Refractor considerations

[Nikodemuzz]

54 minutes ago, Deadlake said:

You could also look at a LZOS 130/F6. That would be same price range as the CFF. Not heard negative reviews. CFF is an oil triplet, so what are the temperature ranges you will use?

More pictures taken with this scope available, but this is one from a new owners first run.

https://www.astrobin.com/full/c3vcip/0/

he has a thread on CN.

There is discussion about the temperatures earlier in this thread, but let's just say it is a concern with oil spaced scopes. Catalin from CFF actually wrote me that any lens employing FPL53, 55 or fluorite should be considered a risk in these temperatures. I asked some follow up questions but he hasn't had the chance to reply yet. Since I'm not exactly ready to accept that I need to forgo refractors altogether, I accept that I need to take precautions regardless of the design.

The LZOS is a good shout, and it is on my "list" (well of course it is an Excel spreadsheet!). I'm pretty sure I haven't seen any negative reviews either, quite on the contrary. Originally I had put it aside due to price, but now perhaps the only thing might be that the focal length is a bit shorter natively, meaning that it has slightly less reach for smaller targets. On the other hand, it makes shooting at native focal length more viable as the system is faster. One could always get a camera with a smaller sensor to go after the galaxies... In that sense there aren't many arguments as to why it wouldn't be a contender now that I think about it again. As you said, the price is pretty much the same as the CFF, and about 500€ more than the Tak. I'll have to ask for availability. Seems like I still haven't quite thought this through, have I?!

Edited February 17, 2021 by Nikodemuzz
Typo

[Deadlake]

3 minutes ago, Nikodemuzz said:

There is discussion about the temperatures earlier in this thread, but let's just say it is a concern with oil spaced scopes. Catalin from CFF actually wrote me that any lens employing FPL53, 55 or fluorite should be considered a risk in these temperatures. I asked some follow up questions but he hasn't had the chance to reply yet. Since I'm not exactly ready to accept that I need to forgo refractors altogether, I accept that I need to take precautions regardless of the design.

The LZOS is a good shout, and it is on my "list" (well of course it is an Excel spreadsheet!). I'm pretty sure I haven't seen any negative reviews either, quite on the contrary. Originally I had put it aside due to price, but now perhaps the only thing might be that the focal length is a bit shorter natively, meaning that it has slightly less reach for smaller targets. On the other hand, it makes shooting at native focal length more viable as the system is faster. One could always get a camera with a smaller sensor to go after the galaxies... In that sense there aren't many arguments as to why it wouldn't be a contender now that I think about it again. As you said, the price is pretty much the same as the CFF, and about 500€ more than the Tak. I'll have to ask for availability. Seems like I still haven't quite thought this through, have I?!

It's complicated always have to accept a tradeoff's. I went with the F6 over F9.2 so the scope was fast enough for NV, turned out it will be good for wide field as well and for visual I can always use a Barlow on planets. 

Availability is as good as Taks.

The LZOS lens is made from OK-1/OK-4, not sure of the temperature level. I thought there where constraints around when a lens cell would start pinching the lens for all scope makes.

AP states don't use the scopes around -25 oC due to it being oil triplet based. 

[Nikodemuzz]

1 minute ago, Deadlake said:

It's complicated always have to accept a tradeoff's. I went with the F6 over F9.2 so the scope was fast enough for NV, turned out it will be good for wide field as well and for visual I can always use a Barlow on planets. 

Availability is as good as Taks.

The LZOS lens is made from OK-1/OK-4, not sure of the temperature level. I thought there where constraints around when a lens cell would start pinching the lens for all scope makes.

AP states don't use the scopes around -25 oC due to it being oil triplet based. 

I would expect the Russians to know how to deal with the cold. If anything, their winters are even harsher than ours (depending quite a bit on location to be fair). I'll ask from APM about this.

[Deadlake]

8 minutes ago, Nikodemuzz said:

I would expect the Russians to know how to deal with the cold. If anything, their winters are even harsher than ours (depending quite a bit on location to be fair). I'll ask from APM about this.

Not going to affect me where I live, unless I visit family in Wales but good to know the answer.

Edited February 17, 2021 by Deadlake

[Carl Au]

Only a few short years ago you didn't find many folks out there with a Tak, wow how things have changed. If money is no object and since Tak's appear to be the gold standard, and no doubt rightly so (I have never seen one for real, nevermind looked through one) then no doubt a Tak will be the one you buy and will love ever minute of using it too I imagine, of course you will why wouldn't you?

