Swift Achromat vs Nikon Fluor

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LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#31 Post by LouiseScot » Tue Mar 30, 2021 9:41 am

Scarodactyl wrote:
Tue Mar 30, 2021 4:40 am
To me the improvement in color correction looks pretty dramatic, and definitely makes for much nicer photos. I suppose that suggests the swift system is neither non-correcting or at least weakly correcting, at least on CA.
Yes, the Nikon's better colour correction is clear! I was chasing the hoped-for improved resolution but didn't appreciate the finer points of how to achieve higher resolution with the larger NA. I feel more educated now. The Swift objectives are plain achromats but I think they are great value for money. The Nikon fluor cost what I paid for the complete 380T.

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#32 Post by LouiseScot » Tue Mar 30, 2021 9:53 am

Hobbyst46 wrote:
Tue Mar 30, 2021 5:34 am
I find it fairly difficult to achieve affordable perfect diatom slides that conform with the specifications of the optics.

Affordable slides and coverslips are less expensive than research-grade ones by an order of magnitude. I buy the cheap stuff from China.

Very thin coverslips are more fragile, both during the preparation and afterwards. I use #1.5 coverslips.

When mounting diatoms in resin, it is difficult to achieve a very thin layer of the resin. Too little resin, and air bubbles form. Too much resin, and the coverslip shatters or is blown off by the bubbling resin (during the mounting heating).

The diatoms are initially attached to the coverslip rather than the slide, before the resin is added and heated. Hence, ideally, if during the mounting heating they stayed attached, the thickness of the sample (not counting the slide) is practically the thickness of the coverslip, plus the thickness of the diatom itself.

It just happens that most of my high NA objectives are marked 160/- so coverslip thickness is not an issue - maybe. Still, all that said - it might be tempting to try and mount on the thinnest possible coverslips. Lets see...
I don't have any complaints! :) The Nikon fluor has a correction collar so it can cope with small variations around the nominal 0.17. It seems the sample thickness can be potentially be an issue. As I mentioned I measured your slides and the sample thickness was not significant so no problem with your slides. I also previously had good results with the 100x oil immersion. I just wanted to compare the newly-acquired Nikon fluor with the Swift achromat. I've learned a lot through doing that, thanks to help I've had on here :)

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

Placozoa
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Re: Swift Achromat vs Nikon Fluor

#33 Post by Placozoa » Tue Mar 30, 2021 10:12 am

Taught me something too. I didnt know parfocal extenders could compensate for spherical aberration. Or, put another way, that changing the tube length could act in a similar way as a correction collar.

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#34 Post by LouiseScot » Tue Mar 30, 2021 10:25 am

Placozoa wrote:
Tue Mar 30, 2021 10:12 am
Taught me something too. I didnt know parfocal extenders could compensate for spherical aberration. Or, put another way, that changing the tube length could act in a similar way as a correction collar.
I'm not sure that's true. As I understand it, variation from 160mm finite tube length can cause problems for high NA dry objectives specified for 160mm tube length. It's not such a problem for lower NA objectives. As Viktor posted:
https://www.microbehunter.com/microscop ... 10#p101160

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#35 Post by LouiseScot » Tue Mar 30, 2021 10:32 am

LouiseScot wrote:
Tue Mar 30, 2021 10:25 am
Placozoa wrote:
Tue Mar 30, 2021 10:12 am
Taught me something too. I didnt know parfocal extenders could compensate for spherical aberration. Or, put another way, that changing the tube length could act in a similar way as a correction collar.
I'm not sure that's true. As I understand it, variation from 160mm finite tube length can cause problems for high NA dry objectives specified for 160mm tube length. It's not such a problem for lower NA objectives. As Viktor posted:
https://www.microbehunter.com/microscop ... 10#p101160

ps I suppose if an extender brings the objective you're using to it's specified tube length then that would be a good thing. But as I found out, being parfocal isn't sufficient - you have to be parfocal and have the correct finite tube length.
Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

viktor j nilsson
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Re: Swift Achromat vs Nikon Fluor

#36 Post by viktor j nilsson » Tue Mar 30, 2021 10:50 am

It is true, actually. Old draw-tube microscopes worked on this principle - by increasing or decreasing the tube length, the user could -- to some extent -- compensate for differences in the coverglass medium thickness/RI and reduce spherical aberration. I believe that it introduced other aberrations at the same time, though. Binocular heads and objectives with correction collars has made this technique rather obsolete.

