Search found 86 matches

by patta
Sun Jan 29, 2023 2:38 am
Forum: Equipment Discussions
Topic: Optimal DSLR cameras vs 35mm film resolution
Replies: 11
Views: 8777

Re: Optimal DSLR cameras vs 35mm film resolution

Yes, fully agree with the above clarification. Sorry for the Oversampling blunder. More than math&physics, my argument against high MP sensor comes from practical experience with old objectives & sub-optimal arranged setups: After editing the image, cropping the corners because they're invariably a ...
by patta
Sun Jan 29, 2023 1:19 am
Forum: Equipment Discussions
Topic: Optimal DSLR cameras vs 35mm film resolution
Replies: 11
Views: 8777

Re: Optimal DSLR cameras vs 35mm film resolution

My arguments about (against) getting a dedicated full-format R: (just a personal summary, there are extensive discussions and tests in other threads) - You are already at the resolution ceiling, that is about 4MP. More megapixels on the sensor is oversampling, that is useful somehow but won't do mir...
by patta
Thu Jan 26, 2023 6:06 am
Forum: Equipment Exchange
Topic: For Sale - Canon EF 100mm L
Replies: 1
Views: 1356

For Sale - Canon EF 100mm L

I have this lens that is too luxurious for me, bought it used a while ago. It is great for shooting in the field. I don't have the "standard" 100mm Canon macro to compare against; I have Tamron and Sigma macros, this Canon L looks better built and has better autofocus. All are sharper than I could m...
by patta
Thu Jan 26, 2023 2:53 am
Forum: Equipment Discussions
Topic: 1:20 to 1:5 (0.05x to 0.2x)
Replies: 95
Views: 8788

Re: 1:20 to 1:5 (0.05x to 0.2x)

I couldn't resist, the observation by Rik that, in practice, we are looking for an objective lens with a native resolution of 600 MP, prompted the urge to make this graph: How much a lens cost vs its resolution. It is a quick ballpark; Hubble and the scanner are in just for fun
by patta
Wed Jan 25, 2023 7:46 am
Forum: Equipment Discussions
Topic: 1:20 to 1:5 (0.05x to 0.2x)
Replies: 95
Views: 8788

Re: 1:20 to 1:5 (0.05x to 0.2x)

I see that you're based in Korea... The world's best lenses for your job are already (all) there, in the factories of LG and Samsung to inspect TV screens. Line-scan for large format, price new is a couple of cars. But, there is an urban legend saying that they change those lenses pretty often and s...
by patta
Wed Jan 25, 2023 7:10 am
Forum: Equipment Discussions
Topic: 1:20 to 1:5 (0.05x to 0.2x)
Replies: 95
Views: 8788

Re: 1:20 to 1:5 (0.05x to 0.2x)

A bit of a silly observation - hope not to offend... - the main complaint of current lenses seems to be Chromatic Aberration; - the artworks are black and white. --> can't you go monochromatic?? No more CA! Either get illumination with blue LEDs; or a narrowband color filter (see Baader); or from th...
by patta
Fri Jan 13, 2023 7:11 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Polarization, polychromatic stacking
Replies: 5
Views: 2717

Re: Polarization, polychromatic stacking

I've made a couple more decent images with this method; one is with chunks of Muscovite; the color represent the direction of the birifrengence axes. The other are polyester fibers, that are birefrengent along the fiber. Note that there is no "estinction direction". I've made a mistake before, the t...
by patta
Mon Jan 09, 2023 4:57 am
Forum: Equipment Discussions
Topic: Dodging the infinity hump
Replies: 50
Views: 14724

Re: Dodging the infinity hump

In the Quekett article he uses an old Zeiss quartz condenser with NA 0.85, likely Abbe type. There are a lot of lenses made of fused silica / quartz in the market today, like for laser cutters, so it may be possible to put together a crude condenser similar to the Zeiss with stock components for ~10...
by patta
Fri Dec 23, 2022 11:37 am
Forum: Equipment Discussions
Topic: Dodging the infinity hump
Replies: 50
Views: 14724

Re: Dodging the infinity hump

Yes two-coverslip mounts do break easily; but they can be held by a "dummy slide". Even more relevant to the line of the thread, just got the Winter 2022 "Quekett journal": There is a whole article about "UV imaging of Diatoms" by a certain Jonathan M. Crowther, who modified an Olympus BHB. Heused 3...
by patta
Sun Dec 18, 2022 7:03 am
Forum: Equipment Discussions
Topic: Dodging the infinity hump
Replies: 50
Views: 14724

Re: Dodging the infinity hump

Sorry, just realized how much my previous posts were off-topic to the thread.... Anyway, my approach to the "infinity hump", (to make use of the NikonPA 20x 0.75) has been to use a standard finite microscope and mount the camera with a telephoto as tube lens, see for example link at previous post, a...
by patta
Sat Dec 17, 2022 11:59 am
Forum: General Discussion Forum and Community Announcements
Topic: Videomicrography: water drops.
Replies: 7
Views: 2988

Re: Videomicrography: water drops.

The double slit experiment is so beautiful, like observing green photons in slow motion!
by patta
Sat Dec 17, 2022 10:04 am
Forum: Equipment Discussions
Topic: Dodging the infinity hump
Replies: 50
Views: 14724

Re: Dodging the infinity hump

About darkfield at high NA Likely you can have another source No other sources, that's just me, made about 5 of those condensers last winter; confirm the weird NA 1.4, more or less measured and tested; but in that case the specimen is better to be mounted between two coverslips, that is a discrete h...
by patta
Sat Dec 17, 2022 7:04 am
Forum: Equipment Discussions
Topic: Dodging the infinity hump
Replies: 50
Views: 14724

Re: Dodging the infinity hump

late to the party, here some stray, know-it-all comments: - The old Solid Immersion, I buy small spheres from Mowen /BohrOptics on Aliespress. For Sapphire they list only full spheres but likely they can grind some to half for moderate $$, or the OP showed that it can be done at home... Another simi...
by patta
Sat Dec 17, 2022 6:38 am
Forum: Equipment Discussions
Topic: Checking objectives
Replies: 5
Views: 909

Re: Checking objectives

Two a bit more laborious methods: - You can mount the objective in front of a camera macro lens, then focus the macro inside the objective; it is the same as "phase telescope" but the view is a bit better. To do that I usually mount macro lens + camera in the camera port of the microscope, then focu...
by patta
Wed Nov 02, 2022 9:48 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Attaching an Objective directly to a smartphone?
Replies: 15
Views: 3230

Re: Attaching an Objective directly to a smartphone?

I've used for a while a microscope made by the phone, plus a lens pillaged from another phone, sticked in front of it (like the Sphere from previous posts). Magnification 1:1 and once set up worked well, sharp all over. There are several scientific paper describing this "simple field microscope" set...