20 replies to this topic

[noisejammer]

Years back, I was interested in a pair of Docters - but I very seldom observe with one eye and a pair would run to $1400 before shipping and taxes. I passed.

 

Two years back, APM brought out their alphabet soup, an eyepiece that quickly gained a reputation as serious competition for the Docter. Violet Friday arrived on a day when there was a bit of room in my toy budget .. so I bought a pair. They arrived and so did the clouds, rain, hail and lightning.

 

Last night was their first light. In short they are stunning eyepieces. They are comfortable visually and physically. The eye-guard is very soft and creates an effective light seal. The 84° field is much wider than my binocular vision but the peripheral image is nice.

 

They are sharp across the field and the diffraction pattern was easily visible at (notionally) 88x. The E & F stars of the Trapezium were easy ... but I became conscious of needing to re-focus frequently. It was weird - it felt that my eyes were gradually drifting out of focus.

 

Then I did the face palm ... These things are heavy. Installed in a pair of Mk V's, my focuser was carrying 2.1 kg (4.6 lbs). This is quite a lot, even for a FTF3545. In all honesty, I don't think these will be usable with binoviewers in anything smaller than a FTF3035.

 

As time and weather permit, I'll do some comparisons. For now, I'm very pleased.

[junomike]

Some nice info!

Considering a pair myself.

[noisejammer]

Right - a second light report.

 

Initially Don (Starman1) reported these eyepieces have quite a lot of EoFB compared with the Docters. This was confirmed by several others. On the other hand, Tammy reported on these as the best eyepieces APM had ever made. Don subsequently made a rather curious discovery.

 

I had seen some EoFB on my first night out but wanted to refresh my memory on this thread before commenting further. In short - I experienced the same effect as Don, viz the EoFB is only visible when my eyes were pointed well off axis; it disappears when I was more or less looking at the middle.

 

When binoviewing, I could observe the EoFB by looking downward in the field but it was barely perceptible looking to the left, right and upward. This is quite strange - it means the eyepiece is considerably better suited to binoviewing than it is to cyclops mode.

 

Other observations

1. There appears to be a little glow right in the centre of the field, perhaps subtending 10°. I suspect this is ghosting from within the eyepiece because I could see it whether or not I was using an observing hood. It is very faint and disappeared when I installed a NPB filter.

 

For completeness, this could also be an interaction with my binoviewers (Mk V) so I'll check it soonest.

 

2. The apparent field is large enough that I once picked up a strongly distorted ghost image from my binoviewers when a bright star (Alnitak) was just outside the extreme edge of the field. This is clearly a multi-path binoviewer problem but it was quite odd.

 

3. The transparency and comfort of these eyepieces is excellent - I had some of my best ever views of the moon (including the Lunar X). The 3D effect on the lunar Apennines was stunning.

 

4. I ran Mars up to around 180x. It's getting small but I was able to reel in Mare Cimmerium, Mare Tyrrhenum, Syrtis Major. The polar cap was easy. Overall, the APM eyepieces are very capable for planetary observation but ZAO II's have less scatter.

 

5. They work well on nebulae. A lot of structure was easily visible on M42. Even though the moon was up & less than 60° away, I was able to pull out IC434 when using a nebula filter and observing hood. NGC 2023 and 2024 were quite easy. I may have glimpsed B33 but I'm not claiming it.

 

Overall then, I'm well pleased with these eyepieces. They are really sharp and putting all the light where is should be is the first part of going deep.

 

Scope - TOA150 / AP - Barcon / T2-01B prism / Mk V / APM 12.5 Hi-FW

[Deadlake]

Any update on these EP’s. Considering a pair of HI-FW’s or Nikon 12.5 hw’s.

The APM’s are half the cost of the Nikons but the EOFB reports are making me think twice on them.

Of course Doctor EP’s are unicorns.

Edited by Deadlake, 02 September 2021 - 02:50 AM.

[noisejammer]

I suspect that the EOFB is related to sky illumination but I haven't had a chance to test this theory. I'm going on a desert observing trip over the next new moon. The sky is typically 21.8^m - 22.0^m (depending on whether the MW is visible.) I'll advise what I see after I return.

 

Comparing the NAV 12.5 HW vs the APM 12.5 Hi-FW is a bit unfair - the NAV runs $910 ea while the APM is $375. If eye relief, weight and ka-ching are no object then a pair of the Nikons would be the way to go.

[Deadlake]

I suspect that the EOFB is related to sky illumination but I haven't had a chance to test this theory. I'm going on a desert observing trip over the next new moon. The sky is typically 21.8^m - 22.0^m (depending on whether the MW is visible.) I'll advise what I see after I return.

