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#1 Astrojensen

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Posted 05 December 2019 - 03:56 PM

... The replacement lens for the poor one in my APM 152/1200mm ED arrived Monday December 2nd. Sorry for not posting earlier, but I've had quite a hard week at work, so I've not had much energy to post. 

 

Would you believe it, if I told you, it was clear Monday evening, the same day the lens arrived? Well, it was. The seeing was not super good, but quite usable. Quite hazy, though, and very cold. 

 

Interestingly, the new lens has a much lower serial number, 223 (the old one was 252). 

 

I set it up shortly before dinner and initially, I wasn't very impressed. There didn't seem to be much of an improvement and I saw massive spherical undercorrection in the star test and ronchi test. There was, again, a halo around bright stars, although not nearly to the same degree as before. This was after almost an hour of cooldown. I was so disappointed I actually took the lens off the scope again to check if it was assembled incorrectly. This didn't appear to be the case. I put it back in and put the scope outside for an hour with the lens cap and the rear plug off. 

 

An hour later, I tried again. Much better. The halo was *almost* completely gone and views were drastically improved. Low power views were insanely good in a 17mm ES92. Contrast was through the roof, considering the conditions. Despite somewhat hazy skies and a barely visible winter Milky Way I could see much detail in a lot of deep-sky objects, proving that the scope is a powerful deep-sky machine. Some highlights:

 

- M33 spiral arms and NGC 604 as a clearly visible little glow (71x)

- NGC 206 in M31. Hints of dark bands in M31 (71x)

- NGC 404 extremely obvious near Mirach (71x)

- NGC 7789 a huge cloud of pinpoint stars

- details in NGC 7662 at 600x

- details in IC 2149 at 600x

- NGC 2158 near M35 partially resolved (71x)

- hints of details in NGC 2022 (179x)

 

Once the scope was fully cooled to ambient, it began to deliver some impressive double-star views. Theta Aurigae was extremely easily resolved at 179x. I looked at Gamma Andromedae at 600x and the spurious disks were tight and sharp with hard outlines, albeit with maybe slightly too prominent diffraction rings. The first lens, #252, never showed views this good, no matter how long I let it cool, there was always a haze around brighter stars.  

 

I suddenly discovered that it was well past my normal bedtime, so I mildly panicked at packed up in a hurry, so I forgot to do a ronchi test after the scope had fully cooled, which irritates me now. Ah, next time, I suppose.

 

I hope to soon get a clear night with the Moon high in the sky, so I can get a better assessment of the scope's capabilities as a planetary instrument. It clearly has enormous potential as a visual deep-sky instrument. A downside is that it apparently takes a very long time to cool down. I had not expected a cooldown time in excess of 1.5 hours for a doublet. Some planning ahead will obviously be needed and it's not a scope for quick views, at least in the cold season. 

 

 

Clear skies!
Thomas, Denmark 

 


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#2 Erik Bakker

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Posted 05 December 2019 - 04:03 PM

Thanks for the update Thomas. Enjoy your new scope.

#3 BillP

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Posted 05 December 2019 - 04:08 PM

Sounds wonderful Thomas!!  Not sure what your temp delta was when you put the scope outside, but with my APM/Lunt 152ED when the delta is 30-40 degrees F then not unusual for it to take a full 2 hours to cool.  The characteristic of my scope is that is has noticeable SA when not acclimated.  I actually like that behavior as it becomes easy for me to tell when the lens is not there yet.  And once it reaches full acclimation, well then it is absolutely killer even at very high magnifications.

 

Given the performance you were getting out of it using magnifications up to 100x/inch, why even bother with a ronchi test?  I mean who cares what that test might show when visually it is performing beyond expectations really as 100x/in is not what folks should be expecting from a non-premium level scope.  Personally, my observing exceeding 50x/in with any scope amounts to a small fraction of a percent of the time, and never for any good reason lol.gif

 

Anyway, glad to hear you have a 6" performer on your hands!!

 

PS - a long time ago I asked Markus about the serial numbers on these and he said they are not sequential and done by the factory that makes them and not him so basically they hold no meaning from his perspective.


