University Optics 25mm MK-70 Eyepiece:
Due to clouds, I had nothing to say about my new University Optics MK-70 25mm Konig. So, in March 1998, a friend asked, "What do you think about the UO MK70, just looking at it, not thru it? Nice?" The following was my response:
It does have a modern look to it. Nice, is a good description. The barrel is contoured so as to snag on the focus set screw should the eyepiece decide to move on its own. It looks like a baby 7/70. Got the rubber grip ring and all. When a person spends around $200 for an eyepiece, he likes to see a lot of glass. This one does not have as much glass in it, especially up front. But, it is as pictured in the catalog.
It is threaded for filters both top and bottom. Kind of a different and new idea to be able to put a filter on top of the eyepiece. It has a 2 inch barrel.
The biggest disappointment so far is that the thing seems to have inadequate eye relief. Just holding it up to the shop light and approaching the eyepiece so as to see the field stop; and, by the time I am there, my eyelashes are brushing against the housing when I blink.
Eyeglasses would be out of the question if in focus usage of the eyepiece takes place around the range where the field stop is visible. I couldn't do it with my glasses using the shop light as the test.
Darwin
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March 24, 1998 Evening
I caught a short break in the clouds and quickly pulled out my 80mm f/6.25 UO refractor for a look at Orion with the 25mm MK-70.
There is no way to see the whole field of view of the MK-70. The eye relief is grossly inadequate for eyeglass use. With my glasses on, the field of view looks like that seen through the average orthoscopic.
With my eyeglasses off, the eyepiece's field of view takes on the dimensions of a wide field eyepiece. But, in actual usage it is impossible to see the whole field. The eyepiece is threaded to take 2 inch filters on both the top and the bottom. The eye relief is not sufficient enough for a filter up front in my opinion, a waste of effort threading the front for filters. Also the threads up front seem to cut and grind at my glasses -- not desirable. Filters up front would have been a great idea if the eyepiece had any eye relief.
Without glasses, I found you can smash your eye in there so as to see the whole field of view, but by that point huge chunks of the view blackout. If you get too close, the eyepiece will kidneybean and/or blackout. There is a range to put the eye with no blackout, but it is impossible at that point to see the whole field of view.
Panning the scope with the 25mm MK-70 eyepiece is difficult as the eyepiece seemed to easily blackout with side to side motion.
It is a Konig, judging by all the blackout. I didn't find the stars to be perfectly sharp from edge to edge either, just like with my other Konigs. The performance of the eyepiece reminded me much of the 32 UO Konig and the 40mm UO 7/70 Konig. The stars are sharp and pinpoint through much of the field until you get to the outer edge, then they coma dramatically.
In actual usage, I found that I had to cock my head and look at the stars by the field stop in order to see that they had turned into seagulls. During normal usage of the eyepiece, the eye relief is inadequate enough that you don't see the stars on the edge, so the stars look basically perfect across the field of view that you can see.
I could put the three belt stars of Orion into the same field of view at 20X. The view was very much like that seen through a good pair of binoculars.
The performance of the MK-70 eyepiece is right on par with the 40mm UO 7/70 Konig. The 25mm eyepiece looks like a baby 7/70 and performs as one with a few exceptions. The eye relief of the MK-70 is inadequate. As you get closer to the eyepieces, more of the field of view can be seen through the 7/70 before blackout starts to take place. The 'too close' blackout starts to happen a little too quickly with the 25mm UO MK-70 in my 80mm refractor.
Now I am going to step out on a limb and make some guesses without any proof; but, the seller of the 25mm UO MK-70 invites the comparison, and I have been asked to speculate. In the advertising copy, the 25mm UO MK-70 is compared by inference to the 27mm Panoptic. I have not used a 27mm Panoptic, but I have used a 35mm Panoptic. A handful of people have told me that the 27 Panoptic blacks out and shows central obstructions more easily than the 35 Panoptic. By that I would guess that the 25 MK-70 and 27 Panoptic are probably on par with each other blackout wise. From what I have heard about the 27 Panoptic and seen with my 35 Panoptic and MK-70, I would expect the 27mm Panoptic to be sharper from edge to edge than the 25mm MK-70 on star fields. I would expect the 27mm Panoptic to have better eye relief, and that more of the field of view would be seen in the Panoptic.
All Panoptics that I have seen or heard about have distortion and color on the fringes; therefore, I would expect the 25mm MK-70 to be more pleasing during daytime usage. But, the MK-70 is going to be pestered during the daytime with blackout. I just don't know if the daytime blackout is going to be at the level of annoyance like it is in the 24mm 1.25" UO Konig, or if it will be more tolerable as to make the eyepiece usable during the day as with the 32mm UO Konig.
If you already have a 27mm Panoptic and are using it for deep sky, I don't think the 25mm MK-70 would be an improvement over what you already have. If you are using those Panoptics during the daytime, I think most anything could be an improvement if my 35mm Panoptic's daytime performance is an indication. I also think a 28mm Pentax XL would be superior to the 25mm MK-70 for most applications, if the Pentax XL's I currently own are any indication.
