How common is pinched optics in the winter on Esprit APOs?

[Adam J]

2 hours ago, cfinn said:

Does anyone know what metal/alloy the Esprit lens cell is constructed of? Steel is supposed to be the best because it has very similar thermal properties as the glass, which minimises the risk of this happening.

Yes but to be clear even the premium brands generally use aluminium not steel. 

[Spongey]

I believe that most manufacturers use Aluminium as it's strong, cheap and light, but I know that LZOS uses a steel lens cell for maximum temperature compensation. Another user mentioned that TMB said that pinching should not be an issue with LZOS cells until around -30 degrees C (source).

This had been called 'over-engineered' by some and aluminium tends to do the job just fine, except when it doesn't...

 

[KP82]

The steel lens cell of the LZOS adds substantial amount of weight to the scope. Among the premium brands I believe APM/LZOS scopes are some of the heaviest. For example, my APM115 weighs 8kg whereas a slightly larger aperture TSA120 is only 6.7kg. I suppose the weight difference is partially downto different metals used for the lens cell. However I've never read any reports of pinched optics on the TSA120.

[Deadlake]

1 hour ago, KP82 said:

The steel lens cell of the LZOS adds substantial amount of weight to the scope. Among the premium brands I believe APM/LZOS scopes are some of the heaviest. For example, my APM115 weighs 8kg whereas a slightly larger aperture TSA120 is only 6.7kg. I suppose the weight difference is partially downto different metals used for the lens cell. However I've never read any reports of pinched optics on the TSA120.

The TSA120 is an outlier on weight. I believe Takahashi claims -25 degrees is the limit on operating temperatue.

The APM's (mark II models) use a phenolic tube (composite) which reduces the weight to balance out the weight of the steel lens cells.

Edited March 24, 2021 by Deadlake

[Ken82]

1 hour ago, Deadlake said:

The TSA120 is an outlier on weight. I believe Takahashi claims -25 degrees is the limit on operating temperatue.

The APM's (mark II models) use a phenolic tube (composite) which reduces the weight to balance out the weight of the steel lens cells.

Did I read somewhere about some APM scopes being made of Kruppax (phenolic)

[cfinn]

Hi all, just thought I would share an update on this. The replacement unit arrived this week. All in excellent working order, except for the focuser which couldn't hold any weight. I found the four grub screws underneath the body of the focuser that control the focuser tension and a couple of them had become a little loose from shipping. I tightened them up gently and all is now completely fine. The dew shield assembly on this unit is also better than my last. It slides along the tube much better and does not sag as much as the previous one, so that is a bonus. Those blue shock absorbing balls in the case also stay in place a lot better!

I had clear skies and temperatures of 4C ambient last night, so I took the opportunity to do a quick test on a bright star (Capella). A visual star test at high magnification looked good - collimation spot on and nice even energy in the diffraction pattern either side of focus. I also used this as first light for my new QHY 268M with a single 30s exposure in luminance. The stellar halo is not free of artefacts, but I think that is to be expected for a star of this magnitude. It looks reasonably well controlled, and the stars across the rest of the field appear perfectly round with nice clean halos. So, for the time being I am satisfied. The real test of course will be next Winter season, but right now I am just pleased to have a telescope back to enjoy using once again. I purchased a Herschel wedge as well, so I can get some good use of it during the summer with some solar observing.

Charles

Edited April 23, 2021 by cfinn

[Jonny_H]

On 23/04/2021 at 15:48, cfinn said:

Hi all, just thought I would share an update on this. The replacement unit arrived this week. All in excellent working order, except for the focuser which couldn't hold any weight. I found the four grub screws underneath the body of the focuser that control the focuser tension and a couple of them had become a little loose from shipping. I tightened them up gently and all is now completely fine. The dew shield assembly on this unit is also better than my last. It slides along the tube much better and does not sag as much as the previous one, so that is a bonus. Those blue shock absorbing balls in the case also stay in place a lot better!

I had clear skies and temperatures of 4C ambient last night, so I took the opportunity to do a quick test on a bright star (Capella). A visual star test at high magnification looked good - collimation spot on and nice even energy in the diffraction pattern either side of focus. I also used this as first light for my new QHY 268M with a single 30s exposure in luminance. The stellar halo is not free of artefacts, but I think that is to be expected for a star of this magnitude. It looks reasonably well controlled, and the stars across the rest of the field appear perfectly round with nice clean halos. So, for the time being I am satisfied. The real test of course will be next Winter season, but right now I am just pleased to have a telescope back to enjoy using once again. I purchased a Herschel wedge as well, so I can get some good use of it during the summer with some solar observing.

Charles

That is good to know, Charles. I am glad the replacement has worked out alright.

