[HN Gopher] DIY microscope lenses on BMD pocket 6K camera
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DIY microscope lenses on BMD pocket 6K camera
Author : Cullinet
Score : 80 points
Date : 2021-03-11 17:35 UTC (5 hours ago)
(HTM) web link (www.schweinert.com)
(TXT) w3m dump (www.schweinert.com)
| dylan604 wrote:
| other than for the lulz of "i shot photos with a video camera",
| this would have been so much easier with a mirrorless or DSLR.
| why record 160 frames to just export 1 frame. also easier to get
| >6K images as well.
|
| sometimes, the "just because" really just makes me shake my head.
| I love the 3D printing of an adapater and playing with lenses in
| ways never envisioned by the vendors. after going through all of
| that hassle, to just tack on the hassle of exporting stills from
| video sequences is just odd.
| jiofih wrote:
| Focus stacking is indeed done with a DSLR most of the time. You
| cannot get nearly enough DOF at this scale with any kind of
| lens.
|
| The author can do it from video because he has a 6K camera, and
| that is actually way easier compared to manually taking 160
| separate shots + changing focus for each of them (you need
| specialized hardware for that, most cameras will give you a
| dozen shots at most due to coarse focus increments).
| dylan604 wrote:
| How do you figure? You take a single image, then move the
| camera or adjust focus, lather, rinse, repeat. In video, you
| do the same thing, except now you have to process each video
| clip to get export the single frame.
| jiofih wrote:
| Oh, now I see why you'd think that. That would be insane.
|
| No, you record a single video while moving focus and export
| each frame - that's what makes it easier.
|
| > The camera itself is mounted on an old edelkrone slider
| with a motion module. I record short 4K ProRes422HQ clips
| and use them for focus stacking directly in helicon focus.
| For this fly I used an average of 160 frames [from one
| clip]
| dylan604 wrote:
| Did you read the article?
|
| "I record short 4K ProRes422HQ clips and use them for
| focus stacking directly in helicon focus. For this fly I
| used an average of 160 frames."
|
| Clearly, he recorded multiple clips, and then exported
| individual frames from individual clips.
|
| After all of that, he didn't even record in RAW.
| jiofih wrote:
| Why the aggressiveness? If you want to believe that, be
| my guest.
|
| This is a film production company, they most certainly
| have a stack of DSLRs they could use it it was that much
| more convenient, and with much better resolution. Not
| sure why you'd assume stupidity.
|
| The software supports importing videos directly:
| https://m.facebook.com/heliconsoft/photos/new-version-of-
| hel...
|
| As for RAW, unless you need that bit of extra dynamic
| range, it makes no difference (they don't here, as it's a
| studio shot with fully controlled lighting), ProRes422 is
| enough for 10-bit HDR even.
| devb wrote:
| Processing 160 (or more, many many more) RAW files is
| much more of a pain in the neck than just taking the time
| to get everything right in camera and dealing with the
| jpegs.
| mlyle wrote:
| He says he records short clips and uses 160 frames from
| them. I don't see why you'd choose to read it as
| "recorded one video per depth".
|
| And sure, it's not raw, but ProRes422HQ is pretty damn
| good, being both high pixel depth and very high bitrate.
| michrassena wrote:
| This has to be the method. It makes the most sense given
| the strengths of a 6K video camera. Record lots of frames
| and use a dolly to take focus slices of the subject.
| dang wrote:
| " _Please don 't comment on whether someone read an
| article. "Did you even read the article? It mentions
| that" can be shortened to "The article mentions that."_"
|
| https://news.ycombinator.com/newsguidelines.html
|
| Also, can you please make your criticisms thoughtfully
| rather than as shallow dismissals or snark? Your comments
| in this thread are rather on the wrong side of the line,
| starting with
| https://news.ycombinator.com/item?id=26427684. You
| obviously know a lot about this topic, which is great,
| but the thing to do with that knowledge is share some of
| it, so the rest of us can learn, and leave out the
| putdown aspect.
|
| https://hn.algolia.com/?dateRange=all&page=0&prefix=true&
| sor...
| devb wrote:
| As someone with extensive experience in doing what you're
| describing with a DSLR, the video option sounds like a
| wonderful shortcut and I've wondered if it was possible to
| do it with my current equipment.
| GordonS wrote:
| I've never done macro photography before, so this might be a
| silly question - but could you really get shots like this from
| a single DSLR image? Most macro photos I see have some part of
| the image in razor sharp focus, then a strong bokeh effect for
| the rest.
