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05-18-2020, 04:27 PM - 2 Likes   #1
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Astrophotography lenses that will work on Pentax!

SharpStar has made a new lineup called Askar that can use either a standard Pentax mount T adapter, and M48 then T mount adapter, or a normal 2" nosepiece with T adapter depending on the one you use onto the back of the thing and you've got a super flat field setup for Astrophotography or landscape. I've used some of their products before and I think I may need to get the 400mm f/5.6 and then the f/3.9 adapter for it too. They are all full frame compatible too.

I think it is cool of a company to release stuff like that that isn't just a "all but Pentax mount" setup.


Product|ASKAR|Jiaxing Ruixing Optical Instrument Co., Ltd.-Jiaxing RuiXing optical instrument co., LTD

05-18-2020, 05:55 PM   #2
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Nice find, thanks for sharing. The astrophotography buffs will appreciate this information.
05-19-2020, 08:19 AM   #3
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You just want me to spend more money.
Nice find something to have as a distraction for the daily status meeting later today.
05-19-2020, 08:03 PM   #4
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Looks really nice. Tempting. If you get one, be aware: The site states that the FRA400 has a 44m(m) image circle and it includes a M48 adapter. If you're using a aps-c or smaller sensor, it should not be an optical issue to use some sort of adapter that goes as small as a T2. If you're using a full Frame sensor though, there's a good chance that a T2 / m42 adapter will vignette. (Depends on the optical design.) It's quite hard to find M48 to K adapters - I ended up having to make one one, and It made a big difference in vignette when using the K1's on faster instruments like 400mm F4 and 1016mm F4.

05-19-2020, 08:40 PM   #5
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QuoteOriginally posted by jbondo Quote
The site states that the FRA400 has a 44m(m) image circle and it includes a M48 adapter. If you're using a aps-c or smaller sensor, it should not be an optical issue to use some sort of adapter that goes as small as a T2. If you're using a full Frame sensor though, there's a good chance that a T2 / m42 adapter will vignette. (Depends on the optical design.)
The site has a FF reducer listed for the FRA400.

class5|ASKAR|Jiaxing Ruixing Optical Instrument Co., Ltd.-Jiaxing RuiXing optical instrument co., LTD
05-20-2020, 05:17 AM   #6
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Here is a US distributor of their products.

Looks like new stock will be arriving in the near future.

Askar 200mm Focal Length Terrestrial / Astrophotography Camera Lens # ACL200
05-20-2020, 03:59 PM   #7
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Truly dangerous products.
05-21-2020, 06:17 PM   #8
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Original Poster
QuoteOriginally posted by jbondo Quote
Looks really nice. Tempting. If you get one, be aware: The site states that the FRA400 has a 44m(m) image circle and it includes a M48 adapter. If you're using a aps-c or smaller sensor, it should not be an optical issue to use some sort of adapter that goes as small as a T2. If you're using a full Frame sensor though, there's a good chance that a T2 / m42 adapter will vignette. (Depends on the optical design.) It's quite hard to find M48 to K adapters - I ended up having to make one one, and It made a big difference in vignette when using the K1's on faster instruments like 400mm F4 and 1016mm F4.
I get mine from Williams Optics. They make really nice M48->Pentax K mount adapters.

https://agenaastro.com/william-optics-wide-48mm-t-ring-for-pentax-k-mount-ca...r-m48k-tg.html

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