WO 22.5-7.5mm Zoom II on PF65 EDA II (1 Viewer)

Well, I just pulled the trigger on the new WO zoom. WO was selling them on ebay for 199 plus 19 for shipping so I bought one. 15 day "all expense paid" return policy so if it doesn't reach full focus I can return it.

Anyway, I have a Pentax XW 14 and a Pentax XF 8.5 for comparisons. I use my scope mainly for sheep hunting and the two Pentaxes worked great except they are about 19oz and I have to carry two ep's. The 8.5 does allow me to see more detail at long distances half mile +. Very good view. I think the scope can handle higher mag. I would still like to try an XW 7 on it but I'm not going to carry around two XW's at 26ozs and 600 bucks if I can find a decent zoom that will give over 50x with decent ER. Better off to cough up the extra bucks and just buy a swaro 65 with 20-60x.

If this zoom is a good compromise I may sell the other two eyepieces. I don't expect it to give as good an image at 14mm as the XW but from what I have read at cloudynights.com it gives great views. It only weighs 9ozs and will give 17-53 x on the PF 65. 20 mm ER and 43-69 degree FOV. Plus the convience of one ep only to deal with.

My only concern is that WO does not say it's weatherproof. Although they do say it is weatherproof on thier Swan APO 82 scope. The EP does have a different connector though. Similar to the swaro type. maybe the mechanism of the ep itself is weather resistant and in the Pentax compression system it is more weather resistant than in a typical astro scope.

Any thoughts on this eyepiece staying fog free internally in moist conditions? I don't plan on putting it in direct downpour.

Anyway, I will post my findings on this eyepiece when I get it.

I (and probably others) are anxiously awaiting your report! I was so disappointed when the Hyperion Zoom didn't focus in my scope.

I love my XL-14 but I would trade it in for the convenience of a good widefield zoom.

eitanaltman said:

I (and probably others) are anxiously awaiting your report! I was so disappointed when the Hyperion Zoom didn't focus in my scope.

I love my XL-14 but I would trade it in for the convenience of a good widefield zoom.

Click to expand...

Ya, that's kind of where I am. The XW 14 is really awesome as is the 8.5 but I would trade them both for one good acceptable zoom for what I'm doing.

I'll post a detailed write up with pics of all the eyepice side by side in a week or two.

Well, here is a report. This thing is big! A little bigger than my XW14. But, it's lighter. The first thing I noticed is how big around the eyecup is. For my face (overhanging brow and high cheek bones) this is an issue. At 22.5mm I can see the full fov without my face touching the eyepiece much, this is with or without eye glasses. However, the ER drops off and FOV closes as power increases. WO told me that the FOV is 66 at 22.5 and 42 at 7.5. I was under the impression it was the other way around like most zooms. The greater FOV at the shorter focal length. I thought I was going to get 52X and 66 degree FOV with my little Pentax but according to WO it's 42 at 7.5mm.

Anyway, I like to use my scope and binos without my eyeglasses on. The scope and binos focus works fine for me normally. At 22.5 there is not enough focus. If I put my glasses on it will just come into focus but the focus knob is maxed to its stop point and it only focuses out I would guess 4-500 yds. With or without glasses it will come into focus to infinity as I increase the magnification to about 17mm. But, then the ER drops off and in order to see the full fov I need to remove my glasses and touch my face against the eyepiece. I can do it softly and tip my head just right but it's not near as comfortable as the Pentax XW 14 wth 20mm ER. My Pentax XF8.5 has 18mm ER and it is fine for me but then again it's not as big around. I'm not sure what the ER is at 7.5 on the WO, it may be close to 18 but since it's so big and hits my face I think it gives the impression that it's less. WO specs just say 20mm. I thought that was 20mm from 22.5 to 7.5. It is definitely not 20mm at 7.5.

The Pentax has the compression ring to hold the ep in the scope. For those of you that have one you will notice that there is a plastic insert that actually crimps around the ep. It also keeps the ep from dropping in as far as it could go. About 16th an inch or so when you tighten it. I took that out and put the ep in. If I do that I can get it to reach full focus at 22.5 without my glasses on but not to infinity, but the focus knob is maxed or just ever slightly not. One would have to make an insert in order to hold the ep in and allow it to "bottom out" thus giving a little more room to focus. I think that this could be a solution if you want to get creative. The barrel is short enough to where it's not a problem.

