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Post by michaelmorris on Feb 1, 2014 12:42:23 GMT
I'm putting together a new video set up for recording meteors based on a Watec 902H2 ultimate with an f1.4 4mm auto-iris lens. Any suggestions on a good source of inexpensive but optically sound domes gratefully received.
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Post by BillW on Feb 1, 2014 17:26:11 GMT
Hi,
It's a problem getting good optical quality. Edmund Optics sells small domes that might be worth considering. Do a google for their web site.
I've tried 2 different perspex types and they've both been pretty rubbish optically. Looking trough you could see all the distortions.
At 4mm can you not get away with a standard enclosure using a flat window with the lens close to the window.
This works with my own zoom lenses but they're set to around 5mm. That might make all the difference!
Edmund also do a range of thin anti reflection coated windows which aren't too expensive. you might need a slightly larger window than on a standard cctv enclosure but at least the quality of image would be better. So a home made version might be in order.
I would recommend tilting the lens with respect to the window a little to minimse internal reflections.
Let us know how you get on if you do find a good dome.
Cheers,
Bill.
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Post by leolion on Feb 1, 2014 17:38:44 GMT
Replying to the question re optically sound domes :- I sourced mine from Surplus Shed in the States in both 4" and 5" sizes.They do not have them listed currently.I've checked my files for UK sources and believe this firm,Talbot Deigns, would suite www.talbotdesigns.co.uk/acrylic-domes/ . There is a link on there website to a PDF with pricing , flange sizes etc.Prices look OK and they have provided for Antarctic research. As you are using a 4 mm lens on an 1/2" CCTV camera the usual flat window 'box' housing should be OK unless you plan to use a pan/tilt arrangement. |
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Post by stewartw on Feb 2, 2014 7:25:12 GMT
Hi Michael,
Agreed - I know a couple of operators who use 3.8mm lenses in standard CCTV housings with flat front screens and they have no problems with the edge of the housing restricting the FOV.
What stellar limiting magnitude are you able to achieve with the 4mm f1.4 lens?
Best regards
William
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Post by stewartw on Feb 21, 2014 7:50:09 GMT
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Post by astroshot on Mar 1, 2014 22:58:47 GMT
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Post by BillW on Mar 21, 2014 22:49:19 GMT
Hello Astroshot,
Appologies for the tardiness of my response.
Welcome to the forum!
cheers,
Bill.
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Post by michaelmorris on Mar 28, 2014 15:34:02 GMT
Thanks for the heads up on the lens - looks to be exactly what I'm after. I've just ordered one. |
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Post by BillW on Mar 30, 2014 0:29:08 GMT
Yep, me too! I've made a new mounting plate for the equatorial mount so the camera's carrying the 12mm f0.8's will maintain their position relative to the radiant. A third camera will have this wide field lens on it so I can see what meteors leave what (if any) spectra.
I only hope the weather gives us a break for the Lyrids! I've only had a few hours since the start of the year with very little going on.
cheers,
Bill.
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Post by BillW on Mar 30, 2014 0:32:56 GMT
A quick PS.
It was interesting, maybe shocking might be a better word though!!!, to see SonotaCo say he paid $400 for this lens when they were on general sale.
If they are in new condition with a correction lens I think we have got the deal of the decade even with steep shipping!
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Post by BillW on Apr 7, 2014 18:18:59 GMT
Hi, Had a few hours of clear sky yesterday evening so had a chance to use the 2.6mm f1 lens. Here's a nice bright meteor....  Gamma Ursa Minor can just be made out, this is mag +3! I'm impressed, Nice! cheers, Bill. |
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Post by stewartw on Apr 8, 2014 6:58:51 GMT
Hi Bill,
Very nice indeed - I didn't think you'd be able to get that deep! Well done.
Cheers
William
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Post by michaelmorris on Apr 8, 2014 7:27:37 GMT
A quick first try with my 2.6mm f1 lens with my Watec 902H2 Ultimate is showing stars down to around mag 2. I'm sure this can be improved with a little tweaking of the set up.
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Post by michaelmorris on Apr 8, 2014 7:35:46 GMT
I'm looking at domes and need to decide on what diameter to go for. This will, to an extent be informed by where is best position within the dome to place the lens. From doing a little reading on the web it seems there may be two conflicting criteria. Various bits of advice from the underwater photography community suggest putting the front of the lens at the base of the dome gives the least optical distortion of the image. Advice to the security camera community suggests mounting the lens as far forward as possible to reduce internal glare. Does anyone have any experience of the best option for a meteor set up (f2.6 f1 lens)
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Post by michaelmorris on Apr 8, 2014 7:50:44 GMT
A quick PS. It was interesting, maybe shocking might be a better word though!!!, to see SonotaCo say he paid $400 for this lens when they were on general sale. If they are in new condition with a correction lens I think we have got the deal of the decade even with steep shipping! These are great lens and they're seriously under priced (£29.64 delivered). I've just ordered a second one as a spare! |
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