Edited by BillP, 05 December 2019 - 04:09 PM.

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#4 Astrojensen

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Posted 05 December 2019 - 04:19 PM

Hi Bill

 

 

Not sure what your temp delta was when you put the scope outside, but with my APM/Lunt 152ED when the delta is 30-40 degrees F then not unusual for it to take a full 2 hours to cool.

 

The temp delta was around 25°C. And two hours sounds close to what I experienced. 

 

 

why even bother with a ronchi test?

Because science! wink.gif

 

 

PS - a long time ago I asked Markus about the serial numbers on these and he said they are not sequential and done by the factory that makes them and not him so basically they hold no meaning from his perspective.

That's really odd. I wonder what the logic behind that is, if there is any. We use serial numbers on the batches we produce in the factory where I work and even though they may appear random to an outsider, they actually have their own logic behind them. 

 

 

Clear skies!

Thomas, Denmark



#5 aneeg

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Posted 05 December 2019 - 04:38 PM

Great tests, Thomas. You finaly seem to get your dream scope.

Next on your list must be an obsy so the scope always will be at ambient temp.

 

Arne


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#6 drd715

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Posted 05 December 2019 - 05:31 PM

For date reference I received sn #235 January 2018. Coming up on 2 years now. I don't like cold so much below 50 degrees F is not for me. Mostly 60/70 degrees (winter) F here in Florida. Lots of atmosphere density and somewhat higher moisture percentage, but usually stable atmosphere to view through. Have to go to better areas outside of town to get away from light glow. So basically I will never see the temperature delta you have. Enjoy the 152. Hope you post a comparison to the 102ed F-11. That scope is still calling me as a good camping scope on altaz for simple setup. -Dan-

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#7 John Fitzgerald

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Posted 05 December 2019 - 06:14 PM

I can very rarely use more than 40x per inch due to seeing.


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#8 moshen

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Posted 05 December 2019 - 06:20 PM

Nice report, thanks for sharing Thomas. I’m curious if you got a test report with your scope or if Markus is not including those anymore?



#9 Wildetelescope

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Posted 05 December 2019 - 06:59 PM

... The replacement lens for the poor one in my APM 152/1200mm ED arrived Monday December 2nd. Sorry for not posting earlier, but I've had quite a hard week at work, so I've not had much energy to post.

Would you believe it, if I told you, it was clear Monday evening, the same day the lens arrived? Well, it was. The seeing was not super good, but quite usable. Quite hazy, though, and very cold.

Interestingly, the new lens has a much lower serial number, 223 (the old one was 252).

I set it up shortly before dinner and initially, I wasn't very impressed. There didn't seem to be much of an improvement and I saw massive spherical undercorrection in the star test and ronchi test. There was, again, a halo around bright stars, although not nearly to the same degree as before. This was after almost an hour of cooldown. I was so disappointed I actually took the lens off the scope again to check if it was assembled incorrectly. This didn't appear to be the case. I put it back in and put the scope outside for an hour with the lens cap and the rear plug off.

An hour later, I tried again. Much better. The halo was *almost* completely gone and views were drastically improved. Low power views were insanely good in a 17mm ES92. Contrast was through the roof, considering the conditions. Despite somewhat hazy skies and a barely visible winter Milky Way I could see much detail in a lot of deep-sky objects, proving that the scope is a powerful deep-sky machine. Some highlights:

- M33 spiral arms and NGC 604 as a clearly visible little glow (71x)
- NGC 206 in M31. Hints of dark bands in M31 (71x)
- NGC 404 extremely obvious near Mirach (71x)
- NGC 7789 a huge cloud of pinpoint stars
- details in NGC 7662 at 600x
- details in IC 2149 at 600x
- NGC 2158 near M35 partially resolved (71x)
- hints of details in NGC 2022 (179x)

Once the scope was fully cooled to ambient, it began to deliver some impressive double-star views. Theta Aurigae was extremely easily resolved at 179x. I looked at Gamma Andromedae at 600x and the spurious disks were tight and sharp with hard outlines, albeit with maybe slightly too prominent diffraction rings. The first lens, #252, never showed views this good, no matter how long I let it cool, there was always a haze around brighter stars.

