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Question about the FL80s and cameras

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#1 xandos

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Posted 21 July 2021 - 11:00 PM

Hi all!

 

I've been lurking on these forums for a while, but this is my first post. The occasion is that I've managed to get my hands on a Vixen FL80s (which is why I am posting in the 'classics' section).

 

I am planning to attempt doing astrophotography with it. I'm hoping to get my hands on the reducer at some point, but know that it might be a while before one pops up. In the meantime, does anyone happen to know what parts I need to connect the telescope to my camera? The camera is a full-frame pentax DSLR.

 

Thanks for all the help in advance!


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#2 photoracer18

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Posted Yesterday, 11:58 AM

Depends on the era yours came from and what focuser it has on it. If you are using a K-1 or K-1ii and your focuser is only available with 1.25" you will get some vignetting in the corners regardless if your camera adapter is using a 42mm T-ring or a 48mm T2 ring. Early ones from the 80's like I had had a 2" adapter that was basically unobtainable as no one had made it in decades. So I did research and found an adapter that allowed me to put a Starlight FT2025 2" focuser on it. At that point you would need to use a generic focal reducer like the Tele Vue 2008. There were 2 different focal reducers from Vixen, an FL-80S dedicated one and one that was for both the FL-80/FL-70. Never owned one, just saw them for sale at different times. If you have a 2" version Vixen focuser or the one with the 53mm barrel that does have a current 2" adapter then it depends on whether your images are going to be from a modded or unmodded camera version. I say that because you might want to use filters. Otherwise just buy a 2" to T adapter that accepts 48mm T2 rings and buy the Pentax K 48mm T-ring adapter. Remember to go into the menu and set the aperture control to manual


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#3 xandos

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Posted Today, 12:36 AM

Thanks a lot for all the information. I'm not sure what era mine is from, it is still on the way. The auction pictures of the lens cell were not too great, so I'm hope its in as good a shape as advertised. It looks like this (picture from the auction) and seems to indeed only come with the 1.25" back. I'd assume though, that like earlier versions the 1.25" holder does screw out. and then I should be left with a threaded tube. I'll have to confirm this all when it arrives of course.

 

Vixen still makes these:

https://global.vixen...roduct/3878_09/

 

If I understood correctly, that might fit the FL80s when removing the 1.25" adapter, but I'm not sure, do you happen to know?

 

A pentax-T ring is on the way.

 

So far I've been doing some beginner-level astrophotography with the pentax K-1 (unmodded) and the 300mm prime lens. This will be my first real scope, so I'll have a lot to learn!

 

i-img1200x900-1626651336hgc0ro295922.jpg



#4 xandos

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Posted Today, 02:35 AM

To anyone else who might be interested, I asked a telescope shop in Tokyo about the compatibility of the new reducers/flatteners for the SD81 etc. to the FL series. It would need to be one of the 60mm drawtube versions to be compatible, so quite a few of the FL scopes with the smaller drawtubes are not compatible.

 

Apparently the performance of these on the FL series is something that vixen has made public, although I had not found the information before. The figures are here:

 

https://www.vixen.co...df/sdhd_old.pdf

 

I'm new to these type of graphs, but if I understand correctly, the flattener and reducer both pretty drastically improve performance.




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