| michrassena wrote:
| Macro photography in my limited experience is as much about
| technique as equipment. No matter the camera, with that level
| of magnification you have to stack the images to get that
| much of the subject in focus. You can increase the depth of
| focus using the Scheimpflug principle and a smaller aperture,
| but there are real physical limits to how much. Decreasing
| the diameter of the aperture is limited by diffraction -- the
| image becomes less sharp even if more is in focus.
| dylan604 wrote:
| No. That's the point of focus stacking. However, using a
| still camera, you eliminate a lot of the work that was added
| because this was video.
| sigstoat wrote:
| you can use the same software this guy was using, and take
| multiple photos and stack them https://www.heliconsoft.com
|
| the comment you're replying to was pointing out that using a
| camcorder and extracting stills from the video is a PITA, and
| it would be more straightforward to use a DSLR that can
| simply take stills. and they're right, but if the blackmagic
| was all this fellow had... well, it clearly worked well and a
| DSLR or mirrorless would've cost a few hundred dollars more.
|
| since he was using a 3D printed adapter instead of buying one
| for $10, i can only assume he blew his entire budget on the
| blackmagic hardware.
| dylan604 wrote:
| The actual article said he didn't want to wait for 4 weeks
| while something shipped from China, so he 3D printed.
| Nothing implied not being able to afford a $10 part.
|
| I would also stipulate that someone with a BMD 6K camera
| has other cameras as well. The BMD is typically the
| upgraded to vs started with type of camera. Sure, edge
| cases and what not
| mhb wrote:
| Not from a single image. The reason for the set up is to
| obtain many images at different focal distances. That can be
| done by either moving the camera (of any kind) or by changing
| the focus for each image.
| dylan604 wrote:
| Typically, it is not done by adjusting focus, and uses a
| sliding rig to change the position of the focal plane. For
| most camera lenses, the precision of the focus ring
| mechanism is too dodgy to precisely change the focus. With
| the slider, the focus ring is left alone, and the precision
| of the slider is use to bring the next "layer" into focus.
| The author even commented on the slider he used was not as
| precise due to it being belt driven and that switching to a
| lead screw system would have provided more accuracy.
| mhb wrote:
| OK. I have no first hand experience, but I saw that
| Helicon makes a product which incrementally adjusts a
| camera's focuser.
|
| https://www.heliconsoft.com/heliconsoft-products/helicon-
| fb-...
| numpad0 wrote:
| According to a web page I found from 5-minute googling[1]:
| Depth of Field[mm] = (2 * u^2 * N * c )/ f^2
|
| where:
|
| u = distance to object[mm], N = f number(focal length divided
| by effective aperture diameter), c = diameter of acceptable
| circle of confusion[mm], f = focal length[mm]
|
| Assume Sony A7M4 with Milvus 2/100: let u, N, c, f = (160mm,
| f/22, 4um, 100mm): DoF = 0.396mm ~ 1/3rd of a penny thick
|
| The answer is no, not possible without focus stacking. But
| focus stacking is a SLR technique anyway, so the part that
| he's flexing his fancy camera a bit is true.
|
| 1: https://damienfournier.co/dof-the-simplified-formula-to-
| unde...
| michrassena wrote:
| I think the flex here is photographic quality images from a
| video camera. 6000 pixels across is a higher resolution
| than the top digital cameras from a few years ago. Combine
| that with an easy way to extract hundreds of frames which
| can be stacked and you have a relatively simple way to
| create these deep macro photos. Similar techniques (e.g.
| lucky imaging) have been used for years by astro-
| photographers even in the days of 320x240 webcams.
| numpad0 wrote:
| It's a mirrorless with 24MP APS-C sensor. Top mirrorless
| from _a decade_ ago already had 24MP APS-C sensors. Top
| smartphone from _a decade_ ago had _better_
| resolution(41MP).
|
| I'm not saying the camera can't be impressive, I'm saying
| you're vomiting marketing script.
| zokier wrote:
| Kinda opposite direction, with the launch of new very high res
| ("50 megapixels") Sony a1 I started thinking that with a macro
| objective you could use it as a sort of low-magnification
| microscope. With a 1:1 macro, if you crop a 4k section from the
| full-resolution image and draw it on a 32" display you'd get 40x
| magnification (sort of) if I did my math right; 1px on screen
| would correspond to roughly 4um which gives some ballpark on what
| sort features you could see with it. But it gets better still,
| there are at least some 2:1 magnification macro lenses [1] out
| there, those would double the magnification you get.