I suddenly discovered that it was well past my normal bedtime, so I mildly panicked at packed up in a hurry, so I forgot to do a ronchi test after the scope had fully cooled, which irritates me now. Ah, next time, I suppose.

I hope to soon get a clear night with the Moon high in the sky, so I can get a better assessment of the scope's capabilities as a planetary instrument. It clearly has enormous potential as a visual deep-sky instrument. A downside is that it apparently takes a very long time to cool down. I had not expected a cooldown time in excess of 1.5 hours for a doublet. Some planning ahead will obviously be needed and it's not a scope for quick views, at least in the cold season.


Clear skies!
Thomas, Denmark


Loosing track of time is a sign of a well spent evening!!!
Congrats!!

Jmd
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#10 edif300

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Posted 06 December 2019 - 03:27 AM

A downside is that it apparently takes a very long time to cool down. I had not expected a cooldown time in excess of 1.5 hours for a doublet. Some planning ahead will obviously be needed and it's not a scope for quick views, at least in the cold season.


Clear skies!
Thomas, Denmark




Big lens, big mass!!!
Enjoy with the scope.

#11 GlenM

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Posted 06 December 2019 - 06:34 AM

... The replacement lens for the poor one in my APM 152/1200mm ED arrived Monday December 2nd. Sorry for not posting earlier, but I've had quite a hard week at work, so I've not had much energy to post. 

 

Would you believe it, if I told you, it was clear Monday evening, the same day the lens arrived? Well, it was. The seeing was not super good, but quite usable. Quite hazy, though, and very cold. 

 

Interestingly, the new lens has a much lower serial number, 223 (the old one was 252). 

 

I set it up shortly before dinner and initially, I wasn't very impressed. There didn't seem to be much of an improvement and I saw massive spherical undercorrection in the star test and ronchi test. There was, again, a halo around bright stars, although not nearly to the same degree as before. This was after almost an hour of cooldown. I was so disappointed I actually took the lens off the scope again to check if it was assembled incorrectly. This didn't appear to be the case. I put it back in and put the scope outside for an hour with the lens cap and the rear plug off. 

 

An hour later, I tried again. Much better. The halo was *almost* completely gone and views were drastically improved. Low power views were insanely good in a 17mm ES92. Contrast was through the roof, considering the conditions. Despite somewhat hazy skies and a barely visible winter Milky Way I could see much detail in a lot of deep-sky objects, proving that the scope is a powerful deep-sky machine. Some highlights:

 

- M33 spiral arms and NGC 604 as a clearly visible little glow (71x)

- NGC 206 in M31. Hints of dark bands in M31 (71x)

- NGC 404 extremely obvious near Mirach (71x)

- NGC 7789 a huge cloud of pinpoint stars

- details in NGC 7662 at 600x

- details in IC 2149 at 600x

- NGC 2158 near M35 partially resolved (71x)

- hints of details in NGC 2022 (179x)

 

Once the scope was fully cooled to ambient, it began to deliver some impressive double-star views. Theta Aurigae was extremely easily resolved at 179x. I looked at Gamma Andromedae at 600x and the spurious disks were tight and sharp with hard outlines, albeit with maybe slightly too prominent diffraction rings. The first lens, #252, never showed views this good, no matter how long I let it cool, there was always a haze around brighter stars.  

 

I suddenly discovered that it was well past my normal bedtime, so I mildly panicked at packed up in a hurry, so I forgot to do a ronchi test after the scope had fully cooled, which irritates me now. Ah, next time, I suppose.

 

I hope to soon get a clear night with the Moon high in the sky, so I can get a better assessment of the scope's capabilities as a planetary instrument. It clearly has enormous potential as a visual deep-sky instrument. A downside is that it apparently takes a very long time to cool down. I had not expected a cooldown time in excess of 1.5 hours for a doublet. Some planning ahead will obviously be needed and it's not a scope for quick views, at least in the cold season. 

 

 

Clear skies!
Thomas, Denmark 

I thought APM were very strict on testing these before selling them? It's good to hear all is now well with the scope.

 

Glen.



