Wild fluotar 10x ph 0.4

Mr.Stone · Post by **Mr.Stone** » Mon Sep 17, 2012 7:10 am

Good afternoon all.

I got hold of a wild m20, it has a Wild fluotar 10x ph 0.4 on it...

Can i take pictures with this through bellows? It has no tube length on the objective.
And will the 0.4 na require a cover slip? ive seen in faq that no slip is required up to na .30...
I dont want to go and do a full stack and waste time doing it wrong.
And i dont have a butterfly wing around. Im sure some one on the forum has tried a .40 na objective before..

Thank you

rjlittlefield · Post by **rjlittlefield** » Mon Sep 17, 2012 11:06 am

I believe the Wild M20 is finite, with a 160 mm tube length. Yes, those objectives will work well on bellows.

There is a tiny loss of quality from no cover slip at NA 0.40, but you'll never see it at 10X.

The image HERE was shot with 10X NA 0.40.

Biggest problem with NA 0.40 is that it will have very shallow DOF compared to more typical NA 0.25 objectives. DOF is roughly proportional to inverse square of NA, so you're looking at roughly 2.5X more frames in the stack at NA 0.40 than at 0.25. Focus step will need to be around 4 microns (preferably less) to get a clean stack.

If you're using Zerene, run the stack first with all the check marks removed at Options > Preferences > Alignment. This will avoid the risk of getting bogus alignment errors due to wide aperture effects. Depending on how stable your stacking rig is, you may then need to add back the check marks for Shift X and Shift Y, but I strongly recommend to leave Scale turned off. At NA 0.40, trying to computationally track Scale is very likely to produce bad results.

--Rik

ChrisR · Post by **ChrisR** » Mon Sep 17, 2012 2:21 pm

Would that objective range not be designed for eyepiece CA correction?

rjlittlefield · Post by **rjlittlefield** » Mon Sep 17, 2012 3:10 pm

Good question. I don't know if Wild objectives require eyepiece correction. Perhaps somebody else knows, or in any case that question can be quickly answered by experiment: one shot of a flat subject and see if it has radial color fringes.

--Rik

Mr.Stone · Post by **Mr.Stone** » Mon Sep 17, 2012 11:53 pm

Thank you for the reply Rik

Wow

Sure is alot more pictures then at .25 na!! Wonder if its worth it. The picture in the link you gave is clear, but i dont see a real advantage over some of the nikon .30 na results that ive seen around here.
I think the objective is semi corrected, but dont take my word for it.

Flat subject such as sand paper?

Ill give it a shot, maybe tonight.

rjlittlefield · Post by **rjlittlefield** » Tue Sep 18, 2012 11:45 am

Mr.Stone wrote:Wow Sure is alot more pictures then at .25 na!! Wonder if its worth it. The picture in the link you gave is clear, but i dont see a real advantage over some of the nikon .30 na results that ive seen around here.

I agree. If I had a 10X NA 0.40, I don't think I'd be using it very much for stacks.

Flat subject such as sand paper?

Yes, but with sandpaper you need to be cautious about interpreting the results. It's a very demanding subject that makes highly visible some kinds of CA that don't matter much in practice. See for example http://www.photomacrography.net/forum/v ... 8056#58056. The image on right side has lots of color fringes but they're at random orientations with respect to the frame. That sort of CA tends to get removed in the stacking process because it's mostly associated with out-of-focus highlights. It's the classic radial fringing for in-focus detail that indicates lateral (transverse) CA with a need for corrective eyepieces.

--Rik

Mr.Stone · Post by **Mr.Stone** » Wed Sep 19, 2012 2:01 pm

I did a stack with the wild 10x na .40 and then compared it too the 10x na .25 that i have.
I used 240 grit sandpaper, redish color, i know, likley not the best to use but this is what i had at hand. It was lit by a single led light, no diffusion (a tad on the bright side). Both objectives on bellows at 150mm extension.
Stacks were done in Zerene, pmax.
The results are quite wild!!!

Ok first a single slice of the wild 10 na .40 :

And now a single slice of the 10x na .25

And now the stacks:

1st is the wild 10x na .40.(i think i did not move in small enough increments with this but its done)

Center crop of the above @ 100%

Lower right corner @ 100%

Now the 10 na .25...

Center crop of the above @ 100%:

And lower right @ 100%:

Although the wild na .40 is "superior" to the na .25 in theory,the na .25 is far better and much more practical for the kind of thing that we do around here. Well that is my opinion

I also compared the wild 4x .10 to another 4x .10 and then took the na .25 and turned it down to about 4-5 x and compared it to the two 4x objectives

For now ill keep the wild on the microscope where it belongs.

Pau · Post by **Pau** » Wed Sep 19, 2012 2:40 pm

Like ChrisR asked (and others like myself suspected) the Wild objective do need considerable corrections at the eyepiece, like most ones form its time.
If you look trough the microscope eyepieces you likely will see an orange halo just at the field limit, indicating that it's a corrective eyepiece.

Yes, the microscope is the adequate place to stay.

rjlittlefield · Post by **rjlittlefield** » Wed Sep 19, 2012 2:47 pm

Thanks for the test results -- most appreciated. Sorry I overlooked the CA problem in my first response!

--Rik