GUF testing

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McConkey · #1 Post by **McConkey** » Mon Nov 20, 2017 11:29 pm

After seeing the post Suphot made here I decided to give making a GUF a try. I spent the last few days re-reading over all posts in reference to this filter and printed several different designs, shapes, sizes and colour combinations to try at various stages of the light path.

I'm still experimenting to figure out the best location of the filter for my setup but so far I am really enjoying the results. I'm still on the fence if the oblique technique i use on my microscope yields better details but i wanted to quickly post the first images i snapped today. I didn't think to do a comparison of this object with the GUF and oblique...that would have made too much sense!!

Unfortunately my current sample dish doesn't have too much going on right now as all my water sources are frozen but i am hoping to get better samples later this week.

AO20, 10x/.30 PlanApo, 11 image stack

mrsonchus · #2 Post by **mrsonchus** » Mon Nov 20, 2017 11:33 pm

A pretty good start I'd say - there's definitely some 3D and textural detail there - well done.

zzffnn · #3 Post by **zzffnn** » Mon Nov 20, 2017 11:54 pm

Karl,

That image is beautiful. You could probably fool people onto believing that it is DIC.

Did you use blue gradient? The gentle gradient as shown in your image works really well at this magnification.

What I found in my experiments was that GUF works better (more contrast/less glare/more pleasing color)at lower than NA 0.65, for transparent protists. Above NA 0.65, offset oblique or COL works better, resolution wise. But it may depend on implementation (for example, my condensers may not offer the same access points for filters as yours).

rnabholz · #4 Post by **rnabholz** » Tue Nov 21, 2017 1:02 am

I thought I was looking at DIC - really excellent results.

Keep going and be sure to educate us all on your process and tools.

Well done!

Rod

McConkey · #5 Post by **McConkey** » Tue Nov 21, 2017 4:30 am

Thanks John! I hope you are well! For $10 and about an hour of arts and crafts it'd be really neat to see what others can come up with!!

Fan - Thank you! I think i still have a ways to go before fooling the DIC experts but i'm getting closer! For this image yes, i used a blue gradient! I'm still not too sure which variation of the filter is giving me the best results but thank you for feedback! I remember reading about the NA "restrictions" with this type of filter so i will keep your experiences in mind. I'm wondering if theres a way to modify the filter for higher NA use. I'm having alot of fun experimenting though!

Rod - I appreciate the very kind comment! Thank you! Right now i have 3 different levels of gradient...in 2 different colours...in 3 different sizes...18 variations to play with! At some point this week once i get some better samples I'll post some comparisons of the same subject and see if theres a standout winner. I'm really looking forward to pushing this filter to its maximum potential and sharing the journey with everyone!

apochronaut · #6 Post by **apochronaut** » Tue Nov 21, 2017 1:35 pm

definitely great work, Karl. i am curious what portion of the frame you are capturing there? it's the # 1054, eyepiece?

Francisco · #7 Post by **Francisco** » Tue Nov 21, 2017 3:44 pm

Very beautiful and interesting. It certainly seems made with DIC

KurtM · #8 Post by **KurtM** » Tue Nov 21, 2017 4:08 pm

McConkey wrote:I remember reading about the NA "restrictions" with this type of filter so i will keep your experiences in mind.

Beware such warnings...

"They didn't know it was impossible, so they did it." - Mark Twain

Can't wait to see more of your GUF images!

McConkey · #9 Post by **McConkey** » Wed Nov 22, 2017 12:43 am

Francisco - Thank you for the kind comment! It's pretty crazy how close this little filter replicates DIC!

Phil - The image was taken through the trinoc but no cat.#1054 eyepiece is being used. I never ended up getting one as i had to leave shortly after our discussion about it but now I'm back I'll start looking!! I'm still using the AO phototube with the already installed telon lens, the FoV is less than what you get via the eyepiece but it is parfocal, I've yet to figure out a way, with the accessories i have, to get full FoV via the trinoc AND have my camera parfocal. I'll keep my eyes open for the #1054!! Thanks for reminding me!

Kurt - ahah ok ok! I'll stop doubting myself! Thank you, I'm hoping to get some samples tomorrow or Thursday so the experiments can continue!!

vasselle · #10 Post by **vasselle** » Wed Nov 22, 2017 4:09 am

Bonjour
Très bon résultat car image est réussi avec un bon effet.
Cordialement seb

McConkey · #11 Post by **McConkey** » Wed Nov 22, 2017 5:51 am

Thanks Seb! I am really enjoying the effect of these filters!

