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Askar FRA600 Quintuplet Astrograph initial impressions + unboxing

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#51 coinboy1

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Posted 07 March 2021 - 08:27 PM

For fun I decided to throw the FSQ106N (fluorite model on there). The old fluorite that I had I remember being super sharp visually with very little to no color abberation visually and photographically. It makes sense the FRA600 is slightly worse as far as chromatic aberration correction as the spots are larger.

 

Attached Thumbnails

  • SpotsCompared2.jpg

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#52 coinboy1

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Posted 07 March 2021 - 08:33 PM

[post removed as requested]


Edited by coinboy1, 08 March 2021 - 06:47 AM.


#53 RogeZ

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Posted 07 March 2021 - 08:34 PM

Here are a couple of test images with the FRA600 and the 6200MM

 

get.jpg?insecure

 

get.jpg?insecure

 

Mind you my EQ6R had a worm defect, so every 4 images I would have a small trail. I would say the scope will get much better with basic tilt adjustment and a good mount.

 

My impression is the scope is better than FRA400 for FF. As discussed above, this scope has larger spots than FSQ but overall works well.



#54 coinboy1

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Posted 07 March 2021 - 09:03 PM

Nice results! Very round stars across the field. You are right spots are a bit larger but certainly good as an astrograph. Even some FSQ owners had problems with the optics in their scopes but so far looks like FRA owners have round stars! No reports with pinched optics or triangular stars so far AFAIK.

#55 coinboy1

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Posted 07 March 2021 - 09:49 PM

Here is my quick and dirty result of the Leo Triplet with the FRA600. First time using the FujiFilm XT3 and processing in Pixinsight with no flats and no darks. It is an integration of 42x30sec subs. (21 minute total integration). Red/White zone light pollution. Excuse the dust motes since no flats. 

 

LeoTriplet.jpg

 

Also attached is the aberration inspection with the color stretched so you can see some separation of colors in final stacked image. 

 

integration_DBE_mosaic.jpg


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#56 coinboy1

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Posted 07 March 2021 - 09:52 PM

Close up of M65/M66 to show resolution capability of the FRA600. Focus could be off slightly since I had no automated focuser attached. This was purely focused using the zoom function with the FujiFilm XT3 and no bahtinov mask. 

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  • m65m66.jpg

Edited by coinboy1, 07 March 2021 - 09:53 PM.


#57 edif300

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Posted 07 March 2021 - 10:39 PM

After reading frist impressions about FRA600 against FSQ my initial high expectation are decreasing now. I want to see this scope at its full framing capability by heavy cam rather than lightweight with happy format camera or by a FF format highly optical quality demanding new generation cam. After all this is a newly designed quintuplet...

Edited by edif300, 07 March 2021 - 10:41 PM.

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#58 whwang

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Posted 08 March 2021 - 04:40 AM

Hi Tony,

 

Thank you for posting your image and the spot diagrams compared against FSQ.

 

Based on your image of the Leo triplet, I would say the star sharpness is very fine. This is especially true given that the pixels in your image are just 3.7 um (vs. 5 to 6 um commonly seen in FF cameras).  However, this just does not match what's in its spot diagrams.  If I just look at the spot diagrams, I would consider this a horrible astrograph.  Spot sizes of 20 (red) to over 30 um (blue) would translate to 6 to 8 pixels in your aberration inspection image, but I just don't see that.  The size of faint stars in your image appears to be more like 5 to 6 pixels, rather than 6 to 8, and this includes seeing effects and all the other possible real-world imperfections.

 

I just can't reconcile these.  All spot diagrams from ASKAR and Sharpstar look like this, unreasonably bad and scary when compared to similar products from other manufactures (not necessarily TAK).  However, when look at their pictures, I don't generally get this kind of bad impressions.  Many of them look just fine.  Do you have any explanation to this?  I am very puzzled.

 

Cheers,

Wei-Hao


Edited by whwang, 08 March 2021 - 04:42 AM.


#59 AnakChan

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Posted 08 March 2021 - 05:26 AM

Here are a couple of test images with the FRA600 and the 6200MM

 

get.jpg?insecure

 

get.jpg?insecure

 

Mind you my EQ6R had a worm defect, so every 4 images I would have a small trail. I would say the scope will get much better with basic tilt adjustment and a good mount.

 

My impression is the scope is better than FRA400 for FF. As discussed above, this scope has larger spots than FSQ but overall works well.

Thanks, this is a good post. I gather the backfocus for the ASI6200MM is correct for the FRA600. This is a pity, I had high hopes for this to be a credible alternative to the FSQ. Similarly I’m now curious on how the rest SharpStar’s assault on the Tak range is gonna go (PNT vs Epsilons, SCA260 vs CCA250). 



#60 coinboy1

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Posted 08 March 2021 - 07:31 AM

Hi Tony,

 

Thank you for posting your image and the spot diagrams compared against FSQ.

