TecnoSky152 H-alpha scope - worth the price?

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TecnoSky152 H-alpha scope - worth the price?

Post by GaborKiss » Thu May 26, 2016 12:03 am

Hi all,

Anyone has any experience with this setup? https://www.secure-eshop.com/epages/www ... GTEC152BUN

Doesn't it problematic to have internal ERF? Can it die due time because of heat?

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by marktownley » Thu May 26, 2016 5:45 am

It's a great scope for the money Gabor!
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GuillermoBarrancos » Thu May 26, 2016 6:18 am

For imaging it's perfectly fine. Others here use such setup on their 152's.

I use the 2inch Baader ERF myself with my Esprit 120 and place it in front of the diagonal.

Though, I remember Daystar recommend using a front mounted ERF on apertures larger than 120mm.
If you want to use this setup for visual as well, I would contact Jen at Daystar if it's safe to use such large aperture with internal ERF only for visual observation.

Better safe than to be sorry.

My 2 cents.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by Valery » Thu May 26, 2016 2:00 pm

1. Ohara does not have K9 and F4 glass in their catalog. It is plain lie.

2. If one lie once, he can lie twice or more.

3. Summarize: 152/900 OTA + Quark + 35nm filter and see the difference vs complete package.

4. The results is a high res will be at least 2x worser than an 8" solar scope within your budget.


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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GuillermoBarrancos » Thu May 26, 2016 7:35 pm

It's really suprising, as this error is being made With a lot of these Scopes under different brands all over the internet.
I am quite shocked that TS in Germany seem to be making the same "typo" on theirs:
http://www.teleskop-express.de/shop/pro ... ctive.html

K9 glass is almost certainly chinese origin (Chinese Optical Borosilicate Crown Glass) and is often used in budget ED scopes and standard achromats.
So I can only assume that is the glass that is in these scopes.

Schott makes BK7 glass, but that is almost always used together with Ohara FPL-51 / 53 glass in higher priced ED / Triplet refractors.
https://www.pgo-online.com/intl/katalog/BK7.html

I have no idea what F4 is, as SCHOTT only has F2 and F5 in their catalog. So must be chinese origin as well, or it's actually SCHOTT N-SF4 glass?

Anyhow, If you want a 152mm ED / APO scope with Ohara FPL-51/53 glass, you not going to find one under 3000 euro's.
http://www.teleskop-express.de/shop/pro ... cuser.html

If you want a really good ED refractor with FPL-53 glass with a minimum of 120mm aperture, then this one from Skywatcher is really good and has proven itself over the years:
http://www.teleskop-express.de/shop/pro ... -case.html
But it's still 1700 euro's for just the optical tube.

I almost bought the Equinox 120 myself two years ago, but got a good deal on the Esprit 120 (triplet APO), so went with that one instead.


PS. Here is a Nice diagram from current Ohara / SCHOTT optical glass:
http://www.ohara-gmbh.com/e/katalog/dow ... m_neve.pdf

-----------------------

EDIT: I found an earlier post mentioning exactly this on Cloudy Nights about this 152 Scope that goes under many different brand names:

Posted 20 December 2015 - 12:06 AM

It's odd.

Kunming makes the scope.

But the version sold by Altair Astro claims Schott glass, but the version by TS claims Ohara glass.

Even odder, Ohara makes neither a "K9" or an "F4". But CDGM makes K9. And CDGM makes glass used in many other Kunming scopes. F4 is a Hoya catalog number and a Schott Catalog number (suggesting that TS is mistaken and Altair is being accurate as to glass source).

If the scope actually used Ohara glasses the equivalent catalog numbers would be S-BSL7/PBM4.

http://universalphot...CDGM_TD-USA.pdf

Something fishy here around glass source claims. :thinking:

In any case, this is not a new scope. It's the same scope that has been sold under many brands for many years. And the color correction is poor on anything bright at any magnification that is not minimal. Even the TS color crossing chart shows poor color correction:

http://www.teleskop-...-farbfehler.jpg

Regards,

Jim

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by DSobserver » Thu May 26, 2016 8:31 pm

One of the best results with this setup are produce by italian friend Sulcis2000 with internal 75mm erf : http://solarchat.natca.net/viewtopic.php?f=4&t=19884


I use same setup and I'm very happy too!

