20X Objective Quest

Have questions about the equipment used for macro- or micro- photography? Post those questions in this forum.

Moderators: rjlittlefield, ChrisR, Chris S., Pau

JW
Posts: 249
Joined: Wed Feb 23, 2011 7:38 am
Location: New Haven, CT, USA

20X Objective Quest

Post by JW »

So far I've had two orders for a Mity 20x objective cancelled and refunded in the past month, after receiving confirmation of order and payment :?

I've a lead on two additional objective lenses, on is another Mity 20x, but with significant superficial? damage (appears as if a gorilla took a pipe wrench to the lens barrel in order to turn it), the other is a like-new Nikon LU Plan ELWD 20x 0.40A. I've heard good things about the LU Plans, and its about 50% less than the Mity. Use will be a typical stacking scenario (no cover glass, Raynox tube lens, etc.). WD is of consideration.

Is there any reason to pick one over the other. I'm getting a little antsy over this as I now need to go to 20X for a job just starting - material received.

(in the duh department, I dropped my old inexpensive and just adequate no-name 20x onto the concrete floor, twice :x , so needless to say the CA is now horrible).
It's not what you look at that matters, it's what you see - Henry David Thoreau

Scarodactyl
Posts: 1617
Joined: Sat Apr 14, 2018 10:26 am

Re: 20X Objective Quest

Post by Scarodactyl »

Lu plans are reputedly good but have notable axial CA. The mitutoyo 20x doesn't. On the other hand nikon lenses seem more durable than mitutoyos--I recently got a tu plan fluor 50x cheap with scratches and dings on the barrel but it still works great.

Pau
Site Admin
Posts: 6053
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Re: 20X Objective Quest

Post by Pau »

Another good one is the Olympus LMPlanFl 20/0.40, small but visible longitudinal CA and high quality field smaller tnan the mitu but very good for APSC
Pau

JW
Posts: 249
Joined: Wed Feb 23, 2011 7:38 am
Location: New Haven, CT, USA

Re: 20X Objective Quest

Post by JW »

Thank you - appreciate the answers. Axial CA is bad for the minerals and crystals that I photograph, so I'll go with the Mitutoyo, if its bad the seller has a return policy
It's not what you look at that matters, it's what you see - Henry David Thoreau

Duke
Posts: 100
Joined: Tue May 12, 2020 10:06 am
Location: Leningrad, USSR
Contact:

Re: 20X Objective Quest

Post by Duke »

I have a selection of 20x objectives:
Finite:
Nikon BD Plan DIC 20x 0.40 210/0
Nikon E Plan 20x 0.40 160/0.17
Nikon CFN Plan DIC 20x 0.50 160/0.17

Infinite:
Nikon CF Plan 20x 0.46 ∞/0
Nikon CF Plan BD DIC 20x 0.46 ∞/0
Nikon CF Plan ELWD 20x 0.40 ∞/0
Nikon CF Plan SLWD 20x 0.35 ∞/0
Nikon CFI60 PlanApo DIC 20x 0.75 ∞/0.17
Nikon CFI60 PlanApo VC 20x 0.75 ∞/0.40
Olympus LMPlanFl N 20x 0.40 ∞/0
...Number of LOMO's 20x
(Actually, my collection of 20x's is on the "smaller side", compared to 4-5x, 10x, 40-50x) 8)

I'm planning to make proper testing on them, only thing is figuring out what is the proper way to do it.
More specifically, I need to find a way to measure LoCAs, before I only measured LaCA (CMD), field curvature, image circle, etc.
For this purpose I have selection of resolution targets - USAF 1951 (0,500 - 228 lp/mm), slide micrometers (0,005/1mm + 0,01/10mm + 0,1mm/50mm), various semiconductor chips.
Recently I've bought couple of precision tilting tables - one is Thorlabs GM100 gimbal mirror mount, other is platform-type 60x60mm for prisms or other flat objects (not sure what is the proper term for it), both can do precision tilting of the target of 0,01° in range of 2,50° total. This I was planning to use for precision leveling of the target, but maybe it can also be used to incline the target so LoCA may be measured, isn't this the way LoCA are measured in case of photographic objectives?
Suggestions?
(P/S I'm not buying Mitty's - you get one, then "This is getting out of hand, now there are two of them" (c), comes another, next thing you know you need all of them! Nope...Too much trouble of gettin' working one, and too expensive!)
“Thoroughly conscious ignorance is the prelude to every real advance in science.” - JCM

Scarodactyl
Posts: 1617
Joined: Sat Apr 14, 2018 10:26 am

Re: 20X Objective Quest

Post by Scarodactyl »

Mitutoyos aren't that bad if you really park eBay and watch for deals, and are also willing to return one if it's not good. The 20x is an awfully good objective.
I'd love to see results of that 20x test--sounds like an odyssey.

Macrero
Posts: 1166
Joined: Thu Sep 01, 2011 8:17 am
Location: Valladolid , Spain

Re: 20X Objective Quest

Post by Macrero »

The Mitty is a solid bet, just be ware of possible optical issues if buying used. 3 out of the 5 Mitty's 20X I've owned over the years had that spotting-like delamination on inner element/s.

The Oly's UIS/UIS2 LM and M 20 Fluor are very nice optics too. If you don't need the LWD, the "regular" (not L) one is a very good performer. Not as well corrected as the APO, logically, but I never found the CA's to be an issue. The Oly can be found on the second-hand market significantly cheaper than the Mitty.

Best,

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

JW
Posts: 249
Joined: Wed Feb 23, 2011 7:38 am
Location: New Haven, CT, USA

Re: 20X Objective Quest

Post by JW »

Again, thanks everyone for the comments. I did indeed end up getting the Mitutoyo 20x with the horrible barrel damage. Wasn't as bad as the posted images, and there does not seem to be anything wrong with the objective. Test images show nearly no CA of any type. However, there is a noticeable color balance shift in the warm direction, easily fixed by using a custom white balance.
It's not what you look at that matters, it's what you see - Henry David Thoreau

Scarodactyl
Posts: 1617
Joined: Sat Apr 14, 2018 10:26 am

Re: 20X Objective Quest

Post by Scarodactyl »

I have had one mitutoyo clone which had an image that was noticeably warm. It seems to be the result of delamination in that case.

JW
Posts: 249
Joined: Wed Feb 23, 2011 7:38 am
Location: New Haven, CT, USA

Re: 20X Objective Quest

Post by JW »

Yikes! I'll take a close look at the lens under the microscope, maybe I'll see something...

thanks for the tip, Scarodactyl
It's not what you look at that matters, it's what you see - Henry David Thoreau

Post Reply Previous topicNext topic