YKSE

Nice to know that using camera for measurement, do you know how the quantify the measurement? any link to this measurement? As to RD and AMD, my understanding is slightly different than yours, with AMD, the straight lines will keep straight across the field of view, but the spaceing between the lines gets narrower and narrower closer to the edge. While with RD, there're two types of RD, pincushion distortion where straight lines close to edge look like )(, and barrel distortion, where straight lines close to edge look like (). RD and AMD are part of Geometrical Distortions (GD), Chris Lord has more detailed discussions about distortions here, what I can understand is that GD depends only on FOV, the wider FOV, the more GD, you can trade between RD and AMD, but you can't reduce the total Geometrical Distortions. The fact that most astronomical eyepieces choose to correct AMD, is because AMD will cause close double stars smear together close to the edge, not because of astigmatism, also there are no straight lines in night sky to show this distortion, while in daytime use, AMD is more preferred because we have too many familiar staight lines in the view. You can increase GD (AMD or RD) to correct astigmatism (some Nikon eyepieces has more AMD than calculated total GD for correcting astigmatism), or you can increase field curvature to correct astigmatism (like some Pentax eyepiece).

Ruud, Can you show your formula for calculation field stops? How do you estimate how much Rectilinear in an eyepice? I mean in term of measurement, not the calculated geometrical distortion.

That's some seriously nice old glasses, Alan. My approach is a little different, watch the weight all the time

Nice updates Vox45 and Indibush , kee using your gears, read more and take your before each and every update, only you youself can take best care of your money.

Maybe you accidentally looking at some shinny shoes when you took in the package?

That's actually an interesting question On one hand, Televue indeed doesn't mention any changes about Panoptic, on the other hand, Televue doesn't announce all the improvement to their eyepieces either. Take Radians as an example, if you read enough, especially comments on other sites, you'll get quite different opnions about Radians' transmission and colour tint, and my guts feeling is that people were talking about different Radians (Televue hadn't anounced any changed about Radians), as shown in here. Panoptics have been around for longer time than Radians, only Televue knows the answer to your question. If I were you, I would prefer a newer Panoptic over an older one. Just my two cents.

Nice collection Paul that 18mm BCO looks like a midget there Why do I have a feeling that a new case is needed?

I can't say that I'd be surprised then

Looks like that TS has the cloned MWA here: http://www.teleskop-express.de/shop/product_info.php/info/p7921_TS-SWA-100--Ultra-Series-21mm-2--Xtreme-Weitwinkel-Okular.html Constant 16mm eye relief, 6 lens in 4 groups, some variation of 12mm T4 Naglers?

Go ahead and do it. Just don't make it a habit to continueously update it, that'll be a costly habit.

Agnes, A question about your calculation of refractors, are those achromats or perfect APOs? I'd assume that there're some differences in fine contrast between these two types, because of the chromatic aberrations in achromats.

Sorry, just opened it in google chrome. It must be that my Internet Explorer is of older version.

Very interesting work Agnes, thanks for sharing I have difficulty in accessing the source code link giving in your blog, can't download it either.

You put the pictures in this thread, what else can you do with it now?

Nice one, Mr. Spock, the case and the eyepieces seem to have been very stable to me.

Great first light Alan, looks like the one magnitude increase from 12" does make great difference, in addition to better optics

Mine is from 2013, S26403, starbright XLT coatings, orange tube, not going anywhere to my knowledge

Mike, Nice piece of work as well as the EPs. you'll have only two small spaces left to fill after 3.5XW