Nikon Z 35/1.8 S - hard to find a well centered copy?

Started 4 months ago | Discussions thread
kenw Veteran Member • Posts: 6,324
Re: Nikon Z 35/1.8 S - hard to find a well centered copy?

michaeladawson wrote:

I think there's actually two separate topics here. One is about seeing conditions and the other is about being picky about the potential IQ of the lens.

An astrophotographer is going to be much more picky about flat-fieldness, decentering, tilt, etc. If they don't have a good lens, seeing conditions aren't going to matter. And I don't think anyone was actually suggesting using a star field to test the lens.

Yes, that was my point.  An astrophotographer is going to notice IQ issues in their day to day (well, night to night) photography without even doing any testing that a portrait photographer isn't.

Using a star field as an actual lens screening tool is probably not a good idea except for an experience astrophotographer who knows what to expect and how to evaluate conditions and the appropriateness of doing so for any given setup.

Seeing conditions is a separate topic. I haven't done any wide field astro photography so I can't comment there. But I used to be an avid telescope user for looking at nebula, planets, etc. And I can tell you that there can easily be bad viewing conditions pointing straight up. Bad enough that it looks as if you're viewing Jupiter behind a shimmering Coke bottle. Now, granted, that is highly magnified viewing that is going to significantly amplify the effects of any atmospheric turbulence.

Oh my goodness yes it can be really bad at high magnification.  Having done amateur astronomy from a desert I can attest to that!  But for reference Jupiter is about 30 arc seconds in size at the moment, or just around 3 pixels for a 100mm lens on a Z7.  So even if Jupiter were to jump half the width of its disk in your telescope (which would be unimaginably bad seeing) it would be a tiny amount of blur for a 100mm on a Z7.

But, anyway - we are drifting well off topic!  The important take away is actually "testing" a lens on a distant terrestrial target is not a particularly critical test and especially for longer focal lengths can even lead someone to think there might be something wrong with their lens when there isn't.  For shorter focal lengths as Jim pointed out it does have the benefit of being difficult to screw up and readily available to most people - with all the caveats Jim outlined.  I use it and variations on it as part of my lens screen testing as it is one of the fastest and easiest tests to do quickly.

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Ken W
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Panasonic Lumix DMC-GM1 Olympus E-M5 II Nikon Z7 Nikon Z 14-30mm F4 Nikon Z 24-200mm F4-6.3 VR +37 more
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