Stargazers Lounge Uses Cookies
Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.
Search the Community
Showing results for tags 'lens'.
Found 24 results
-
[A few more photos are in the imgur album] Made this telescope for observing sunspots. The Sun gets projected onto a piece of paper after bouncing from 3 mirrors inside the frame. It's compact, light, takes only a few seconds to point at the Sun, and sketching sunspots is as easy as circling the spots on a piece of paper. It can even project the Moon: The design is inspired by a commerically available telescope, but I’ve done all the designing myself, just for the fun of it. Sunspotter is full of little details that make it interesting. How do you fix the eyepiece in the exact place where it needs to be? How do you keep the lens in place and perfectly aligned? Building the telescope was a lot of fun, I’ve learned to use a jigsaw, X-Carve and a 3D printer. The plan is to use it to complete the Astroleague Sunspotter Observing Program, but unfortunately I completed it at the minimum of a Sun cycle, and won’t see any sunspots until next year. Telescope parameters: Magnification: 75x Size: 41cm x 41cm x 15cm Weight: 1kg Design: Keplerian Projection size: 75mm Materials needed: Lens: Ø52mm f=750mm achromatic doublet Mirrors: 1, 2, 3 Eyepiece: Baader 10mm ortho 1.5m² of 10mm plywood Wooden glue 5m of PLA filament 12 nails Compressed air Isopropyl alcohol Tools I used: Jigsaw with a 30° bevel capacity X-Carve 1000 3D printer A laser pointer Clamp Learned modelling basics in: LibreCAD Easel TinkerCAD Fusion 360 Part 1: Choosing the lens The idea of a sunspotter is that the light goes through the lens, travels inside the telescope, bouncing from 3 mirrors, enters an eyepiece and the image gets projected on one of its sides. The distance the light travels before entering an eyepiece is the focal length and it determines the size of the telescope. I chose a Ø52mm f=750mm achromatic double. Observing the Sun doesn’t require a large aperture, 50mm is more than enough. I wanted a high magnification and went for the longest focal length I could find, which was 750mm. Achromatic doublet design is what people use in refractors. If it is good enough for a refractor, it’s definitely good enough for my project. With the focal length chosen I could design the wooden parts. A drawing showed that the frame needed to have sides 30cm long, but I wasn’t sure about the placement of the mirrors and went for 31cm sides, planning to shorten the light path as needed by adjusting mirror positions. This is the LibreCAD drawing of the layout of parts on a piece of plywood: Part 2: Building the base Having a drawing of the base in LibreCAD, I printed the drawing 1:1 scale on multiple A4 sheets of paper and glued them together. I transferred the drawing to a piece of cardboard and cut it out. Applied this cardboard template to the sheet of plywood, and cut out two parts with a jigsaw.. I’m not an experienced user of jigsaw, and couldn’t manage to cut half-circles accurately enough. Even worse was that the two parts were very different. I didn’t want the frame to randomly tilt left or right when adjusting its altitude, and had to spend a lot of time with sandpaper to make the halves as similar as I could. Glued the two large parts with three small parts in the middle. Additionally nailed the parts and the base was ready. Part 3: Frame The frame is simply a triangle made of three pieces, with short sides cut at a 30° angle. Most jigsaws can cut at 45°, but not at 30°. Had to buy a new jigsaw with a 30° bevel capacity. Cut out three sides, cut short sides at a 30° angle, but didn’t put them together just yet. The lens needs to be perfectly aligned with the Sun-facing part of the frame, otherwise the Sun projection isn't circular but elongated. My solution was to carve a hole with a little step as shown on the image. The inner hole is Ø46.5mm, the outer hole is Ø50.8mm. The outer hole is the exact size to let the lens fit, but with a little bit of friction. Had to carve several holes to find the minimal size the lens could fit in. The step is just large enough to have enough surface for the glue to keep the lens in place, I didn't want to reduce the aperture too much. I used an X-Carve for carving and Easel for modelling. With all 3 sides ready, I could assemble the frame. It appeared that my 30° angle cuts were not very precise, but after some sandpapering the sides started fitting together alright. Glued the parts together and left them to dry for a day. To apply some pressure on the joints, I wound several twine loops around the frame really tight, made sure all sides fitted well together and left it to dry like that for a day. Part 4: Mirrors When selecting mirrors I was looking for the smallest