164 replies to this topic

[rgsalinger]

I bought what has to be one of the first of these telescopes - ordered it as soon as I saw it was coming out - as I loved the idea of an F4 scope with what is effectively a Petzval design which means I don't need to fuss with a reducer. I also noted the claim that it had a 43mm imaging circle and was suitable for use with a full frame camera. So, for Xmas my wife kindly chipped in and the scope arrived about a week ago in time for it to be a holiday gift.

 

It sat in its box until 2 days ago when I saw that we were going to have a clear night on Xmas eve. I unpacked it and found the build quality to be excellent. It comes with a nifty case as well and two adapters - M48 and M54 so it's easy to set up an imaging system on it. I set up the scope with an EAF, replaced the Vixen dovetail with a much stronger Losmandy and installed an ASI2600 camera. I then drove out to my observatory and installed it on my MYT using an ASI2600 that I had used for a different project. (I wasn't brave enough to try it with my ASI2400 even though they "said" it would work.

 

I finished up around 4PM and opened the roof so that the scope could cool down as the temperature dropped. I planned to go unguided at that short focal length as I've been successful with unguided imaging with my trusty ASKAR FRA400 when using a large TPoint model. I figured at 280mm it would be even easier. I fired up the SKYX and NINA and within maybe 15 minutes I had a good autofocus run. Looking at the stars, I could see a problem - they looked like comets. I've seen this once before when my TV127is managed to hit the ground hard. That cost me about a grand to get it rebuilt at Televue (excellent job by the way). 

 

So, I figured that it just needed some time to adjust to the temperature and went on to polar align the mount using the SkyX (as that pier can't see polaris). Platesolving failed on about 1/3 of the exposures but I kept at it for 30 minutes and achieved reasonable alignment. Then I ate dinner and waited another hour to retest the scope. No difference - the scope is way out of collimation. Now please rember that this design doesn't require any particular back focus - I just attached the 2600 with an M42 to M48 adapter, screwed it together and focused it. Stars in the center were pretty good. 

 

Here's a screen shot of what the stars looked like over most of the frame. 

 

 

For the record I moved the scope around the sky to different locations and the results were the same - stars like comets. Here's a link to my google drive so you can see 3 of the images I took last night. 

 

So, I recommend that if anyone is contemplating buying this scope, wait until at least one imager gets a good one. I sure didn't. I'm just glad that I got around to testing it before the dreaded 30 day return period expired. I would not want to ship this back to Taiwan and hope that it survived the round trip.If it couldn't get here in working order, doubling the chances of damage is very unattractive. 

 

So, should I ask for another one or get something else? Curious to see what the crowd here thinks about all this.

 

FWIW I owned on WO71 F4.9 for years and years and it was a terrific little scope but my FRA400 is better optically so the WO71 was sold. 

Edited by rgsalinger, 25 December 2023 - 01:31 PM.

[hyiger]

So, should I ask for another one or get something else? Curious to see what the crowd here thinks about all this.

 

FWIW I owned on WO71 F4.9 for years and years and it was a terrific little scope but my FRA400 is better optically so the WO71 was sold. 

My guess is you just got one that was banged up in shipping and got knocked out of collimation. Maybe try collimating it yourself before sending it back. Otherwise, get another one. If it's also bad then maybe there is a general issue with these scopes. I've had my eye on this scope as well. 

Edited by hyiger, 25 December 2023 - 02:18 PM.

[Dereksc]

I bought what has to be one of the first of these telescopes - ordered it as soon as I saw it was coming out - as I loved the idea of an F4 scope with what is effectively a Petzval design which means I don't need to fuss with a reducer. I also noted the claim that it had a 43mm imaging circle and was suitable for use with a full frame camera. So, for Xmas my wife kindly chipped in and the scope arrived about a week ago in time for it to be a holiday gift.

