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Denkmeier S-1 Power Switch/Filter Slide for SCTs

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I've been observing for just three years now, so I'm a newcomer to this field. I live in Maryland and have no specific interests yet, so when my friends who focus on DSOs are complaining about moonlight polluting their night skies, I'm enjoying the lunar views. I've jumped into observing with both feet as I have a NexStar 8SE (my initial scope), built an ExploraDome observatory in my backyard, and added a CPC1100 as my observatory scope. The addition of the observatory has really increased my time under the moon and stars so although I am a relative newcomer, I've had some time to play with various pieces of equipment. I'd like to tell you about a great device that really makes observing easy and efficient. It's the Denkmeier S-1 Power Switch/Filter Slide from Denkmeier Optical, Inc. (http://deepskybinoviewer.com/index.cfm). This device, with optics by Williams Optics, rolls 4 devices into one: 1) star diagonal; 2) 2x Barlow; 3) 0.63 focal reducer; 4) filter slide.

You should know that I am in no way connected with Denkmeier though as you'll see, I obviously like this product.

You may be familiar with Denkmeier's other products that involve binocular viewers. You can get a binoviewer with all the capability of the S -1, but part of my purpose in getting the Denk was to spend less money on eyepieces so I chose not to have to invest in duplicate eyepieces when I do buy them. After all, good eyepieces are expensive enough as it is! I got the so-called "Shorty" version of the Power Switch that is designed to work with SCT telescopes and offeres the shortest extension possible from the back of the OTA. Power switches that work with refractors are also available.

So what's so great about the Denk Power Switch? Basically, it turns any eyepiece you own into three. For example, I put my Meade Series 5000 SWA 24mm eyepiece in my NexStar 8SE and get a magnification of 85x and a FOV of 48 minutes. But I really need a larger FOV for some deep sky searching and getting larger objects in view. On an SCT, that would normally involve unscrewing the diagonal and visual back, threading on a focal reducer, reattaching the visual back and diagonal and then observing. Reverse the process to go back to normal magnification. Needless to say, I found I seldom used my Celestron focal reducer. With the Denk, all I need do is slide a focal reducer lens built into the device into place, refocus, and I've got 53x mag in a 76 min FOV, which makes observing the Double Cluster a piece of cake! And I haven't had to change my eyepiece at all.

OK, so now I'm tooling along and find I want get some more magnification on say, M13- The Great Hercules Star Cluster. In the past, I would have had to reverse the whole focal reducer process to remove it, remove the eyepiece, insert a Barlow lens in the diagonal eyepiece holder and refocus. With the Denk, I just slide out the reducer lens and slide in the 2x Barlow lens from the opposite side of the device, refocus, and BAM! I'm looking at M13 at 169x in a 24 min FOV. It really doesn't get much simpler and I've just effectively used 3 different eyepieces without ever having to change one. The upshot is that I find I change eyepieces less frequently and use my available FOV/mag options a lot more with a final result that I get a lot more enjoyment out of viewing. Because I don't hesitate to change the optics to exactly suit my needs (it's so easy to do) I find I make better, more detailed observations.

Now let's consider filters. Suppose I'm hunting planetary nebulae and land on the Dumbbell Nebula. It looks pretty bright, but I can't quite see the narrowing in the center which gives M27 its name and to some makes the nebula look like an hour glass. I know either a light pollution (e.g., LP-2) or Oxygen III (O-III) filter will enhance the view, but which one will work best on this target? The answer used to involve observing the object in visible light, removing the eyepiece, screwing in an LP-2 filter, reinserting the eyepiece, observing, going through all the steps to remove the filter and repeating the process ending with an O-III filter in place. Then I'd spend some time deciding which filter really worked best because a significant amount of time had elapsed between viewing with the one then the other. With the Denk, I preload the LP-2 and O-III filters in the Filter Slide cartridges before I begin observing.

Then I make my observation in visible light, slide in the LP-2, observe, slide in the O-III as I slide out the LP-2 and check the view in the second filter in about 1 second after seeing it in the first. Want to compare views? I just slide the filters back and forth and settle on the one I like.

And all this without touching the eyepiece or threading anything! Doing lunar or planetary work and want to try some color filters to enhance features? Just replace the nebula filters with the colored filters you want and you can again make multiple comparisons.

The bottom line is the Denk Power Switch/Filter Slide was worth every penny I paid for it. I initially purchased just the Power Switch ($389) as I had a Lumicon filter slide and used it with the switch. That worked fine, but it was just a bit more complex and bulky a setup. So I eventually sent my Power Switch back to Denkmeier where they upgraded it by adding the filter slide ($189). That may sound like a lot of money, but think of what you're getting. My observing sessions are more effective and efficient because I always have optimal viewing setups. That's due to the fact I never hesitate to try magnifying or reducing the view because it is so easy to do. But the big advantage is that if I didn't pay for the Denk, I probably would have sunk the same amount or more money in some additional eyepieces over time. As it stands now I own 3 quality eyepieces from the Meade Series 5000 line: SWA 24mm and 16mm and UWA 6.7mm eyepieces. Couple those three with the Denk (unaltered, Barlowed, reduced) and I effectively have 9 high quality eyepieces: 24, 12, and 38mm; 16, 8, and 25mm; 6.7, 3.8, and 11mm. The only combination in either my CPC 1100 or NexStar 8SE that exceeds my scopes' theoretical magnification limits is the Barlowed 6.7mm lens. Even with the one useless magnification option, that's still a great deal in terms of leveraging my eyepieces, and if I ever did decide to buy another eyepiece, I'd be getting a 3 for 1 deal! However, I've had my Denk for about a year now and find I feel no need to buy another eyepiece.

Here's a few more technical specs for you. The Denk comes with a 2" star diagonal and a built in 1.25" eyepiece adapter so no matter what size your eyepieces are, they'll fit in the Denk. It comes with two 2" filter cartridges and 1.25" inserts so any filter you have will fit them. If you're primarily a deep sky observer, those two cartridges for a couple of nebula filters may be all you'll ever need. But if you have additional deep sky filters, or do planetary/lunar work, you may want to invest in 2-4 additional cartridges so you can load up a variety of filters to speed up filter changes while observing.

I hope I've given you good reason to get yourself one of these great devices. If you do, you'll never look back because you'll always be looking Deep!


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