All posts by Peter Y Lin

Analysis Of Misalignment Between Optical And Motion Axis For Focus Stacking.

I have been asked many times about why there are streaking patterns around border of final stacked image. Well, the most common cause of these streaking patterns is due to the optical instruments used — the magnification of optical instrument changes when the distance between the subject and sensor changes. When stacking algorithm attempts to align all images, there will be mismatch of subject size. Information in one image just does not exist in another, thus stacking software often fills the final image with some arbitrary (arbitrarily chosen) pixels. However, if a telecentric optical instrument is used, due to the nature of telecentricity, there is no change in magnification, therefore there should be no or very little streaking patterns. But many still get streaking patterns even when a telecentric optical instrument is used. What gives? Here is why!

Streaking

 

Continue reading Analysis Of Misalignment Between Optical And Motion Axis For Focus Stacking.

Reading Digital Caliper From Arduino

I have just encountered the need to read a digital dial indicator for another personal project. However, most of these digital dial indicators are “expensive” (normally cost about 30 – 100 USD), so I figure to just get a cheap digital caliper costing about 3 USD to start with. I totally understand that a cheap digital caliper might have different data protocols, but from what I gathered on the internet, most of these Chinese digital measurement tools use similar format — a clock and a data.

CaliperProofArduino output matches (closely) caliper reading. There are some discrepancy, but I think it the poor caliper that is displaying wrong data

Not able to find my USB logic analyzer and my oscilloscope is dead, I decided to use an Arduino as signal analyzer. read more

Hazy Stack? Watch Your Diffusion Setup.

Admit it, you have encountered this, after so much effort capturing images for stacking and painfully waiting for stacking software to finish, you ended up with an image with a lot of haze. So much so, your skillful Photoshop tricks can’t help it. Oh OK, sometimes Photoshop does help, but I still believe to get it right at the first place.

Setup_08So what happened? What happened is that your diffusion setup is causing light beams entering your lens, causing glare and haze. read more

Diffuse Your Light, Or Else!

OK, that sounds a bit harsh. Then again, almost every (extreme) macro photographer knows this and tries very hard to put as much diffusion as possible. Just visit any Facebook group about macro photography or any forum, you will find talks of diffusion in abundance, there are all kind of setups to diffuse light, all kind of DIY and professional equipment, there are . . . So, yeah, we get it for sure, now go away! Cool, it is almost everybody gets it, but here I am going to present you an extreme example of what would happen if you do NOT diffuse your light!  read more

Checking Microscope Objective Chromatic Aberration

What is chromatic aberration for an optical system? Well, according to Wiki, it is the failure of a lens to focus all colors to the same convergence point. You usually see this effect when you have high contrast edges in your image. Well, it happens not just with microscope objectives, you will also see this effect with normal photographic lenses, for example along the edges of a mountain and the sky. But I will focus on this for microscope objectives as it is rather important.

CACheckMitutoyo QV 2.5x 0.14, a 5x 0.15 “APO”, and a generic 4x PLAN objective. read more

A Nice Microscopy Setup

Be honest to you, I have neither owned a microscope, nor have I used one extensively. However a recent quest to shoot some butterfly scales at 50x magnification made me build a nice setup capable of doing 50x work using a cheap digital microscope stand. Before this, I have had hard time shooting butterfly scales at high magnification and I was using horizontal setup. First problem is mounting the butterfly vertically, fiddling with specimen holder so that the butterfly is parallel with the objective’s front element, then moving camera back and forth to pre-focus it. Believe me, all of these sound easy to over come, but they are really not. After building the setup discussed here, it is a lot easy and here is one example of it:

SSMW01

The above image was captured using this setup at 30x magnification  read more

Venus Optics (Laowa) 60mm F/2.8 2x Macro Lens

When I first started doing macro photography back in late 2015, I have heard a lot of macro lenses, such as Canon EF 100mm f/2.8 macro lens, Canon EF 60mm f/2.8 macro lens, Nikon 105mm f/2.8 macro lens, and some third party macro lenses, such as Tamron 90mm f/2.8 macro lenses. However, these have maximum 1:1 magnification and because their focal length is fairly long, it is hard to get to, say 2:1. However around the same time, there is this lens, named Laowa (老蛙, old frog, in Chinese) 60mm f/2.8 with 2:1 magnification.

laowa_2Laowa (老蛙, old frog) 60mm f/2.8 2:1 Macro Lens

I was a little skeptical as it is a Chinese lens and it sounded just too good to be true. Then again, being in China, I have seen enough of images taken with this lens and my curiosity grew and eventually bit the bullet last Feburary (2016). more …