#12 edif300

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Posted 06 December 2019 - 06:34 AM

Are those test reports corresponding to the lens provided?
Or generic info for what you would expect to?
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#13 daquad

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Posted 06 December 2019 - 11:02 AM

... The replacement lens for the poor one in my APM 152/1200mm ED arrived Monday December 2nd. Sorry for not posting earlier, but I've had quite a hard week at work, so I've not had much energy to post. 

 

Would you believe it, if I told you, it was clear Monday evening, the same day the lens arrived? Well, it was. The seeing was not super good, but quite usable. Quite hazy, though, and very cold. 

 

Interestingly, the new lens has a much lower serial number, 223 (the old one was 252). 

 

I set it up shortly before dinner and initially, I wasn't very impressed. There didn't seem to be much of an improvement and I saw massive spherical undercorrection in the star test and ronchi test. There was, again, a halo around bright stars, although not nearly to the same degree as before. This was after almost an hour of cooldown. I was so disappointed I actually took the lens off the scope again to check if it was assembled incorrectly. This didn't appear to be the case. I put it back in and put the scope outside for an hour with the lens cap and the rear plug off. 

 

An hour later, I tried again. Much better. The halo was *almost* completely gone and views were drastically improved. Low power views were insanely good in a 17mm ES92. Contrast was through the roof, considering the conditions. Despite somewhat hazy skies and a barely visible winter Milky Way I could see much detail in a lot of deep-sky objects, proving that the scope is a powerful deep-sky machine. Some highlights:

 

- M33 spiral arms and NGC 604 as a clearly visible little glow (71x)

- NGC 206 in M31. Hints of dark bands in M31 (71x)

- NGC 404 extremely obvious near Mirach (71x)

- NGC 7789 a huge cloud of pinpoint stars

- details in NGC 7662 at 600x

- details in IC 2149 at 600x

- NGC 2158 near M35 partially resolved (71x)

- hints of details in NGC 2022 (179x)

 

Once the scope was fully cooled to ambient, it began to deliver some impressive double-star views. Theta Aurigae was extremely easily resolved at 179x. I looked at Gamma Andromedae at 600x and the spurious disks were tight and sharp with hard outlines, albeit with maybe slightly too prominent diffraction rings. The first lens, #252, never showed views this good, no matter how long I let it cool, there was always a haze around brighter stars.  

 

I suddenly discovered that it was well past my normal bedtime, so I mildly panicked at packed up in a hurry, so I forgot to do a ronchi test after the scope had fully cooled, which irritates me now. Ah, next time, I suppose.

 

I hope to soon get a clear night with the Moon high in the sky, so I can get a better assessment of the scope's capabilities as a planetary instrument. It clearly has enormous potential as a visual deep-sky instrument. A downside is that it apparently takes a very long time to cool down. I had not expected a cooldown time in excess of 1.5 hours for a doublet. Some planning ahead will obviously be needed and it's not a scope for quick views, at least in the cold season. 

 

 

Clear skies!
Thomas, Denmark 

I can easily see 2158, but I have never noticed any resolution with the winter Milky Way barely visible, which is usually the case from my site.  It's remarkable that you were able to even partially this globular. I'll have to try harder next time.  Thanks for the report, Thomas.

 

Dom Q.

 

M35 and 2158 resize.jpg

 

Edit: looks like it is partially resolved in this 60 second photo with the APM 152 ED and Pentax K10 DSLR.


Edited by daquad, 06 December 2019 - 11:04 AM.

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#14 BillP

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Posted 06 December 2019 - 11:46 AM

I don't know how many times I've observed M35 and never noticed 2158.  Then a few years ago with the 152 ED I was "memorizing" the star pattern of M35 and the other two nearby open clusters so if I was just scanning around I would know immediately which it was.  It was while observing in that manner that I saw it sitting there as a dim little patch.  Moving up to 150-200x could resolve the stars.  Nice little companion.


Edited by BillP, 06 December 2019 - 11:46 AM.

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#15 Astrojensen

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Posted 06 December 2019 - 11:58 AM

Nice report, thanks for sharing Thomas. I’m curious if you got a test report with your scope or if Markus is not including those anymore?