Placozoa
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Re: Swift Achromat vs Nikon Fluor

#37 Post by Placozoa » Tue Mar 30, 2021 10:53 am

Thanks viktor. Appreciate the confirmation. I have a 0.85 NA dry lens that I thought could be better, now it might be. :D
Last edited by Placozoa on Tue Mar 30, 2021 10:58 am, edited 1 time in total.

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#38 Post by LouiseScot » Tue Mar 30, 2021 10:57 am

viktor j nilsson wrote:
Tue Mar 30, 2021 10:50 am
It is true, actually. Old draw-tube microscopes worked on this principle - by increasing or decreasing the tube length, the user could -- to some extent -- compensate for differences in the coverglass medium thickness/RI and reduce spherical aberration. I believe that it introduced other aberrations at the same time, though. Binocular heads and objectives with correction collars has made this technique rather obsolete.
I only think in terms of what I have!

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

Placozoa
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Re: Swift Achromat vs Nikon Fluor

#39 Post by Placozoa » Tue Mar 30, 2021 11:08 am

LouiseScot wrote:
Tue Mar 30, 2021 10:57 am


I only think in terms of what I have!

Louise
If you have infinity lenses I think you could still unscrew the objective a bit, or use parfocal extenders, or move the tube lens if possible, to change your tube length. I think moving your eyepiece would do nothing. Correcting collar is way simpler, but I dont have one on my 0.85 NA dry lens.

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#40 Post by LouiseScot » Tue Mar 30, 2021 11:36 am

Placozoa wrote:
Tue Mar 30, 2021 11:08 am
LouiseScot wrote:
Tue Mar 30, 2021 10:57 am


I only think in terms of what I have!

Louise
If you have infinity lenses I think you could still unscrew the objective a bit, or use parfocal extenders, or move the tube lens if possible, to change your tube length. I think moving your eyepiece would do nothing. Correcting collar is way simpler, but I dont have one on my 0.85 NA dry lens.
Well, the topic of this discussion is my finite Swift380T fitted with a Nikon CF fluor 40/0.85. So I have to maintain the tube length very close to 160mm to get the best from the fluor - both visually and photographically. I also have to be aware of the slide/sample/coverslip properties - and the lighting, of course. As discussed above, I achieved parfocality with the trinocular tube eyepiece by focusing with the original Swift oculars and then adjusting the trinocular height to get focus on the camera sensor. I actually adjusted the photo EP height to get visual focus with it and relative to the Swift oculars. I then fixed the photo EP height (it's on a helical focuser) before attaching the camera afocally - a Canon 1100d plus lens. Previously I just adjusted things to achieve parfocality between the oculars and the camera sensor. That's fine for most objectives but not for high NA ones. It's quite some effort to get everything right but it's both fun/interesting and educational! As it happens, I do also have an infinity system which can use a Nikon CFI60 20x/0.75 Lambda plan apo (amongst others). It has a wd of 1.0 and specified for a 0.17 coverslip. Tube length is 'infinity' but sensor distance is determined by the tube lens focal length (200mm) focused on infinity. The other slide/coverslip/sample/illumination factors still come into play :)
Anyway, I hope I've got it all 'right' now and I think I understand things better also.

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#41 Post by LouiseScot » Tue Mar 30, 2021 5:49 pm

I calculated the theoretical resolution for the Nikon fluour 40x/0.85 to be about 359nm i.e. 0.359um @500nm. (I used the simple (0.61 x Lambda)/NA equation). I'm not sure I can achieve the theoretical value in practice but I'll do my best!