To sum this up, I cannot use the ep with my eyeglasses on at anything above 22.5 and I need them on at 22.5 to get it to focus and even then the focusing knob is maxed out and it won't focus to infinity. ER drops off significantly (or so it seems due to ergonomics) as power increases.

Ok, having said all that, once you get to 17mm and head to 7.5 it will focus. Without the slight scope mod the focus wheel is maxed out or just about. There is not much room to move. With compression ring out it's better. Good enough to be usable but only without eyeglasses because of the shorter er. I was viewing houses and trees, etc. at 2-5 miles away.

Now the image. When it's in focus the image looks good to me. When compared to the XW 14 though it's not even close though. The xw is much brighter, crisper, better contrast and depth of field. The zoom at 22.5mm is dimmer than the XW14. But I didn't expect it to be as good and I think that's an apples and oranges comparison. So, how does it compare to the XF 8.5mm? The XF 8.5 gives 46x on my scope and is brighter, has more contrast and better depth of field than the zoom at 7.5 (52x) on down to probably 10mm or so. When you get lower power it gets brighter but you lose the magnification so... the zoom gives no advantage over the XF8.5mm on my PF65 EDA II. It is more ergonomic for me as well.

I'm probably spoiled with my two Pentax eyepieces. If I only had the zoom and had never owned the XW or XF I would probably be pretty impressed. But, for me, for what I am doing I don't see any advantage with this zoom. It may not be the same for you. If you have a Pentax scope and want a zoom give this one a try. The ergonomics may be better for you. Your eyes might like it better. In the PF80 or 100 you may not have the focus issues and of course it should be a little brighter. For me I do not see this as a compromised replacement for my two Pentax ep's.

One other issue. At 22.5 there are what appear to be black specs on the lens. When looking into the eyepiece removed from the scope and tilting it so you get a black out they look like white dots/specs. Bubbles in the glass? Specs in the coatings? I'm not sure but it's going back to WO. No biggie, any company can have an issue from time to time. Don't let that stop you from buying the eyepiece.

This is no doubt a nice unit. I am a little disappointed in the FOV issue and the shorter than expected ER. If it weren't for these issues and the fact that I'd have to modify my scope to make it work, I'd probably keep it. I think I could deal with the ergonomics. I wonder if I just got a bad one considering the specs/bubbles on the lens. Part of me wants to try it out before I send it back with my contact lenses and maybe just exchange this one instead of returning it. But, at this point I'm thinking I'll just return it.

thanks a lot for the report. too bad...

:-(

that kind of sucks -- so are you saying it will not reach infinity focus at all unless you remove that compression ring?

It's somewhat disappointing too that you say it's dimmer at 22.5mm than the XW at 14mm -- generally it should get brighter as you decrease magnification!

Have you ever used the Vixen or TV or similar zooms? I'm curious how this WO zoom compares to those.

So at high magnification, the XF 8.5 is the clear winner?

(PS Thanks for the report Snyd!! I got to be the unfortunate Hyperion Zoom guinea pig, thanks for being the brave soul to take on the WO zoom).

Update on Zoom Test on PF65 EDA II...not so fast!

Well I'm not one who will give up easily. I did some more testing and found that I can get scope to focus this eyepeice! I simply pulled out the plastic compression insert and replaced it with a homemade smaller one that fits inside the housing. This allows the ep to drop in about an additional 8th of an inch or slightly more. It allows the compression ring to screw all the way down fully and allows the ep to drop fully into that ring. It makes a HUGE difference in being able to focus through all focal lengths. I have plenty of focus wheel adjustment to use the ep without my glasses! I have some pics and will figure out how to post or share them. In the meantime, today I will get out and do some more testing now that I can focus it comfortably. Also, I'm not sure what to make of the FOV issue. Like I said, WO told me it was 42 at 7.5mm. But, I did a very unscientific test. I put in my XF 8.5 which is 60 fov, focused on a distant tree, put the top of the tree at the top of the image and made a mental note of what I could see at the bottom and sides of the image. I then put on the WO zoom with my new system and did the same thing with the zoom at 7.5. I swear I saw just as much in the FOV. So, I'm not done with this testing yet. I may end up keeping it. However, this particular ep will go back to WO because of the issue with the spots. If I put it at 22.5 and hold the ep up to the sky and can see lots of small clear/white spots. Makes me think they are bubbles? Any thoughts?

Stay tuned for more!!

