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Equipment Discussions >> Electronically Assisted Astronomy

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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
5-100mm F1.4 Auro Iris Varifocal CCTV Lens new
      #5681067 - 02/15/13 10:16 AM

What happens if we use a 5-100mm F1.4 Auto Iris Varifocal CCTV Lens on a CCTV with DC Iris to view large DSOs (e.g. M31,etc)?

Considering the lens has Auto Iris, will the CCTV keep the iris wide open at night when shutter speed is on manual?

I'm talking about a lens like this http://www.spy-shop.ro/supraveghere-video/lentile/lentila-varifocala-cu-auto-... .

If I'm not wrong, the image scale of DSOs with this lens+CCTV will be similar to the one given by a APS-C DSLR + ST80 scope, considering the much smaller sensor of the CCTV and inherent magnification (I think 4 times more than a APS-C DSLR).


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: 5-100mm F1.4 Auro Iris Varifocal CCTV Lens new [Re: Moromete]
      #5681162 - 02/15/13 11:00 AM

Or maybe this lens is better having manual iris too? http://www.bhphotovideo.com/c/product/414191-REG/Tamron_13VM20100AS_13VM20100...

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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: 5-100mm F1.4 Auro Iris Varifocal CCTV Lens new [Re: Moromete]
      #5684980 - 02/17/13 11:11 AM

Anyone?

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bhuvfe
member


Reged: 01/14/11

Re: 5-100mm F1.4 Auro Iris Varifocal CCTV Lens new [Re: Moromete]
      #5685245 - 02/17/13 01:36 PM

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5359670/page...

Maybe of interest?


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ccs_hello
Postmaster
*****

Reged: 07/03/04

Re: 5-100mm F1.4 Auro Iris Varifocal CCTV Lens new [Re: Moromete]
      #5685348 - 02/17/13 02:35 PM

The linked one (sold by BH) is a cheapie.
On that 20-100 f/1.6 zoom, f/1.6 is not going to happen on the long focal length side.

For astro application...

Bottom-line, unless you can get a deeply discounted (e.g., one cent on the dollar) used "Studio Grade" video camera lens (you still have to do your own lens mount adaptation), you'd rather get a telescope OTA.

Also, (again for astro), do not use any form of IRIS control! Keep it wide open.

Clear Skies!

ccs_hello


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: 5-100mm F1.4 Auro Iris Varifocal CCTV Lens [Re: bhuvfe]
      #5686427 - 02/18/13 04:42 AM

Thank you.

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