stars would make a 2+4 star alignment take a very long time. I am of course talking here about the Celestron way of doing alignments. When I was using an Atlas my alignment only consisted of 3 stars, but even with 3 less stars this procedure would take a very long time as well. And again, without the PXS, I would not have done an alignment with this many steps anyway, even on 3 stars. . I find that when performing my alignment in this fashion, EVERY OBJECT THAT I ISSUE A GOTO COMMAND FOR IS DEAD CENTER IN THE EP FOV!! I am not over exaggerating here. Every object, from one side of the sky to the other, all night long, every night is dead center in any EP!! I have read many posts by many different people expounding on the need for a precise alignment. Well, this procedure is VERY precise and works very well for me.

Now, all is not peaches and cream with using the PXS, whether it is on alignment stars or for visual observing after an alignment, as you must re-focus after each change in the optical components just as would have been necessary without the PXS. But to me, having only to re-focus is a small price to pay for the convenience of 3 different views through the same EP without removing the EP from the diagonal.

To continue on in our use of the PXS as it pertains to an observing session it goes like this: I will start in RC mode for the initial GOTO. Let’s use M42 as our example. Normally I would start with my 17mm Nagler T4 in the RC mode giving me a nice, fairly wide FOV that encompasses most of the M42 region. The Trapezium clearly shows its 4 members, and on a couple of nights I have been able to discern the “E” component as well. Wanting to now see a little more detail of the region around the trapezium I would switch to Native mode at F10. All this requires is simply sliding the knurled slider switch out of the optical train and then re-focusing. After re-focusing, most nights around my observatory, it’s steady enough to see both the “E” and “F” stars in the trapezium. Some nights are of course better than others but that is an entirely different discussion.

Now suppose the seeing is really good. With the same 17mm Nagler T4 in the diagonal let’s say I really want to study the trapezium in more detail. Simple. I just slide the B side knurled switch toward the center of the assembly and there I am at 2X Barlow mode. Of course I would then have to refocus after putting the scope in the 2X mode, but that is far better than having to remove the EP, insert the Barlow, and then re-insert the EP, and then refocus, in my opinion anyway.  

Now you may be asking, how are the views through these lenses installed in the PXS? Well, I’m glad you asked. The RC mode is just as crisp and clear as the Celestron F6.3 FR that I have used for many years. I get no field curvature using any of my TeleVue EP’s (Naglers, Panoptics, and Ethoses). Stars are sharp all the way across the entire FOV. Depending on the EP FOV of course, dictates how wide that FOV is. In the native F10 mode I experience the same thing as above. Nice sharp star points all the way across. Of course your view will vary depending on the EP used. I have been lucky enough over the years to be able to acquire what I feel are the best EP’s on the planet. Since the view through the PXS is dependent on which EP is used, I can only comment on those that I use. I will list all the EP’s that I use with the PXS at the end of this article/review, but, I may add, that list is going to be shortened very soon as I am finding that in using the PXS I am really getting 3 EP’s for 1. Remember how in the beginning people would recommend a Barlow to effectively double your EP collection? Well, with this wonderful piece of gear, we can TRIPLE our EP collection!!! As a matter of fact, I find myself only using 2 or 3 of my EP’s on any given night when the skies are clear and I open up the observatory. I think I’m going to be selling off a couple of my EP’s that have now become redundant.

When using the 2X mode it is of course very dependent on seeing conditions and EP choice. Obviously if the seeing is bad you will not be using a 6mm Ethos in the 2X mode, or maybe you would. I have tried it on Jupiter when the seeing was so-so and found that, even though the view was a bit soft, it was still fairly nice with quite a bit of detail discernable across the cloud bands of this beautiful planet. One night I was viewing ole Jupe while Io was in transit and used my 6mm Ethos in the 2X mode. The seeing this night was average for my location and it was extremely easy to see both Io itself, as it moved across the surface, but Io’s shadow was very prominent as well, as it also moved across the face of this gas giant.