EDIT: Just to confirm. I just spent a quick 15 minutes doubling checking the focus ability to infinity from 22.5 to 7.5. No prob. Works great

Here are a couple pics before and after the mod. Note the spaces at the tip if each pencil. Probably almost an 8th of an inch each. Maybe a little less. the second pic shows no spaces present. Sorry thier a little fuzzy.

Pics of the mod

Here are some pics of the quick mod I did. I'm going to make one that's a little better but this gives you an idea. It's a ring used to seal fittings with pvc pipe. Just a beveled piece of plastic. I cut the space out so it can compress. I made this one a little too loose. When you turn the compression ring is pushes it down forcing it to thghten around the ep. Since it sits inside it does not push the ep up and it allows the compression ring to tighten up closer to the scope body. This is what allows the ep to drop into the tube enough to get plenty of focus!

Over the next couple days I will try to spend some time with it and really compare the XW14 and XF 8.5 to it again. The only other zoom I have tried on this scope is the Pentax XF. This one is much better IMO. I only tried it for a short time today but I think the view through it now that I can use it properly is very acceptable. It does resolve good detail at all mags. I tested it out to about 5 miles. I still think the Pentaxes are brighter. Especially the XW. Not as much diff with the XF. But, then again. Fixed versus zoom. The zoom will be a compromise. But, I got this zoom delivered for $220 and it weighs about 10ozs I think. My two Pentaxes cost twice that and weigh about 18ozs. This zoom may be a good compromise.

Update on the spots...

I am getting the feeling that WO has great customer service. I have communicated with them quite a bit over the past few months. Even before getting this EP. Here is what WO said about the spots.

"Sorry, for that. That is not bubbles in the glass that is oil. We put too much oil inside and after eyepiece was cleaned with high pressure air, in some eyepieces oil spreads on the glass. Our QC person missed it, because these dots only can be seen at 22.5mm. We found this problem this week and fix it already. We can either replace eyepiece for you or give you full refund after we will receive it back."

(keep in mind I just bought the ep a few days ago so I am still in the 15 day refund policy period. The warranty period is 2 years. See WO for warranty details)

I'll be heading out today for more testing. Conditions are 10-25 degrees f, some snow on the ground. High clouds, maybe a little sun. Light may end up being kind of low flat light. I will be testing it against the XW14 and XF 8.5 from close range out to over 3 miles. From what I have seen so far it resolves as much detail as the two pentaxes but is a little dimmer. I was testing last night looking down the street about 400yds with only a few street lights. I could see as much detail with it as I could with the 2 pentaxes. The xw is defenately brighter though, even when the zoom is on 22.5. I would say the XF 8.5 and the zoom are VERY close as far as brightness. Maybe a very slight edge to the xf but not a drastic difference. Keep in mind I had the zoom at 7.5 (52x) compared to the xf at 8.5 (46x). FOV seems about the same, huh. This is good.

Well, I really have to back peddle and eat crow after my first post. Now that I can focus this eyepiece I really like it. I spent some time with it today and found that even though the xw14 is a little brighter this zoom is definitely bright. I did not feel at all that is was dim in any way. It is also neck and neck with the xf as far as brightness at higher power. Plus the zoom goes to 52x where as the xf is 46x. It made a difference today. I was looking at a sign about a mile away. There was lettering that I could not read with the xf at 46x but I could read it with the zoom at 52x and it was sharp. The extra power made a difference. I checked and rechecked a few times. I could not read the lettering with the xw 14 or the zoom at any lower power. 52x did it.

This zoom is clear and sharp all the way up to 7.5. The fov at 7.5 is so close to the same as the xf a 8.5 that I call them equal. In other words at 52x I can see as much as I can with the xf at 46x. The zoom must have a wider fov than 60. Must be 66 instead of 42 at 7.5. Maybe the WO rep that told me it was 42 at 7.5 was mistaken. Obviously it has much less fov than the XW 14 which is 70. But, for me that's ok. I have to say that for my eyes it's as sharp as my pentaxes. I think the xw has more contrast or something though. The view with the xw14 really is nice. But, with the zoom at higher power I can see more details.

One other thing I noticed. After comparing today I noticed that when using the xw it is easy for me to move slightly and get kidney beaning because of the wide fov and/or er. I have to be carefull or I loose the image. I have never really tought of it much until today. But, I found that with the zoom it did not happen.

I didn't really find anything wrong with the views with this eyepiece.

Bottom line is that if you replace the plastic compression insert so the eyepiece drops in a little further so you get full focus I say this is a keeper. I could see using my PF 65 EDA II with only this eyepiece for hunting and general viewing and it would work great. It gives bright clear views and is capable of showing more detail at 52x than the xf at 46x at long distances.

