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Askar Fra600 Triplet Apo 108 f5,6 Petzval

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#1 ippiu

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Posted 15 November 2020 - 12:29 PM

Hi to all.

I'm really tempted by this scope just for imaging (i don't do visual).

I don't find anywhere, either on the web, or on Askar site, which glass the lens are made of: from the price, it seems it's Fpl53.

Does anybody confirm this?

http://www.askarlens...roduct/208.html

 

Thanks 


Edited by ippiu, 15 November 2020 - 12:33 PM.


#2 MikiSJ

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Posted 15 November 2020 - 12:42 PM

I believe Petzval lenses have 4 or 5 elements, not three.

 

See a description at https://en.wikipedia...ki/Petzval_lens


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#3 ippiu

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Posted 15 November 2020 - 12:55 PM

I believe Petzval lenses have 4 or 5 elements, not three.

 

See a description at https://en.wikipedia...ki/Petzval_lens

yes, sure...

But i mean the glass of the triplet obviously...The other 2 lenses are for correct the field and make it a flat field...



#4 junomike

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Posted 15 November 2020 - 01:25 PM

Made by Sharpstar.

IME If it's made with FPL-53/55 or something similar, It's listed as such.



#5 amery

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Posted 16 November 2020 - 10:39 PM

I'm also highly tempted by this sharpstar, with the reducer becomes f3.9!, but I don't know if my CEM40 can handle it 😥

#6 amery

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Posted 16 November 2020 - 10:47 PM

Made by Sharpstar.

IME If it's made with FPL-53/55 or something similar, It's listed as such.

anyone knows what's the FRA400 made of? they don't list it either



#7 amery

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Posted 16 November 2020 - 11:17 PM

teleskop-express.de listed it in this forum as FPL53. https://forum.astron...b-lager.297593/

 

German and Italian distributors now list it as in stock, for 2700€

 

opinions?


Edited by amery, 16 November 2020 - 11:41 PM.


#8 ippiu

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Posted 17 November 2020 - 12:17 PM

I'm also highly tempted by this sharpstar, with the reducer becomes f3.9!, but I don't know if my CEM40 can handle it

I have cem40 and in the beginning i would have liked to buy APM140 doublet....But this scope is over the limit for the cem40, for sure not the askar fra600 that for me it's the perfect combo for cem40.

I have the triplet 115/800 on cem40: no problem and a good combo...:)



#9 ippiu

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Posted 17 November 2020 - 12:18 PM

teleskop-express.de listed it in this forum as FPL53. https://forum.astron...b-lager.297593/

 

German and Italian distributors now list it as in stock, for 2700€

 

opinions?

I'm Italian but no italian seller has it in stock...

For what i know from 2 italian sellers, just TS has it in stock....



#10 amery

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Posted 17 November 2020 - 12:25 PM

I'm Italian but no italian seller has it in stock...

For what i know from 2 italian sellers, just TS has it in stock....

I thought I saw it available at telescopi-artesky.it last night :-/



#11 amery

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Posted 17 November 2020 - 12:29 PM

I have cem40 and in the beginning i would have liked to buy APM140 doublet....But this scope is over the limit for the cem40, for sure not the askar fra600 that for me it's the perfect combo for cem40.

I have the triplet 115/800 on cem40: no problem and a good combo...smile.gif

may I ask what 115/800 do you refer to? ;-)



#12 ippiu

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Posted 17 November 2020 - 12:36 PM

I thought I saw it available at telescopi-artesky.it last night :-/

no...not yet...https://www.telescop...5517136157.html

Just TS has it in stock...

 

may I ask what 115/800 do you refer to? ;-)

https://www.tecnosky...115-800-v2.html


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#13 ippiu

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Posted 18 November 2020 - 04:33 AM

I wrote to TS germany and asked about fpl53 fra600 lenses.... This is their answer...

thank you for your request.

No, the ASKAR 108mm does not use FPL-53 glass, however its color correction is very comparable to FPL-53. It's a Petzval "special glass".

Have a good day!