Overall impressions and Conclusions

This is not an inexpensive 2” star diagonal that I have stated before, but with the Interlocking Visual Back, and the Power X Switch, to me without doubt, it is worth every penny that I spent for it. Its ease of going from the different viewing modes, i.e. RC Mode, Native Mode, and then 2X Mode with only 1 EP is, in my mind, worth the price of admission. Couple that with the fact that the IVB portion allows you to place any EP in the diagonal, regardless of weight, and not have to be concerned with the diagonal/EP combination slipping due to gravity and clunking you in the head, or worse, having the whole thing fall out and come crashing to the ground. On this point I will again refer back to my first review of this product that was written back in October of 2013.

I find that I can start viewing an object, change my viewing mode, refocus, and continue viewing without becoming distracted by changing out EP’s. Most of the time, I don’t even remove my eye from the EP. I just reach up, change the mode switch, refocus, and keep on keeping on!! As I’m sure you can tell I am quite smitten with this product. I guess I should say right here and now that I am in no way affiliated with Denkmeier Optical except as a very satisfied customer who will highly recommend this product to anyone who will listen.

Any negatives or concerns? Not really so much in the grand scheme of things. The only thing that I can think of is the fact that, when the PXS is in the Native mode, there is a small opening between the 2 switches that could in theory allow contaminates to enter into the optical path. If you look closely at the picture above of the PXS before I installed it onto the IVB, you will be able to see what I am talking about. There are 2 ways to eliminate this potential for contamination: 1) remove the IVB diagonal after each session and replace it with a cover. I’m sure the folks that are not in an observatory environment will do this anyway. Since I don’t tear everything down after my sessions (I just close the roof), I have found that option number 2 is the work around for this. 2) Simply slide one of the switches into the center position and this will effectively block the opening. I usually keep the RC mode switch engaged and make sure I’m in focus with whichever EP I was using at shutdown time before removing the EP to storage. This way, at the start of the next session, I can put this same EP back into the focuser and be ready to go very quickly.

On a side note, I have been talking about using this fantastic product with an SCT. It will also work for refractors as well, the only difference being in the way that it connects to the draw tube of the scope. Since I do not use a refractor as a visual instrument, I can’t speak on how this connection is made, however, a quick call to Russ at Denkmeier Optical will, I am sure, answer this question. As I have stated before, and I will say it again, Russ is just a great person to do business with.

So in conclusion, let me say that the Denkmeier 2” IVB Star Diagonal with Power X Switch is a product that has made my observing time much more productive, fun, and safe (both for my head and my EPs). Again, this is not an inexpensive piece of gear. But for what you get for those dollars, in my mind anyway, makes it very much worth the money spent.

As promised earlier, here is the list of my equipment that I have used with the Denkmeier 2” Interlocking Visual Back with Power X Switch:

Celestron C11 with Starbright XLT coatings

                FL 2800mm

                Focal ration F10

                280mm aperture

Eye Pieces used

                22mm Panoptic AFOV 68degrees

                17mm Nagler T4 AFOV 82degrees

                15mm Panoptic AFOV 68degrees

                13mm Ethos AFOV 100degrees

                12mm Meade Illuminated Reticule AFOV 45degrees

                11mm Nagler T6 AFOV 82degrees

                9mm Nagler T1 Smoothie AFOV 82degrees

                6mm Ethos AFOV 100degrees

At this point I would like to thank Russ Lederman with Denkmeier Optical for helping me stream line my observing sessions and provide a product that is very truly one of the most innovative products I think I have ever seen in my small part of the world of observational astronomy.

I would also like to thank Cloudy Nights and Astronomics for providing a vehicle for amateur astronomers worldwide in which discussion and conversation about this fantastic hobby can be freely exchanged.

I also thank the Supreme Maker for a fantastic job on creating the Universe. You really out did yourself.

Kevin “Scopefreak” Vaught

  • kbooky and pgs/sdg like this


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics