Refractor considerations

[jetstream]

7 minutes ago, Deadlake said:

At the end just left with price to tell us if any good all other things being equal. 

This can be a problem too IMHO- off topic but we bought an expensive Maytag washing machine years ago because of their reputation-it lasted a year before the pump seal etc went. no problem right?!! Huge warranty for a long time. The repair man told me it would be $600.00 out of my pocket.I called Maytag and yes it had a great warranty! But! I was told to read the fine print...the pump seal etc was excluded. The repair man told me it was a common failure.

We now own Bosch- 6 yrs old and going strong.

Yeah, these days using price as a consideration of quality needs to be closely examined.IMHO.

[Deadlake]

7 minutes ago, John said:

And feedback from owners / users on forums ?

Sometimes you need to "read between the lines" but I've found that you can build up a reasonable picture if you read (critically) feedback.

 

 

 

Yes, skywatcher 120ED for instance. Lots of praise and good test results.

[KP82]

12 minutes ago, Deadlake said:

I suspect APM's reputation from LZOS has been used here, but in someway I'm not sure APM FPL51/53 scopes are any better then Skywatcher etc, given the price and manufacture.

As an aside for instance most diagonals are made by United Optics or GSO (Baader being the exception). However all the diagonals have different specs, from the same production line if you test them you will see different quality.

At the end just left with price to tell us if any good all other things being equal. 

The APM non-LZOS are indeed no better than Skywatcher, TS Optics, AT, etc. equivalent, but they are also priced accordingly. For example I paid £1,699 for my APM 107/700 (made by sharpstar). Other mass produced 4" triplets are priced similarly. I don't think the 140/152 ED doublets that APM have been selling have had any negative impact on their reputation.

 

[Deadlake]

6 minutes ago, jetstream said:

This can be a problem too IMHO- off topic but we bought an expensive Maytag washing machine years ago because of their reputation-it lasted a year before the pump seal etc went. no problem right?!! Huge warranty for a long time. The repair man told me it would be $600.00 out of my pocket.I called Maytag and yes it had a great warranty! But! I was told to read the fine print...the pump seal etc was excluded. The repair man told me it was a common failure.

We now own Bosch- 6 yrs old and going strong.

Yeah, these days using price as a consideration of quality needs to be closely examined.IMHO.

I have Bosch too, very good. Only issue is the brushes going and not having time to replace them or get someone in due to the pandemic. I should of specified telescopes being built in the same factory in this case.

Presume Maytag and Bosch are not, but a lot of telescopes are.

Edited February 10, 2021 by Deadlake

[johninderby]

Maytag used to be the very best available. My mum had one for 25 years with not a single fault or repair needed. Unfortunately that brand isn’t what it used to be. 

Not been the same since they were acquired by Whirlpool in 2006.Now the Maytag brand is stuck on Whirlpool appliences.

Edited February 10, 2021 by johninderby

[Deadlake]

21 minutes ago, johninderby said:

Maytag used to be the very best available. My mum had one for 25 years with not a single fault or repair needed. Unfortunately that brand isn’t what it used to be. 

Great handles??? 😀

PS: I'm wondering if @JeremyS is going to beat me to this punchline...

Edited February 10, 2021 by Deadlake

[garryblueboy]

2 hours ago, Deadlake said:

Let's say it came up while discussing buying a LZOS scope and would it also work with NV. I thought Jeff's scope was LZOS when its not.

 

2 hours ago, Deadlake said:

TMB 130 F7. This is one of the earliest Chinese made scopes from United Optics that was made for Thomas Back. Unless there are other TMB 130 F7 out there...
Thomas was partners with Markus at APM for the ‘TMB Apo’s using LZOS lenses, but TMB branded Chinese scopes are not related. They were a separate business that started and eventually closed after Thomas died. 

Jeff Morgan has one, he had some great NV pictures. LZOS are better and more expensive, the TMB is better value for sure.

The TMB 130ss lens was a Japan lens then moved and made in Taiwan Thomas said this before he died but wouldn’t say who made it due to the competition in the market place 

[Deadlake]

2 minutes ago, garryblueboy said:

 

The TMB 130ss lens was a Japan lens then moved and made in Taiwan Thomas said this before he died but wouldn’t say who made it due to the competition in the market place 

I’m going on what a dealer told me, however working out fact on the internet is always hard....

[JeremyS]

2 minutes ago, Deadlake said:

I’m going on what a dealer told me, however working out fact on the internet is always hard....

