Olympus/OM new 90mm macro lens

[dancingcat]

OM is releasing a new 90mm macro lens for Olympus bodies next year.  I use the excellent Oly 30mm macro for UV flower shots, and could use a little more working distance.  Unfortunatley my old Oly 90mm macro (used for years in visible range) does not pass UV.  Does anyone have any insider OM skinny on the transmission for the new 90mm lens?  I've tried asking OM and get only "we will let you know after release" kind of response.  If the older 90mm does not pass UV, can we assume that the new one has a similar construction and will also not pass UV?

[dabateman]

I would assume,  like the 60mm Macro,  that the new 90mm will not pass much UV.

I was happy that the 30mm Macro works. That might be our only UV option. 

[enricosavazzi]

16 hours ago, dancingcat said:

[...]

If the older 90mm does not pass UV, can we assume that the new one has a similar construction and will also not pass UV?

[...]

We should assume that the new 90 mm will have a completely new optical scheme (different image circle, registration distance, magnification range, etc.). We are only guessing at this point, but likely the new lens will have a significantly larger number of elements than the 9 elements in 9 groups of the old 90 mm f/2, and use types of glass that were not available in the 1980s. Neither thing bodes well for UV transmission. The current 60 mm macro uses 13 elements for example, and the 30 mm only 7 elements (in part thanks to an aspheric element that does the job of multiple spheric elements). In its time, the old 90 mm had an unusually complex optical scheme in order to achieve an f/2 speed. At that time, many macro lenses still had only 5 or 6 elements and often just a rear floating group, or none at all.

 

We still have no information on the physical dimensions and whether it will have a tripod collar. The latter would make a great difference to the ergonomics of the lens.

 

Added: Some time ago Olympus patented a design for a 100 mm f/2.8 1x macro lens, see https://asobinet-com.translate.goog/info-patent-olympus-100mm-macro/?_x_tr_sl=ja&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc

This is obviously not the same lens as the 90 mm f/3.5 2x that will (hopefully) enter production next year. However, the optical scheme (15 elements in 12 groups, 3 moving internal subassemblies for focusing, one subassembly for IS) may be related to the latter.

[Stefano]

Related to lens transmission, is there a way to test a large number of lenses (to get them just for testing)? Like asking a shop or other people to allow for testing of all their lenses? UV shouldn't damage them, they are exposed to it under sunlight all the time (often even with a UV filter, as we know).

 

One could look at how much "color" they have, like here, to find the best ones which could then be measured with an actual spectrometer by the few members who have one.

 

There could be modern lenses that go to 350 nm or even lower, like the Canon 40 mm pancake.

[Jan Steinman]

Have you tried any of the old Olympus range-specific macro lenses? They'll require a bellows or the outstanding and versatile Telescoping Extension Tube.

 

It seems the likelihood of passing UV is inversely related to the number of elements. The old OM Zuiko 50mm ƒ/3.5 macro only had five elements, as does the 135mm ƒ/4.5 macro. The newer 20mm and 38mm macro heads had six elements, although previous versions of these lenses also had only five. The 80mm also has six elements.

 

Contrast to the OM Zuiko 90mm ƒ/2 and 50mm ƒ/2 macros, which each have nine elements.

 

I'd be happy to do some tests on the OM Zuiko 20, 38, 50/2, 80, 90, and 135 macros, if you can tell me the best way to do this! I don't have access to a spectrometer, but I have a UV-LED flashlight, fluorescent paper, and a conventional light meter…

[nfoto]

I've done UV with the 38mm f/2.8 Olympus. It will not go deep into the UV, but results otherwise are very good.

[dancingcat]

My Olympus/OM/M.Zuiko 90mm macro lens came today.. I can't test yet for UV as I need a stepdown ring for my Baader U, but here's my first test in visible. 

 

Subject is a mini-tomato flower... I'm growing them from seed indoors as it isn't safe yet weatherwise to put them outside, so it was handy.  The flower is tiny, about 1.5mm across.  Camera was about 6mm from the flower to the front of the lens... closest focus. 

 

Camera Olympus EM-1mk2, shot at f/11, iso 640, 1.5 sec.  In-camera stack of 15 images.  The only post I did was some dehazing and a little sharpening in Topaz as I thought the image coming out of the stack process was a bit soft (seems to be common with the in-camera stack).  The stacking also threw some minor artifacts which I didn't remove.  For Oly shooters, the stack differential was 8.  Oly limits the in-camera stack to 15 images, so it isn't sharp everywhere but I thought the background was nice. 

 

The lens is a bit front-heavy for a micro-four-thirds rig.  It probably moved a little during the exposure even on my relatively bomb-proof RRS ball head.  Would have been nice to have a lens collar to get the support centered up a bit.

 

One nice thing about this lens which might make up for it's supposed inability to pass UV is that it probably can double as a bird lens.  The 90mm MFT is 180mm full frame equivalent, and with a 1.4x teleconverter it has pretty respectable reach.  Am going to go hunting red-tailed hawks tomorrow.. :-).

 

More when I can test for UV.

[colinbm]

This lens is looking pretty good.