Like a lot of the boys and girls on here I am going offer my opinions on the scope I have just bought, or at least one made in the same factory. The Technosky, TS Optics, Altair Astro range of refractors are in my opinion the best value for money in 4 and 5 inch ED scopes out there. The optics are extremely good, I mean really good for a sub £1000 refractor. I know I ended up having to but a 2 inch star diagnonal, a finder and a flight case (I highly recommend the purpose built case which TS in Germany sell to go with them, but it is still less than 1,500 quid for what is a quality refractor with an excellent build quality, the R&P rotatable focuser really is a nice piece of work. I am sure whatever you will buy will be amazing and I am all for buy once and getting it right.

To be honest I couldn't really afford to buy what I have and I feel very priviallaged (and a little guilty) to have been able to do so at all, I know not everyone is as lucky as me, especially in these most troubling of times.

 All I am saying I guess is that these scopes are worth looking at, why they cost as little as the do is something of a mystery to me? You could even buy a 6 inch and still have plenty of money to spare for those eyepieces you have been looking at for weeks? 

Edited February 17, 2021 by Carl Au

[John]

1 hour ago, Carl Au said:

Only a few short years ago you didn't find many folks out there with a Tak, wow how things have changed. If money is no object and since Tak's appear to be the gold standard, and no doubt rightly so (I have never seen one for real, nevermind looked through one) then no doubt a Tak will be the one you buy and will love ever minute of using it too I imagine, of course you will why wouldn't you?

Like a lot of the boys and girls on here I am going offer my opinions on the scope I have just bought, or at least one made in the same factory. The Technosky, TS Optics, Altair Astro range of refractors are in my opinion the best value for money in 4 and 5 inch ED scopes out there. The optics are extremely good, I mean really good for a sub £1000 refractor. I know I ended up having to but a 2 inch star diagnonal, a finder and a flight case (I highly recommend the purpose built case which TS in Germany sell to go with them, but it is still less than 1,500 quid for what is a quality refractor with an excellent build quality, the R&P rotatable focuser really is a nice piece of work. I am sure whatever you will buy will be amazing and I am all for buy once and getting it right. To be honest I couldn't really afford to buy what I have and I feel very priviallaged to have been able to do so at all, I know not everyone is as lucky as me, especially in these most troubling of times.

 All I am saying I guess is that these scopes are worth looking at, why they cost as little as the do is something of a mystery to me? You could even buy a 6 inch and have plenty of money to spare for those eyepieces you have been looking at for weeks? 

Some very good points there Carl

I've been in this hobby for around 40 years now and up until 2016 I had not owned or even looked through any of the what are considered premium brand scopes. In the Summer of 2016 I came into some money with no strings attached to it so decided to "see for myself" by purchasing a top end refractor. After some consideration I went for a Tak FC100-DL and then managed to get a great deal on a pre-owned TMB/LZOS 130mm F/9.2 triplet. So I was able to squeeze two premium scopes out of my budget.

These are still the only scopes of this class that I have observed with so it has been an interesting experience comparing them with my other scopes and comparing what I've been seeing with reports on here from others who own similar quality instruments.

One thing that has surprised me is how well my "lesser" scopes have compared with the premium ones. Yes, there are differences, but they are generally subtle and the seeing conditions that I'm generally observing under probably act as an equalizing factor as well.

I do really enjoy owning and using these top end telescopes and don't regret purchasing them at all but I'm not under any illusions any more that they are key to my continued enjoyment of astronomical observing. I'm sure that I would have enjoyed astronomy just as much and seen just as much without owning them 

 

 

 

 

[jetstream]

7 hours ago, Nikodemuzz said:

Catalin from CFF actually wrote me that any lens employing FPL53, 55 or fluorite should be considered a risk in these temperatures.

Well, my 90mm Raptor and the TSA120 have survived years of sub -30c temps, both with FLP53. Last night was no exception as my lunar report indicates. The lens cell in the TSA120 has never twisted up in the cold, the Raptors has and no glass exploded out of it.

If I was selling scopes I'd probably say don't do it- so no one could come back with broken glass saying "you said it was ok!".

Last night in cold temps the TSA120 took all the mag I could test it with... a testament to its lens cell and glass. Its pretty big though and needs a substantial mount IMHO.

