Search found 86 matches
- Sun Jan 29, 2023 2:38 am
- Forum: Equipment Discussions
- Topic: Optimal DSLR cameras vs 35mm film resolution
- Replies: 11
- Views: 8834
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 ...
- Sun Jan 29, 2023 1:19 am
- Forum: Equipment Discussions
- Topic: Optimal DSLR cameras vs 35mm film resolution
- Replies: 11
- Views: 8834
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...
- Thu Jan 26, 2023 6:06 am
- Forum: Equipment Exchange
- Topic: For Sale - Canon EF 100mm L
- Replies: 1
- Views: 1409
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...
- Thu Jan 26, 2023 2:53 am
- Forum: Equipment Discussions
- Topic: 1:20 to 1:5 (0.05x to 0.2x)
- Replies: 95
- Views: 9021
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
- Wed Jan 25, 2023 7:46 am
- Forum: Equipment Discussions
- Topic: 1:20 to 1:5 (0.05x to 0.2x)
- Replies: 95
- Views: 9021
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...
- Wed Jan 25, 2023 7:10 am
- Forum: Equipment Discussions
- Topic: 1:20 to 1:5 (0.05x to 0.2x)
- Replies: 95
- Views: 9021
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...
- Fri Jan 13, 2023 7:11 am
- Forum: Macro and Micro Technique and Technical Discussions
- Topic: Polarization, polychromatic stacking
- Replies: 5
- Views: 2840
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...
- Mon Jan 09, 2023 4:57 am
- Forum: Equipment Discussions
- Topic: Dodging the infinity hump
- Replies: 50
- Views: 14884
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...
- Fri Dec 23, 2022 11:37 am
- Forum: Equipment Discussions
- Topic: Dodging the infinity hump
- Replies: 50
- Views: 14884
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...
- Sun Dec 18, 2022 7:03 am
- Forum: Equipment Discussions
- Topic: Dodging the infinity hump
- Replies: 50
- Views: 14884
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...
- Sat Dec 17, 2022 11:59 am
- Forum: General Discussion Forum and Community Announcements
- Topic: Videomicrography: water drops.
- Replies: 7
- Views: 4341
Re: Videomicrography: water drops.
The double slit experiment is so beautiful, like observing green photons in slow motion!
- Sat Dec 17, 2022 10:04 am
- Forum: Equipment Discussions
- Topic: Dodging the infinity hump
- Replies: 50
- Views: 14884
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...
- Sat Dec 17, 2022 7:04 am
- Forum: Equipment Discussions
- Topic: Dodging the infinity hump
- Replies: 50
- Views: 14884
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...
- Sat Dec 17, 2022 6:38 am
- Forum: Equipment Discussions
- Topic: Checking objectives
- Replies: 5
- Views: 944
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...
- 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: 3310
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...