mirror that fit the cone of light. Small mirrors are a lot easier to place, and they let me better control the length of the light path. I considered using elliptic mirrors, but they were bulky and really hard to place. All mirrors are first surface mirrors, otherwise planning their locations would be a lot more confusing. This was my original plan of placing the mirrors: As you can see, all the angles and distances were carefully measured, and I wanted to simply make mirror holders of those exact dimensions. This was clearly a bad idea. I 3d-printed some parts like this: And only later I realized that the frame angles are not exactly 60°, and that there are drops of glue along the edges that don’t let me fit the pieces deep enough in the joint between the sides. I cut angles from all the mirror holders: After I put the first mirror in place I realized the angles are all wrong, and that I needed to re-do the holder. Separating the mirror from the holder was a huge pain, which resulted in an accident. The mirror fell off the desk and got damaged. Luckily, only the back side got damaged, the front side was still working: The final designs of mirror holders looks like this: The holes in the front surface let me apply pressure on the back of the mirror if I ever want to separate it from the holder. The recesses collect the excess glue to avoid mirror skewing when gluing them. All other holes are simply to save the filament. Part 5: Placing mirrors What I learned is that you can’t plan positions of several pieces with high precision and just hope that it all comes together. I needed a feedback about the precision of mirror positions. I used a laser pointer to verify mirror positions at each step. In the picture you can see that the laser is firmly set in a hole in another piece of wood, with layers of isolation tape on the tip of the laser pointer to make it stable. A clamp holds the piece of wood in place, ensuring that the laser ray goes in the same direction as a solar ray would. A crosshair of black thread at the center of the lens ensures the laser goes exactly through the center of the lens. When placing each mirror, I marked the spot where I expected the laser to end up. While gluing the mirror holder to the frame, I kept the laser as close to that spot as possible. If for some reason, the laser couldn’t hit the expected spot, I did my best with placing the mirror, and recalculated locations of the following mirrors. I saw the first sunspots after placing all the mirrors and simply holding an eyepiece in hand. Part 6: Eyepiece holder I tried eyepieces of different focal length and liked the picture I got with a 10mm eyepiece the most. An eyepiece needs to be in a very exact spot to produce a sharp image. At this point it was obvious that my frame doesn’t match the model, and that I didn’t even know what exactly was wrong with the frame. I didn’t want to rely on the model and moved forward with trial-and-error. I printed several parts to hold the eyepiece, with different eyepiece locations: The part in the photo was a total disaster. It needed quite a lot of filament, at the same didn’t have enough surface area to be glued to the frame, and not enough surface area to hold the eyepiece firmly. The next iteration was a lot better: This part has a lot more surface area, and needs less filament to be printed. I intentionally printed the hole for the eyepiece too small, and had to sandpaper it a little bit, to make the eyepiece stay firmly fixed. Adjusting the focus is done by sliding the eyepiece up and down until the Sun becomes a circle with well defined borders. Part 7: Dust All optical parts should be kept clean. Dust on the mirrors and the lens will make the image darker. Dust on the eyepiece will show up as artifacts on the projected image. Unlike sunspots, the artifacts will not move with the Sun. To clean the eyepiece I used compressed air. To clean the mirrors I used isopropyl alcohol. Part 8: Fire safety Don’t leave devices with magnifying lenses lying around. Once the Sun happened to be in such a spot that its light went right through the lens, burning through the cap of the eyepiece. Luckily, nobody was hurt and no other damage was done. Part 9: Future work Build quality of the base is very poor. The frame tilts sideways when adjusting its altitude despite all my efforts. I’d like to build a new base, but leave all the work to the machines. I already have a model for an X-Carve to make both base parts, compatible with my current frame: A notch along the edge of the half-circle should eliminate the tilt. The precision of the machining should make the base very stable. Maybe next year, when sunspots become a common daily sight, I’ll get to this project. Thank you for reading this far! I hope you enjoyed it.