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GuillermoBarrancos » Thu May 26, 2016 8:36 pm

DSobserver wrote:One of the best results with this setup are produce by italian friend Sulcis2000 with internal 75mm erf : http://solarchat.natca.net/viewtopic.php?f=4&t=19884


I use same setup and I'm very happy too!
Yes, you have to take that note about color correction on Cloudy Nights with a grain of salt, as that is totally related to nighttime observing.
Good color correction is not needed for Solar Ha imaging. Though you still want good optics though, especially when imaging at very high resolution.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by grimble_cornet » Fri May 27, 2016 12:13 am

I'm never really sure how seriously to take the specs given for telescope optics - I have a pretty wide range of refractors ranging from a 'cheapo' achromat to a 'sophisticated' apo and I'm not convinced that there is that much difference when used for Ha imaging.

Just for a bit of fun........ here are 6 images:

Two are taken with the Quark plus an Equinox 120 with ED glass as mentioned above.
Two are taken with a Tal100 - a 'cheapo' achromat costing 20% as much as the Equinox.
Two are taken with a Lyra 152mm f5.9 - one of the many 'badged' versions of the Tecnosky scope which I understand is the same OTA used for the Lunt 152?
A1.jpg
A2.jpg
B1.jpg
B2.jpg
C1.jpg
C2.jpg
The two A images were taken with one scope....
The two B images were taken with a second scope...
The two C images were taken with a third scope.

All images were taken using a Quark Chromosphere and Grasshopper camera.
The six images were taken on different days under a range of conditions but mainly in 'reasonable seeing'.

I was pretty happy with each image at the time I produced it and would find it quite difficult to 'rank' the three scopes based on these results.

Maybe I'm just too close to the action?

What do you think.......... bonus points if you can identify the 3 scopes :D
.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GaborKiss » Fri May 27, 2016 12:31 am

Let me guess:

B, 152mm Lyra (these are the best resolution images)
A, 120 ED (hard to guess but seems a bit better resolved than C, but can be seeing)
C, TAL

So? :)
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by grimble_cornet » Fri May 27, 2016 10:23 am

Interesting ......... I can see your reasoning........ I'll wait to see if anyone else wants to play.
.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GuillermoBarrancos » Fri May 27, 2016 12:38 pm

Those are all six very nice images. Impossible to say as they are different targets, most likely also taken on different days under different seeing conditions?

But like I said before, good color correction basically only matters for nighttime seeing and photography and not so much for Ha imaging, since you only image in a single wavelength.
So a good quality Achromat will be good enough if only used for Ha viewing and imaging.

I happen to have the Esprit 120, as I use it for night time too and want to start with deepsky imaging next year, after I have moved to our new house out of the city later this year. I always wanted a nice APO, hence why I made that investment.

The V2 Version of that 152 tecnosky scope seems to be a decent scope and perfectly fine for Ha imaging. So if you go for it, make sure you get the V2 version and not the old one.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by grimble_cornet » Fri May 27, 2016 8:35 pm

I think the old version had a 2" focuser rather than the rather good 3" one on the latest version.
I agree with all of your points about achromat/apochromat for solar/dual use. I originally bought the Equinox 120 as a planetary scope before I got a C9.25 but ended up using it mainly for solar work. My only reservation is that the focuser is not in the same league as the Feathertouch on my LS100, the Moonlite I fitted to my Tal100 or the 3" on the 152mm scope - (not really surprising considering the price of these 'top draw' focusers although I must say that the 3" on the 152 scope comes pretty close). The Equinox unit is perfectly adequate for most things but tends to slip under the weight of the Quark or large Atik cooled CCD plus filter wheel. I have to lock the focuser when using the Quark and even then I suspect that there is a tiny bit of 'droop' which takes the edge off of the Quark's performance. The Esprit hadn't been released when I bought the Equinox so........ not sure if its focuser is significantly better.
.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GaborKiss » Fri May 27, 2016 9:35 pm

Mike, so which picture with which scope?