I have to admit, I placed an order for an Esprit 100ED back in Feb which I initially cancelled pending the outcome of this amongst other related topics elsewhere. Having said that after a few email conversations with the wonderful FLO team I reinstated the order last month and very much looking forward to receiving it..... it might be a long wait though 😩

[Wretmo]

Astro Sweden warned me about this problem and told me that I am on my own if this occurs. I then contacted Optical Vision to check what support and help I could receive, and they let me know that they would replace any faulty telescopes. After confirming with Astro Sweden I ordered the telescope.

Today, five days later, I was contacted on this issue again by Astro Sweden. They had further discussed this with Optical Vision, and the message now was that the warranty will not cover pinched optics in low temperatures. No operating temperature range is given. "Low temperatures" is the normal condition for the astrophotography-season in Sweden. I was given the option to cancel the order. Makes me unhappy, seems to be an excellent telescope otherwise.

[Spongey]

On 23/04/2021 at 15:48, cfinn said:

Hi all, just thought I would share an update on this. The replacement unit arrived this week. All in excellent working order, except for the focuser which couldn't hold any weight. I found the four grub screws underneath the body of the focuser that control the focuser tension and a couple of them had become a little loose from shipping. I tightened them up gently and all is now completely fine. The dew shield assembly on this unit is also better than my last. It slides along the tube much better and does not sag as much as the previous one, so that is a bonus. Those blue shock absorbing balls in the case also stay in place a lot better!

I had clear skies and temperatures of 4C ambient last night, so I took the opportunity to do a quick test on a bright star (Capella). A visual star test at high magnification looked good - collimation spot on and nice even energy in the diffraction pattern either side of focus. I also used this as first light for my new QHY 268M with a single 30s exposure in luminance. The stellar halo is not free of artefacts, but I think that is to be expected for a star of this magnitude. It looks reasonably well controlled, and the stars across the rest of the field appear perfectly round with nice clean halos. So, for the time being I am satisfied. The real test of course will be next Winter season, but right now I am just pleased to have a telescope back to enjoy using once again. I purchased a Herschel wedge as well, so I can get some good use of it during the summer with some solar observing.

Charles

Looks like a decent test Charles! There is definitely some structure in the halo which looks like it could be the six-spoked collimation screws, but it's a very acceptable result. The real test (to me) is the smaller stars, once they start distorting and all looking like hexagons, as in my images, then it's not acceptable.

I'd be interested to see a defocused star test, if you could perform one; if you can see any notches in the edge of the star halo in these then that is indicative of pinching, and will be more visible than in-focus images.

This does seem to be a design issue with the Esprit lens cell, and appears to have been more prevalent in production runs over the last few years. 

1 hour ago, Wretmo said:

Astro Sweden warned me about this problem and told me that I am on my own if this occurs. I then contacted Optical Vision to check what support and help I could receive, and they let me know that they would replace any faulty telescopes. After confirming with Astro Sweden I ordered the telescope.

Today, five days later, I was contacted on this issue again by Astro Sweden. They had further discussed this with Optical Vision, and the message now was that the warranty will not cover pinched optics in low temperatures. No operating temperature range is given. "Low temperatures" is the normal condition for the astrophotography-season in Sweden. I was given the option to cancel the order. Makes me unhappy, seems to be an excellent telescope otherwise.

That is most disappointing of OVL. They clearly acknowledge the problem but are not willing to do anything about it. As you say, the Esprit is an otherwise fantastic scope.

[Adam J]

6 hours ago, Wretmo said:

Astro Sweden warned me about this problem and told me that I am on my own if this occurs. I then contacted Optical Vision to check what support and help I could receive, and they let me know that they would replace any faulty telescopes. After confirming with Astro Sweden I ordered the telescope.

Today, five days later, I was contacted on this issue again by Astro Sweden. They had further discussed this with Optical Vision, and the message now was that the warranty will not cover pinched optics in low temperatures. No operating temperature range is given. "Low temperatures" is the normal condition for the astrophotography-season in Sweden. I was given the option to cancel the order. Makes me unhappy, seems to be an excellent telescope otherwise.

I don't find this that shocking. It's a mass produced optic and in some parts of northern Sweden average temperatures can be -15c....that's average not lowest. The esprit range is sold world wide from Australia to Alaska and could encounter in the extreme temps from -20c to +30c it's just not reasonable to expect it to perform its very best over a 50c temperature range.  They have to design for a core temperature range of maybe -5c to +20c. If you really want something that's going to operate over that range take up CFF On the custom cell or get a tak which is more likely to take such temp variation into account given the weather in Japan. But expecting a sub 2k triplet to work optimally at -10c or below is not reasonable. 

