Search found 33 matches

by Malcolm Storey
Thu Mar 09, 2017 2:31 pm
Forum: Equipment Discussions
Topic: LWD and no-coverslip Olympus objectives
Replies: 15
Views: 2492

Blur

PS: they look a lot better at half-size!
by Malcolm Storey
Thu Mar 09, 2017 2:30 pm
Forum: Equipment Discussions
Topic: LWD and no-coverslip Olympus objectives
Replies: 15
Views: 2492

20x and 40x

At that magnification I'm usually working with (temporary) slides, so I use UPlanFLN objectives. I assumed the slight blur was out-of-focus detail from adjacent frames in the stack. Or I didn't spend enough time retouching/in PhotoShop! The camera is an EOS1000D (quite old now - I've had it since 09...
by Malcolm Storey
Thu Mar 09, 2017 1:08 pm
Forum: Equipment Discussions
Topic: LWD and no-coverslip Olympus objectives
Replies: 15
Views: 2492

Inverted microscope

I've had the 20x and 40x objectives for a couple of years but hardly used them. Both objectives have adjustable collars for slide/coverslip thickness, which I guess derives from their use from below so they peer thru the slide rather than the coverslip. Otherwise, it never ocurred to me that it woul...
by Malcolm Storey
Sun Feb 07, 2016 2:03 am
Forum: General Discussion Forum and Community Announcements
Topic: Hoping someone can help me - getting artistic
Replies: 14
Views: 5352

Math

On this side of the pond we distinguish between arithmetic (taking 7 from 20) and mathematics (maths) which is the theory behind it. You can be an expert on football without being able to kick! re the image: The problem is that the detail is in individual pixels. I wonder what would happen if you sc...
by Malcolm Storey
Sat Feb 06, 2016 3:46 am
Forum: Frequently Asked Questions (FAQs)
Topic: FAQ: Assessment of empty magnification using GIMP
Replies: 13
Views: 11421

Apologies

Bushman's right that he used auto-levels just to demonstrate that the detail related to the subject, rather than as the final step of the procedure, but you do have to read it fairly carefully (aka "properly"!) to pick that up. My apologies for reading it too fast and diving in. What we're really in...
by Malcolm Storey
Fri Feb 05, 2016 2:27 am
Forum: Frequently Asked Questions (FAQs)
Topic: FAQ: Assessment of empty magnification using GIMP
Replies: 13
Views: 11421

Clarification

Sorry I wasn't clear. An image with a factor of two empty magnification still has the full number of pixels. In some sense only 25% (ie half in two dimensions) of the pixels contain information and the other 75% are in some sense "interpolated" by the physics of the lens. I realise the information i...
by Malcolm Storey
Thu Feb 04, 2016 7:47 am
Forum: Frequently Asked Questions (FAQs)
Topic: FAQ: Assessment of empty magnification using GIMP
Replies: 13
Views: 11421

Does this actually work?

I have to say I'm not quite convinced by this technique. After trying a variety of images, there always seems to be a information at scale 1 that only becomes visible after extreme manipulation of levels. Sometimes it contains fine detail like your example (which I presume means it's proper detail);...
by Malcolm Storey
Mon Oct 26, 2015 2:21 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: NA greater than 1
Replies: 14
Views: 2434

Getting sufficient brightness isn't a problem. But the resulting illumination will come from all angles so should make full use of the N.A. 1.30 of the oil immersion 100x objective.
by Malcolm Storey
Mon Oct 26, 2015 7:57 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: NA greater than 1
Replies: 14
Views: 2434

Thanks for your thoughts but none of these address the limiting factor that refraction at the air surface reduces the cone of illumination. What I'm trying to do is use a diffuser bonded to the lower surface of the slide (and so optically part of it) to create a larger angle than is possible with an...
by Malcolm Storey
Sun Oct 25, 2015 3:24 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: NA greater than 1
Replies: 14
Views: 2434

Yes, a dry condenser. That was the point really.
by Malcolm Storey
Sun Oct 25, 2015 2:20 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: NA greater than 1
Replies: 14
Views: 2434

I bought some so-called frosted slides ("SuperFrost") but they just had a layer of white plastic paint on one end for writing on. Anyway, I gave it a go using the frosted part of the slide (frosting down) with the 100x oil immersion obj and photographed the result. Running the image through Gimp/Wav...
by Malcolm Storey
Sat Oct 17, 2015 11:37 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: NA greater than 1
Replies: 14
Views: 2434

Beatsy: agreed, paper oiled to underside would be equivalent - although a little messy! Pau: Was aiming to raise the condenser NA to closer to that of the objective, rather than trying to exceedt it. Too high an NA can be useful reduce contrast in very contrasty subjects at low mag. Anyway I've orde...
by Malcolm Storey
Sat Oct 17, 2015 3:02 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: NA greater than 1
Replies: 14
Views: 2434

NA greater than 1

100x oil immersion objectives are typically marked NA 1.3. Without using an oil immersion condenser the NA is always less than 1.0 due to diffraction at the slide lower surface and the angle subtended by the condenser exit pupil. How about using a slide with a ground glass under-surface? The Kohler ...
by Malcolm Storey
Sat Oct 17, 2015 2:42 am
Forum: General Discussion Forum and Community Announcements
Topic: A plug for Encyclopedia of Life and DiscoverLife
Replies: 0
Views: 1219

A plug for Encyclopedia of Life and DiscoverLife

There are many outstanding images on photomacrography.net but they get lost among the other postings. It’d be nice to get such high quality images more widely visible in a structured archive. Encyclopedia of Life (EOL) is a nice structured archive to which you can upload CC images. https://www.flick...
by Malcolm Storey
Mon Sep 21, 2015 1:47 pm
Forum: Equipment Discussions
Topic: LWD and no-coverslip Olympus objectives
Replies: 15
Views: 2492

Don't be so sure - shine a laser through it and you could etch silicon chips or trigger fusion in a deuterium pellet! :)