DCS 760 without filters?

What happens if you use a DCS 760 without the filters under studio flash conditions? I'm asking because sometimes when I shoot into a white background I seem to get a general flare. If I'm using Profoto strobes with UV coated tubes will I have a problem with IR? And how will it manifest itself?

Thanks, Kirk

Kirk Tuck said:

What happens if you use a DCS 760 without the filters under studio
flash conditions? I'm asking because sometimes when I shoot into a
white background I seem to get a general flare. If I'm using
Profoto strobes with UV coated tubes will I have a problem with IR?
And how will it manifest itself?

Thanks, Kirk

Click to expand...

Kirk I never use any filter on DCS 760.

George
http://www.1000gkphotos.com

Kirk Tuck said:

What happens if you use a DCS 760 without the filters under studio
flash conditions? I'm asking because sometimes when I shoot into a
white background I seem to get a general flare. If I'm using
Profoto strobes with UV coated tubes will I have a problem with IR?
And how will it manifest itself?

Click to expand...

Hi Kirk,

Completely removing the filter (no AA and no IR) will give you a much sharper image an reduce a ton of flare in the system....
However, there are 2 downsides:

1) Your focus will be slightly off (not really an isssue if you shoot at or above f8..)

2) You will need to add an IR filter to your lens (if get a "Hot Mirror") or you will get magenta highlights (from IR contamination)..
(If you shoot under tungsten you should hunt down a BG40 or a BG39)

For the Absolutely SHARPEST image from a 760, I'd reccomnend taking out the filter...

-Jay

Jay Kelbley

Jay, if you're still here:

Jay Kelbley said:

Completely removing the filter (no AA and no IR) will give you a
much sharper image an reduce a ton of flare in the system....
However, there are 2 downsides:
1) Your focus will be slightly off (not really an isssue if you
shoot at or above f8..)
2) You will need to add an IR filter to your lens (if get a "Hot
Mirror") or you will get magenta highlights (from IR
contamination)..

Click to expand...

Ummm .. can you elaborate on this a bit?

On my DCS720x (w/AA filter) and DCS760 (w/IR filter), the "focus is on" in the sense of the AF and focus indicators.

BUT, the markings on the lens (any lens, from 15mm to 300mm) are waaaay off. On, say, an F2 or F3, one can set the distance (e.g. 5m) on the lens, for an object at 5m, and it will be in focus. With the DCS7xx cameras, set it to 5m, and the object will not be in focus. IIRC, I would need to set the distance to an indicated (on the lens barrel) 3m or so (say, on a 105mm lens) for an object at 5m to be in focus.

Similarly, objects at infinity require the lens to be set to something quite a bit shorter than infinity to be properly focused.

This really screws up hyperfocal settings, etc.

I'm not the only person to notice this -- another aerial photographer made a strong point about not trusting the hyperfocal distances with these cameras.

I've tested the DCS720x and DCS760 (with standard and 6x waist-level finders) against a variety of other Nikon 35mm SLRs, and the result is always the same.

So, what's up with that? Does the filter (IR or AA) ahead of the mirror change things n terms of where a lens focuses it image on the film plane / imager?

--Andrew

andrew kalman said:

So, what's up with that? Does the filter (IR or AA) ahead of the
mirror change things n terms of where a lens focuses it image on
the film plane / imager?

--Andrew

Click to expand...

Hi Andrew,
In summary, yes...

However the sensors in the 760/720x are positioned (focussed) assuming that the filters are installed..

So, if you take the filters out, then the focus should be off.. (ie. it should be "on" with the filter installed)..

-Jay

--

Jay Kelbley

Jay Kelbley said:

In summary, yes...
However the sensors in the 760/720x are positioned (focussed)
assuming that the filters are installed..
So, if you take the filters out, then the focus should be off..
(ie. it should be "on" with the filter installed)..

Click to expand...

Interesting ...

What I've never understood is how the lens focus indicator can be off, even if the view through the finder shows correct focus (which would seem to me to indicate that the imager is at the usual Nikon lens-flange-to-film-plane distance (of 46.5mm, IIRC) and the body's focus indicators also show correct focus.

Thanks for your reply. A longer explanation would be really great, but hey, you're not at Kodak anymore, so you're not obliged ...

--Andrew

Jay on DCS 760 I never use any filter and never had any problem with AF focus on lens from 16mm to 400mm including converters.

George
http://www.1000gkphotos.com

Jay Kelbley said:

andrew kalman said:

So, what's up with that? Does the filter (IR or AA) ahead of the
mirror change things n terms of where a lens focuses it image on
the film plane / imager?

--Andrew

Click to expand...

Hi Andrew,
In summary, yes...
However the sensors in the 760/720x are positioned (focussed)
assuming that the filters are installed..
So, if you take the filters out, then the focus should be off..
(ie. it should be "on" with the filter installed)..

-Jay

--

Jay Kelbley

Click to expand...

Dear 760 shooters. I posted the same query on RobGalbraith.com and one individual knew about a modification to the d760 that is user implementable. It is call modification #1 and is a piece of self adhesive foam that is applied to the inside of the AA or IR filter from to "prevent internal reflections....". The mod is Kodak service code 3874 or 4882. If you call customer service they will send you the piece, with instructions, free of charge. I have effected the repair and it does improve resistance to general flare. Hope this helps someone else as much as it helps me.

Kirk