scampo said:
The Nikon was, objectively, the brightest image and was the one I liked the best out of the three. I don't know what the reviewers in the Birdwatch test were doing when they reviewed those scopes. What I do know is that very little objective testing was done; also, the discrepancies over the Nikon reviews is too much to be acceptable.
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It seems that dumbed down subjectivity is all these days - that, and a general lack of discernment or real interest. Perhaps that's what is wrong?
Hmmm.... well, I'm going to pick a nit here. What was the objective test that you did to determine which was the brighter image? If you used just one person's eye or even just two person's, I'm not sure I could agree that you have an objective test. Now if you measured it with a calibrated instrument (or perhaps even an uncalibrated one) or surveyed 15 or more people's impressions of brightness, then I might buy that the test was objective.
Did you like the view throught the Nikon because it was brightest, or perhaps it seemed brighter because you liked the image better? Of course, maybe the image was, in fact, brighter - whatever that means. Does "brighter" refer to average brightness or how well dark areas are revealed. Imagine a scope of high contrast and one of somewhat lower contrast. Two different people might come to differnent conclusions about which was brighter depending on what type of image they were looking at and what portions of the image were important to them. Can color casts affect impressions of brightness? I'd bet that they do.
When someone aims the scopes at a white wall of known and controlled brightness and measures the light coming out of the eyepiece of a scope - then, perhaps we'll know which scope's light transmission is greater. But I'm still not sure if we'd know which is "brighter". And considering the state of optics and coatings, I'm betting that the transmission differences will be pretty small given the same scope aperture and magnification.
And while we are on about objectivity, I've tried to do objective resolution testing of scopes while digiscoping. And frankly, its darned hard to be truly objective because of the great number of variables to keep under control. Its easy to come up with a wrong conclusion because you failed to control some variable like camera f-number or proper camera to eyepiece placement. And maybe the optics of one camera just happen to match up better with a certain scope while another camera's optics match up better with another scope. And when you are done, its hard to even say when a scope makes a "better" image than another - even if we narrow our conclusion to the use of a particular camera.
For instance, I set aside an hour this afternoon and shot resolution targets through a Swarovski ATS80HD with 20-60x zoom and through a Lomo 70 (a small relatively inexpensive catadioptric) with a 35mm Siebert eyepiece. Equivalent focal lengths were about 1500mm. Both resolved esentially the same level of detail but the Swaro was sharper as it had more acutance. But the edge sharpness of the Lomo was far better than the Swarovski. The Swaro was a half stop faster than the Lomo which is what we'd expect given the larger aperture and the Lomo's central objstruction. But maybe a shift in outside brightness is what really accounts for the difference?
You can conclude objectively which is better in a limited circumstance about specific attributes. But I don't think a person can objectively say which takes a better image while digiscoping at a 1500mm equivalent focal length with a CP5000.
But my subjective impression of the scopes would have me bet that 10 out of 10 people will prefer the Swarovski's image while direct viewing. It just has more "pop" and a more neutral color. So don't assume that the scope that gives you the direct view that you prefer is necessarily the best scope for digiscoping - or visa-versa.
And while I think scope reviewers should do objective testing of the scopes in their reviews, such tests shouldn't replace subjective evaluations either. They should be offered in addition. Both matter and its a shame that the objective tests are almost always absent.