 

Based on your image of the Leo triplet, I would say the star sharpness is very fine. This is especially true given that the pixels in your image are just 3.7 um (vs. 5 to 6 um commonly seen in FF cameras).  However, this just does not match what's in its spot diagrams.  If I just look at the spot diagrams, I would consider this a horrible astrograph.  Spot sizes of 20 (red) to over 30 um (blue) would translate to 6 to 8 pixels in your aberration inspection image, but I just don't see that.  The size of faint stars in your image appears to be more like 5 to 6 pixels, rather than 6 to 8, and this includes seeing effects and all the other possible real-world imperfections.

 

I just can't reconcile these.  All spot diagrams from ASKAR and Sharpstar look like this, unreasonably bad and scary when compared to similar products from other manufactures (not necessarily TAK).  However, when look at their pictures, I don't generally get this kind of bad impressions.  Many of them look just fine.  Do you have any explanation to this?  I am very puzzled.

 

Cheers,

Wei-Hao

Hello Wei-Hai,

 

I too am having trouble why the Askar spots are so much larger than the Tak spots. I could be doing my analysis incorrectly. After reading this thread here: about Spot diagram comparisons I don't think scaling is as simple as it seems. There are other factors involved such as focal length or f/ratio. Also I think the spots always seem to look much worse on paper then on actual stars. I mean no one gets stars shaped the same way in images as what the spot diagrams show. 

 

As another fun comparison, I looked up another scope, a Takahashi FS-60C. A decent compact visual scope and obviously it is not designed for imaging but rather visual. You can see it actually has similar spots on-axis as the FRA600. The scaling is about the same with the large box representing 100 microns. 

 

TakCompared3.jpg



#61 coinboy1

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Posted 08 March 2021 - 07:39 AM

Thanks, this is a good post. I gather the backfocus for the ASI6200MM is correct for the FRA600. This is a pity, I had high hopes for this to be a credible alternative to the FSQ. Similarly I’m now curious on how the rest SharpStar’s assault on the Tak range is gonna go (PNT vs Epsilons, SCA260 vs CCA250). 

I would say the FRA600 is not nearly as good optically as the FSQ106. An FSQ106 with an upgraded focuser will certainly outperform the FRA600. I did have a major problem with my FSQ106N that I had, it had major focus shift during temperature changes. This was very common and I mean focus shift was BAD. I didn't notice this too much with the FRA600 on my first night with it, however it was quick session and I didn't do in depth analysis since I don't have an automated focuser to read differences in focus position. 

 

I am thinking Takahashi is very hard to beat optically, they are near perfection. Takahashi has some work to do with mechanics, that is why some of their latest offerings of refractors have the optional Feathertouch focuser. Sharpstar and Askar major selling point is price. They are 1/3 to 1/2 the cost of Takahashi. For the optical purist where money is no object, Takahashi is #1. For everyone else, money matters...


Edited by coinboy1, 08 March 2021 - 07:40 AM.

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#62 alfogator

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Posted 08 March 2021 - 07:42 AM

To be fair you should compare it with the FS-60 with the multiflattener:

 

FS-60CB_flattener_MFL1-04X_spots.png



#63 coinboy1

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Posted 08 March 2021 - 08:07 AM

Yes you are correct, I will add that to the comparison later :-)

#64 IonClad

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Posted 08 March 2021 - 08:44 AM

Yes you are correct, I will add that to the comparison later :-)

Have you by chance used the matched reducer with the 600? IMO one of the big attractions of this scope is that there's a matched reducer. Spot diagram of the reduced field actually improves over the native one off-axis: http://www.askarlens...61009593011.jpg

 

I'm considering this and the Esprit 100, but the latter, based on what I've seen on astrobin, doesn't seem to have a good reducer currently available that fits APS-C or larger.



#65 coinboy1

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Posted 08 March 2021 - 09:18 AM

That’s interesting, I have not had the chance to use the reducer. Your right the spot does seem to be improved. I will do some spot comparisons soon with reducers.

#66 coinboy1

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Posted 08 March 2021 - 09:49 AM

Ok here are the reducers compared. You are right, now the performance is REALLY close to each other. 

 

reducers compared.jpg


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#67 Uggbits

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Posted 08 March 2021 - 10:49 AM

This is a quick 8s image to test the reducer without my triband filter in the optical path. There is some minor separation between the red channel and the green/blue channels (which aligns with the spot diagram above). I measured the focal length out at 415mm, which is slightly under spec. As a consequence, there may be an opportunity to adjust my camera spacing for some small improvements.

 

_2S6A2795_mosaic.jpg

 

The bigger issue for me was adequately correcting the field with flat frames. I wound up cropping down my first attempt a fair bit just do to uneven illumination I couldn't correct without better flats. However, this may not have been tied directly to the reducer, as I was testing from a downtown balcony, and I have been fighting flare from nearby car lots.   