Here is an image i managed to grab tonight with the GUF. The vorticella stayed still long enough for me to grab 7 frames. Unfortunately he was moving a little too much for me to do a full comparison of different GUF variations.

Taken with the black gradient, not quite as strong an effect as my original image but that's half the fun of experimenting!!

McConkey · #12 Post by **McConkey** » Fri Nov 24, 2017 12:40 am

Another test from today. I manged to collect some fresh water samples from a small creek not 100% frozen yet. While i'm waiting for it to settle i wanted to take a quick look and continue with the GUF testing. The mount has started to dry so it wasn't the best situation to start taking pictures but still fun regardless!

10 Image stack taken with the 10x /.30 Apo using the blue GUF. I'm thinking the blue combined with the 10x /.30 Apo is giving the best results.

KurtM · #13 Post by **KurtM** » Fri Nov 24, 2017 1:08 am

The Vorticella shot is nice enough, the oblique lighting and subdued BG really make it interesting. But that last image is wonderful! Bet you could fool more than a few into believing it's DIC. Super cool image!!

apochronaut · #14 Post by **apochronaut** » Fri Nov 24, 2017 2:17 am

Microscope optics began their life using the blue of the sky as a light source and have evolved over time to utilize the neutralizing quality of blue light to soften and contrast the hard edged yellow to red wavelengths. For natural subjects it would be hard to see that some wavelength(s) in the blue section of the spectrum would not usually be best.

McConkey · #15 Post by **McConkey** » Sun Dec 03, 2017 11:19 pm

For now i'm going to keep posting my GUF testing images here rather than flood the forum with additional topics!

Thank Kurt for the very kind words! This technique works the best at 10x and marginally alright at 20x. I think oblique is still better for 40x though as i havn't been able to recreate the effect as well past 20x.

Phil - Very....enlightening! See what i did there!!

I'll keep the properties of blue in mind as i keep trying out different things with these filters! I will say that the blue is absolutely giving better results!

This image was taken using 20x /.50 AdvPlanAchro. Blue GUF filter placed under the condenser and position for best effect. Quick stack of 8 images, some stacking defects are noticeable but the little sucker was moving quite alot so i'm happy with what i managed to grab!

billbillt · #16 Post by **billbillt** » Sun Dec 03, 2017 11:45 pm

I think this turned out real well..

BillT

nickols · #17 Post by **nickols** » Thu Jan 11, 2018 8:12 am

Wonderful work!

Culicoides · #18 Post by **Culicoides** » Thu Jan 11, 2018 10:26 am

Sorry to appear “thick”, but what is a guf filter? Can anyone post a link to what/how
Many thanks, John

KurtM · #19 Post by **KurtM** » Thu Jan 11, 2018 4:34 pm

Thank you for pointing out that a bit of baseline info was omitted. The homemade filter in question is called a Gradient Universal Filter. I believe Wim van Egmond got the ball rolling on it, so Rod N. honored him by calling it the van Egmond filter. Here you go, these should get you going:

https://tinyurl.com/ybhsrxos

viewtopic.php?t=2686

Culicoides · #20 Post by **Culicoides** » Thu Jan 11, 2018 7:50 pm

Many thanks, Kurt. Guess what I will be doing this weekend. Best wishes, John

KurtM · #21 Post by **KurtM** » Fri Jan 12, 2018 1:26 am

Pictures, or it didn't happen.

McConkey · #22 Post by **McConkey** » Fri Jan 12, 2018 2:04 am

Hey John, the original post I made back in November had a link to the topic where the GUF is explained and all the details on how to make one. Here it is again for reference.

viewtopic.php?f=28&t=5449

One of the links Kurt posted is also linked in this link....ahah a link within a link within a link....

I'm dizzy already! Thanks for posting the links Kurt! The Van Egmond filters and GUF's are beyond incredible and really really effective! For $10 it's really impressive what you can achieve!!

There is also this topic which discusses the Van Egmond filter a little more.

viewtopic.php?f=14&p=33270#p33270

I can't wait to see your results and how you adapt it to your own scope! Also as Kurt said....Pics or it didn't happen! Really looking forward to seeing some images!!

Karl

Culicoides · #23 Post by **Culicoides** » Fri Jan 12, 2018 5:00 am

Many thanks, Karl, I missed your original post. John

McConkey · #24 Post by **McConkey** » Fri Jan 12, 2018 5:21 am

No worries John! I blame the italics! I had a really fun time making these filters and experimenting with them, I hope they treat you just as well!! Feel free to ask any questions as you dive into the wonderful world of homemade filters!

*EDIT*....Thank you Bill and nickols for the kind words!

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