-
2 x Computar HG0808 FCS-HSP ultra fast CCTV lenses Very rare, high quality DC Auto iris CCTV lens designed for ultra-low light conditions. Ideally for use with CCTV cameras with a 1/2" chip, such as the Watec 902H2 series CCTV cameras. Ideal for ultra low light conditions such as night time video capture of meteors. Both lenses in very good condition, with recently tested auto iris control, no scratches on glass and no fungus. One lens comes with original optional IR correction filter, but no front lens cap - £100 The other lens has no IR correction filter - £90 Postage £6.00 (insured and tracked) -
National Geographic 90/1250 maksutov is my telescope and thanks for all the replies and support of my previous post it helped me alot and i figured out how to see the moon for example in beautiful quality but there's the problem i have. I can only see good views and a sharp sight of the moon but that's about it. Do i need a better lens that can zoom even more out or is this the limit of my telescope? Please let me know if you know a solution to this. -
hi I have a dobsonian 150p 6", when I first asked about this , everyone said what a brill scope for a 1st one , I can see m31 but not clearly just like a dense mist or fog or splodge, is this right or is it just cause im using basic lens what came with it , I bought a vixen npl 8mm eyepiece , still asplodge , got a barlow x2 a basic one , I can see m31 just as good with 10 x 50 binocs, ....... so my point is , am I using it right , and just expecting to much , or badly need new eyepieces or would it be best to get 15x70 binocs or sell my dob and get something a bit better , I did manage to see Saturn in july which was amazing, but I thought id get a better view of m31 -
My first go at imaging m45 shot using a vintage super takumar 135, f3.5 iso640 best 80%of 35 120second subs. The camera was mounted on a star adventurer and polar alignment was rough -
-
Hi everyone, just looking to get into astrophotography but looking at a DSLR as I'd like to use it for daytime use too, I know usually it's better for them to be modified but I've seen this can be done to allow use for both with only white balance adjustment. I've seen 1300d's going around £200 on eBay with the 18-55mm lens but the 4000d is a couple of years newer and there is currently one with 18-55mm + 75-300mm going for £350 at Currys. From what I can work out there isn't much difference between them besides a smaller screen on the 4000d and the release date. I'm just wondering if there is some reason people go for the 1300d instead or is it just because of it being older it turns up cheaper? Sorry for the long winded post but I'm doing lots of research to make sure I get the best one that'll last me the longest, thanks for any help.