Please shout out if you think a WO or TS or Altair etc etc would on average fair better in negative double figure temperatures. I'll point you to many example that strongly suggest they don't. 

I returned my esprit as it showed an issue at around 0c or below. If it had only showed that at -10c I would never have sent it back as I would not think that reasonable. To put that into context I have seen many other brands that are pinched at room temperature. 

Type pinched William optics into Google and see what you get....then type pinched esprit 100 into Google and virtually only get my thread from 2019 and this one. 

You even get hits if you type pinched Takahashi into Google.

https://www.cloudynights.com/topic/601587-pinched-optics-with-nikon-d750-and-takahashi-85-fsq/

My overall point here is 1) that if you go looking for problems on the internet you will find them and 2) you can't expect a refractor to preform at its best below -10c. 

 

 

 

Edited April 26, 2021 by Adam J

[Louis D]

I also couldn't find much on TEC or AP scopes having pinched optics.  Perhaps they have better designed objective cells?

[Adam J]

2 hours ago, Louis D said:

I also couldn't find much on TEC or AP scopes having pinched optics.  Perhaps they have better designed objective cells?

News flash AP produce better engineered scopes than budget brand Skywatcher.

Do you expect Skywatcher to match TEC let alone AP or that it's fair to judge them by those standards? Of course not. Just because it's possible to make a scop operate at highly sub zero temps doesn't mean it's reasonable to expect it consistently from a sub 2k mass produced scope. I think it's ok to expect no pinching at 0c but -10c?

It's arbitrary anyway because you could not buy an AP scope even if you could afford one. 

 

 

Edited April 26, 2021 by Adam J

[Louis D]

2 hours ago, Adam J said:

News flash AP produce better engineered scopes than budget brand Skywatcher.

Do you expect Skywatcher to match TEC let alone AP or that it's fair to judge them by those standards? Of course not. Just because it's possible to make a scop operate at highly sub zero temps doesn't mean it's reasonable to expect it consistently from a sub 2k mass produced scope. I think it's ok to expect no pinching at 0c but -10c?

It's arbitrary anyway because you could not buy an AP scope even if you could afford one. 

 

 

I expect ES Esprit scopes to come very close to A-P/TEC scopes since they are priced within 50% to 75% of their new prices for similar size/type.  If you're going to price like a premium line, you'd better live up to that pricing.

I don't expect a $1000 90mm triplet to match a $3600 A-P 90mm APO.  However, a 90mm ES Esprit triplet, if it existed, would be priced around $2100, roughly 60% of A-P's pricing.  Considering that Chinese engineering salaries are less than half that of their US counterparts, and other Chinese overhead costs are a fraction of their US counterparts, you could certainly expect a similar level of engineering quality at that pricing ratio.  Otherwise, all we can assume is that either the Chinese are incapable of matching US engineering quality at a similar adjusted price point, or they are simply inflating the price of sub-par engineered products to create a perception of quality.

I've seen this with high end hiking boots.  When Vasque moved production to China from Italy, prices remained the same, but quality plummeted.  They looked the same, but they disintegrated within 6 months of heavy hiking usage, something that rarely happened before even after years of punishing hiking.  Clearly, someone was inflating the price of a sub-par product to match Western designed and manufactured pricing.

[Spongey]

9 hours ago, Adam J said:

I think it's ok to expect no pinching at 0c but -10c?

I would generally agree with this statement, but it has been shown in this thread that the Esprit scopes can, and have, pinched at temperatures above 0c. 

I mirror your sentiment with regards to engineering quality though; the Esprit line are known for their price to performance ratio, but I don't think anyone is claiming that they are in the same league as premium refractors.

They can and do get close to the results produced by premium brands in favourable conditions, but when pushing those limits, it is unsurprising that the Esprit falls down first.

[Deadlake]

15 hours ago, Adam J said:

I think it's ok to expect no pinching at 0c but -10c?

Takahashi are ok to -25 oC, APM LZOS lower and TEC and AP being oil based,  I think around -20 oC from memory.

I'd expect most scopes to work for AP usage to work at -10 oC given  it will be left out over night for image capture on those clear winter nights (well not this year😀)  

[AndyThilo]

I had 3 Esprit 80's, all were awful. I also had a WO GT81 and that was perfect, same temperatures.

Personally I wouldn't touch another Esprit with a bargepole.

 

 

 

[PadrePeace]

What about the hypothesis that people that own seriously expensive kit don’t feel the need to publicise issues on forums such as this as they reasonably expect a certain level of customer after sales care for the price they have paid and likely get it as the top dollar brands don’t want the negative publicity anymore than the owners do. Just saying....