Here is one I took using the Swift LED and slightly oblique illumination to improve contrast a bit. I added some scale info:
Med_Nikon_40x_Obl_Crop100pc_scale1423.jpg
Med_Nikon_40x_Obl_Crop100pc_scale1423.jpg (54.81 KiB) Viewed 4211 times

I did another (different individual but same species and slide) with a 500nm filter but no oblique illumination:

Med_Nikon_40x_500nm_Crop110pc_scale0001.jpg
Med_Nikon_40x_500nm_Crop110pc_scale0001.jpg (49.38 KiB) Viewed 4211 times


The little 0.5um (approx.) line is a guide to the 0.359um theoretical. I'm not sure the 500nm light is a great improvement. I'll have to try some more with it. Still, it looks like I haven't done too badly overall. I shall continue to work towards improving things :)

I'll have a look at what's growing in my pond/river jars tomorrow. There's plenty of green algae, if nothing else!

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

Hobbyst46
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Re: Swift Achromat vs Nikon Fluor

#42 Post by Hobbyst46 » Tue Mar 30, 2021 6:38 pm

Louise Scot wrote:The little 0.5um (approx.) line is a guide to the 0.359um theoretical. I'm not sure the 500nm light is a great improvement. I'll have to try some more with it. Still, it looks like I haven't done too badly overall.
I think that the resolution is OK. Here is why. I copied the last photo to Irfanview and enlarged it until the 10um double arrow measured 80mm on my computer screen. Inspected the black lines that separate nearby squares on the diatom. They are resolved entities, and their thickness is no more than 3mm (approximately). That makes them 0.38um thick. Quite approximate, but adequate IMO. Best resolution is obtained with blue light (or UV :lol: ), but that is rather unpleasant on the eye.

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#43 Post by LouiseScot » Tue Mar 30, 2021 6:56 pm

Hobbyst46 wrote:
Tue Mar 30, 2021 6:38 pm
Louise Scot wrote:The little 0.5um (approx.) line is a guide to the 0.359um theoretical. I'm not sure the 500nm light is a great improvement. I'll have to try some more with it. Still, it looks like I haven't done too badly overall.
I think that the resolution is OK. Here is why. I copied the last photo to Irfanview and enlarged it until the 10um double arrow measured 80mm on my computer screen. Inspected the black lines that separate nearby squares on the diatom. They are resolved entities, and their thickness is no more than 3mm (approximately). That makes them 0.38um thick. Quite approximate, but adequate IMO. Best resolution is obtained with blue light (or UV :lol: ), but that is rather unpleasant on the eye.
I could repeat it with blue light though the camera sensitivity is highest in the green part of the spectrum. That shouldn't affect resolution. I have a UV light source and a full spectrum 1100d - it might be interesting to try but I expect any increase in resolution would be marginal. I'm not sure how the glass in the optical train above the objective would cope with UV but no harm in trying!
The double arrow 'scale bar' is ~38mm long on my screen at 100% size. So you must have enlarged it just over 200%?

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#44 Post by LouiseScot » Tue Mar 30, 2021 7:43 pm

Here is blue light version. It's actually 486nm which is obviously quite close to the green (501nm) so I wouldn't expect an obvious increase in resolution. I did have to adjust the focus for the blue, though.

Med_Nikon_40x_486nm_Crop100pc_0002.jpg
Med_Nikon_40x_486nm_Crop100pc_0002.jpg (40.96 KiB) Viewed 4199 times

I don't have a shorter wavelength blue filter - only UV, and a UV source. Have to be careful with the UV source even though it's longish UV - 365nm (UVA) and not especially bright (compared to sunlight!). It reminds me that I have some fluorescent dyes to mess about with too, though I mustn't get sidetracked!


Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#45 Post by LouiseScot » Wed Mar 31, 2021 12:00 am

I did a couple more using both a blue camera filter and the condenser blue filter. Nothing like as good as the narrowband filters I used previously. In fact, even though they look blue they let a substantial amount of red and green light through. It's possible to effectively remove the red digitally but if you try and do the same with the green then all the detail seems to disappear. Now I know I could separate the channels and only use the blue channel but it's a bit of effort and I wasn't really in the mood.. Anyway, even though these weren't pure blue, I did get a fair bit of detail. I did two images with slightly different focus positions. I really must get into doing the stacking soon! I also used a 3W LED (below the condenser but without a diffuser or lens)

So, 'Blue' filters:
Med_Nikon_40x3W_BlueBlue_BW_Crop100pc_a0006.jpg
Med_Nikon_40x3W_BlueBlue_BW_Crop100pc_a0006.jpg (32.6 KiB) Viewed 4194 times

Med_Nikon_40x3W_BlueBlue_Crop100pc-2_0007.jpg
Med_Nikon_40x3W_BlueBlue_Crop100pc-2_0007.jpg (33.46 KiB) Viewed 4194 times

I'll have to have a look at the emission spectra of some coloured high power LEDs to see if any can give a purer blue light (or even violet). That would be much better than using filters.