3 hours ago, John said:

One thing that has surprised me is how well my "lesser" scopes have compared with the premium ones.

Agree. In fact my little 90mm with Chinese glass does very well.

[Carl Au]

Tis the astronomic law of diminshing returns...

[Nikodemuzz]

7 hours ago, Carl Au said:

Only a few short years ago you didn't find many folks out there with a Tak, wow how things have changed. If money is no object and since Tak's appear to be the gold standard, and no doubt rightly so (I have never seen one for real, nevermind looked through one) then no doubt a Tak will be the one you buy and will love ever minute of using it too I imagine, of course you will why wouldn't you?

Like a lot of the boys and girls on here I am going offer my opinions on the scope I have just bought, or at least one made in the same factory. The Technosky, TS Optics, Altair Astro range of refractors are in my opinion the best value for money in 4 and 5 inch ED scopes out there. The optics are extremely good, I mean really good for a sub £1000 refractor. I know I ended up having to but a 2 inch star diagnonal, a finder and a flight case (I highly recommend the purpose built case which TS in Germany sell to go with them, but it is still less than 1,500 quid for what is a quality refractor with an excellent build quality, the R&P rotatable focuser really is a nice piece of work. I am sure whatever you will buy will be amazing and I am all for buy once and getting it right.

To be honest I couldn't really afford to buy what I have and I feel very priviallaged (and a little guilty) to have been able to do so at all, I know not everyone is as lucky as me, especially in these most troubling of times.

 All I am saying I guess is that these scopes are worth looking at, why they cost as little as the do is something of a mystery to me? You could even buy a 6 inch and still have plenty of money to spare for those eyepieces you have been looking at for weeks? 

There is a lot of truth in your post.

It is easy to get sucked into the vortex of comparing, reading reviews and discussions and contemplating things that are essentially minor details. All the while talking yourself into getting products that you want, rather than what you need. Or what would match one's skill level. Reading this thread from the beginning you can observe how my own targets and budget drift. I'm quite aware of this, and have read my earlier posts just to remind myself of it. 😃 In terms of value, you are probably very correct, and I would think that the Pareto principle applies here as well. Meaning that one can probably get 80% of the performance of the high end scopes with 20% of the cost. That 80% would possibly be enough quality that it would never become a limitation in my astronomy hobby. And yet, accepting all of this, I'm still considering owning one of the high end units.

To be in a position to even consider such an investment, or investment in a hobby of any sort during these times means that one is indeed fortunate, and in a privileged position compared to many others. I think that for many people who are lucky enough to have a steady job despite the pandemic, things have changed quite a bit. Suddenly you might have a lot of free time in the evenings. There are no costs related to hobbies, travel, eating out, or basically anything besides the basics, which means that you might actually have a bit more disposable income than before. One can observe this from the comments of the astro gear vendors. I believe FLO is breaking sales records, and some of the scope vendors have described an "avalanche of new orders" during past months. The fact that nobody has stock isn't only because there has been production disruptions, it's also because people are buying a lot of new stuff. It is a bit absurd all things considering, and on the other hand very understandable.

[Nikodemuzz]

2 hours ago, jetstream said:

Well, my 90mm Raptor and the TSA120 have survived years of sub -30c temps, both with FLP53. Last night was no exception as my lunar report indicates. The lens cell in the TSA120 has never twisted up in the cold, the Raptors has and no glass exploded out of it.

If I was selling scopes I'd probably say don't do it- so no one could come back with broken glass saying "you said it was ok!".

Last night in cold temps the TSA120 took all the mag I could test it with... a testament to its lens cell and glass. Its pretty big though and needs a substantial mount IMHO.

Agree. In fact my little 90mm with Chinese glass does very well.

It is always great to hear your experiences!

I think you are right, a vendor more or less has to say something to that effect. I know from my own profession how easily customers take your words as promises and guarantees even though they might have been just educated guesses, so one must err on the safe side.

The CEM60 should be able to handle the TSA allright, I think.

 

[John]

1 hour ago, Nikodemuzz said:

There is a lot of truth in your post.