Now for a couple of disclaimers. First, I went out on a limb this time and guessed how the eyepiece is going to perform without any proof. Also, all my deep sky tests have been done on my 10 inch f/4.5; so, I would not be surprised to have the MK-70 perform differently with my 10 inch scope than it did with my 80mm refractor.
Darwin Bagley
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March 27, 1998
Comparisons using my 80mm f/6.25 UO refractor on the mountains and roof tops during the day.
The 25mm MK-70 was much more pleasing to use during the day with my 80mm UO refractor. The MK-70 has a noticably larger field of view than the 1.25" 24mm UO Konig.
The 25mm MK-70 has a good usable range. If you got too close it would blackout on you, but I just instinctively during the daytime could stay in a good usable range where there was no blackout. There were slight shadows from time to time, if in my wabbling while standing I happened to get too close to the eyepiece.
The MK-70 had no lateral color and no false color anywhere. It's a Konig!!
The MK-70 does not have enough eye relief to comfortably see the whole field of view. There is what I like to call a 'good sizable artificial field stop'. Though you cannot see the real field stop, the portion of the field you can see seems to be sharply defined and good stuff, an artificial field stop. Put another way, a usable artificial field within the real field of view.
Anyway, the 'artificial' field of the MK-70 is much larger than the real field of the 24mm UO Konig, and what is seen is good stuff. In the 1.25" 24mm UO Konig, you can see the field stop at all times.
The 25mm MK-70 has distortion. The roof across the street is bent. If you cock your head to the side and look directly at the 'real' field stop of the 25mm MK-70, you notice that the mountains on the edges get stretched severely as they pass out of the real field of view.
I have come to believe that the outer part of the field of view of the MK-70 is full of problems. Full of distortion during the day, and full of coma at night. The funny thing is that in actual usage, the outer portion of the field cannot be seen unless one goes looking for it directly. The outer portion is 'off limits' due to the fact that the eyepiece will blackout if you try to get close enough to see the whole field of view of the MK-70. It's just as well that the blackout prevents a person from seeing the whole field, because what is left in the central 'artificial' field is good and usable stuff.
The MK-70 is a case of an eyepiece aspiring to be more than it should be. There should probably be a field stop in there to cut off crisply the outer 'unusable' part. A decade ago I heard the same complaint about the 20mm University Optics Wide Scan; I even heard of some folks opening up their 20mm Widescan and putting in a field stop in order to turn it into a 'perfect' eyepiece.
Now, if you want daytime perfection in the '25mm' range with my 80mm UO refractor, then you need to try a 21mm Pentax XL. The 21 XL and my 80mm UO refractor are a match made in heaven.
There is basically no distortion with the 21mm XL, you really have to go looking for it, by moving a straight roof to the extreme edge of the field of view to see the slightest bending.
You can pan the 80mm refractor with the 21XL, with only slight periodic shadows appearing as my eye loses track momentarily of the panning of the scope. Being able to pan a rich field scope is helpful at times. The 21XL allows it to be possible! Blackout prevents panning with the 24mm and 25mm Konig eyepieces.
Of course, the 21mm XL has perfect eye relief allowing you to see the field stop and whole field of view at all times. The whole field is perfect and color free. The XL has noticably less field of view than the 25mm MK-70.
Overall, I found the 25mm UO MK-70 more pleasing during the day in my rich field refractor than I found it to be during the night.
Darwin Bagley
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March 31, 1998 Afternoon Mountain Time
I tried my MK-70 in my 6 inch f/15 Quantum Maksutov during the day. Clear with 30 mph winds. The winds made viewing the mountains problematic in that there was so much air turbulence that it was actually hard to get a good clean focus. Viewing the trees across the street was more productive even if they were swaying.
At f/15 in the Q6, I found that the 25mm MK-70 had less blackout problems than in the 80mm refractor. I found the eyepiece to be quite pleasing actually -- the best in comparison to all the other eyepieces I tried. A case where the wide field of view put it a step above all the others.
The 24mm 1.25" UO Konig was clear and sharp, but narrow in comparison to the MK-70. The 21mm Pentax XL, which was noticably superior to everything with my 80mm refractor, seemed soft and not as bright in the Quantum 6; maybe this is a function of the increased magnification taking effect. The MK-70 also had a much wider field of view even it you couldn't see it all due to the MK-70's inadequate eye relief.
I have found my Q6 to be particularly good with Konigs over time.
The 25mm MK-70 would blackout if you moved side to side; but, you had to move the head about 1/2 inch away from axis to achieve partial blackouts. In actual Q6 usage, the eyepiece would never blackout from side to side motion -- I had to go looking for it. The MK-70 will kidneybean if you get too close. Focussed nearer to infinity on the mountains I noticed some vignetting on the edge of field of the MK-70. With the MK-70, the view is everything everywhere present. The eyepiece does not tunnel in when getting closer or farther away like the 21 XL. Getting closer just allows you to see more of the field of view. The everything everywhere present nature of the MK-70 and the wide field of view quickly made the MK-70 preferable to the other eyepieces.