Louise

ps looking back to earlier images above, I really like the obliquely lit one. Ok, it's not DIC but it's quite good in itself :)
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#46 Post by LouiseScot » Wed Mar 31, 2021 9:34 am

I've ordered some 3W blue (~440-470nm) and violet (~410-430nm) LEDs - another comparison to do :D There may not be much practical difference between them but violet is the shortest visible wavelength. Using the (0.61xLambda)/NA formula, 418nm gives a theoretical resolution of only 300nm @ 0.85! The Lambda/2NA gives an even smaller value - 246nm. Of course a 100x/1.25 is capable of resolutions of 204nm or even less. I might need to use a mono astro camera with small pixels in order to approach any of the above sorts of resolutions. No colour, but no CA either, with a monochromatic light source :) .

Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

jeffery163
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Re: Swift Achromat vs Nikon Fluor

#47 Post by jeffery163 » Tue Apr 06, 2021 6:14 pm

LouiseScot wrote:
Thu Mar 25, 2021 3:54 pm
Hi

I received a Nikon CF Fluor 40x/0.85 from Japan yesterday so thought I'd post a comparison with the Swift 40x/0.65 achromat. As my scope is currently set up for darkfield I thought I'd leave it like that for now, though I may not necessarily be getting the best from the high NA fluor. I don't really have the experience to judge these things. Light source is a 10W warm white LED but still using the Swift 'beehive' illuminator.
Anyway, here is a direct comparison between the two objectives using my trusty Pleurosigma formosum vintage slide:


Pleuro_Swift40x_NikonFluor_40x.jpg




Both images cropped to 50%. I was pleased to see there was a difference! The Nikon cost me $295 which is about the same as the Swift380T cost me last year! Still, I think the Nikon has potential. Not sure if I'm getting increased resolution here but there's certainly less CA. I still think the Swift achromat is very good. I will try the new fluor out in brightfield/oblique soon.

There is a paper with data and SEM for the Pleurosigma here:https://www.researchgate.net/publicatio ... lariophyta if anyone is interested (you can download the .pdf).

Louise
Very nice comparison

LouiseScot
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Re: Swift Achromat vs Nikon Fluor

#48 Post by LouiseScot » Tue Apr 06, 2021 6:23 pm

jeffery163 wrote:
Tue Apr 06, 2021 6:14 pm
LouiseScot wrote:
Thu Mar 25, 2021 3:54 pm
Hi

I received a Nikon CF Fluor 40x/0.85 from Japan yesterday so thought I'd post a comparison with the Swift 40x/0.65 achromat. As my scope is currently set up for darkfield I thought I'd leave it like that for now, though I may not necessarily be getting the best from the high NA fluor. I don't really have the experience to judge these things. Light source is a 10W warm white LED but still using the Swift 'beehive' illuminator.
Anyway, here is a direct comparison between the two objectives using my trusty Pleurosigma formosum vintage slide:


Pleuro_Swift40x_NikonFluor_40x.jpg




Both images cropped to 50%. I was pleased to see there was a difference! The Nikon cost me $295 which is about the same as the Swift380T cost me last year! Still, I think the Nikon has potential. Not sure if I'm getting increased resolution here but there's certainly less CA. I still think the Swift achromat is very good. I will try the new fluor out in brightfield/oblique soon.

There is a paper with data and SEM for the Pleurosigma here:https://www.researchgate.net/publicatio ... lariophyta if anyone is interested (you can download the .pdf).

Louise
Very nice comparison
Thanks! I've since posted much better images taken with the Nikon Fluor e.g.

https://www.microbehunter.com/microscop ... =9&t=12487


Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo

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