Wouldn’t it say the country of manufacture on the lens cell? Tak puts “Japan” proudly on theirs?

[garryblueboy]

16 minutes ago, Deadlake said:

I’m going on what a dealer told me, however working out fact on the internet is always hard....

I was going on a chat from Thomas himself to a vender in the states when asked about the source 

[garryblueboy]

13 minutes ago, JeremyS said:

Wouldn’t it say the country of manufacture on the lens cell? Tak puts “Japan” proudly on theirs?

I think it was early days in the the development of the 130 ss then Thomas got sick I’ve not taken the lens out but going on 

others on CN it’s not marked but there is lots pointing to Japan glass and assembled in Twain that’s from a conversation from Thomas  

[John]

30 minutes ago, garryblueboy said:

 

The TMB 130ss lens was a Japan lens then moved and made in Taiwan Thomas said this before he died but wouldn’t say who made it due to the competition in the market place 

The link I posted earlier in this thread were Thomas posting on CN and thats what he said.

[Nikodemuzz]

Interesting discussion about the origins of the TMB optics (and washing machines)! 

I have no doubts about the quality of the optics, regardless of their source. What I am a little bit wondering about is the cool-down time. I read two articles about the TMB 130SS, and both mentioned slow cooling. First, here: http://articles.adsabs.harvard.edu//full/2008JRASC.102...77S/0000077.000.html

"First tests were done in September when the temperature was still around 5C. Smaller and lighter refractors would have been serviceable within half an hour, but these relatively massive refractors took some time to lose the last of the tube currents and surface turbulence...The TMB also seemed totake longer than the AP to reach equilibrium in these milder conditions...The acclimation time from a cool room temperature of 15C down to an outdoor temperature of -15C took far longer than expected. Both refractors were not totally acclimated even after 1.5 hours, although the AP was giving acceptable views by that time. The TMB did not show any detail at this point..."

And here: https://www.cloudynights.com/articles/cat/cn-reports/telescope-reports/cn-report-tmb-130-signature-series-r1634

"There were some minor cool down issues.  One winter session, as the temps kept falling, it never did equalize.  That's somewhat to be expected with that huge mass of glass up in front.  Even though the cell is designed to be temperature compensating, it's just not capable of keeping everything perfect through the most extreme temps."

Take yesterday for example. It was overcast most of the afternoon and evening, -10C. During the night the sky cleared and the temperature dropped to -25C in a couple of hours. By morning the clouds were back, and the thermometer was at -20C. I would say that for midwinter this is pretty typical scenario. Autumn/spring it is similar but the evening temp might be 15C, dropping close to 0C in the night. I wonder if a slow cooling air-spaced scope is capable of following the ambient temperature, in other words, be usable for the majority of the nights.

Then there is the thermal shock risk with the oil spaced scopes. Would it be enough of a precaution to use the flight case as a buffer, bringing the scope in and out inside the case? This would prevent the scope from ever experiencing the full thermal shock.

[John]

I was a little concerned about cool down times when I was considering my 130mm F/9.2 triplet. I had read mixed reports. I don't get it too cold here, 5 below is a really cold night here, but the scope does live in a centrally heated room. So far, (I've owned the scope since Summer 2016) I have not noticed any particular issues with cool down times. The scope needs a bit longer than my ED120 but 30-40 minutes at most and it's delivering excellent high power images. 

My triplet is an air spaced LZOS. Maybe the F/9.2 focal ratio means that the glass thickness of the elements is a little less than the faster versions ?

 

Edited February 11, 2021 by John

[Nikodemuzz]

To be fair, the above consideration of mine is not valid only for the TMB130SS. I'm sure the same goes for all of the air spaced heavyweights (Esprits, TOA's etc). How about the TSA-120, being so light for its aperture?

Edited February 11, 2021 by Nikodemuzz

[Captain Scarlet]

18 hours ago, John said:

... Markus was able to supply me with the copies of the original paperwork and tests for my scope - he keeps them all on file apparently. The previous owner of my scope had lost the copies that had been supplied with the scope so I was glad to be able to get another set of them.

Funnily enough when I bought my APM-LZOS 105/650 from a fellow SGL-er I emailed Markus to ask about some handwritten numbers on the inside of the lens cell, and the veracity of the scope (yes all was good) and to ask if he had a better copy of the test report for the scope, as the report I had was a bit tatty and water-stained. He replied to say that no he didn’t have a copy of that particular report.

