First light PST-B120

In terms of the FSQ, that's a quadruplet, is that correct?

In terms of the Daystar filter, do you know it it passes IR? One of the reasons why the Baader C-ERF and D-ERF are popular is that they control UV and IR very well. If it were me, I would check out this issue first to ensure you don't get a build-up of heat internally in the scope between the leneses in a quadruplet. I remember looking into this issue at one time and for this reason, I didn't use my Pentax 75SDHF when using my Daystar ERF and T-Scanner. I thought I had more info to hand on the Daystar ERF - can't find it now though.

For comparison, below is a chart for the Baader C-ERF
www.sonnen-filter.de/Filter-1/Ba-CERF-log.gif

and the Thousand Oaks ERF
www.sonnen-filter.de/Filter-1/Oaks-ERF-log.gif

Coronado SM60 front element
www.sonnen-filter.de/Filter-1/Cor-SM60-log.gif

Data obtained from here:
www.sonnen-filter.de/

In terms of f/9.3, I reckon this is plenty close enough to f/10.

Michael.

Michael,

Yes, the FSQ is indeed a quadruplet.

I will send an email to Jen Winter at Daystar to get some feedback as to the passthrough characteristics of the ERF I have. I do not see any sort of serial number but hopefully it will not really matter.

I can always place a UV/IR-blocker at the other end but obviously it will do nothing in relation to heat build-up within the OTA itself.

By the way, I just missed out on a blemished PST late last week available for sale on Astromart for $250 (the original purchase price). The hunt and chase continues.

Anthony.

Michael,

I just sent a message to Jen Winter at Daystar.

I visited the Daystar website and immediately found the following:

"Energy Rejection Filters reduce the heat load on your filter assembly by absorbing or reflecting UV and/or I light and transmitting light in the desired visual spectrum. These filters are sometimes Red or Yellow glass, or dielectric IR and UV, but pass light in the desired visual spectrum. The ERF can also serve as an aperture mask to accomplish a straight angle of incidence for light entering the filter."

Source: www.daystarfilters.com/energy.shtml

It seems we have All Systems, Go.

Thanks nevertheless for the heads-up!

Anthony.

Anthony,

I think that is more of a generic note re ERFs rather than specific to the Daystar one.
AFAIK, the Daystar ERF has evolved over the years and a couple of different flavours are available.
Is yours red or yellow?

Michael.

Michael I didnt get them :blush: I know the crowd I use for my site were hacked into recently and I had to change passwords etc so maybe something got lost there.... I'll have to look into it.
Yes there are uneven field issues, this is an f/8.3 and I would say is on the bare minimum for f ratio. You have to be very gentle with tuning the etalon and there's a bit of post processing invloved also as real flat fields are really possible in HA.

Anthony, Sebastien's images are great but I think I would be agreeing with Michael here about risking something as good as an FSQ

DG

ayiomamitis wrote: Do you remember where you got your 2" PST adaptor and for how much? I am also looking for such a beast.
Anthony.

Hi Anthony. I got mine from Arthur (Ambermile). It's ages ago and I can't find the original mail in my archive but I believe it was something in the region of £30. There's also a guy in Austria that used to make these. I'll pm a link to you - not sure if they have them anymore though.

Thanks for the info Dave. Mine is going to be a much more modest affair. 80mm F11 achro methinks - still a big jump for the 40mm of a pst.

Trevor