Synd,

The WO rep certainly got the apparent field widths over the zoom range wrong. 42 degrees at the lowest magnification and 66 degrees at the highest makes sense, the reverse really doesn't.

An image at 22.5mm no brighter than the 14mm XW is a very curious result which I don't think can be explained by any difference in light transmission between the eyepieces. Does the exit pupil in the zoom grow larger at lower magnification as it should? I'm wondering if some sort of vignetting is the explanation. Of course it's best to try to compare light transmission at exactly the same magnification. A 1% difference in magnification normally causes a brightness difference that roughly corresponds to a 2% difference in light transmission. That means in the same telescope there would need to be more than a 100% difference in light transmission for a 14mm eyepiece to be brighter than a 22.5mm.

Henry

Henry,
You know, the brightness could just be a perception thing on my part. Also keep in mind I am a relative newby when it comes to all this so I don't have years worth of comparisons etc. There is snow on the ground here and the xw14 has a huge fov which resulted in me seeing lots of white and I would guess also maybe more reflected light?? I may be using the word "brighter" to describe the overall view with the xw14. Anytime I use the xw14 at first glance it always seems to give the impression "wow, I need some sun glasses!" With the xw the fov entirely fills what I see when i look throught the eyepiece. With the zoom at 22.5 I see a circle with the image inside of it. When zooming the image grows to fill the view through the ep. Make sense? I think this may be part of the perception thing also. The viewable area with the xw is bigger therefore seeming "brighter".

I held my little Olympus sylus up to the ep and snapped a couple pics just to see if I could. The first one is at 22.5 the second at 7.5. The dish is about 400 yds away.

Snyd - thanks for the updates!! It's exciting to hear that the new WO Zoom gives equal resolution at ~50x power as the XF 8.5 with equivalent AFOV. That makes it a real viable alternative for the person (like me!) who doesn't want to deal with switching eyepieces.

Another question -- how do you like the wide end for panning/scanning? Obviously, the XW is a champ for this with it's huge FOV and brightness, but how does the WO Zoom do for wide-work?

By my back-of-the-envelope calculations, the XW 7mm should give a true FOV of about 2.51 degrees: (14mm)x(70 degrees AFOV)/(390mm focal length of scope).

If the AFOV of the WO zoom is really 40 degrees at 22.5, it should give a true FOV of about 2.31 degrees.

Do you find this is borne out by your observations? i.e. will the WO Zoom zoomed all the way out to 22.5 give a slightly smaller true field-of-view than the XW 14?

Thanks again for your willingness to be a guinea pig!

eitanaltman said:

Snyd - thanks for the updates!! It's exciting to hear that the new WO Zoom gives equal resolution at ~50x power as the XF 8.5 with equivalent AFOV. That makes it a real viable alternative for the person (like me!) who doesn't want to deal with switching eyepieces.

Click to expand...

Yes, and it did actually allow me to resolve more detail than the 8.5. I also emailed Pentax to see if I can get 2 of the plastic rings. I think I can modify one to work with the WO zoom. I just don't want to hack up my only one!

eitanaltman said:

Another question -- how do you like the wide end for panning/scanning? Obviously, the XW is a champ for this with it's huge FOV and brightness, but how does the WO Zoom do for wide-work?

Click to expand...

The xw wins hands down. Even at 14mm is shows a larger area than the zoom at 22.5

eitanaltman said:

By my back-of-the-envelope calculations, the XW 7mm should give a true FOV of about 2.51 degrees: (14mm)x(70 degrees AFOV)/(390mm focal length of scope).

If the AFOV of the WO zoom is really 40 degrees at 22.5, it should give a true FOV of about 2.31 degrees.

Do you find this is borne out by your observations? i.e. will the WO Zoom zoomed all the way out to 22.5 give a slightly smaller true field-of-view than the XW 14?

Thanks again for your willingness to be a guinea pig!

Click to expand...

Yes, the zoom gives a smaller true fov than the xw. In the area of fov the zoom is a compromise at lower mags when compared to a wide angle ep like the XW14 that's for sure. But, being able to turn the ring and be at 30x or higher just like that is really cool! Especially for what I am doing. Personally I find myself not really using all the fov with the xw. I mean my eye cannot take in the whole view. I have to purpuosefully "search around" if you know what I mean. I like the view out of the zoom at around 30x. and when cranking it up to 50x it doesn't really loose that much brightness. I'm happy. I sent mine back to WO today to get one without the oil on the glass. Not sure if I mentioned it but WO said a few got through qc. The put too much oil internally and when the hit it with high pressure air it speckled the glass. A guy at cloudy nights had the same thing. I should have my replacement in a couple weeks. It goes back to Taiwan.