-
Hi, i seem to have a dirty lens on the telescope side of the lens. Anyone disasemble this before ? I already checked the camera, filter, and focal reducer seperatly, the "staines" are from the telescope-side of the lens (already cleaned the outside of the lens to) Flat frame
-
Hi, I'm going to the US this summer to view the solar eclipse on Aug 21. I'm trying to think what kit to bring over there to photograph the event. I have a Canon 700D. Taking my scope is out of question so I'm looking for a reasonably priced lens to do the job. I only have a 10-22 and a 60mm so need something with much more focal length. I've been doing quite a bit of reading on the topic. i'd like to capture the coronae up to 4x the sun diameter, so thinking around 400mm / 500mm FL. I've come across some russian mirror lens like 3M-5A-MC or MTO 500/f8 or 3M-6A 6.3/500mm. The latter is a bit faster at 6.3. I'm wondering if anyone has experience doing astro shots with either of these? Otherwise I'm considering a Canon 100-400 5.6 but it is much more expensive... Any idea, feedback? -
Hi everyone, I am just starting to use my canon 1200D with my telescope using a t-ring and ofcourse want more magnification but i want a set of barlow lenses not just say 2x or 3x, so i hit ebay looking for cheap but sort of ok quality ones, I came across datyson ones for under £10 which on at least one site have good reviews but obviously i am not going to take the word of a site i dont know that sell thems word for it so I figured i would ask here, if anyone has tried these and can give a honest assessment of them it is the members on this site
-
Dear all! I am looking for a good Grab and Go Scope / Tele lens with a total price tag below 1000 EUR. I have 5 candidates so far: (1) TS Imaging Star 70mm f/6,78 QUADRUPLET ED - Flatfield ED Refractor - 474mm focal length 599 Euro, no TSFLAT2 necessary + case 60 = 660 euros. astrobin sample w/ DSLR: https://www.astrobin.com/160820/ (2) Skywatcher dublet Apo 80/600 EvoStar ED OTA, FPL 53, 649 Euros +case 60 + flattener 179 = 890 Euros astrobin sample w/ DSLR: http://www.astrobin.com/236429/ (3) TS Imaging Star 65mm f/6.5 Quadruplet Astrograph - 44 mm field diameter 900 euros + case 60 = 960 euros astrobin sample w/ DSLR: http://www.astrobin.com/12039/ (4) TS PHOTOLINE 80 mm f/7 FPL53 Doublet Apo - rack and pinion focuser 745 euros + tsflat 179 + case 60 = 980 euros astrobin sample w/ DSLR: http://www.astrobin.com/213138/0/ (5) TS Photoline 80mm f/6 Triplet Super-Apo with FPL53 triplet - 2" Crayford focuser + case 798 euro + TSFlat 179 euro == 980 euros. astrobin sample w/ DSLR: http://www.astrobin.com/210940/ Edit: i was aiming for a total cost of max 1000 eur, a weight for the OTA of up to 4-5kg, and a max length of about 60 cm. I would really like your suggestions on that gear, as well as suggestions for good scopes that i may have missed... thanks a lot!!! -
Hi can anyone help "PLEASE" I recently found my lens cell on my GT81 was dirty and having Badder wonder fluid and the correct clothes, I attempted a clean on both sides of the cell. Doing everything correctly I find now I have an oily smear on the inside lens. Panicking I spoke to SC Telescopes who advised I hadn't damaged the coatings and that using the soft disposable J cloth type and breathing on the lens I should be able to remove the smears. I have tried this and it isn't working. I would like to get it properly assess and professionally cleaned as I've cocked it up and want the job done correct ( and hopefully I haven't damaged the objectives) Can anyone recommend a company that offer the service. If local to the midlands I can drop the lens cell over and collect, failing that all I'd need to do is send the cell by recorded delivery and well wrapped and insulated against travel damage. Thanks Allan
-
Hi everyone, Last night I tried to observe the moon, I could clearly see the moon through my finderscope but when I looked through my telescope all I could see is just yellow light. Could you guys give me advice on what lenses should I use? I have a 70060 refractor with 1.5 Erecting Eyepiece, Barlow Lens 3x, and H20mm, H12.5mm, SR4mm. Thanks! -
Got a fairly simple question here that i've been thinking about. Are there any barlows designed for imaging? I dont own a scope yet but i'm always thinking about the rig i am trying to build. I started reading about reducers earlier and then that got me thinking about increasing a scopes focal length. Would a barlow distort or exaggerate any optical flaws the glass may have? Or even cause a loss of contrast or colour? I had never searched for a barlow so i was quite surprised when i seen they are much much cheaper than i thought they would be. All around the same price. Is there a 'high end' barlow lens that would be a better choice to use over others? This is all just late night chit-chat really a barlow lens will not be in my kit for a while yet probably, its in the double digits of a long list! I'm just curious Cheers
-
Does anyone have any recommendations for an affordable lens for the Canon 60Da? I can't afford to spend hundreds on a wide angle lens and to be honest I'm not so much interested in big wide angle shots but more specific targets like the constellation Orion. I love my camera, I've used it many times with my Nexstar Evolution but it's not practical taking my scope with me when I travel (sadly!).
