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Issues with HPX-370 and 2/3" lenses

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Ian Liuzzi-Fedun
Issues with HPX-370 and 2/3" lenses
on Jun 19, 2015 at 1:42:48 am

Recently I tried throwing a 2/3" lens using a 1/3" to 2/3" adapter on my 370. For some reason the image was soft with haloing around objects. Any idea why? I have checked the lens and tried other lenses that are known-working. I have spoken with other 370 users and they appear to have the same issue.

Only way to get any level of sharpness was to zoom in to the last 40 or so mm on the lens.



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Ian Liuzzi-Fedun
Re: Issues with HPX-370 and 2/3" lenses
on Jun 19, 2015 at 1:45:44 am

As a corollary - I did try like hell to adjust the back focus.



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Tom Matthies
Re: Issues with HPX-370 and 2/3" lenses
on Jun 19, 2015 at 9:14:42 pm
Last Edited By Tom Matthies on Jun 19, 2015 at 9:16:28 pm

A 2/3-inch lens will do this if the lens is in a wide open setting-the iris is full open. Light rays will bounce all around between the rear of the lens and the MOS sensors.If you can stop the lens down a stop or two, the problem will usually go away or at lease minimize. Dial filter #1 into position to let the maximum amount of light into the camera. If you are using it outdoors on a sunny day, use filter 2 or 3 to avoid too small of an f-stop. The "sweet spot" for 2/3-inch lenses on a 370 seems to be around f5.6-f8. Performance will also depend on the speed (minimum f-stop) of that particular lens. Generally the faster the lens, the more light it can gather and the smaller the f-stop you can use in dim light.
Light your scene as best you can and stop the lens down to f2.8-f4 and it will look much better.

Not my monkeys. Not my circus.


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Ian Liuzzi-Fedun
Re: Issues with HPX-370 and 2/3" lenses
on Jun 22, 2015 at 2:10:01 pm

Quite interesting. I have heard this before.

In fact the only way I was able to get it sharp when it was at the wider angle was to either use some serious ND or iris down to around F8.

All this being said I've used many EX-3s with B4 mount 2/3" lenses and haven't had this issue. Is the 2/3 to 1/2 difference really not as significant as the 2/3 to 1/3. This makes using 2/3" lenses quite impractical for concert-type work.



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