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Jan van Gastel's video's
เข้าร่วมเมื่อ 8 ธ.ค. 2011
Hi,
I am Jan van Gastel. I was born in 1947 an live in the Netherlands. In this channel I share my video's about my most important hobbies: Mountainbiking, Astronomy (mirror making), Microscopy and tropical fish.
Enjoy.
I am Jan van Gastel. I was born in 1947 an live in the Netherlands. In this channel I share my video's about my most important hobbies: Mountainbiking, Astronomy (mirror making), Microscopy and tropical fish.
Enjoy.
Het bouwen van een drijfhut (floating blind) voor het fotograferen van watervogels
Om een laag camerastandpunt voor de camera te creeeren en dichtbij de vogels te kunnen komen heb ik een camouflage-drijfhut gebouwd. Hier loop je met een waadpak aan onder, zodat je onzichtbaar bent voor de vogels die je wilt fotograferen
มุมมอง: 89
วีดีโอ
(Meest) gravelrit door Het Gooi
มุมมอง 866 หลายเดือนก่อน
Dit is een video van een (meest) gravel MTB-rit in Het Gooi, met in de laatste kilometers wat pittiger stukken door bos en hei.
Natte, modderige bos en hei MTB-rit in Het Gooi.
มุมมอง 466 หลายเดือนก่อน
Pittig rondje over de natte, zachte grond. Eerste video met mijn nieuwe DJI action 4 camera. Prima stabilisatie. Wel een foutje gemaakt met het koppelen van de ritgegevens, waardoor die op zijn kop staan de laatste paar minuten.
Impressie rondje bos en hei in Het Gooi
มุมมอง 546 หลายเดือนก่อน
Deze video geeft een impressie van een 'bos- en hei ronde' in Het Gooi. In het eerste deel reed ik samen met iemand anders en deden we wat technische dingen (bochtentechniek e.d.). Deze gedeelten zijn niet in de video opgenomen, uitgezonderd de stukjes waarin ik voorop reed.
MTB route Soest
มุมมอง 18410 หลายเดือนก่อน
Dit is de gehele route, op enkele langere stukken verharde weg na. Helaas hier en daar last van de laag staande zon die in de camera schijnt. Voor mij als 76 jarige een zware route. Wel erg mooi.
MTB-route Austerlitz, Utrechtse heuvelrug
มุมมอง 12710 หลายเดือนก่อน
Gereden op 6 okober 2023. De video is in 4K. Mooie route.
MTB-rit Gooise heidevelden
มุมมอง 6711 หลายเดือนก่อน
Deze video is mijn MTB-rit van 28 augustus 2023 over de Gooise heidevelden. Lange gedeelten zijn - in totaal iets minder dan een half uur - ingekort. Totale ritduur 1:33:36 over 32,3 km.
Opening the channels of a pitch tool
มุมมอง 1K2 ปีที่แล้ว
This video shows the re-channeling of a 140 mm diameter pith tool with a one sided razor blade . At the end microfacetting with a steel brush is shown. In fact, I could have worked somewhat longer with this tool before re-channeling, but I had no tool at hand with almost closed channels. Sometimes small chips come off, but that's no problem. The chip at the edge was already off before I started.
Hogging out a flat surface blank for a 40 cm f/4.5 mirror on the Mirror-o-Matic
มุมมอง 4.7K3 ปีที่แล้ว
Tools used: 240 mm diameter tool, glass tiles on alumium disk and 300 mm diameter tool, glass tiles on dental plaster. Grit used: Carborundum #80 and carborundum #180. At the end of 180 grit the mirror will not be perfectly spherical (high center), but will get perfectly spherical during fine grinding.
Ciliate: Paramecium bursaria
มุมมอง 3503 ปีที่แล้ว
There are lots of Paramecium bursaria in my small pond. Sometimes they group together under the microscope. I tried to make a video of such a group, but when the light of the microscope hit them, they started to move and only a few stayed in the place I was targetting.
Ciliate: Spirostomum minus
มุมมอง 1.5K3 ปีที่แล้ว
I found this ciliate in my small pond. Length is about 700 microns. The adoral zone of membranelles is about 1/3 the body length. First part of the video is bright field, last part is oblique illumination and 2.5x larger magnification.