M

[mikeDnight]

1 hour ago, Nikodemuzz said:

Interesting discussion about the origins of the TMB optics (and washing machines)! 

I have no doubts about the quality of the optics, regardless of their source. What I am a little bit wondering about is the cool-down time. I read two articles about the TMB 130SS, and both mentioned slow cooling. First, here: http://articles.adsabs.harvard.edu//full/2008JRASC.102...77S/0000077.000.html

"First tests were done in September when the temperature was still around 5C. Smaller and lighter refractors would have been serviceable within half an hour, but these relatively massive refractors took some time to lose the last of the tube currents and surface turbulence...The TMB also seemed totake longer than the AP to reach equilibrium in these milder conditions...The acclimation time from a cool room temperature of 15C down to an outdoor temperature of -15C took far longer than expected. Both refractors were not totally acclimated even after 1.5 hours, although the AP was giving acceptable views by that time. The TMB did not show any detail at this point..."

And here: https://www.cloudynights.com/articles/cat/cn-reports/telescope-reports/cn-report-tmb-130-signature-series-r1634

"There were some minor cool down issues.  One winter session, as the temps kept falling, it never did equalize.  That's somewhat to be expected with that huge mass of glass up in front.  Even though the cell is designed to be temperature compensating, it's just not capable of keeping everything perfect through the most extreme temps."

Take yesterday for example. It was overcast most of the afternoon and evening, -10C. During the night the sky cleared and the temperature dropped to -25C in a couple of hours. By morning the clouds were back, and the thermometer was at -20C. I would say that for midwinter this is pretty typical scenario. Autumn/spring it is similar but the evening temp might be 15C, dropping close to 0C in the night. I wonder if a slow cooling air-spaced scope is capable of following the ambient temperature, in other words, be usable for the majority of the nights.

Then there is the thermal shock risk with the oil spaced scopes. Would it be enough of a precaution to use the flight case as a buffer, bringing the scope in and out inside the case? This would prevent the scope from ever experiencing the full thermal shock.

I'm not sure its the amount of glass or the thickness of the lens that causes the problem, but rather the cell in which the lens is secured.  I had a beautiful NP101 IS ( a quad) that just didn't like the cold. It easily took an hour before it gave good star images on a night of -5°C. I have observed with it when the temperature had dropped to -15°C, at which point it just didn't want to play at all.  None of my Takahashi refractors ever had issues with accliatisation, not even the 152mm fluorite doublet, and I'd regularly use them while they were caked in ice. With the Tak's, the lenses are mounted in a cell that is mounted in a cell, so the lens doesn't get stressed by the outer cells contraction to the same degree as some other scopes on sub zero nights.  The FS152 for example was at full power after 15 to 20 min's no matter what the temperature drop. Granted, I can't ever remember observing at -25° C though. 

[John]

9 minutes ago, mikeDnight said:

I'm not sure its the amount of glass or the thickness of the lens that causes the problem, but rather the cell in which the lens is secured.  I had a beautiful NP101 IS ( a quad) that just didn't like the cold. It easily took an hour before it gave good star images on a night of -5°C. I have observed with it when the temperature had dropped to -15°C, at which point it just didn't want to play at all.  None of my Takahashi refractors ever had issues with accliatisation, not even the 152mm fluorite doublet, and I'd regularly use them while they were caked in ice. With the Tak's, the lenses are mounted in a cell that is mounted in a cell, so the lens doesn't get stressed by the outer cells contraction to the same degree as some other scopes on sub zero nights.  The FS152 for example was at full power after 15 to 20 min's no matter what the temperature drop. Granted, I can't ever remember observing at -25° C though. 

I agree that objective cell design does have an influence on cooling times.

 

[garryblueboy]

1 hour ago, Nikodemuzz said:

To be fair, the above consideration of mine is not valid only for the TMB130SS. I'm sure the same goes for all of the air spaced heavyweights (Esprits, TOA's etc). How about the TSA-120, being so light for its aperture?

The TSA and TMB are about the same cool down wise as I own both they are ready to go in 30-40 mins if it’s really cold and they have come from a warm room 

[Deadlake]

For cooling it's the air in the gaps between the lens which acts an insulator, hence air space triplet will take longer than an oil spaced cell to accumulate.

AP state for oil triplets don't go below -25 oC as this can cause issues. @jetstream knows more on this subject. 

LZOS (and I think Tak, Stellarvue in newest models) use steel based cells as it has better thermal properties for a lens cell, you don't want the cell to pinch the lens.