 

It sat in its box until 2 days ago when I saw that we were going to have a clear night on Xmas eve. I unpacked it and found the build quality to be excellent. It comes with a nifty case as well and two adapters - M48 and M54 so it's easy to set up an imaging system on it. I set up the scope with an EAF, replaced the Vixen dovetail with a much stronger Losmandy and installed an ASI2600 camera. I then drove out to my observatory and installed it on my MYT using an ASI2600 that I had used for a different project. (I wasn't brave enough to try it with my ASI2400 even though they "said" it would work.

 

I finished up around 4PM and opened the roof so that the scope could cool down as the temperature dropped. I planned to go unguided at that short focal length as I've been successful with unguided imaging with my trusty ASKAR FRA400 when using a large TPoint model. I figured at 280mm it would be even easier. I fired up the SKYX and NINA and within maybe 15 minutes I had a good autofocus run. Looking at the stars, I could see a problem - they looked like comets. I've seen this once before when my TV127is managed to hit the ground hard. That cost me about a grand to get it rebuilt at Televue (excellent job by the way). 

 

So, I figured that it just needed some time to adjust to the temperature and went on to polar align the mount using the SkyX (as that pier can't see polaris). Platesolving failed on about 1/3 of the exposures but I kept at it for 30 minutes and achieved reasonable alignment. Then I ate dinner and waited another hour to retest the scope. No difference - the scope is way out of collimation. Now please rember that this design doesn't require any particular back focus - I just attached the 2600 with an M42 to M48 adapter, screwed it together and focused it. Stars in the center were pretty good. 

 

Here's a screen shot of what the stars looked like over most of the frame. 

 

wo68x.jpg

 

For the record I moved the scope around the sky to different locations and the results were the same - stars like comets. Here's a link to my google drive so you can see 3 of the images I took last night. 

 

So, I recommend that if anyone is contemplating buying this scope, wait until at least one imager gets a good one. I sure didn't. I'm just glad that I got around to testing it before the dreaded 30 day return period expired. I would not want to ship this back to Taiwan and hope that it survived the round trip.If it couldn't get here in working order, doubling the chances of damage is very unattractive. 

 

So, should I ask for another one or get something else? Curious to see what the crowd here thinks about all this.

 

FWIW I owned on WO71 F4.9 for years and years and it was a terrific little scope but my FRA400 is better optically so the WO71 was sold. 

There is a thread on AB where a couple of people have reported receiving their WO68's and have given positive initial impressions.

 

https://www.astrobin...ades-68/?page=2

 

If you scroll down the page (2) a couple of people have posted images (full frame camera).

 

Hopefully that means yours is an outlier and you can get a replacement ASAP.  It should be worth trying another one before giving up on the scope. From the looks of the images you put in the google drive it does seem as though something got misaligned during shipment.

 

Please update when you can - it is a very interesting scope.

 

Good luck!

 

Derek

[dcm_guitar]

.....

 

FWIW I owned on WO71 F4.9 for years and years and it was a terrific little scope but my FRA400 is better optically so the WO71 was sold. 

Just curious, why not try the 0.7x reducer on the FRA400 and get the same 280mm FL and f/3.9 versus a whole new OTA?  The only thing I can think of is that the Pleiades has no backspace issues while the reduced FRA400 does require 55mm of backspace.  FWIW, I just bought a FRA400 and reducer.  I tried it out on an ASI2400 on Decmeber 23rd and was quite pleased.

 

Don't get me wrong, I love WO OTAs.  I have an FLT132 that I adore; only wish it was faster.  I had a GT81IV that I REALLY liked, but wanted to do FF imaging.

[rgsalinger]

Looks to me as if I may have misread the manual. I wasn't careful about the back focus requiremnt of 55 mm. I suspect I was quite a ways off. I'll have to find a way to try it one more time, I guess. Still, I would not expect comets like that from poor back focus. I'd expect oblong stars in the corners. 

 

I had trouble with the FRA400 reducer the one time I tried it but I may not have gotten the backfocus correct. If you have a good result I'd like to see your image train.  I doubt that it would meet my "standards" for results with an APS-C chip. Again, like to see an FRA400 with reducer success story. 