Ciliate: Frontonia acuminata
มุมมอง 1573 ปีที่แล้ว
I think this is Frontonia acuminata because of the black spot on the rear end. Length of this ciliate is a little over 100 microns. Normally there's a black spot at the anterior end of the cell, but, according to9= Bruce Taylor, this ma be an anomalous specimen.
Tardigrade eating
มุมมอง 3943 ปีที่แล้ว
This tardigrade is eating. The colored stuff in its body is food in its stomach, I suppose. I wonder what de many roundish things in its body are.
Ciliate: Uroleptus
มุมมอง 2113 ปีที่แล้ว
This ciliate is a little over 150 mcirons long. I also uploaded one some time ago (th-cam.com/video/073boB2IViY/w-d-xo.html), of about the same length. That one though, had less cirri at the rear end of the body.
Amoebe: Not clear which species this is.
มุมมอง 2763 ปีที่แล้ว
Amoebe: Not clear which species this is.
Hello Jan! Now, when it’s a little cooler, I’m preparing to parabolize a 16-inch mirror. So I'm carefully studying your example of parabolization. Based on the formulas you provided below, I wrote a small software that calculates the overhead and maximum offset. But there are several questions. When figuring about 10:51 for a 160mm tool I get a maximum overhead of 19mm and a maximum offset of 37mm. How do you get a set of overhands and offsets? Thanks! Oleg
Oleg, I calculate the maximum overhang and offset with those formulae. Sometimes I deviate from those numbers, depending on the actual figure of the mirror; its a matter of excperience. Then I start at offset 0 (or sometimes 5 or 10) and then decide how many offset positions I want to use. Most of the time this will be 5 or 6, sometimes 7 in the beginning of parabolizing and sometimes 4 at the end stages, when less parabolization is needed. I also decide beforehand about the number of overhang positions. Most of the time I do 5 or 6, sometimes 7-8 at the early parabolization stages, sometimes 3-5 at the end stages. Most of the time I diminish the overhang 3 mm at a time, sometimes, closer to the end 4 mm or, when I only use a few overhang/offset positions in the end stage, even 5 mm. I hope this helps.
@@janvangastel6763 Thanks for the detailed answer. I'll try to apply it to my mirror with an optical diameter of 406 mm. For the edge zone we have a 240 mm tool. According to calculations, the maximum offset is 68 mm and the overhead is 72 mm. Using your tips, we will choose 7 times at the beginning of parabolization. Will have Offset: 0, 10, 19, 29, 39, 49, 58, 68 mm and OVH 72, 69, 66, 63, 60, 57, 54, 51 mm. Time spent in each overhang position similar to video 10, 5.5, 4, 3.5, 3, 3, 3, 3 minutes. In your opinion, is this the correct calculation and time for the initial stage of figuration? Thanks!
@@oleggerashchenko2201 Yes, I think this is correct. But it is always important to check after a session, if the result is as it is meant to be. Sometimes, especially in the beginning, the edge zone will lag behind. And if that's the case it will be necessary to adapt the progression accordingly.
Astigmatismo só se tira esmerilhando. Polimento não elimina astigmatismo!!
Not true, what's polished in can be polished out.I did this by at least 30 mirrors.
Total length of stroke is 4 cm ( or 2 cm ) via excenter ? This critical??? Thanks!
No, stroke length is 2 cm. This is not critical at all. Might also be 3 cm or something like that.
@@janvangastel6763 Thanks! What speed do you usually use for the table and eccentric during polishing? A good sphere is made.
Boa tarde você pode me informar ande consigo comprar este tipo de vidro? Obrigado.
A good place to buy glass to make mirrors is here: www.stathis-firstlight.de/spiegelschleifen/material.htm
Você faz espelhos? E quanto custa?
No, I do not make mirrors commercially.
Bom dia colega você pode me informar onde eu consigo o vidro na medida de 115m m
What concentration of сerox do you use? He is almost invisible in the video. Thank you!
I use a concentration of about 1:100 when parabolizing. When polishing about 1:50.
@@janvangastel6763 Thanks for the answer! In other words, for 100 ml of water you should take about 1 gram of cerox. Did I understand correctly? Does this affect smoothness???