-
Hey Guys, I'm not a newbie to astronomy (or reading on SGL ), but am a Newbie to AP (and writing on SGL ). I have a Sky watcher 8 inch dob, and had SW 120 and 102 achromatic in the past. I have a pretty solid Visual background (messier, top 111 NGC and so on), and did some decent job on photographing Sun, Moon and planets with the dob. Now I want to do more serious things in AP field. I have to mention I live in Iran. AP gear can be found here, but it is usually twice or even thrice the price of online markets. For example a SW ProED 80ED has an online price tag of $650 while here is being sold $1300 (Online markets does not deliver in Iran). Fortunately lenses are far better priced and found here, a little higher than their real price. While searching online for a rig, i encountered another alternative, using a telephoto lens instead of a refractor, and found a particular one, AF-S NIKKOR 200-500mm f/5.6E ED VR (http://www.nikonusa.com/en/nikon-products/product/camera-lenses/af-s-nikkor-200-500mm-f%2f5.6e-ed-vr.html). I have read a couple of reviews (mostly daytime reviews) for this glass, all saying that it can't beat prime supertele lenses but is far better than similar junk-brand lenses (Tamron and Sigma 150-600mm f/5-6.3). It has a little CA which can be removed in post. It is a buy once and buy good scenario for me, the optic I buy is going to be mine indefinitely because there is no AP gear buyers here. (Having a hard time selling my dob, let alone AP gears.) Now with the given situation, my question is: Can I buy a telephoto lens for large deep sky objects, instead of an apo telescope, without sacrificing quality? ( I will buy a longer FL telescope (say a RC or SCT) in future, but now i have to start with shorter Focal Lengths. ) Lens ads for me: - Can do wildlife in daytime (another fav genre, but AP has priority) - Has a wide Focal Length range, so i can do composition shots of deep sky and landscape - Has a fixed focal Ratio (junk brands FR is not fixed) - More Portability - Can sell it (with a very low price, say a quarter) - Focus is easier - 95 mm aperture (instead of 80mm on apo) Lens cons for me: - if stepped down 2 or 3 steps, star diffraction takes place - Stuck with Nikon system - Cant use filters - Little CA (I don't know if it is going to be a problem, It has 3 ED out of 19) - Price is higher than the apo (around $150 which is not a problem) Thanks in Advance, and sorry for bad English, ReZ.
-
Hi friends, I'd like to make this sunspotter device for my personal use. It seems that I need to buy the following components: - Achromatic lens, 60mm, focal distance 700mm - Mirror 50mm x 50mm - 2 Mirrors 25mm x 25mm But I can't find any website selling any of those . I've seen lots of parabolic mirrors being sold in sizes >= 6'', I've seen tiny achromatic lenses, or lenses costing a fortune. Any advice on where to get lenses and mirrors is appreciated. I haven't looked for the plywood yet, but getting it should be easy
-
Hi! Last week I received my Star Adventurer, and I'm learning how to use it. I had no issues aroud 0 - 80mm, but yesterday I was out trying to take pictures with my 200mm Takumar (300mm on my DX body), and I was struggling to point it towards my target (Andromeda). I know where it is, I could see it with my own eyes, yet, I wasn't able to point my lens towards, only after like 40 minutes... :/ I don't know how others do it, so any advice would be appreciated! What I was thinking about: 1. hot shoe adapter + phone holder + phone / tablet with stellarium, so I would see in the app where my lens pointing (adds weight) 2. some kind of hot shoe adapter + a reflex sight 3. some kind of hot shoe adapter + a green laser pointer 4. a small scope, maybe a finder scope attached to the other end of the declination unit 5. maybe it's overkill, but is it possible to make the Star Adventurer GoTo somehow? Thanks in advance!
-
hi, Which lens is good for astrophotography? i have nikon d3200...
