Deadlake

1 minute ago, johninderby said:

So similar strehl to the Tecnosky then.

Question is can they be collimated? That's how a dealer can push the performance, or so Rupert told me in the case of the 125 mm Tecnosky doublet.

6 minutes ago, KP82 said:

I thought FPL55 was supposed to be more friendly to figure and polish, so theoretically it should be easier to achieve the desired min strehl than the FPL53 counterpart. Maybe the new 55 model has other improvements to warrant a £500 price increase.

If there are comparing it to LZOS then the figuring is pushing up the price. Cannot see any other way there can justify the cost. I've not seen a review of any of these scopes.

32 minutes ago, johninderby said:

This is the TS equivalent.

https://www.teleskop-express.de/shop/product_info.php/info/p7717_TS-Optics-PHOTOLINE-130-mm-f-7-FPL53-Triplet-Apo---3-7--Focuser.html

No test certificate though.

I was thinking this one, given the price and certificate:

https://www.teleskop-express.de/shop/product_info.php/info/p12851_TS-Optics-CF-APO-130-mm-f-7-FPL55-Triplet-APO-Refractor-with-Certificate.html

I'd imagine getting to a certain Strehl costs time..

Is this a new model?

https://astrograph.net/epages/www_astrograph_net.sf/en_GB/?ObjectPath=/Shops/www_astrograph_net/Products/AGTEC130-7

10 years ago minimum Strehl >= 0.95 would be premium only.

On 13/04/2021 at 13:50, amaury said:

Where did you buy from @Deadlake? Astrograph?

Yes Astrograph. Checked e-mail, Baader is end of April, APM is listed as late....

34 minutes ago, Captain Magenta said:

Oops I just remembered I never answered this.

I did run them through MTFmapper, and the results demonstrate that both my skymax 180 and my M603 seem to be truly terrible. I was left scratching my head, as they certainly aren't terrible when I look through them either at night-sky objects or terrestrially. As you can see I photographed my A3 test target at about 35 metres, essentially the minimum focus distance for either scope. Various things could have conspired to render the sharp edges on the test sheet to become soft: missed focus, either because the cardboard target-back might have shifted in the wind; poorly printed; camera-shutter-shake. Or, the scopes ARE terrible, but I don't think so.

I'll have to do it again with better-controlled conditions.

Cheers, Magnus

What you want is this:

https://www.cloudynights.com/topic/757247-ai-based-wave-front-sensing-and-collimation/

If I follow correctly you want the wavefront..

8 minutes ago, John said:

If this has the optical performance qualities of the Morpheus and achieves the other characteristics that APM specify, I think it will fly of the shelves at that price. 

I am imagining a set comprising the APM XWA 20mm, an APM Super Zoom and a Powermate or similar quality barlow / extender. Could be all an observer needs ?

For the SCT / Mak-Cassegrain user, just the 20mm and the zoom.

 

 

I think APM are shooting for Leica quality, but made by KUO. If they get them working with F6 scopes then they will work with any scope. As long as they turn up by September should be good....

8 hours ago, Stu said:

My apologies, was just attempting to contribute to the conversation.

Sorry @Stu if I've caused offence, just surprised at the number of comments when noting contrast and exit pupil.

ETA for delivery of EP’s from KUO is end of April.

19 minutes ago, jetstream said:

Contrast is fixed and is the difference between sky brightness and the surface brightness of the object.

What do you mean by surface brightness for an object, what happens when that object is extended, that is difficult to define.

@jetstream still waiting for Tele Vue filters and APM EP’s.

38 minutes ago, Stu said:

I think you are perhaps missing the significance of the difference in exit pupil between these two. It’s not all about TFOV or mag.

As @Deadlake says, the 30mm would give benefits from larger exit pupil which will likely give better views with UHC or OIII filters. The 20mm will give you more image scale which helps detect the smaller objects and also does darken the sky background when you have more light pollution to contend with. I accept that it also dims extended objects but object visibility is a complex subject and your statement that contrast is independent of exit pupil is not the whole story, see this visibility calculator from Mel Bartels who has forgotten more about this stuff than I will ever know 😉.

https://www.bbastrodesigns.com/VisualDetectionCalculator.htm

Thanks @Stu, i’ll remember that contrast is on the hot list of subjects like the glass question etc..😃😀😃

26 minutes ago, amaury said:

I'll do my homework with this. 

It helps yes. The thing is that with my scope (8" 1200mm f/6 Dob), the APM 20 gives me 1.67deg TFOV, that makes the APM 30 UFF redundant as it almost overlaps in terms of TFOV (1.75 TFOV for the UFF).

