Does anyone have any idea of comparisons between a Daystar ERF and the Baader D-ERF. I saw somewhere that the Daystar ERF works best at F30 or slower not sure if this makes much difference or not. Havent seen any focal ratios mentioned for the Baader D-ERF. Thanks Cam
Cam,
It's not the ERF that needs the f30 beam, but the Ha filter system that DayStar use.
The DayStar ERF is completely different from the Baader, but can do the same job.
What set-up are you considering?
The reason I was looking at the Daystar ERF is I can get it for less than $400 in a custom made cell to fit the scope Im going to use. The 90mm Baader is about $480 unmounted at current exchange rates. Although Im not sure how much I would need to spend for a cell if I had nothing suitable here. They both mention UV/IR blocking and keeping heat out of the tube. Not sure what the differences are I dont know enough about them.
Finally got all the parts together for the stage 1 mod YAAY!!! put it together this afternoon. I cut 80mm off the tube and was fairly close. had to rack out focuser only a few mm to achieve focus.It was late in the afternoon by the time I got it back together and the Sun was really low. I didnt get enough time to play and compare.Already have a SCT-2" adapter on its way for the stage 2 mod. Thanks Ken for that great file you sent and for answering all my questions. Couldnt have done it without you. Cam
I can assure you that the red filter plus UV-IR combo makes an excellent ERF.
The real problem is getting suitable optical filters. I find the photographic filters are not always up to the job. The Baader ERF for instance is almost 6mm thick and has a 1/10 wave surface accuracy....
An easy, quick test of an ERF is to focus the image of the sun on the back of your hand - if you feel any heat or discomfort then it's no good.
I really need to work on a finder for the solar scope. Took it to work to use at lunchtime and spent most of it getting the Sun in the FOV. Very frustrating. I really dont want to be wasting time like that when I take it to my childrens primary school for the Venus transit on the 6th. The whole school is going to look through it cloud permitting.
I use a short length of aluminium tube. 18mm diameter, about 150mm long; a bit of Gaffa tape pierced with a needle at the sunward aperture and a bit of masking tape (with a cross hair marked) at the other.
This can be mounted similar to a finder or laser pointer on the scope.
Very simple and works well.