Anyway. Here is some other info just for fun.

A couple weeks ago I emailed WO and asked them how to calculate what the fov would be at 14mm. Here is the response I got:
FOV for 14mm will be 52.4.
The formula is :
((66-42)/(22.5-7.5))x(x-7.5) + 42

So lets run the numbers...
24/15= 1.6

1.6 x (14-7.5) + 42

1.6 x 6.5 = 10.4

10.4 + 42 = 52.4

However, if you run the numbers for 7.5 or 22.5 instead of 14 this calc give the fov 66 at 22.5 and 42 at 7.5.

If you change the formula to:

((66-42)/(22.5-7.5))x(x-22.5) + 42

24/15= 1.6

1.6 x (14-22.5) + 42
(drop the - from the value)
1.6 x 8.5 = 13.6

13.6 + 42 = 55.6

So, 55.6 FOV at 14mm as compared to the XW 14 at 70 or the XL at 65. Not too bad if you ask me.

If you run the numbers for 7.5 with the changed formula it comes out at 66:

24/15= 1.6

1.6 x (7.5-22.5) + 42
(drop the - from the value)
1.6 x 15 = 24

24 + 42 = 66

Not sure if this makes sense or if I screwed up the numbers.

Snyd,

Rather than calculating the FOV from a formula that assumes a linear change as magnification is changed (something that may not actually take place), why don't you simply measure the true fields by placing a tape measure say, 100 feet away and perpendicular to your line of sight? Then view the tape with your scope and record what length just fits within the view at any given zoom focal length.

A little more trouble, perhaps, but more accurate results.

Kimmo

Snyd - one more question, what do you think about edge-to-edge sharpness, and does it differ from lower mags to higher? It seems that you are more interested in hunting applications, so center-field resolution is your priority, but does the image degrade severely towards the edge of the field? That is one of my favorite things about the XL/XW eyepieces, they are so sharp almost the whole way out... obviously, I wouldn't expect a zoom to equal it, but I'm still interested!

Thanks again, hopefully I can get my hands on one of these for less than the $299 list price!

eitanaltman said:

Snyd - one more question, what do you think about edge-to-edge sharpness, and does it differ from lower mags to higher? It seems that you are more interested in hunting applications, so center-field resolution is your priority, but does the image degrade severely towards the edge of the field? That is one of my favorite things about the XL/XW eyepieces, they are so sharp almost the whole way out... obviously, I wouldn't expect a zoom to equal it, but I'm still interested!

Thanks again, hopefully I can get my hands on one of these for less than the $299 list price!

Click to expand...

Edge to edge was pretty good I think. I'll check it out again when I get my replacement and I can answer more for you.

No need to spend 300 bucks. WO is selling them on ebay. They had them for buy it now for 199 when I bought mine. Last week they were just on regular auction. It went for 213. There is one there now. Check it out: WO Zoom II

No way I was going to spend over 300 bucks on one. I figured for 218 delivered it was worth it.

Perry

Snyd said:

I also emailed Pentax to see if I can get 2 of the plastic rings. I think I can modify one to work with the WO zoom.

Click to expand...

Which plastic ring are you referring to? The compression ring that goes inside the screw-on thingy that tightens the eyepiece?

I played around with some of that when I was trying to get the Baader Hyperion Zoom to focus, but could never get enough travel...

eitanaltman said:

Which plastic ring are you referring to? The compression ring that goes inside the screw-on thingy that tightens the eyepiece?

I played around with some of that when I was trying to get the Baader Hyperion Zoom to focus, but could never get enough travel...

Click to expand...

Yup, that's it. You can see where I pulled it out it in my pics in my previous post. I think I can whittle and sand it to allow the ep to drop in further. If not I'll just improve on my plumbers ring replacement.

Interesting, I think mine is actually metal, not plastic, which is why I asked. I have the v.1 PF-65ED-A, you have the v.II, right? Maybe they switched the compression ring to a plastic piece, or maybe my memory is just poor!

Keep us updated on the progress of your "mods", I think I'm going to try and buy that one that's on eBay right now and see for myself...