The one thing I would be giving up with the 20/100 is eye relief (15mm). I only have very small corrections (-0.5 Sph and -0.5 Cyl) so I think I can do visual observing without glasses. Maybe I am wrong here and I am being too optimistic. 

I totally understand that usefulness now. I just never considered  ~20mm / 100 degree eyepieces because of the massive price premium of those specs. I was aiming more towards 24mm/82 deg or 30mm/70 because they have an equivalent TFOV in my scope, better eye relief, and better prices, at the expense of more exit pupil (which wouldn't be an issue in truly dark skies, but it doesn't get better than bortle 4 for me).   

Its a trade off between contrast with the 20mm and exit pupil with the 30 mm for filter usage, see:

I didn't see the point of both until it was posted out by @jetstream too.

33 minutes ago, Stu said:

It’s well worth checking it out carefully. I did email Astroshop.eu the other day, and they reassured me by way of this reply:

We offer a special service for our UK customers whereby we offer greatly reduced shipping costs and pay any incurrable customs fees. This means, you don't have to deal with customs paperwork and further payment at your end!
In this case the VAT will not be deducted.

Still not totally sure it would be without additional cost or hassle but I guess we won’t know until we’ve tried! Check with each individual retailer though.

Astrograph also list the same eyepiece in the U.K. which is likely a safer bet but they are not showing any stock at the moment.

https://astrograph.net/epages/www_astrograph_net.mobile/en_GB/?ObjectPath=/Shops/www_astrograph_net/Products/AGLE20HDC&Locale=en_GB

They are excellent eyepieces. I had one and sold it, but considering getting another soon when funds permit.

Astrograph have a shipment in at the end of April, pending APM's large shipment to come in from KUO. I'm waiting on some APM EP's which I got before the price rise. As far as performance goes, when I purchased I discussed with another SGL user who has both the E21 and the APM 20 XWA, he told me skip the E21, the APM is sharper in the middle, weighs half as much and only losses out to the E21 with a small amount of astigmatism at the edge which you would notice unless under SQM > 21.8 skies. So I did, also got the APM 30 UFF as will show more contrast on darker skies.  Hope that helps.

2 hours ago, John said:

Me neither.

All my setups have to be reasonably portable and quick to setup / tear down.

With hindsight the Istar 150mm F/12 on the EQ6 / Meade Giant Field tripod was not my smartest decision

My neither, I went for an SXP2 because it’s lighter then the competition. I can be in and packed up in 10 minutes at the end of the night. That means the scope, mount and tripod are disassembled and stored.

21 hours ago, Stu said:

I’ve had the pleasure of looking through @GavStars AP 130GTX, and it was wonderful I must say. Pretty sure I preferred it to his TEC140 for undefinable reasons, just something about the purity of the views. I seem to recall having a wonderful view of the Trapezium with all six stars better presented than I’ve ever seen before, or since. There’s always a chance that I’m confusing that memory with the views through Gavin’s TEC160 but I don’t think so 🤔

Anyway, an AP130GTX is certainly high up on my wish list, highly portable for its aperture. I do have a constant (though currently totally hypothetical) argument in my head as to whether I would go f6 or f9 for ‘my’ 130mm premium apo when my number come up finally. I suspect f6 due to my love of widefield and for the improved portability, so the GTX is still up there.

@GavStar told me he sold the TEC because he preferred the views thru the AP, backed up by club members. Nice choice to have. I’ve not asked him how he managed to get hold of the GTX and a stowaway. Original I was going to get a 130 mm/F9 LZOS. However after discussing the F6 has more utility in wide field, Bino or NV usage then the F9. As @jetstreamsays you can always Barlow the scope for high magnification. The only downside of fast scopes have a slight lower Strehl, but going from 0.99 to 0.98 is a first world problem that my young eyes will not notice.

The phenolic tube gets more complicated. The original tubes from APM had flocking inside them, at some point in the past APM had to find a new tube maker (someone retired) and the new phenolic tubes do not have the flocking inside.

Astrograph have phenolic tubes with the flocking for LZOS lens cells, plus they added a collimating flange for easier access to the lens cell.

Not sure why APM does not have access to the same tube fabricator as Astrograph.

“The APM ‘CNC-LW / LW-II’ series is the original range of tubes that used to be offered for any LZOS lens. These are phenolic tubes and our AG tube follows on from these. The original builder of these tubes no longer works with APM. An alternative builder offered a version which is not flocked internally. APM now focus sales of LZOS on the aluminium tube versions which are turn key tubes. As I mentioned these can be fitted with the Starlight Focuser.