 

Rgrds-Ross

Edited by rgsalinger, 25 December 2023 - 07:21 PM.

[dcm_guitar]

Looks to me as if I may have misread the manual. I wasn't careful about the back focus requiremnt of 55 mm. I suspect I was quite a ways off. I'll have to find a way to try it one more time, I guess. Still, I would not expect comets like that from poor back focus. I'd expect oblong stars in the corners. 

 

I had trouble with the FRA400 reducer the one time I tried it but I may not have gotten the backfocus correct. If you have a good result I'd like to see your image train.  

 

Rgrds-Ross

I was literally about to start a thread showig my FRA400 results on a 2400 full frame sensors when I saw your thread.  I'll share the info in a bit on a new thread and am happy to any details and/or subs if you'd like.

Edited by dcm_guitar, 25 December 2023 - 07:23 PM.

[hyiger]

Looks to me as if I may have misread the manual. I wasn't careful about the back focus requiremnt of 55 mm. I suspect I was quite a ways off. I'll have to find a way to try it one more time, I guess. Still, I would not expect comets like that from poor back focus. I'd expect oblong stars in the corners. 

 

I had trouble with the FRA400 reducer the one time I tried it but I may not have gotten the backfocus correct. If you have a good result I'd like to see your image train.  I doubt that it would meet my "standards" for results with an APS-C chip. Again, like to see an FRA400 with reducer success story. 

 

Rgrds-Ross

As you pointed out, if it were back focus then the stars would look like hotdogs and not comets. Another thing to consider. Were you running a dew heater and if so, could this be heat plumes?

[rgsalinger]

No dew heater at all. I never use one. I close the observatory automatically if the humidity hits 92 percent. There was no condensation on the objective - I checked it when I saw the results. 

 

Rgrds-Ross

[dan_hm]

As you pointed out, if it were back focus then the stars would look like hotdogs and not comets. Another thing to consider. Were you running a dew heater and if so, could this be heat plumes?

No, I think these aberrations exhibit a spacing error.  Stars start round in the center and get progressively more distorted as you move out. 

 

Ross, it would be helpful to see how your stars look when you dial in the backfocus. f/3.8 is pretty unforgiving.

Edited by dan_hm, 25 December 2023 - 11:13 PM.

[rgsalinger]

 I've never seen stars like this in my 15 years of imaging under any circumstances when there was NOT an optics problem. I don't want to lose my 30 day return window and have to send the scope back and forth the Taiwan with no guarantee that it will work when it comes back. If Agena Optics resets the return clock to 30 days from "now", I guess I could carefully adjust the spacing and see what I get. When I used ASTAP on the images they there was increasing distortion of the stars in all directions. We just get so few clear nights this time of year.

 

Rgrds-Ross

Edited by rgsalinger, 26 December 2023 - 01:13 AM.

[dan_hm]

This scope is not a Petzval like the Redcat series.  It has a 55mm backfocus requirement.  If you were significantly off from this spec, you cannot judge the quality of the optics properly. 

 

Unfortunately, William doesn't announce this well in any of the product literature, but the website does suggest that it's a triplet with a four-element flattener. The manual also seems to advise 55mm backfocus, albeit in a confusing way:

 

Edited by dan_hm, 26 December 2023 - 10:44 AM.

[rgsalinger]

I guess I have to give it another try as I thought the "Already preset" and "best result" meant that you could just attach a camera to the back of the OTA and you were good to go like a Petzval. I wouldn't have bought it if I needed to spend my time perfecting the BF, though. 

 

Rgrds-Ross 

[hyiger]

I guess I have to give it another try as I thought the "Already preset" and "best result" meant that you could just attach a camera to the back of the OTA and you were good to go like a Petzval. I wouldn't have bought it if I needed to spend my time perfecting the BF, though. 

 

Rgrds-Ross 

Yeah, but even if your back focus was that far off I wouldn't expect to see aberrations like in your image. You do have me thinking though. I wouldn't consider buying this if it wasn't Petzval. I'd rather then have something with a reducer/flattener I can remove so I have 2 focal lengths to play with. 