It is easy to get sucked into the vortex of comparing, reading reviews and discussions and contemplating things that are essentially minor details. All the while talking yourself into getting products that you want, rather than what you need. Or what would match one's skill level. Reading this thread from the beginning you can observe how my own targets and budget drift. I'm quite aware of this, and have read my earlier posts just to remind myself of it. 😃 In terms of value, you are probably very correct, and I would think that the Pareto principle applies here as well. Meaning that one can probably get 80% of the performance of the high end scopes with 20% of the cost. That 80% would possibly be enough quality that it would never become a limitation in my astronomy hobby. And yet, accepting all of this, I'm still considering owning one of the high end units.

To be in a position to even consider such an investment, or investment in a hobby of any sort during these times means that one is indeed fortunate, and in a privileged position compared to many others. I think that for many people who are lucky enough to have a steady job despite the pandemic, things have changed quite a bit. Suddenly you might have a lot of free time in the evenings. There are no costs related to hobbies, travel, eating out, or basically anything besides the basics, which means that you might actually have a bit more disposable income than before. One can observe this from the comments of the astro gear vendors. I believe FLO is breaking sales records, and some of the scope vendors have described an "avalanche of new orders" during past months. The fact that nobody has stock isn't only because there has been production disruptions, it's also because people are buying a lot of new stuff. It is a bit absurd all things considering, and on the other hand very understandable.

All makes a lot of sense

My experience would suggest to me that 90% of the performance of the high end scopes for 50% of the cost is realistic but such figures are subjective of course

 

 

 

[Nikodemuzz]

On 17/02/2021 at 12:17, Deadlake said:

The LZOS lens is made from OK-1/OK-4, not sure of the temperature level. I thought there where constraints around when a lens cell would start pinching the lens for all scope makes.
 

Markus stated that they guarantee their scopes perform until -30C, below which one can expect pinching. Although there are nights when the temperatures do fall below that (just the other night), the vast majority of situations would be OK in that respect. In that sense I would be fine with that.

[Sunshine]

4 minutes ago, Nikodemuzz said:

Markus stated that they guarantee their scopes perform until -30C, below which one can expect pinching. Although there are nights when the temperatures do fall below that (just the other night), the vast majority of situations would be OK in that respect. In that sense I would be fine with that.

I was going to ask if you plan on being out in those temps regularly, then i saw where you live and figured i better not ask lol.

[Nikodemuzz]

1 minute ago, Sunshine said:

I was going to ask if you plan on being out in those temps regularly, then i saw where you live and figured i better not ask lol.

Yeah, no choice if astronomy is your thing here, I'm afraid. 😅

[Sunshine]

Just now, Nikodemuzz said:

Yeah, no choice if astronomy is your thing here, I'm afraid. 😅

I bet the northern lights are something to behold from Finland, lucky you!

[Nikodemuzz]

While having discussions with different scope providers, I have started to think again about the Esprit 150. Essentially, going back a full circle.  Being used to mounting the C11, I don't really have experience in handling bigger refractors. Seeing this video was a bit of a revelation: 

Silly me, I didn't know you could use the rings like that. 🤓 Anyhow, seeing that I'm pretty confident that I wouldn't have too much trouble handling an Esprit 150. I believe the CEM60 should also be able to carry it, although it is on the heavier side of its capabilities.

The question would then be the same that has been the topic of discussion lately, thermal performance. Assuming no defects on the scope build or design, the pinching behaviour should be similar to others, or no? I would assume that it would be the slowest one to cool from the models that have been in the discussion. If the scope is too slow to cool I might never get the best out of it, in which case it is the wrong model for me.

[Nikodemuzz]

8 minutes ago, Sunshine said:

I bet the northern lights are something to behold from Finland, lucky you!

They are, especially in the northern parts of the country. Where I live (in the middle) we see them only occasionally. They are a pretty sight to see, but for astrophotos they are a nuisance!  

[Deadlake]

7 minutes ago, Nikodemuzz said:

While having discussions with different scope providers, I have started to think again about the Esprit 150. Essentially, going back a full circle.  Being used to mounting the C11, I don't really have experience in handling bigger refractors. Seeing this video was a bit of a revelation: 

Silly me, I didn't know you could use the rings like that. 🤓 Anyhow, seeing that I'm pretty confident that I wouldn't have too much trouble handling an Esprit 150. I believe the CEM60 should also be able to carry it, although it is on the heavier side of its capabilities.

The question would then be the same that has been the topic of discussion lately, thermal performance. Assuming no defects on the scope build or design, the pinching behaviour should be similar to others, or no? I would assume that it would be the slowest one to cool from the models that have been in the discussion. If the scope is too slow to cool I might never get the best out of it, in which case it is the wrong model for me.