I am curious! :)))
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by grimble_cornet » Fri May 27, 2016 11:29 pm

A=Tal100
B=Lyra152
C=Equinox120
.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GaborKiss » Fri May 27, 2016 11:30 pm

Thanks Mike. Lyra had 160mm ERF in front?
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by grimble_cornet » Fri May 27, 2016 11:36 pm

Yes, and the others had the 2" Baader UV/IR cut filter mounted in the diagonal or extension tube BEFORE the Quark.
As Guillermo said; different targets, different seeing etc. but.......... whatever 'glass' the 152mm has, it seems to perform at a similar level to a 'cheapo' achromat (Tal100) and an ED (Equinox).
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by GaborKiss » Fri May 27, 2016 11:37 pm

One thing "disturbed" me, that 2 scope images were invert (which I don't like but personal taste many of you prefer), and the Lyra was "normal". Can we continue the game with 3 "normal" ones perhaps? Would be more fair I guess and shows more the difference. Thanks :)
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by Valery » Sat May 28, 2016 6:02 am

You stated that you are seeking for scope for high resolution works.

You also have told that you will a frequent guest at the Canary Islands.

150mm scopes are OK, of course. But with them you will mostly far behind
the telescopes of 8" and up apertures.
Doing High Res at the top of Canaries with 6" scope will be a real time wasting
(on such a summit). No real sense to go to Canaries with such a scope.

See what is an 8" SCT equipped with a full size (here is ARIES one) D-ERF and
a simple PST etalon. You will never get such pictures with 6" aperture.
With the sun going to the minimum this will become more and more actual.

Also, EQ5-Pro is absolutely enough for C8, while 6" refractors is problematic
in a windy days.


Click on the image for the full resolution.
VD
Attachments
08 25 2015 UT 06h 54m C8 203mm 214mm D-ERF PST.png
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by fjabet » Mon May 30, 2016 6:51 pm

200mm is a nice balance. Lower (152) the resolution difference is quite important, higher (>250mm) and you'd better have a very very very good site. I have a 280mm HaT, and I use much much more my 203mm :)

Regarding the glasses, there is a real potential "glassgate" in the amateur market.
When the manufacturer mentions ED glasses, you can expect rather FK61 or FK71 chineses glasses rather than Ohara S-FPL51 or 53 :)
HK9 is the chinese version of the BK7.
For this last case, there is no difference in term of quality between N-BK7 or CDGM HK9.

For flint crown (LAK/LAF/LASF and all highly abnormal glasses) and low dispersion glasses, I'm would bet that the chinese glasses are as good as german/japonese glasses. Not because of their intrinsic performances (the FK71 is a very good glass, not far behind the S-FPL53) but regarding tension and overall homogeneity. I would not be surprised that chinese ED lens manufacturers use the lowest price and quality FK blanks.
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by mdwmark » Tue May 31, 2016 3:58 am

My concern with this scope is the internal ERF. The idea of the ERF was to keep the heat out of the scope. If there where fans moving the air through the scope then out. Then the internal ERF is fine. But with an enclosed scope you have problems with temperature gradients. This is just saying the image will not be as good as it could be.
The images, all but 3,4 where all over processed. 1,2,4(little),5,6 where all in the red wing.
3 was a good .7-8 Ang image. not sure about image #2
Valery image is such a small field,even at .7Ang it would look impressive.
As for the glass ,as long as an scope is corrected is it really a big deal.
For solar scopes, I have seen designs for air spaced doublets made out of BK-7(both elements)
They where F/10 and up, work great, because they where design for one wavelength.
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by Astrograph » Sat Jun 04, 2016 10:56 am

I see lots of valid comments here but as the UK importer for Tecnosky, i think I should comment about the glass. I also am involved with another company and so have become quite familiar with United Optics products. The 152/5.9 is badged by a lot of people. The scope is the same wherever you get it and the only difference you will really encounter is if the supplier has bothered to collimate it (I do) or is trying to charge you more.