Oil based triplets will cool faster then air based ones, but you need to be careful in the temperature range.

@Tyson M mentioned a good plan is to store the APO in a case when bringing them in so they have time to accumulate to indoors, instead of a temperature shock.

 

Edited February 11, 2021 by Deadlake

[Nikodemuzz]

2 hours ago, mikeDnight said:

I'm not sure its the amount of glass or the thickness of the lens that causes the problem, but rather the cell in which the lens is secured.  I had a beautiful NP101 IS ( a quad) that just didn't like the cold. It easily took an hour before it gave good star images on a night of -5°C. I have observed with it when the temperature had dropped to -15°C, at which point it just didn't want to play at all.  None of my Takahashi refractors ever had issues with accliatisation, not even the 152mm fluorite doublet, and I'd regularly use them while they were caked in ice. With the Tak's, the lenses are mounted in a cell that is mounted in a cell, so the lens doesn't get stressed by the outer cells contraction to the same degree as some other scopes on sub zero nights.  The FS152 for example was at full power after 15 to 20 min's no matter what the temperature drop. Granted, I can't ever remember observing at -25° C though. 

Thank you, very interesting!

1 hour ago, garryblueboy said:

The TSA and TMB are about the same cool down wise as I own both they are ready to go in 30-40 mins if it’s really cold and they have come from a warm room 

Thanks for chiming in, Garry! Not many owners of both scopes around, I'm sure, so I value your experience! Your comments are not exactly in line with the articles, which is interesting. It is a positive indication that you haven't noticed long cool down times!

[garryblueboy]

7 minutes ago, Nikodemuzz said:

Thank you, very interesting!

Thanks for chiming in, Garry! Not many owners of both scopes around, I'm sure, so I value your experience! Your comments are not exactly in line with the articles, which is interesting. It is a positive indication that you haven't noticed long cool down times!

Can only go on what’s in front of me 

[jetstream]

We can avoid thermal shock- use an insulated case in and out, but this extends times. I leave 2 of my fracs in the seacan (in their insulated cases).The Tak is in the house with me 😀.

They are in there now in -37c this morning and would be usable tonight. I just can't imagine risking a $10,000 dollar oil spaced telescope with extreme temps.My Tak does fine for cooldown but I do use an insulated case as stated.

 

[Nikodemuzz]

After doing some more thinking and detective work on this subject, I have narrowed it down to two options that are price-wise within a few hundred € of each other fully accessorized:

Takahashi TSA-120 with FT focuser

• Long pedigree and reputation for excellent quality
• Compact size and light weight (6.7kg, assuming without rings)
• Air spaced
• Readily available

CFF 135 F6.7

• Generally highly recommended on CN, but there are also some scathing reviews. Interestingly, being a European maker, is less mentioned on SGL.
• 15mm aperture increase, focal length essentially the same
• Heavier than the TSA, but still quite light for the aperture (10kg with rings)
• Oil spaced
• Lead time of roughly a year

It seems to boil down to do I want to wait for a year to get 15mm larger oil spaced scope from a "new" vendor, or get a slightly smaller one almost right away with proven quality. I'm not at all into taking gambles with this investment, which makes me gravitate towards the Tak, even though I'm tempted by the larger aperture. The wait time is not a show stopper for me, being unsure of getting what I paid for in terms of quality is.

[Deadlake]

14 minutes ago, Nikodemuzz said:

After doing some more thinking and detective work on this subject, I have narrowed it down to two options that are price-wise within a few hundred € of each other fully accessorized:

Takahashi TSA-120 with FT focuser

• Long pedigree and reputation for excellent quality
• Compact size and light weight (6.7kg, assuming without rings)
• Air spaced
• Readily available

CFF 135 F6.7

• Generally highly recommended on CN, but there are also some scathing reviews. Interestingly, being a European maker, is less mentioned on SGL.
• 15mm aperture increase, focal length essentially the same
• Heavier than the TSA, but still quite light for the aperture (10kg with rings)
• Oil spaced
• Lead time of roughly a year

It seems to boil down to do I want to wait for a year to get 15mm larger oil spaced scope from a "new" vendor, or get a slightly smaller one almost right away with proven quality. I'm not at all into taking gambles with this investment, which makes me gravitate towards the Tak, even though I'm tempted by the larger aperture. The wait time is not a show stopper for me, being unsure of getting what I paid for in terms of quality is.

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.

Edited February 17, 2021 by Deadlake