Focal Reducer for ZWO ASI 178

[AJ132]

Hi All.

I am trying to find a 0.8x focal reducer that will fit between my Lunt B1800 BF and my ASI178 camera. Using with the ASI178 with a Lunt LS80MT the ASI178 chip is just slightly too small for FD. I know i could do mosaics, but was hoping to avoid that for now. A fairly detailed search on the internet didn't turn anything up that would work behind the BF. Tele Vue has RFL-4087 model that looks like it might work, but it says it is for " telescopes in the 800-1000mm focal length range". The LS80MT is only 560mm. If anyone has come across a 0.8x FR that will work with the B1800 and a ASI camera I would really appreciate the info.

Thanks for the assistance.

Clear Skies,

Andrew

[EGRAY_OBSERVATORY]

Hello Andrew,
Would a 0.5x FR do the job or have you already tried one ?

Terry

[AJ132]

Hi Terry.

A 0.5x FR takes me from one extreme to other and results in a image that is to small. I checked with Lunt and they recommended a 0.8x. Some messing around with some FOV calculators showed the 0.8x to be a good fit. Unfortunately Lunt does not sell a FR that works with the Blocking Filter. Nearly all FRs online I have found, including the Tele Vue choices ask to remove diagonal to insert FR. Obviously thar will not work with a solar scope. I was just curios if anyone here has by chance come across a manufacture of a FR that can be used after the diagonal. Even 2” would be ok as Lunt sells a 2” eyepiece adapter for the BF.

Andrew

[marktownley]

Use a 0.5x reducer but reduce the spacing between it and the chip (short nosepiece on the camera), this will result in a reduction factor closer to the 0.8x you are after.

[EGRAY_OBSERVATORY]

Mark's comment does sound a good option Andrew, if that can be done with your camera.
They are very readily available in the UK at least...

Terry

[AJ132]

Thanks Mark/Terry.

I can give the 0.5x reducer a go. Are you aware of a 0.5x reducer that can put between the BF and the Camera? Most FRs are designed to go in focuser. Let me know you aware of a manufacture that makes one that will work at the eyepiece.

Thanks again.

Clear Skies.
Andrew

[AJ132]

I think I may have found one that should work. http://scopestuff.com/ss_fr1a.htm

[nicosolcy]

Andrew,

Please check this article on Agena Astro site:

https://agenaastro.com/articles/guides/ ... guide.html

There is a graph there and if it does indeed follow a linear path, this means that 0.8x reduction is achievable at around 30mm from the sensor. So removing the 11mm from sensor to ZWO T2 adapter, you are looking at an additional extension of 20mm + / - and then the reducer.

[nicosolcy]

Also, the 0.5x 1.25" reducer from ScopeStuff is the same as the GSO variant available from most stores that sell astro gear. Teleskop Service can help and they have a ton of extensions and adapters to make this work at the right distance.

[EGRAY_OBSERVATORY]

Hi again Andrew, correctly I think you mean a FR to fit on the camera's 1.25" nosepiece, which is the same as fitting a 1.25" coloured-filter to that camera-position as well as fitting to EP's

The ones shown in the ScopeStuff web-link, are generally the same fitting as those coloured filters - I've mentioned above.

For the relatively small price, trying-out that route as Mark suggested - would certainly be my first choice and indeed is what I use for 'whole-disk' imaging with my small sensor-CCD's into the B1200 BF & Lunt 60mm Ha & Cal-K scopes etc.

Terry