As Frederic points out Chinese glass can be just as good as Schott or O'Hara. It is worth knowing that glass blanks do not usually come with a refund/replacement option so after you make a lens, test it and discover the glass is stressed, the glass company are not interested. As a telescope maker your choice is to bin it and take the cost hit or sell it anyway as many companies do. It is now perhaps a little easier to understand why many companies do not supply tests.

I know that bad glass from CDGM has been replaced by them in the past. I also know that as many glass types are equivalents, UO can swap glass around if it makes purchasing / production sense. Although big, UO still have to commit to a lot of glass and buying in blanks for 6" optics is going to be subject to lower volume to say 4" because they are less scopes models to use it. This can make descriptions something of a lottery. What I can say is that APM's 140 and 152 Doublets which are also made by UO (but not UO's design) now use O'Hara glass and there were problems with CDGM supplies in the past. It may be that UO decided big blanks from O'Hara were more consistant. Who knows.

Bottom line is that the 152 Achromat (and I am very much an APO man) is surprisingly good considering it is an F6 achromat and the examples I have had have all been quite consistant. For solar it represents very good value as Mikes and also Ewans images demonstrate. As for 6" Refractor vs 8" Reflector, the 6" has more resolving power as the real resolving power of an 8" SCT is 5.3". Its extra focal length has some benefits, but as I also sell airylabs HaT I would like to think my view is unbiased. Both scopes have there place and both will do some things better than the other.

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Re: TecnoSky152 H-alpha scope - worth the price?

Post by marktownley » Mon Jun 06, 2016 8:06 pm

Interesting thread chaps!
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by fjabet » Tue Jun 07, 2016 9:33 am

Astrograph wrote: As for 6" Refractor vs 8" Reflector, the 6" has more resolving power as the real resolving power of an 8" SCT is 5.3".
Hello Rupert,

a 8" reflector has the resolving power of a 8" aperture. The resolution only depends on the aperture, CO doesn't account on the PSF size.
Now when looking more closely, the CO does have an effect of the MTF distribution that is a bit tricky.
CO causes some loss in the mid frequency range, but increase resolution above the theorical limit of an obstructed instrument in high frequencies. So for high resolution, it even have a positive side effect :)

Here is a MTF of a C8 HaT with its CO, and without. Those are real measures. To reconstruct the C8 without CO, I passed through a Zernike fit.
You can see that we loose a bit in the low/mid frequencies, where actually we don't care much as the constrast is high, and gain in high frequencies where it does matter as the contrast is low.
The cut off frequency is the same as it depends only on the aperture and wavelength.
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by Astrograph » Tue Jun 07, 2016 10:01 am

Hi Frederic

I will contact you privately about this so we can discuss in more detail. My only comment would be that other tests show that a CO has a visible effect on contrast when it reaches 30% and a serious one at 50%. OK for long exposure DSO imaging but not ideal for high resolution imaging. Taking your logic here an RC would be better still for high resolution which it certainly is not.

This is an MTF curve for a 6" APM-LZOS APO. This is at 546nm as I don't have the graph for 656nm. I am not saying the Tecnosky 152 Achro would perform like this but I would happily put a 6" APO up against any 8" Reflector (even yours :D ) and cannot conceive of a situation where the reflector will outperform it.
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Re: TecnoSky152 H-alpha scope - worth the price?

Post by fjabet » Tue Jun 07, 2016 12:42 pm

You would be amazed to see what is possible even with a RC. If the CO was an issue, planetary imagers would have burn their C14 :)

Below is an image of Emmanuel Beaudoin done with a 200mm RC at 50% CO :

Image

Another with a CN212 (30% CO) from me closing on the max resolution :

Image

And last but not least is a HaT 203mm at its peak by Christian Viladrich, there is no way you could have that with a 150mm refractor. I think this is the most resolved image done with 8" I've seen ever :

Image
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