 

Comparing the NAV 12.5 HW vs the APM 12.5 Hi-FW is a bit unfair - the NAV runs $910 ea while the APM is $375. If eye relief, weight and ka-ching are no object then a pair of the Nikons would be the way to go.

The Nikons are on offer at RO in Japan, about $735. What other EP's are available around 12 mm? Since I'm getting the BV and a pair of 17.5 mm Morpheus as well, economy option would be some Takahashi Abbe 12 mm. Until some more ka-ching is available.

Looking forward to your report from the desert.

[noisejammer]

The Nikons are on offer at RO in Japan, about $735. What other EP's are available around 12 mm?

A good price but you'll be picking up shipping, brokerage and local taxes so be cautious.

 

On eyepiece choice, it really depends on which combination of focuser, diagonal & binoviewers you have As I noted above, my set is a 2.1 kg load so things need to be quite sturdy.
 

I have pairs of 6, 10 & 14 Delos - the 12mm might suit you. Alternatively, you could look at the 13T6. If you are using the Mk V or MB2 binoviewer, you could use a 1.25x or 1.7x glass path corrector and convert the Morpheus into an effective 11.7.

[Deadlake]

A good price but you'll be picking up shipping, brokerage and local taxes so be cautious.

 

On eyepiece choice, it really depends on which combination of focuser, diagonal & binoviewers you have As I noted above, my set is a 2.1 kg load so things need to be quite sturdy.
 

I have pairs of 6, 10 & 14 Delos - the 12mm might suit you. Alternatively, you could look at the 13T6. If you are using the Mk V or MB2 binoviewer, you could use a 1.25x or 1.7x glass path corrector and convert the Morpheus into an effective 11.7.

Scope is 130/F6, FL = 680 mm. Equipped with a 3.5" FT focuser so weight not a concern. Diagonal, well going to see how it does but have either 1.25" BBHS prism or 2" Baader mirror diagonal.

Planning on getting a GPC 2.6 due to the focal length for MB2 BV. 

None of the Televue are cheap either....  

 

Back to 12.5 HI-FW, weight of EP's with above setup should not be too heavy. 

Edited by Deadlake, 03 September 2021 - 11:26 AM.

[noisejammer]

Yep ... but Tak eyepieces are not that cheap either.

 

I've no experience of the Tak Abbe types but the LE's are good.

 

Edit - I meant to make this comment ...

On the weight of the APM 12.5 (or NAV 12.5), my scope has a FT 3545 installed and it handles it easily. With this weight hanging from it, you might want to read this thread - at least to page 5 when Joshua from Starlight Instruments posts an explanation.

 

My interpretation is that the FT brake is badly designed and you need to release it prior to re-focusing. Failure to do this will put chips of brass into the pinion and wreck the mechanism. It seems we need to tighten the silver grub screw a little.

[Deadlake]

Yep ... but Tak eyepieces are not that cheap either.

 

On the weight of the APM 12.5 (or NAV 12.5), my scope has a FT 3545 installed and it handles it easily. With this weight hanging from it, you might want to read this thread - at least to page 5 when Joshua from Starlight Instruments posts an explanation.

Thanks for the post.

 

My scope is with an APM FT3545 focuser attached and hence might not be the generic version that has no reported issues.

I'm going to contact Astrograph to find out if I need to make any adjustments. I have 2x 24mm UFF that I would class as heavy for BV usage, well 331 grams versus 544 grams for the Hi-FW EP.

Edited by Deadlake, 04 September 2021 - 02:54 PM.

[Kunama]

Thanks for the post.

 

My scope is with an APM FT3545 focuser attached and hence might not be the generic version that has no reported issues.

I'm going to contact Astrograph to find out if I need to make any adjustments. I have 2x 24mm UFF that I would class as heavy for BV usage, well 331 grams versus 544 grams for the Hi-FW EP.

The focuser on your APM-LZOS is exactly the same type as the one Kent had the problem with so be careful when using the 'brake' function. Remember to release it when focusing, think of it as a 'lock' not as a brake.  The socket screw on topside is used to adjust the glide action of the focuser.

Edited by Kunama, 04 September 2021 - 05:06 PM.

[Deadlake]

The focuser on your APM-LZOS is exactly the same type as the one Kent had the problem with so be careful when using the 'brake' function. Remember to release it when focusing, thin of it as a 'lock' not as a brake.  The socket screw on topside is used to adjust the glide action of the focuser.

I thought it was custom focuser for TEC that had the issue?

[Kunama]

I thought it was custom focuser for TEC that had the issue?

The same brake mechanism exists in the APM-FT3545 as well.  He is a picture of my APM-LZOS focuser, I think the TEC may just vary cosmetically 

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[noisejammer]

I think Kent hat two problems - damage to the pinion caused by pieces of brass from the brake (which Matt correctly calls a lock.) The second issue was pieces of teflon being shaved off - this is because TEC uses a slightly different glide support.