[zackyd]

If these are designed anything like the redcats, they are built with an optical tube subassembly with fixed optical elements. This subassembly then floats inside so that the focal plane for infinity rays will fall ~55mm from the flange.
This is all you need to be concerned with if the optical components are installed as intended.

[rgsalinger]

I've never seen coma with any telscope that was properly collimated no matter what the back focus error was. And, you can't collimate something like the WO68 yourself. The specification for the scope says 43mm imaging circle.  So, if it doesn't produce perfect stars with a full frame camera it's defective in my eyes.

 

When our CDK14's secondary (long story) was off by about 1" and badly tilted we got bat shaped stars. We corrected that by just eliminating the tilt which took maybe an hour. Now it's essentially perfect. I saw coma exactly like this with my brand new TV127is that clearly was damaged in shipment. (They test these before the leave the factory.) That had to be fixed at the factory. Other than those two incidents, I've only seen back focus errors produce oblong stars. Anyway, if we get a clear night I'll give it another go with the corrected back focus which is easy enough to do. 

 

Now trying to just return it for a credit or to get a replacement, since some have been reported to work OK, Agena Astro won't honor their 30 day return warranty. Turns out that warranty is worthless as it's up to them if they want to take something back and what to charge you for the privilege - it's undefined. You know, I bought from OPT for almost 15 years and they just took back anything I found to be defective or just didn't want within 30 days. I never returned a lot of things, but I liked the fact that if something didn't work or I just didn't want it once I opened it up, they were accomodating. Not the same with Agena I have learned. 

 

Clear skies are a a premium but once this fiasco is over, I'll check all the vendors return policies to see if there's some better return/exchange policy. I've always depended on that 30 day no questions asked guarantee to keep me out of shipping things back and forth the China just to get service. Apparently times have changed. 

 

Rgrds-Ross

Edited by rgsalinger, 26 December 2023 - 06:40 PM.

[PhotonHunter1]

FWIW I owned on WO71 F4.9 for years and years and it was a terrific little scope but my FRA400 is better optically so the WO71 was sold. 

I am following this post and your follow up test results with interest as I’ve narrowed down my next refractor to either the FRA400 or the WO68. 

Edited by PhotonHunter1, 26 December 2023 - 09:21 PM.

[sc02492]

Agena Astro won't honor their 30 day return warranty. Turns out that warranty is worthless as it's up to them if they want to take something back and what to charge you for the privilege - it's undefined. You know, I bought from OPT for almost 15 years and they just took back anything I found to be defective or just didn't want within 30 days. I never returned a lot of things, but I liked the fact that if something didn't work or I just didn't want it once I opened it up, they were accommodating. Not the same with Agena I have learned. 

Ross, can you provide more details regarding the difficulties you are having with returning this item to Agena?  This would appear to be a very straight-forward and legitimate return request on your part, unless I am missing something.

 

Steve

 

www.starrywonders.com

[whwang]

If all the optical elements move together in WO's new sliding mechanism inside the OTA, then there is no back focus requirement.  As long as you can reach focus, you are at the right back focus.  This is the same as those so-called Petzval design.  On a Petzval scope like TAK's FSQ, all optical elements are fixed in the OTA, so they all move together with respect to your camera when you adjust the focus.  Because of this, as long as you can reach focus, it doesn't matter how many spacers you add between your camera and the scope.  The point is that all optical elements must be fixed and must move together when you adjust focus.  It has nothing to do with optical design (i.e., Petzval or not).  It's just that Petzval scopes on the market happen to be the group that adapts the mechanical design with fixed optical elements.

 

So, for Ross, the first thing to check is whether the last element moves inside the OTA when you focus.  If it does, then you can forget about back focus.  It doesn't matter.  Your issue is not a back focus issue.  On the other hand, if the last element stays fixed and only the front element(s) moves while you focus, then back focus matters and you need to be careful about it.  (Though, I agree with you that back focus problem should not lead to stars this terrible.)