@@oleggerashchenko2201 It does affect smoothness a little.
Ну и колхоз !
I like heliozoans
hi sir good
Hi Jan. Nice sequences, I have to say. Very instructive. I did want to ask one little question. Why do you rotate the glass every so often, when the whole thing is spinning on that axis anyway? Steve
Maybe this is not necessary, but it does not cost much time and I do it to be as sure as possible that mirror and tool do not get into resonance.
makes sense - So there is absolutely no possibility of there being any affinity between the two systems I guess. You are decoupling them by rotating every so often, "just in case". @@janvangastel6763
Hey dude, cool video. I’d like to learn more about mirror making, do you have any explanation videos or even any books you could recommend? I struggle to understand how a parabolic shape is created
Very good book is: David A. Harbour: Understandig Foucault. The book covers Foucault testing and different ways of parabolizing. Other very good book, a classic: Jean Texereau: How to make a telescope.
@@janvangastel6763 I appreciate your recommendations👍. Grinding/polishing telescope mirrors is fascinating, I hope I can figure it out and make my own one day
That’s a lost art of conventional polishing they want too do in now on c n c good job nice test !
don't you want a parabolic figure when making a fast mirror ? , if so how do you flaten the outside edge of the mirror and how do you work out how much ?
Yes, after polishing the mirror needs to be parabolized. I have also a video about how I do that.
Great work
Thank you.
The visible zones are likely similar in size to your used pitch square size.
Yes, that's is right.
Nice
看起来很棒❤
Lekker tempo Jan! Ik vraag me serieus af of ik je bij zou kunnen houden.
Je kunt de rit op Strava downloaden en een poging wagen Klaas-Jan.
is this a type of hypotrich?
I think so, but I am not sure.
POV: kirby of the microbe universe
🇹🇷🇹🇷🇹🇷💯💯💯👍👍👍
Nice
Kirby?
Hi sir! Greetings of the day! Si I have a doubt. If the KE reading of a particular zone is higher than the ideal reading for that zone as calculated in figure xp,, the zone is higher than ideal or lower than ideal? I mean how do I interpret if the zone is raised or shallow?
If a reading is higher then ideal - above the 100% in the M-L plot in figure xp - then that zone is overcorrected, so too deep.
@@janvangastel6763 thank you sir for the reply. 🙏
Parece uma Bijū kk
Watching 👀 28/12/22
Beautiful tank
A beautiful tank and fish.
Do you test the mirror with a foucalt test or something? How do you know where the high spots are? With a star test? I have a Meade Lightbridge 12" Dobsonian that is under-corrected and also needs a new coat of aluminum. I do think it has a small amount of astigmatism. When I focus in an out, I can barely notice that the circle is not quite round very close to focus and it changes orientation by 90 degrees when it transitions from inside focus to outside focus.
I test with the Bath interferometer, see this video: th-cam.com/video/YSZZrUhg2DU/w-d-xo.html
Yes! I saw things that looked very much like this when I was trying to grow onion root tip cells by sticking the bottom of an onion in a shallow tray of water!
Very nice!
Nice job, beautful mirror! did you do any manual correction or you just finish the poslishing all in the powered turn table? I'm working on my first mirror and find that turn table poslihing like you show here always ends up with a lower center cave.
I never correct by hand during polishing. The only thing I do by hand is removing astigmatism if necessary. I also have a central hole sometimes after polishing, but I don't care, as long as it is not deeper then it will be after parabolizing. In the early stages of parabolizing, the hole vanishes. Only for an f/7 mirror of longer it can be a problem and should be removed before parabolizing. I do that - on the machine - with a 75% tool, center over center stroke, with 15% overhang.
@@janvangastel6763 When removing the central hole your way, will the curve change? notice you do it with 75% tool and 15% overhang, does the magic also work here that will keep the curve not changed? I'm asking because my goal is to make a optic spherical mirror. BTW, thank you very much for the quick reply, it is very helpful answer!
Bonito video. Creo que podria tratarse de Epiclintes.
сколько стоит
Did you manually hogging the blank to build the curve before using this maching for grinding or you started this maching grinding from flat glass? I'm about to start my first mirror making but heard someone said it might need some manual hogging to build the curve first. thank you.