 

So, everyone with a FT focuser is vulnerable to pinion damage if you focus while the so called brake tightened.... and no, I don't know what tightened means.

[Deadlake]

The same brake mechanism exists in the APM-FT3545 as well.  He is a picture of my APM-LZOS focuser, I think the TEC may just vary cosmetically 

The TEC is different, what the APM brake mechanism is unknown, from starlights post

 

“The standard FTF3545 focuser is assembled with 3 small strips of felt on the inside of the focuser housing which is saturated with a lubricant in which each time the focuser is racked in and out the focuser is lubricated to make it feel smoother.  But for Yuri's requirements at TEC, we build the focusers for him without any oil or wiping felts which make the focusers a bit stiffer as without the lubricant in the felt strip, the focuser has a bit more friction.

This particular issue i have only seen once before, also on a TEC focuser. Those flakes are indeed Teflon being removed from increased friction caused by tightening of the hex nut. I suspect this is an issue particular to TEC focusers, as Yuri requests we build his focusers without the use of oil and wiping felts. Under normal tension, this hasn't caused any issues that I am aware of. But the increased tension and lack of lubrication seems to be causing wear of the Teflon strips within the focuser housing.”

[noisejammer]

I suggest you read the whole thread.

[Deadlake]

My FT is from around June 2021, hopefully it might have the modifications made by Starlight.

Awaiting response from UK dealer on this.

[Deadlake]

The focuser supplied with the LZOS scope is the standard Starlight FT3545 so is lubricated.

On the brake/lock screw:

 

"My view is the ‘brake’ is a lock, not a means of applying drag. It should be applied when you want to fix the position of the focuser after focusing and released when you need to refocus."

[Moravianus]

To bring it back on topic: last 2 nights, I observed with the APM 120 mm binocular and APM 12.5 Hi-FW with APM 24  and Morphei for comparison.

I like the eps like the OP very much. Yes, the rolling ball effect while panning is there but with slower move it is not so pronounced. In my specific situation (F 5.5 instrument, my presbyopic eyes not able to accommodate much, NELM 21.55 skies, some loss of transparency due to light smoke)  the EOFB was only lightly pronounced in the last 15% of field which was not usable anyway because of <?> smeared stars. I did not perceive the difference of EOFB changing depending on aiming the view.

Once seeing improved above average at midnight, I really enjoyed them (M22, M31, double cluster) I use them with eyecups rolled down.

I did not get the chance for head to head with Morpheus 12.5 this time, so much I was into bagging objects. The Starsense Explorer on top of the bino worked very well.

[denis0007dl]

Love my APMs 12.5mm, when rubber eyeguards and metal front rings are removed/unscrewed.

 

Really impressive views, very comfortable, I only wish they have better edge correction, but it doesnt bother me.

 

Here is look through WO 132 FL APO + CZAS binoviewer.

 

Stunning contrast, wide, clean, and comfortable views.

 

Denis

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Edited by denis0007dl, 08 September 2021 - 02:08 PM.

[noisejammer]

I suspect that the EOFB is related to sky illumination but I haven't had a chance to test this theory. I'm going on a desert observing trip over the next new moon. The sky is typically 21.8^m - 22.0^m (depending on whether the MW is visible.) I'll advise what I see after I return.

Yay ... finally I was able to make a desert trip on a moonless night with a clear sky. I did some careful testing of the 12.5 Hi-FW and compared notes with my observing buddies - both of whom have more than 40 years behind the eyepiece.

 

The sky was 21.7 - 21.8 mpsas (the southern MW was up.) We used my TOA150 at f/11 and an AP diagonal. There was negligible background light and we used observing hoods to suppress light bouncing off the eye lens. No filters were used. Seeing was excellent - viewing Sirius, we had 4-5 stable diffraction rings and the Pup was obvious (provided you looked in the right place.)

 

The short version is that edge of field brightening was visible when I looked directly at the edge of the field but this disappeared from my perception when I  looked at the centre of the field. This echoes Don Pensack's observation linked to earlier in this thread. My companions noted the same effect.

 

Noting that we saw no EOFB with our averted vision when viewing on axis, I started to wonder whether the EOFB is caused by interaction of light reflected from the sclera back to the eyepiece optics and then a fuzzy glow appears. When light from the exit pupil enters the eye, very little is reflected and so the EOFB disappears.

 

Finally, I did not perceive a glow in the centre of the field that I reported on previously.

 

So that leaves my well pleased. However, I dropped one of my 12 Hi-FW in the desert sand... got to fix that now.