Kind regards


Simon Großlercher

#14 sl-he

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Posted 18 November 2020 - 04:40 AM

No, the ASKAR 108mm does not use FPL-53 glass, however its color correction is very comparable to FPL-53. It's a Petzval "special glass".

With this answer they confused us even more confused1.gif



#15 amery

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Posted 18 November 2020 - 04:50 AM

With this answer they confused us even more confused1.gif

the one I got from TS was a better:

 

 

 

Hello,

it's not declared because they use chinese glasses. From the informations I have, the chinese glass are almost equivalent to the ones from Ohara in terms of quality and Abbe number. I expect they could be like lanthan glasses, so very close to FPL-53. As well they use 2 of these glasses and the correction provided is very good. if you have any question I'm here,



#16 j1will

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Posted 20 November 2020 - 06:09 PM

the one I got from TS was a better:

I own the Askar FRA400 and am getting excellent results from it, including in depth pixel level post editing.  It's my understanding that now Hoya and perhaps some other glass for lens manufacturers are achieving the same level of performance but can't refer to it by the exact same nomenclature as with the Ohara glass?  I'm looking at either the Askar FRA600 or the Sharpstar 121mm f/5.6 Quintuplet to add to my range.  Probably the 121mm would be a better step in focal length before jumping to the SCT scope ranges for me.


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#17 ippiu

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Posted 21 November 2020 - 12:44 PM

I ordered one....

I can't wait to have it....but until 5th december, i can't pick it up....


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#18 Uggbits

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Posted 23 November 2020 - 10:45 PM

I received mine today. I managed to do a quick visual look between clouds at the moon and a couple planets. It looks promising so far, but it is now just a waiting game for some clear skies and proper testing.

 

Cheers, 

Dan 


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#19 amery

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Posted 24 November 2020 - 05:02 AM

I received mine today.

that was quick, keep us posted!


Edited by amery, 24 November 2020 - 05:02 AM.


#20 Uggbits

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Posted 02 December 2020 - 12:15 PM

So, I have had it out for two nights now. My general take is that it isn't perfect, but I'm not terribly disappointed either. That seems to be about balance for a scope positioned the way this one is in the market. The only lingering worry is how it will behave with the reducer once that is available, as that is one of the perks to this tube over some competing options.

 

The good: the field at f5.6 is quite flat, to the point of very minor FWHM shifts across the frame that look to be focuser sag. It is well illuminated, and the mechanical elements of the system seem to do their jobs (with a minor note below). 

 

The so so: there is some minor chromatic aberration if you pixel peep. I think it may be slightly clearer due to my use of an Hutech NB1 filter during my shots, but it is there. It is easiest to pick out by looking at the isolated channels in Pixinsight, where both blue and green match well, but red is slightly narrower and elongated in the corners. This aligns fairly well with the spot diagram.

 

There is also a very slight amount of sag and image shift in the focuser. It is overall quite good, holding my camera steady without me locking it down, even at the zenith. I will try locking it for the next session to see if it improves the sag.

 

The slight tilt in the system produced some issues for the stars on the bottom left, which did not appear to be as bad on the second night. I've also observed similar distortion from the NB1 filter on my 100-400 lens at f5.6 and using my 105mm at 1.4, so I'm not quite as concerned about that just yet.

 

The mosaic below is a slightly cropped field from my Ra, so it is just between a full-frame and APSC field. I had to crop because the meridian flip killed the alignment in the stack. I will share a single frame example later. 

 

Bubble_First_Process_mosaic.jpg

 

integration_Cropped_L_FWHM.jpg

 

Cheers, 

Dan



#21 RogeZ

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Posted 02 December 2020 - 10:07 PM

Dan:

That is very good :) Mine should be here in 2 weeks :)

#22 ippiu

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Posted Today, 05:05 AM

There is also a very slight amount of sag and image shift in the focuser. It is overall quite good, holding my camera steady without me locking it down, even at the zenith. I will try locking it for the next session to see if it improves the sag.

 

For a such expensive apo triplet scope, for me this is unacceptable...

Considering that on lower cost 2,5" RP focuser this image shift was never found...Probably i ask for a refund from TS...

 

https://drive.google...iew?usp=sharing


Edited by ippiu, Today, 05:14 AM.



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