No test report. 

 

 

Clear skies!
Thomas, Denmark



#16 daquad

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Posted 06 December 2019 - 03:32 PM

I don't know how many times I've observed M35 and never noticed 2158.  Then a few years ago with the 152 ED I was "memorizing" the star pattern of M35 and the other two nearby open clusters so if I was just scanning around I would know immediately which it was.  It was while observing in that manner that I saw it sitting there as a dim little patch.  Moving up to 150-200x could resolve the stars.  Nice little companion.

Bill, thanks for the tip.  I've always observed M35 at lower powers for a pleasing view with 2158 in the field.  I'll try next time at high power to resolve the dimmer glob, although Thomas resolved it at only 71X.

 

Dom Q.



#17 Astrojensen

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Posted 06 December 2019 - 04:03 PM

I only *partially* resolved it, as in, it was evident it was made of stars and not merely a gaseous nebula. 

 

To really resolve numerous stars in it requires higher magnification. Dark skies and good seeing helps, as its stars are faint.

 

 

Clear skies!
Thomas, Denmark 


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#18 daquad

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Posted 06 December 2019 - 08:00 PM

Nevertheless, a nice observation at only 71X with the winter Milky Way barely visible.

 

Dom Q.


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#19 BillP

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Posted 06 December 2019 - 08:38 PM

At 150-200x from my locations (i.e., Milky Way easy to see with dust lanes), that little cluster was a nice mass of twinkling little diamond chips.  150-200x is my recommendation for this target (looking at my notes).


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#20 stevew

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Posted 06 December 2019 - 09:51 PM

You mentioned the conditions were not that great during your test.

 Although you still pushed the magnification to 100X per inch.

What was the temperature??

Were the temps dropping?

I suspect it will perform better under better conditions.

Congratulations, I hope you get many years of use from it.

 

 

 


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#21 Astrojensen

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Posted 07 December 2019 - 02:50 AM

You mentioned the conditions were not that great during your test.

 Although you still pushed the magnification to 100X per inch.

What was the temperature??

Were the temps dropping?

I suspect it will perform better under better conditions.

Congratulations, I hope you get many years of use from it.

The temperature was just below freezing, around -1°C. The temperature was probably dropping slowly, but I didn't check it. 

 

I do suspect it'll perform better in better conditions. 

 

 

Clear skies!
Thomas, Denmark


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#22 Jon Isaacs

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Posted 07 December 2019 - 03:24 AM

I'll try next time at high power to resolve the dimmer glob, although Thomas resolved it at only 71X.

 

 

Just for the record, I believe NGC2158 is an open cluster.

 

Jon


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#23 Astrojensen

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Posted 07 December 2019 - 03:36 AM

Just for the record, I believe NGC2158 is an open cluster.

 

Jon

It is. A very rich, dense one, but an open cluster, nevertheless. It could perhaps be seen as a transition between the two types. An interesting target, in any case, and not anywhere near as difficult to observe, as some sources would have one to believe. I've seen it mentioned as being only visible in a 6" or larger, but from a dark sky site, it's visible without much effort in my 50mm Zeiss refractor. 

 

 

Clear skies!
Thomas, Denmark



#24 Rudi Bjoern

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Posted 07 December 2019 - 03:54 AM

Happy to hear about your positive tests of the new lens cell. Lets hope the Winter and spring will bring us some clear nights, the danish fall has been unusual miserable.

And again, I realy hope, that You can fit your new APO in your car for next year's Starparty, cant wait to have a look in and at it ;-)


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#25 Astrojensen

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Posted 07 December 2019 - 04:12 AM

Hi Rudi

 

Don't worry, I'll bring it to the next star party. It's not THAT big and easily fit in my car. 

 

I'll probably need another case or carrying bag, though, as the transport crate it comes in is ENORMOUS and extremely awkward to handle. It should have been fitted with wheels and a handle on the middle for easier handling. Maybe I'll modify it, now that I know I'll keep the scope for a while.

 

 

Clear skies!
Thomas, Denmark


Edited by Astrojensen, 07 December 2019 - 04:13 AM.

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