For the rest of us we should be thankful that FLO offer arguably the best after sales care in the business. 

Edited April 27, 2021 by PadrePeace

[Louis D]

49 minutes ago, PadrePeace said:

What about the hypothesis that people that own seriously expensive kit don’t feel the need to publicise issues on forums such as this as they reasonably expect a certain level of customer after sales care for the price they have paid and likely get it as the top dollar brands don’t want the negative publicity anymore than the owners do. Just saying....

A lot of high end manufacturers do a significant amount of individual testing of each scope or accessory before shipment.  They also do extensive engineering testing before ever going into full production mode, and can therefore make actual claims about such things as environmental condition limits.  It all adds to the cost of premium products.

Anecdotally, I used to work in mainframe computer design and test.  We had to meet 99.9999% availability targets.  15 minutes of downtime per year was the typical quoted value.  This was inclusive of hardware and software updates that had to happen concurrently with up-time, so we had to design the system to be updated/upgraded in parts.  This level of reliability and up-time added massive costs to mainframe computers.

[Adam J]

5 hours ago, Deadlake said:

Takahashi are ok to -25 oC, APM LZOS lower and TEC and AP being oil based,  I think around -20 oC from memory.

I'd expect most scopes to work for AP usage to work at -10 oC given  it will be left out over night for image capture on those clear winter nights (well not this year😀)  

Ok it took me only 5mins on astrobin looking for images with bright stars in them to find a pinched TSA-120. 

https://www.astrobin.com/271304/C/?page=3&nc=user

I did not even get a significant way through the TSA-120 images to find it. Perhapse it was taken at -30c but I really doubt that. 

Just goes to prove that if you go looking for problems on the internet you will always find them. 

 

Edited April 27, 2021 by Adam J

[Adam J]

5 hours ago, AndyThilo said:

I had 3 Esprit 80's, all were awful. I also had a WO GT81 and that was perfect, same temperatures.

Personally I wouldn't touch another Esprit with a bargepole.

 

 

 

As with the TSA-120 above I just went looking for pinched optics on a WO 102GT triplet. This was literally the first image I checked. If it was not some poor chaps scope it would be funny. 

https://www.astrobin.com/403894/?nc=all

 

[Adam J]

6 hours ago, Deadlake said:

Takahashi are ok to -25 oC, APM LZOS lower and TEC and AP being oil based,  I think around -20 oC from memory.

I'd expect most scopes to work for AP usage to work at -10 oC given  it will be left out over night for image capture on those clear winter nights (well not this year😀)  

They really are not hard to find, this TAK FS102 for example. 

https://www.astrobin.com/238557/B/?nc=all

I don't think that one hit less than -25c in Texas...

And this one...

https://www.astrobin.com/full/260947/0/

Seriously all I am doing to find these is looking at images of M42 and M45 on astrobin. They are way easier to find than you would imagine. 

There are dozens more that are marginal too. 

Edited April 27, 2021 by Adam J

[Adam J]

47 minutes ago, Adam J said:

They really are not hard to find, this TAK FS102 for example. 

https://www.astrobin.com/238557/B/?nc=all

I don't think that one hit less than -25c in Texas...

And this one...

https://www.astrobin.com/full/260947/0/

Seriously all I am doing to find these is looking at images of M42 and M45 on astrobin. They are way easier to find than you would imagine. 

There are dozens more that are marginal too. 

And I just decided to go hunt for LZOS too incase people think I am attacking Takahashi. This is the second image of M45 I checked. 

https://www.astrobin.com/389995/?nc=all

Edited April 27, 2021 by Adam J

[Deadlake]

19 minutes ago, Adam J said:

And I just decided to go hunt for LZOS too incase people think I am attacking Takahashi. This is the second image of M45 I checked. 

https://www.astrobin.com/389995/?nc=all

The above temperature ranges are the manufacture specs…

[Adam J]

6 minutes ago, Deadlake said:

The above temperature ranges are the manufacture specs…

I am sure they are, but clearly there are falling short more often that they would like to admit. 

[AndyThilo]

14 hours ago, Adam J said:

As with the TSA-120 above I just went looking for pinched optics on a WO 102GT triplet. This was literally the first image I checked. If it was not some poor chaps scope it would be funny. 

https://www.astrobin.com/403894/?nc=all

 

It's certainly a risk with any refractor, especially imaging in low temperatures. I just think the manufacturing of the Esprit 80's and to less degree the 100's has gone downhill. Certainly there seemed to be little in the way of inspection or QC. I get a little with my 130 triplet, but only on really bright stars at lower temperatures and certainly not enough for me to worry about.

https://www.astrobin.com/full/srei8d/0/