 

Do you mind showing stars in all the other corners?  This can tell us something more about what's going on.

[rgsalinger]

I've got 3 images you can look at here. They are 10 second exposures taken with a ZWO ASI2600MC camera using a Paramount MYT on a rigid pier.

 

I don't think that the rear element moves. Reading the manual, I thought that that "Already preset" meant that back focus was not critical.

 

I think I have to run another test but I remain, as always, skeptical that it can cover a full frame camera. This time I'm going to use my ZWO ASI2400 and see what happens. I wouldn't have bought the scope if I knew that I'd be sitting in the cold adjusting spacing by .1mm to get the best performance. (At least I would have waited until it got warm again!)

 

I won't comment further on the vendor. I'd advise people to check the fine print before buying at any of the large stores. Things are just different now and caveat emptor has come back into fashion big time.

 

The problem is that when talking about an astrograph, what's "good enough" for one person is garbage to another. I figure a dead camera is probably easily returned.

 

Rgrds-Ross

Edited by rgsalinger, 26 December 2023 - 07:20 PM.

[bmcclana]

With this focuser design, some of the elements are moving instead of the whole camera train moving. If the rear elements don’t move, the front ones do and the backspacing is going to be critical.

If the rear elements move and the front don’t, the backspacing is going to be critical.

Only if all the elements move together is the backspacing (from the back of the scope) not critical and will be set and converge with focus. (Assuming all the other elements are spaced correctly)

The way I read the manual, you have to set the back focus to 55mm. Which makes me think the rear elements are fixed.

[charles.tremblay.darveau]

That's a disappointing first light result,I guess I'll stick to the fra400 with the reducer. Equally disappointing that Agena doesn't honor their return policy on this as the stars are certainly not acceptable for a high end astrograph

[kgb]

Oh man. I'm bummed. When I heard 7 elements, I too thought/assumed this was a Petzval, but I guess the advantage of this scope is that it is purely a fast/flat system that covers a 43mm image circle. Sorry to hear about the issues you are having rgsalinger. I wasn't entirely clear about the return issue you are having. Are you saying that you are interested in returning it for credit because you are no longer interested, but can only for replacement? Or that you can't return it at all because it's past the return window?

Edited by kgb, 26 December 2023 - 10:49 PM.

[rgsalinger]

I think that I misread the "manual", my fault. I still just don't think that you get comer like stars from a back focus error. Only way to tell is to get the BF just right and see what's what. There are credible reports of the scope working. I have no idea what would constitute a fair test given that the entire spec is "43mm imaging circle" which is meaningless. I'll just have to see if I get a clear night, the vendor knows my position, I've had it for about a week, and it's on my credit card so I have recourse if push comes to shove.

 

Rgrds-Ross

[HubSky]

I wondered how many thought this was going to be Petzval-like with seven elements.  To get that f/3.8, it probably has a built in 3 or 4 element flattener/reducer which requires a 55mm backfocus which is shown in the manual.   If you look at the brighter stars in your image where the aberration is fully developed, and then go to Agena and look at the spot diagrams, and then imagine being far off from the required backfocus, then it's not hard for me at least to imagine the results would look like what's in your image. 

[zackyd]

as has been posted prior,
if the front and rear elements move when the focusers is adjusted - then it is a fixed optical subassembly within and you only need to be concerned if your sensor can reach the focal plane which is spec’d to be ~55mm from the flange.

i would use the supplied to bahtinov mask to confirm focus and take an image to be able to show your are in focus (with mask still on) and an image with the same focus position with mask removed. you can the compare with spot diagrams and have concrete data on if it is in spec or not.

if Agena is not going to help, I would be reaching out to WO to see if they will help get Agena into gear, or help make it right themselves. If you don't get any momentum going from either party.. that certainly is something for the community to flag and be aware of. The only reason i would be ordering from a store such as that, would be having the regional support for global products — but if that is not the case anymore… no reason to be purchasing through them.