Darwin Bagley
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March 31, 1998 18:30 to 20:00 Mountain Standard Time
The clouds were getting trapped by the mountains to the west and fed to me one at a time. I got some time to view the moon with my Q6, and a couple of eyepieces.
I really liked the 25mm MK-70 on the moon. You could get close enough to the eyepiece to see the whole moon in the field of view, before the eyepiece would start to kidneybean. It's sharpness and contrast were right in line with the 24mm 1.25" UO Konig. No color on the fringes was seen in the Konig eyepieces. And using the built in 1.75X barlow of the Q6, I found the MK-70 to barlow up perfectly. No blackout, no ghosting, just honest to goodness perfection while barlowed. The 25mm MK-70 with the Q6's built in barlow was every bit as good as the 24mm UO Konig with the built in barlow. I was very pleased with the performance of the MK-70 in combination with the Q6 on the moon.
The 32mm UO Konig seemed a bit washed out due to the passing clouds and the brightness of the moon in comparison to the MK-70.
The MK-70 would blackout if you got too far off axis, and it did at times seem to have a touch of vignetting on the edges especially during twilight. But, there was always a large usable range for movement of my head with no blackout.
The 21mm Pentax XL in comparison to the 25mm MK-70 seemed a little more washed out by the brighness of the moon, and the image seemed softer than the image in the MK-70. Konigs are really great eyepieces with the Q6 on the moon. The slower I can get the telescope, the less blackout problems I seem to have with the Konigs.
The 32mm UO Konig focuses in a totally different spot than most other eyepieces. The 25mm UO MK-70 focuses much in the same position as other eyepieces. I was pleased enough with the MK-70 that I have decided to keep it, so as to have it on hand whenever I want to use the Q6 with the moon. The MK-70 really barlowed up well, and that decided it.
I also tried a Hastings Triplet on the moon. You can get hastings triplets from Edmund Scientific. I had the 25mm Hastings triplet. It seemed to have only moderate eye relief. My eyelashes were touching it, and it also had a narrow field of view.
It was interesing in that used in combination with the 1.75X internal barlow at 14.29mm, it was very similar to the view of a 9mm Intes used unbarlowed on the moon; but, the Hastings triplet did not have all the ghosting that the Intes eyepiece is known for.
The '25mm' Konigs by themselves, or barlowed in the Q6, were better for lunar observation than the Hastings Triplet.
Darwin Bagley
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April 2, 1998 17:30 to 21:00 Mountain Standard Time
I pulled out my 10 inch f/4.5 dob newt telescope.
Twilight. I tried out the University Optics 25mm MK-70 Konig in the 10 inch scope on the moon. The central obstruction was clearly visible which didn't make for a pleasing view -- you had to get uncomfortably close in order to get the central obstruction to expand and fill the field of view.
Also, the MK-70 just barely came to focus; there wasn't enough in-focus. I spent an hour on the collimations screws moving the mirror closer to the diagonal so as to get the focus point a little farther out of the telescope tube.
Later, I then tried the 25mm MK-70 on the Trapezium as Orion was settling into the murk. About 3/4 of the way from the center of the eyepiece, I noticed that the stars in the MK-70 were starting to fall apart or coma. The good news was that all the blackout problems were gone when it came to using this eyepiece deep sky with my light bucket.
After a long time I noticed a strange thing about the MK-70. If I could keep my eye right on axis, the stars were pinpoint nearly to the edge of field. Move the eye ever so slightly off axis, and the stars 1/4 of the way in from the circumference would coma. It was really wierd to watch all the stars pinpoint, and then watch all the stars around the circumference coma, just by moving my eye through the axis of the eyepiece.
The 21mm Pentax XL seemed pinpoint across the field of view on the Orion Nebula. Smaller field of view though than the MK-70.
I then switch up to the zenith for a view of Praesepe or the Beehive Cluster. It was too much magnification for the 21mm Pentax XL. You could almost fit the whole thing into the field of the MK-70, but with some coma.
I then put in my 35mm Panoptic. It was perfect for the Beehive Cluster. Right as the stars would pass out of the field of view they would flare just ever so slightly. The 35 Panoptic is a sharp eyepiece for deep sky viewing.
For wide field eyepieces, I like Panoptics for deep sky, Konigs for the moon, and Pentax XL's to fill in the gaps and to get eye relief at higher power.
Summary: The 25mm UO MK-70 was somewhat disappointing, but in the end I decided to keep it because it worked so well for lunar observation with my Quantum Maksutov. It's always the case of getting the best eyepieces that you can afford and keeping the ones that work the best with the scopes that you currently have.
Finally, there's nothing special about me. I have a kind friend that loans me eyepieces from time to time and likes a report on what I see. And, after reporting to my friend, I like to share the report with others as well. So, I am also thankful to have a special friend, who is willing to let me use his web page to share what has been shared with me. Take care, and best of wishes to you all.
Darwin Bagley