On 6/29/2021 7:48 AM, JOHN DUGGAN via olympus wrote:
Late to this thread but here goes.....
I have GAS at the moment and have just ordered a NISI Apo 77mm doublet. Build quality and reviews are good. Mate in
China has one and is very impressed.
Nisi seems to have a very reputation and close up lenses in general seem to be
as rare as hen's teeth.
Interesting. Questions and comments:
As one reviewer said, "NiSi’s version doesn't have a dioptre value." Its not that hard to measure, but no one seems to
have done it. The pix and text say maximum working distance from front of lens of 30 cm, which suggests a diopter of
3.3. As Mike has pointed out, max. working distance is determined solely by C-U lens FL, independent of primary lens FL.
As their promo text says, 3.3 diopter on a 200mm lens is getting into macro territory, with close focus @ ~ 1:1. Too
strong for longer lenses and things like flutterbys, bees, etc.
They call it an apochromat, which is wrong, it's an achromat.
Only concern is that the lens seems to be a bit of a beast weight wise!
The stronger the diopter, the steeper/deeper the surface curves, the thicker the glass. The Oly "iS/L Lens B-Macro H.Q.
Converter f=40cm" is 55mm thread. Project its 105 g weight to 77 mm and you are over 200 g. Go from its 2.5 diopter to
3.3, and the weight goes up further.
The C-U achromats I use on my long lenses are much weaker diopters, and not
heavy.
Regards, John Duggan, Wales UK
On 6/29/2021 9:13 AM, Wayne Shumaker wrote:
Is that the one with +5 Diopter? Will be curious to hear your experience.
Can't be. Max focal distance of a +5 is 20 cm.
Max Mag Moose
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