No, I do nothing by hand. Here is a video about how I hog out a flat blank: th-cam.com/video/AdCW64TZFaw/w-d-xo.html
@@janvangastel6763 Thank you for your quick response! it is very informative and helpful.
Sir what is the glass thickness please.
The glass thicknes of this blank was 40 millimeters. I have also done blanks of 32 millimeters and 25 millimeter thickness. Largest was an 18 inch diameter blank of 25 millimeter thickness. No problem at all.
@@janvangastel6763 thanks. Also want to know what max f ratio I can go for incase I am making a 16 in mirror with 25mm blank?
@@satyajitbhadraroy7723 The 25 mm thick 18 incher I made was f/3.9 and was no problem at all. I am sure f/3 would be fine too. Making a good support for the back of the mirror is more important then the depth of the curve.
@@janvangastel6763 I have got it sir. You helped me a lot. 👍
Nicely done sir. What pitch you use? Like gugolz and all.
The pitch I use is named 28° pitch. It is comparable to Gugolz 64, with a working temperature between ~20 and ~24 degrees C (~68 - ~75 F).
Hi, I have another question to ask. while grinding a mirror in a mirror o matic machine the barbell plates are placed at the over arm and not directly on the tool why?
I find it easier, but maybe they might also be placed on the tool. I don't know, never tried.
What kind of glass do you use? Is it laminated?
I use borosilicaat glass. It's not laminated.
@@janvangastel6763 Just one more question, I'm about to buy a glass like this here where I live in Brazil but should it be tempered or not? The supplier has two types of glass.
@@Gezielthuler The glass should not be tempered
@@janvangastel6763 Thanks for the answer.
Pretty sure it is Colpodea. We found some when we were doing microscopy to visualize the tissues of a bean plant that had been stored in water a bit too long. These guys were swimming all over our slides.
How much does this lens cost to buy?
I don't know. I don't make mirrors commercially.
I have also studied protozoa
Its amazing bro
Did the fry grow to that size with the parents? I have some at the moment about 6mm long, I don't know whether to separate them!
Yes, they did.
during the fine grinding process, do you normal clean up the work surface to avoid cross contamination? Is the cleaning feasible with the MoM?
I clean the machine after Carborundum 80 and after carborundum 180 because of the large amount of dirt. I do not disassemble the rotating table to do that, just wipe it clean with some water. After 3 micron grit, so before I start polishing, I disassemble the rotating table do be able to do a more thorough cleaning. It's all very easy to do and does not take much time. In this video I see that I did not clean the machine after 180 grit, sometimes I don't and just take care that I do not touch the dirt before touching the mirror surface.
@@janvangastel6763 thank you so much :)
Hi, one question. Could you please tell me how you clean off the machine when required? As the rotating disc of the machine seems to be taken off in the cleaning process.
The rotating disc can easily be taken off, including the drive shaft. And also the drip pan can be easily taken off the machine. Takes only a few minutes. I clean the machine every time when I have finished the grinding phase of a mirror, to be sure there's no grit left that might scratch the mirror surface when polishing and parabolizing. I place everything I want to clean in my garden and use a hose to clean it, after having removed most of the grit-glass mud, so that I do not pollute my garden.
Looks awesome. Could you please give a walk around of the machine? I have visited the website with the details though. But thought I would be nice to see the machine before making one. 👍
I have tried that, but there's not enough space around the machine to get good views from more then one side.
How many hours did it take to get the initial sagitta please?
It took 20 hours to get to the intended sagitta.
@@janvangastel6763 woah!!!! i am building an MoM, and I hope I can hog out an 8" f/5 fast enough.
@@janvangastel6763 how many hours do you think i will require for an 8" f/5 with a steel tool?
@@astrosathya1984 I never used a steel tool, so I don't know. With a 60% (so ~120 mm diameter for an 8 incher) glass tile tool it would take me about 9 hours to get to the right sagitta with #80 carborundum.
Oblique or DIC?
Oblique.
@@janvangastel6763 That's really good oblique. It looks like 400x magnification which is the limit for oblique but this looks absolutely awesome for 400x mag!
@@benjamind2008 Thank you.