What are the lens cells made of? LZOS are steel as is Stellarvue, don't know about other makes. Thats why the LZOS is -30 oC for lens pinching.
 

[Nikodemuzz]

15 minutes ago, Deadlake said:

What are the lens cells made of? LZOS are steel as is Stellarvue, don't know about other makes. Thats why the LZOS is -30 oC for lens pinching.
 

Good question. Didn't find an answer with a quick glance with Google. 

[johnturley]

1 hour ago, Nikodemuzz said:

While having discussions with different scope providers, I have started to think again about the Esprit 150. Essentially, going back a full circle.  Being used to mounting the C11, I don't really have experience in handling bigger refractors. Seeing this video was a bit of a revelation: 

Silly me, I didn't know you could use the rings like that. 🤓 Anyhow, seeing that I'm pretty confident that I wouldn't have too much trouble handling an Esprit 150. I believe the CEM60 should also be able to carry it, although it is on the heavier side of its capabilities.

The question would then be the same that has been the topic of discussion lately, thermal performance. Assuming no defects on the scope build or design, the pinching behaviour should be similar to others, or no? I would assume that it would be the slowest one to cool from the models that have been in the discussion. If the scope is too slow to cool I might never get the best out of it, in which case it is the wrong model for me.

The Esprit 150 is a similar weight to the Tak TOA 150, and like the Tak has an oversized (approx 180 mm diameter tube), and around 14.5 kg heavier than both the TEC and CFF 160), I didn't however have too much trouble lifting the OTA, and I'm 71 years of age, although I do have it permanently mounted, piggybacked on my 14 in Newtonian>

John 

[Nikodemuzz]

I have (again) moved on from the Esprit 150. There were enough reports of pinching (perhaps slight but still) from local colleagues, and the vendor also said it would be somewhat likely to happen in our temperatures.

Now it seems like a two horse race between a new TSA-120 and a used TOA-130F. With the more expensive one being used the prices come very close to each other. I'm very tempted by the TOA, but I think I'm suffering slightly from the illusion of the "good deal".

Factors favoring TOA-130F:

• Presumably better optics, at least by reputation (albeit slightly)
• 10mm more aperture, better choice for shared visual and imaging use as a "keeper for life"
• Good price for a used item in good condition

Factors favoring TSA-120:

• Low buyers risk for a new item with guarantee
• Option of a Feathertouch focuser
• Half the weight
• Faster cooldown

To me it seems as though the things I listed for TSA-120 seem like more concrete and "actionable" benefits than the ones on the TOA side. Did I forget something important?

 

[jetstream]

5 hours ago, Nikodemuzz said:

10mm more aperture, better choice for shared visual and imaging use as a "keeper for life"

In this aperture class I would never use 10mm more aperture to be the deciding factor. A few avid Tak owners/collectors have said that the TOA130 is a tiny bit better than the TSA120-but- they all said they could be "wishing" it to be better, or "might be thinking" it is better...

Either scope is top notch, just pick one based on needs.

[Nikodemuzz]

37 minutes ago, jetstream said:

In this aperture class I would never use 10mm more aperture to be the deciding factor. A few avid Tak owners/collectors have said that the TOA130 is a tiny bit better than the TSA120-but- they all said they could be "wishing" it to be better, or "might be thinking" it is better...

Either scope is top notch, just pick one based on needs.

Exactly, I have read similar comments. And given that the light gathering difference is only about 15%, I wouldn't expect there to be a significant difference. Which further underscores my comment about the factors favoring the TSA-120 seem heavier.

[jetstream]

23 minutes ago, Nikodemuzz said:

Exactly, I have read similar comments. And given that the light gathering difference is only about 15%, I wouldn't expect there to be a significant difference. Which further underscores my comment about the factors favoring the TSA-120 seem heavier.

I forgot what your imaging?

Me, I'm looking for a shorter scope that might be easier to control on the mount.

[Nikodemuzz]

23 minutes ago, jetstream said:

I forgot what your imaging?

Me, I'm looking for a shorter scope that might be easier to control on the mount.

I already have the short end covered with the SpaceCat. Now I'm looking to get a bit closer to the targets that are a too small for the Cat. 600-700mm has been my target, which the TSA/TOA fits nicely when reduced.

Edited March 7, 2021 by Nikodemuzz