Askar FRA400 f/5.6 Quintuplet APO Astrograph review

[simmo39]

12 minutes ago, raadoo said:

When you get a chance to test the reducer, compare star shapes with and without it. I'm getting severely bloated stars with the reducer on; it could still be something different (i.e. dew / frost) but it'd be worth hearing from others with the FRA400.

Will do.

[jpoulette]

Thank you for posting all of this Lee - after a year it should clearly be "resurrected" for posterity. 😀

Jim

 

 

[RobW]

Also interested in thoughts with the reducer - especially pixel scale and whether it's too much undersampled on the 2600MC. Liking the idea of a 290/f3.9 very much - might consider pairing it to a asi294mm pro in bin1 mode for a somewhat better pixel scale match. Alternative would be the FRA500 with reducer, which sits at 350/f3.9

[iantaylor2uk]

Great review. 

I have the FRA 300 and have found it great to use, and with my ZWO 071 APS-C sensor I get a field of view of 4.5 x 3.0 degrees. 

I also analyzed the tilt of the set-up using ASTAP and was pretty happy with the result - shown below.

One of the main reasons I bought an ASKAR scope was to get a complete flat field over an APS-C sensor without having to faff around worrying about backspacing. I don't really understand why one would buy an ASKAR 500 and put a reducer on it when you could just as simply, and more cheaply, buy an FRA 400 or an FRA 300. 

Some images from my FRA 300 are on my blog at: https://chesterastroblog.wordpress.com/

Edited June 26, 2023 by iantaylor2uk
typo

[RobW]

Useful - thanks. The main thing for me is f/3.9 - I'm considering moving to a faster widefield scope. So the decision is 290mm FL @ f/3.9 or 350mm FL @ f3.9, since I'd be putting the reducer on either. There's probably a slight benefit of 90mm vs 72mm primary objective ITO resolving power, but that's not so much a factor in my thought process since we're talking widefield here anyway. FWIW - I did contemplate the Sharpstar 13028HNT f/2.8, but my existing filters could be problematic. On paper they're only rated to about f/3.6.

[Icesheet]

Nice review @Lee_P! I’ve just picked up an ex demo FRA400. Seems to tick a lot of boxes for me. Just a question on the star image at the corner you posted. It looks like CA, which the spot diagrams show may be present but it’s also very consistent with CA I’ve seen introduced with the L-extreme filter. Did you see this when not using the L-extreme also?

[Lee_P]

4 hours ago, Icesheet said:

Nice review @Lee_P! I’ve just picked up an ex demo FRA400. Seems to tick a lot of boxes for me. Just a question on the star image at the corner you posted. It looks like CA, which the spot diagrams show may be present but it’s also very consistent with CA I’ve seen introduced with the L-extreme filter. Did you see this when not using the L-extreme also?

To be honest I'm not sure, and my FRA400 has recently gone to a loving new home to accommodate my 130PHQ, so I can't make any further tests. But in all my time with the FRA400 I was never bothered by CA. Perhaps I'm not enough of a pixel peeper, but I reckon it's a-ok, especially for the price point.

Edited August 6, 2023 by Lee_P

[Icesheet]

Thanks for the quick response. Yeah, it seems like it’s a good deal for the money and I haven’t really seen many negative reviews or comments on this in particular. 
 

Wasn’t sure between this and the FRA300.