Pickup SRA - starting from a 500x microscope

I have a Dino-Line AM3013T that i use to set up SRA for an XV1's and A90 and encounter the same difficulties as the OP using the software (DynoXcope) that came with the scope to determine the angles. If it was a matter of just pointing the scope at the platter/styli and and getting the rake angle with one "click" that would be easy.
I have a Sota Cosmos IV and getting the scope as close to the platter as possible to take a perfect picture is difficult to begin with (due to the plinth).

Once you have done that, using the DynoXcope software, you have to draw an horizontal and vertical line thru the centre of the styli to determine the rake angle. I had sent a few pictures i thought were at 92 degrees to Wally and he estimated one to be at 89d and the other one at 94d when i was convinced that i had hit the 92d mark. I found this exercise very frustrating.

Adjusting VTF, AS, Azimuth, overhang, zenith, is quite easy versus setting 92d SRA accurately with a scope. Unfortunately, for me using this scope and/or software gives me a rough estimation at best.

I agree Smoffatt, it definitely takes a lot of practice. I don't particularly like the Dinolite software.

One can use the following for a trial and see what they they think:

1. Pixelstix - this is great software (< $5) to get the baseline at 180 degrees. This is critical of course for SRA calcualtions. Its very difficult to sometimes get the camera adjusted so the base of the platter is exactly at 180 degrees. You get better and better with practice, but it helps to have a program that corrects the image to 180 degrees.

2. ImageJ - free and very accurate to drawing and calculatiing angles to the hundreth decimal point. Using ImageJ and taking the average of a few measurements will give you a very accurate reading.

Good thread at Audioshark.org with comments and pics of SRA. To see the pics you have to log in.

http://audioshark.org/all-things-analog-21/your-own-sra-pictures-6404-page2.html

Thanks for this Phil. Can you calculate angles with Pixelstix as well or do you just import your image into Pixelstix, correct the image to 180 degrees and then move it to ImageJ to calculate the angles? I will download ImageJ.

Indeed, for me getting a perfect 180 degree image to start with is very difficult.

Thanks for the link too.
Sly

One problem I can think of with using the trusted ear method of determining the proper angle, any of the angles involved, is that you never know when you have achieved a local minimum, in terms of distortion. That is why a technical method should yield better results. Analogous to trying to determine the ideal best sounding speaker locations by ear. Technical solutions should yield better results than ye olde move a little, listen a little method.