Strictly speaking the CNC-LW tube can still be offered as it’s a custom build. It has a 4-6 week lead time (not 2-4 as suggested). The original LW tube does not have a collimation flange and has to be collimated internally which is a pain. I am an advocate of the phenolic tube because its better. However the original tube shows its age. As such we don’t offer this old tube as the AG is frankly a lot better.“

1 hour ago, billhinge said:

I have the 115mm TMB LZOS and was looking to change to a 3.5" ST focuser to fit the Riccardi reducer/flattener, I have been in  touch with Markus at APM and Wayne at Starlight and it seems those old tubes are slightly the wrong size to fit the new ST focusers without an adapter, unfortunately they wanted me to ship the scope out to Germany or US to fit a bespoke adapter 😬

If I do replace the tube I may go the moonraker route, I can get a shiny silver 3.5" ST to match the tube 😄

I ordered mine with the 3.5 FT, if you take the base model add the 3.5 " FT its about £500 off the mark II models. 

Does anyone know how accurate 'Dark Sky Meter' is on iPhones at all?

I have both Sky Safari Pro and Luminos. Luminos has better rendering, however I do like in Sky Safari you can download a tour and then use goto on a mount to visit the targets in the list.

Luminos is good in that it's a pay once fee and the developers are quite responsive.

Also I believe the transits of Io are calculated correctly in Luminos whereas they where out in Sky Safari.

On 31/03/2021 at 19:25, Mr Spock said:

I've been panic buying 😜

Me to to avoid the price rices, for instance 5 Ep's for the price of 4 Ep's now the prices have been raised.

I was asking a dealer about this EP and he had quite a lot to say.

Astro Zooms are normally crap compared to primes. They are basically barlowed so the FOV changes as you zoom (move the barlow). This results in the higher mag having the widest AFOV

Quality at the higher mag / short FL range is normally much worse. Use it un-zoomed and its OK. After that, soft.

The Baader Zoom is OK but still not as good as a prime. APM used to offer quality spotting scope zooms from Leica and Meopta with 1.25” adaption to be used in telescopes. These were £500 but stunning. Every bit as good as the best prime

Markus mentioned this new zoom to me last month. I said it will be great as long as it is equally good at both ends of its range. At the moment it is still being developed, so apart from performance that is the same through the range, it will also be getting clickstops at different FL settings like the Baader.

The Zoom is designed to offer a nice wide flat field with a low focal ratio scope. Very low in fact. The idea being we can use them on the APO Binoculars which are F5.5. If it delivers then it means we could have a Zoom to replace the otherwise very good (as good as a TV EP) UFF range from 15mm down, and that also has a wider field of view.

Hopefully I will get some samples early I can test. If its as good as planned then it will be a winner. They will be tested on 150mm APO Binoculars and Refractors from F6-F8. If they maintain a flat field and sharpness with those, they will work in anything. 
 

Expected price in the UK will be £279 that’s not confirmed due to while an FTA exists (Free Trade Agreement), that only applies to goods manufactured in the EU and are accompanied with a Certificate of Origin. As these Zooms will be made in China, they will get hit with a 4% duty (as all Chinese telescopes / telescope equipment does (but not cameras weirdly). We also get a customs brokerage fee and shipping costs from the EU, particularly Germany, have increased quite bit. A 6” class scope used to be 40€ to ship to us. It is now 100€!

11 hours ago, John said:

My (limited) understanding is that the brighter diffraction ring means that more energy is going there rather than into the airy disk which can be because of modest amount of spherical aberration

There might be other causes as well though.

 

 

The faster scope going to have more field curvature, which will effect the edge of the image. The field curvature can be fixed with a flattener to sync with the EP’s curvature.

I’d argue that most fast scope (F6 and less) have better figured lens (and cost more) so no issue with chromatic shift, and more light into the central airy ring, but spherical abberation hm...

For example John would we see a difference between my LZOS F6 and your F9.2? Difference between a Strehl of 0.98 and 0.99? 😁

5 hours ago, John said:

I've been telling myself that for years 🙄

I've not bought one since December last year, so that's something !

I went and bought 5 APM ep’s (XWA) at the old price, now 5 for the price of 4. 

1 hour ago, Clarkey said:

Don't do it!!

My first purchase was January last year. Everything listed below is since then. Guilty as charged.

I do have a problem though. The house insurance has just come up for renewal and my better half wants to know how much cover to add for my astro gear. 😱😬

Unlimited contents insurance? 😀

@GavStar Great pictures, taken last night? Nice you can do that when the moon is fully (~99%) out.