|
| I haven't really figured out how that compares to "real"
| microscopes, or even like the $100 chinese digital scopes.
|
| [1]
| https://www.dpreview.com/products/venus/lenses/venus_laowa_1...
| and its 65mm counterpart
| Scene_Cast2 wrote:
| Check out Fuji's GFX100S. It's a consumer camera ($6000) that
| can take 400MP photos.
| throwanem wrote:
| I bet medium-format 1:1 macro lenses are _spendy_ , though.
| throwanem wrote:
| Scaling up a crop doesn't really increase magnification at all,
| though. You're still limited by sensor resolution and
| reproduction ratio. Scaling up the result lets you see it from
| further away, but it doesn't _add_ information that the sensor
| didn 't capture. Whatever the reproduction ratio of the lens at
| the focal length you're using, that's going to determine the
| minimum feature size you'll be able to resolve.
|
| I have some wasp shots [1] that I took at or near 1:1 on an
| APS-C (Nikon DX) sensor, and I had three of them printed and
| framed at 36"x24" to hang as a triptych across one of my living
| room walls. [2] They're gorgeous at that size, but they're not
| _sharper_ at that size, you know?
|
| [1] https://aaron-m.com/2019/07/08/polistes-metricus
|
| [2] Yes, I live alone, why do you ask? :) I originally had the
| middle one over my bed, but my boyfriend at the time found it
| offputting. Can't imagine why...
| zwieback wrote:
| We have a lot of Mitutoyo Plan APOs floating around at work,
| sometimes they come up on ebay. If you can get your hands on a 5x
| or 10x those are great for quickie high mag photography. Highly
| recommended.
| avmich wrote:
| I'm disappointed - there is no DIY lenses here, not by my book,
| no glass polishing or optical precision casting, just assembling
| already existing optics.
| dharma1 wrote:
| I tried the same a few years ago with the original Blackmagic
| Pocket (for video, no focus stacking). You can get pretty good
| microscope lenses cheaply on eBay and the rms-m42 adapter is
| cheap.
|
| https://youtu.be/JwIDTtu8XnA
|
| A lot of shakiness at that magnification level though (had to
| stabilise in post) and the depth of field is razor thin - this is
| where focus stacking with stills helps a lot.
|
| Optically I've found regular super-macro lenses are better (2:1
| or more)
| LeifCarrotson wrote:
| The focus stacking technique was news to me. I've been doing some
| macro photography of PCB components with an extension tube, but
| the depth of field is just so shallow that it's hard to see what
| you're doing. You can't read the text on top of an IC and see
| sharp solder joints on the bottom at the same time.
|
| But if you put it on a threaded rod, move the camera, and take
| the in-focus parts from a bunch of pictures, you can see the
| front and back of the fly at the same time. How cool!
| amelius wrote:
| If you're photographing stills (like PCB components) then you
| might as well use a smaller aperture and increase the exposure
| time to get an image that is globally in focus.
| devb wrote:
| This only works up to a point before diffraction sets in and
| the picture quality starts to very noticeably suffer, and
| comes nowhere close to the depth of field acquired with focus
| stacking. In fact, with stacking, the lens should be stopped
| down to the best f-stop anyway (f/8-11).
| sudosysgen wrote:
| On my hacked Sony camera, you can program the camera to change
| focus and take a picture each time in rapid succession, no need
| for anything more than a tripod :)
| [deleted]
| throwanem wrote:
| There's a device called the Helicon FB Tube [1] which comes
| in Canon and Nikon variants, and purports to do this with any
| camera and lens pair it supports.
|
| I've thought about trying one out - it's not that expensive
| compared to most camera things, but I'd want it for shooting
| handheld, and I'm not sure how well it'd play with either the
| recycle rate on my flashes or the movement rate of the
| insects I shoot this way. Probably not well with either, but
| for still stuff I guess it's probably still cheaper than a
| driven macro rail...
|
| [1] https://www.heliconsoft.com/heliconsoft-products/helicon-
| fb-...
| modeless wrote:
| That's pretty cool. Maybe this would actually be a good use for
| the failed Lytro cameras. Changing focus after the shot is
| taken was always a parlor trick with little use in regular
| photography, but for microscopy it could be game changing. Has
| anyone tried microscopy with a Lytro Illum? Seems like you can
| still buy them used.
| TaylorAlexander wrote:
| Jeff Geerling just uploaded a tutorial video on focus stacking
| if you want to check it out!
|
| https://youtu.be/pinYVZxBF2Q
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