4 replies to this topic

[leinbach]

Is there anyone out there who would like to share information with me about double-stacked PSTs?

I am still trying for the best adjustment of mine.  In a nut shell, I have set the PST to what I think is the optimum setting of the ring adjuster.  I get a uniformly illuminated image, with signs of surface details (but I did not find the 2 little filaments which I can see with double-stacking).

When I add the SM40, I expect to see more detail, and indeed in the last two days, I have seen several filaments, and one area of small but enhanced plage.  Thus, I think I must be working at the specified <.6 A bandpass.  However, there are some puzzling things to me.  The greatest filament visibility comes with the T-max set so that there is a noticeable angle between the front and real housings of the SM40.  First rough estimate is an angle of  .7 degrees.  Thus the incident light is also at about .7 degrees to the normal to the etalon.

At this setting, I am seeing bands of light and dark across the field of view, which I suspect are fringes from the etalon. If you move the image across the field of view, it traverses these bands.  Ideally. one would hope not to see the fringes.

One other observation: with the elements set parallel, I see ghost images, the first ghost being almost in contact with the primary ghost. The ghost moves when the T max is adjusted, in the direction of a line that is perpendicular to the line that connects the centers of the primary and ghost images when they are in contact.

Is all of this normal behavior, or indicate that the SM40 is out of adjustment?

Thanks for  any comments.

Harold Leinbach

[redvis]

Hi Harold,

For me, the greatest detail would also come with a noticeable tilt of the T-Max.  However, I never saw bands of light and dark across the field of view and I have looked through three separate doublestacked PSTs in the past - none of them had that sort of banding.

As for ghost images, there sometimes is one ghost image for me but it is never near being in contact with the main image.  It is usually on the extreme periphery of my field of view.

I am not an expert on this however, and I would definitely wait and see if anyone else chimes in with their experiences.  However, just based on my experience it does seem like something is odd.  Are you screwing the SM40 module directly into the PST? 

Cameran

[leinbach]

Thanks for your comments,  Cameran.  I will make more observations on the next cloudless day, and try to be more quantitative about what I am seeing.  And I would think that what I see by eyeball should also  be caught on an image - we will see. 

[cjwaring]

Hi
My method for tuning the double stack PST is first get the best view possible single. Assemble the second filter and adjust just far enough to move the ghost image just out of the field of view. This on my PST at least is always very close to the best view that I am going to get on any given day. I have never seen dark bands in my setup. The amount of visible detail I find depends on two factors, one the seeing and steadyness of the image and second and this may seem obvious the amount of activity, some days their is just not much to see.

Chris.

[redvis]

Harold,

Any word yet on your PST/SM40?

Cameran