Anyone here used LOMO Q-Plan Objectives?

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spongepuppy
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Anyone here used LOMO Q-Plan Objectives?

Post by spongepuppy »

I've seen some good-looking images kicking around Flickr that have been taken through LOMO Q-Plan objectives, which are quite inexpensive from opticsplanet.com: http://www.opticsplanet.com/lomo-ob-qpa4.html

Interestingly, they seem to have fairly large (to my untrained eye) numerical apertures - for instance, the 10X has NA 0.3, whereas my older Lomo 9x is 0.2. Working distance info is here: http://www.lomoplc.com/quasiplanobjectives.htm.

Has anyone here used them? I was pleasantly surprised by the old 9x planachromat I recently acquired, and was curious as to whether LOMO's newer objectives are any good.
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Matt Inman

rjlittlefield
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Post by rjlittlefield »

I have not used these personally, so my comments are based only on what I could find posted by other people.

In a quick search of Flickr for LOMO Q-Plan, I found three images, all by username nebarnix. Two of them are stills, one is a video. One of the still images, Palo verde beetle eye, looks great for evaluation. It is posted up to 2999 x 1992 pixels, it's basically a monochrome gray subject, and the subject has detail that should be sharp from corner to corner. I can't get much about lens quality from the other two images. One of them is a video, Alona water flea with eggs. It looks very good at center but has no sharp detail on edges or corners that might be used to evaluate the objective. The other is a still, the flameskinner eye. That one is posted up to 2015x1343, but the color and transparency of the subject makes it impossible for me to get a good comparison of sharpness across the frame.

Looking critically at the big Palo verde beetle eye, I see an image with excellent center sharpness, little or no lateral CA, and probably a modest amount of longitudinal CA suggested by bluish casts, especially away from center. The corner sharpness is disappointing. None of the corners look good, despite that at least three of them appear to contain subject details similar to what is rendered very clearly at image center. This is documented as having been shot with a Pentax K-7 camera, which has sensor size 23.4 x 15.6 mm.. I used my standard test of shrink/expand/flash-to-compare to see how much of the image area was "sharp at the level of individual pixels" in the sense of obviously losing information when shrunk to 50%. From that test, I get that the center high quality area is around 15 mm diameter. However, I also note that the posted image is only 6 megapixels, already downsampled a lot from the camera's native 14.6 megapixels.

In contrast, the Nikon CFI 10X NA 0.25 that I tested HERE is sharp at the level of individual pixels, across an entire 15.1 megapixel image (sensor size 22.3 x 14.9 mm). I've seen similar performance in the Nikon CFI BE 10X NA 0.25 and in the Nikon Finite Conjugate 10X NA 0.25 sold by Edmund, both of which are the same price or cheaper than the LOMO, even at Optics Planet's "closeout" prices for the LOMOs.

Bottom line is that I'd be willing (not eager) to test one of these new LOMOs if one were to land on my desk, but I'm not inspired to spend money buying one because I don't see any reason to think it would be a "keeper".

I'm sorry for the disheartening evaluation based on somebody else's images. If anyone has other information or a countervailing opinion, I would be delighted to hear about it.

--Rik

spongepuppy
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Joined: Mon Nov 26, 2012 11:03 pm
Location: Sydney, Australia

Post by spongepuppy »

Thanks Rik - in the absence of actual usage, the opinion of someone with a trained eye is nonetheless greatly appreciated. :D
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Matt Inman

Pau
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Post by Pau »

Quote:
"QPA™ The image is always sharp across a much larger center area compared to the image from any other objectives of the same class. A slight curvature is present only at the field periphery."

"QPA™ QUASIPLAN ACHROMATIC OPTICS" (from the laboroscope page)

So IMO they would be qualified as semiplan, not as true plano objectives, (altough for stacking, flatness of field is less important than lack of aberrations).

And at the Laborscope page, the eyepieces listed are compensating, so the objectives are not fully corrected for CA and maybe other issues.
Pau

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