Search for the cheap new aps-c to adapt

Started May 25, 2020 | Discussions thread
OP MOD Tom Caldwell Forum Pro • Posts: 42,753
The Kelda 85/1.8 EF mount updated

There is no doubt in my mind that the lens sold under various brand names as Neewer, Jintu, Kelda and Opteka is a lens made by Changchun Kaila Optronics who use the brand name “Kelda”. In fact my lens bought as a “Neewer” has no maker branding whatsoever and looks identical to a Kelda.  Images of the “Kelda” lens appear to be  unbranded as well. I am not sure if the lens sold as “Opteka” is branded.

I have already discussed what the correct lens formula might be - stated as 6 elements in six groups (6/6) as a Neewer the Opteka Version claims 10/7 but illustrates 6/6 in its promotional material diagram.

Looking at the reviews of the Kelda the Ephotozine one seems the most balanced.  Noting its cheap price not much is complained about other than a gritty focus action and odd aperture lettering. This review claims that the optical formula is 9/7 and states the weight to be 385 gm - I weighed mine and with caps and hood it came to 380 gm which seems within reasonable tolerances.  The review seemed to indicate acceptable quality and good value.  Indirectly from another review (Meike 85/1.8) by the same source of weight 372 gm this weight was considered quite reasonable for such a lens.

There is another review by “NPS” (National Photographic Society)  which I have discounted simply because it is so similar to make it seem to have plagiarised the Ephotozine review.

The Review by “Trusted Reviews” seems more intent on finding a way to not like the lens because it is cheap. One might wonder if each reviewer were checking the same lens.  It was found to have unacceptable Chromic Aberration and lacked Sharpness and was front heavy (unacceptably heavy), the aperture action was stiff but although sold as an aps-c capable lens the angle of view claimed was good enough for FF sensor use.  Noted that the optical formula in this review was stated to be 6/6.

The lens was first marketed in 2015 and the two reviews seem to be so far apart that I might wonder if the reviewers were talking about the same lens.

My image samples and my experience indicates that the lens is not a bad performer the weight is reasonable for what it is the focus action is very smooth and well damped (not at all “gritty”) and the aperture also works smoothly with soft tactile definite feel click stops that are silent-action.  Mine was sold as “aps-c 6/6” but handles FF with no sign of vignette.

The mystery of the exact optical formula remains - is it 6/6 or 10/7 (or even 9/7?)  I am not willing to open up my perfectly good lens that I am more than happy with just to resolve this issue.  These formulas are quite different.  The only one published by a diagram seems to be the illustrated 6/6 which Opteka claimed to be 10/7.

I cannot explain the poor review and reasonably good review of the “same“ lens.  My present (wild) guess is that maybe the lens was first released as 6/6 but was revised - therefore the 6/6 formula was not working well and there were other teething issues.

This was replaced (seems incredible) by a new optical set 10/7 or 9/7 which not only improved the performance but could be done without any apparent change in the exterior design (might this be possible?).  Also why market it as an aps-c lens when it seem a quite capable FF lens?

It seems that there has been quite a lot lost in the translation between engineering and marketing and just why remains a mystery.

From my point of view the one I have is a quite capable, well built and very low priced, good buy.  I don’t care that much just what the optical formula is but if 6/6 is not sophisticated enough for good images then surely it has a 10/7 (or 9/7) optical formula inside.  Which leads to the curiosity - was there some worry that the optics were rather close to someone else’s design that it has been promoted as 6/6 (and aps-c) to throw in a red herring or two? Nobody is going to know for sure without a lens tear-down and the reviewers must just accept the specification as they are told.

Cheap, acceptable build, images well, and a bit of a mystery.

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Tom Caldwell

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