 

This is a heavily cropped frame on the Seagull nebula with a Hutech NB1 from a downtown balcony (probably class 8) using my Canon Ra. It is only 50x3 minutes, so given the conditions it needs quite a bit more data to turn into a final result.

 

Seagull_Reducer_First_Process_Web.jpg

 

Cheers, 

Dan


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#68 coinboy1

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Posted 08 March 2021 - 11:00 AM

Awesome result Dan! Looks like the F3.9 reducer is impressive! Might have to think about getting one now...



#69 sperho

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Posted 08 March 2021 - 11:01 AM

Thank you all for continuing to share your testing results.  I see a lot of comparison with the Tak FS106xyz, which makes sense given the size of the image circle, but at this price point it would seem that the Esprit 100 would also be an obvious choice up through a full frame sensor and APS-C, reduced.  Do any of those with the FRA600 have any comments on how their copy of this scope is performing compared to the Esprit?  


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#70 coinboy1

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Posted 08 March 2021 - 11:02 AM

Added FSQ85 and FC100D + flattener spot diagrams for some comparison. The Askar FRA600 competes with other flat field astrographs with a bit more color separation than other scopes. Overall I still think its a good bang for your buck astrograph.

 

TakCompared4.jpg



#71 Sponge

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Posted 08 March 2021 - 11:26 AM

Thanks everyone for your input on this thread!

 

Based on everything discussed here already, I've just pushed the button on the FRA600 and can't wait to get some tests out under the stars with it!

 

I have to agree that the spot diagrams look very good for the price, all things considered. I never expected this scope to really compete with the FSQ106, but it looks like it comes quite close which is incredible. This will only be matched with my QHY268M, so I won't be pushing the field to it's limits. I hope the quality control process at Sharpstar is good and that I get a good sample (not that I've seen any bad ones yet)!


Edited by Sponge, 08 March 2021 - 11:26 AM.

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#72 IonClad

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Posted 08 March 2021 - 11:28 AM

Thank you all for continuing to share your testing results.  I see a lot of comparison with the Tak FS106xyz, which makes sense given the size of the image circle, but at this price point it would seem that the Esprit 100 would also be an obvious choice up through a full frame sensor and APS-C, reduced.  Do any of those with the FRA600 have any comments on how their copy of this scope is performing compared to the Esprit?  

Not trying to hijack the thread, but since you are doing comparisons the Esprit 100 is very close to the price of the Askar 600 and a logical comparison.

Do you know of any currently available reducers for the Esprit for APS-C or larger? I only find good star shape examples with smaller sensors or that have been cropped. The Apex 0.65 reducer does not seem to support a sensor this size. The Riccardi may, but again lacking examples.

 

Thanks also to everyone for the example images and putting together the spot comparisons.



#73 sperho

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Posted 08 March 2021 - 11:39 AM

Not trying to hijack the thread, but since you are doing comparisons the Esprit 100 is very close to the price of the Askar 600 and a logical comparison.

Do you know of any currently available reducers for the Esprit for APS-C or larger? I only find good star shape examples with smaller sensors or that have been cropped. The Apex 0.65 reducer does not seem to support a sensor this size. The Riccardi may, but again lacking examples.

 

Thanks also to everyone for the example images and putting together the spot comparisons.

The Starizona Apex 0.65X has a specified corrected image circle of 30mm and should support APS-C.  The TSO TSAPORED075 0.74X reducer has an image circle of at least 60mm and supports full frame.  Search on "Esprit" posted by SilverLitz - he has a number of examples of the TSO reducer on his 100 using a full frame DSLR.  Here is one of his threads.


Edited by sperho, 08 March 2021 - 12:07 PM.


#74 IonClad

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Posted 08 March 2021 - 12:08 PM

The Starizona Apex 0.65X has a specified corrected image circle of 30mm and should support APS-C.  The TSO TSAPORED075 0.74X reducer has an image circle of at least 60mm and supports full frame.  Search on "Esprit" posted by SilverLitz - he has a number of examples of the TSO reducer on his 100 using a full frame DSLR.  Here is one of this threads.

Thanks for the references. I have read SilverLitz's threads, but the reducer he uses is no longer available and the updated version is specifically listed as mechanically incompatible with the Esprit100. The Apex is attractive and I agree that on smaller sensors it's a good deal. On APS-C or larger sensors I do not see examples without significant aberrations in the corners. Here's a representative one https://www.astrobin.../full/zfrfe3/0/ (no offense to what is otherwise an awesome image).
 



#75 Joe G

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Posted 08 March 2021 - 12:44 PM

Nothing is perfect in this world.  I have the fluorite Tak FSQ and use it with full frame cameras.

 

Given the price I'd be happy with the Askar from what has been posted so far.


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