Delos Pincushion Distortion

[russ.will]

Hmmm. I've seen this before. Once an eyepiece case has contracted green, the infection can spread quickly. Cutting of the supply of cash to the area is the only known treatment......

I think I'm relatively safe in this instance.

For one, my TVs now run 3-6, 8, 12 & 17.3mm which I feel is a pretty well judged spread for the 480, 1200 & 1500mm FLs of my scopes. I previously had most of the ES82s and I found I wasn't fussed by 82deg AFOV, never mind 100deg AFOV. As my Maxvisions are about as sharp as you can get without spending bucket loads of cash for a SWA, then I'm pretty much sorted, unless TV turn out a longer FL Delos.

I do keep eyeing up the 10mm though, as the subjects I like seem to occupy that sort of FL region. With the ES, I had 8.8, 11, 14, whereas I've only got 8 & 12mm at the moment. However, I'm staying sensible and will wait for the observing season to start proper and see if I actually feel like I'm missing something.

Russell

[russ.will]

Russell,

I do not have the 17.3mm but I have a good few of the others. I have never noticed any pincushion in any of these. I think that viewing a straight pipe like you are would reveal faults in any eyepiece with a wide field. The same with camera lenses, I have some of the best you can buy and you can get the same effect when testing them the same way you are. I think that if the eyepiece offers a pleasing view with the full Moon then that is a test passed, I don't really think any of the wide eyepieces will ever better what you are seeing, maybe the only really true flat field is an orthoscopic. I must find something to look at and repeat the test with some of my eyepieces.

Slightly off topic but one reason behind me getting rid of the 26mm Nagler was the large pincushion where as the 24mm UWA was not really noticeable in comparison.

Alan

I think you see my point - It wasn't a test representative of their intended use, but merely a comment on the fact that doing what they do so well, they MUST forsake other parametres. My ES82s were definitely better in this respect, but under the night sky, I've yet to look at anything so crisp right up the field stop than the Delos. The MVs are surprisingly close though.

I must find some time, now the 8mm has arrived (thank you Green Witch) to do this test with all of my EPs, if only for the sake of completeness.

Russell

[alan potts]

Russell,

I will look forward to seeing that test, you always write things very well and I for one enjoy reading them. Great pictures too.

Alan