-
Hi, As there are many talented imagers here, and i'm struggling with the unfamiliar techniques involved It was suggested I post a thread and hope that anyone can help with the issues I seem to be at a loss on. Apart from inexpensive lenses, the coma and CA I seem to be getting not only vignetting in the corners but a kind of almost 'dirty' area in the middle like vignetting but with a strange colour to it like the whole middle area is not quite stacking right, or its during capture that the problem starts. Also, processing so many stars is overwhelming either the software or me or both, although i'm sort of sure the data is saveable but the processing ive tried so far just seems to make it more messy. Apologies in advance for the bad explanations and babbling, pls be patient with the text in this post. this is double cluster area, the big reddish blotch like a severe vignette - it looks to me like it stacked badly and the centre looks thin and flattened. this looks like gravely snow which got trampled by muddy footprints with ill-defined dark lanes or something. again with the reddish murky look where the 'tracks' are. Sorry for weird analogies but the technical terms escape me. some more vignette type issue. reddish muddy look and the appearance of uneven stacking also in the middle bit. I tried flats but not sure they were done right and the images with flats dont seem any better. These aren't the only problems but i'm not really certain what i'm doing right or wrong to be honest, i'm hoping you folks can shed some light on it. Any help appreciated, and many thanks for looking. Regards Aenima -
From the album: Venture in widefield.
Pleiades - a few 1-2min exp stacked. Nikon d3100 w/nikkor zoom lens© Aenima
-
Hi All, New to the forum and in astronomy. I got my first telescope about 6 months ago along with a set of eyepieces one of which is the Omegon SWA 32mm (http://www.omegon.eu/omegon-swa-32mm-2r-eyepiece/p,14646) Due to my inexperience and an unfortunate series of events I managed one night to actually unscrew the cap that was holding all the lenses in place and as a result they came out ... Now this happened while observing (!) so I didn't note the order unfortunately ... I have put it back together in what I think is the proper order but the view is now distorted at the edges ... I tried to contact Omegon to provide me with the order of the lenses but they said this is not something they can do. I was wondering if someone that does have this eyepiece and has taken it apart (for cleaning maybe?) could tell me what I am doing wrong ... The attached image shows the current arrangement, with the observer being on the left side and the blue rectangles being the metallic divisions. Thanks in advance for any help!
-
I have for a long time wanted a lens to my Canon DSLR fullframe in the range of 120 mm to 180 mm with high quality. Often the Canon 200 mm 1:2.8 are told to be of good quality for astrophotography. Half a year ago I found a used Sigma 150 mm 1:2.8 APO lens. I have read reviews that it's good for normal photography but almost nothing about astrophotographing. I have done some simple tests of it with photos of M31 Andromeda and M45 Pleiades. If I set the aperature to 4.0 I get sharpness of the stars in the corners and not too much vignetting. I feel this will be a good lens for my future needs. I like those widefield photos where you see the space around your deepsky objects. You can read more on my homepage: http://astrofriend.eu/astronomy/projects/project-sigma-150mm-f2_8-lens-vignetting/project-sigma-150mm-f2_8-lens-vignetting.html There is also a fullresolution image of each, look at that! I used it on my Canon EOS 6D camera and a light weigth Star Adventurer mount. Note that the polar alignment is not perfect and I havn't spent much time to get the color correct. Anyway, what's correct colors on a astrophotography? I used AstroImageJ with my own macros and Fitswork to process the image. I wrote this to inform others like me that seek information about this Sigma lens. Hope it helps somewhat. /Lars
-
Lower price £155 - Canon EF 100mm f/2 USM Lens
bamus posted a topic in Sold / Expired Classified Ads
Canon EF 100mm f/2 USM Lens for sale - lower price 155£ Bought it second habd off ebay before Xmas last year and used only few times. Great f number for astro but realy have to step it down to f3.2 to use it of full frame camera. Havent got much time to use it so have to go. Images to follow. Bank transfe or cash on collection please.
