d70 1/500th sync speed q's

goodoneian · May 10, 2009

i know that both the d70 and d70s (and d50 i believe?) have the capability of syncing at 1/500th of a second with flash, as opposed to the 1/250th that most cameras can (including my d300). this seems appealing to me to possibly pick up a used one for those tricky and bright situations where i don't want a ton of depth of field, but i have one question.

since the d70/s iso low is 200, and my d300's is 100, doesn't wouldn't that negate the fact of being able to use a stop faster shutter speed? let's say in a hypothetical situation i'm using my d300 and my settings are iso 100, 1/250, and f/8. with the d70 at iso 200, 1/500th, wouldn't the exposure also have to be at f/8 still?

i could be totally confusing my self haha, but if anyone could clear things up for me that would be apprecaited

epp_b · May 11, 2009

The benefit is that it requires less flash power and therefore, the flash recycles faster, uses less battery life, etc.

If you could sync all the way up to 1/4000th (which you actually can on the D70/D50/D40 by blocking the iTTL contacts; or on others with FP sync) and used ISO 1600, it would still be useful to have the extra sync speed because it requires even less power from the flash.

Garbz · May 11, 2009

ISO like Aperture affect the input of light into the lens. Where as shutter speed affects the light recorded in a given time. Thus Aperture and ISO have a direct effect on flash power for a given photo, but since the flash duration is short it means that shutter speed will not affect the flash exposure at all.

The higher shutter speed will thus allow you to darken the background in relation to the subject which may be lit by the flash. This is good but if your minimum ISO is 200 then the camera is more sensitive overall. The end result is that you need to drop your aperture size to compensate.

goodoneian · May 11, 2009

hmm i think i may have been somewhat misunderstood, but that's my own fault since my original question was worded poorly. i'm fully aware of how aperture, iso, and shutter speed effect the picture when using flash.

what i mean to ask is, isn't 1/250 @ iso 100 the same as 1/500 @ iso 200? i'm pretty confident that it is. so wouldn't there technically be no difference in using the d70/d50 as opposed to my d300? or am i missing something

Garbz · May 11, 2009

What I was saying is that while it is true that for a normal exposure there is no difference, when you are using a flash you end up using half the power. ISO200 instead of ISO100 vs shutter speed which does not affect flash.

Thus you get an additional stop latitude when using balancing flash against ambient light before your flash conks out. But you need to lower the aperture to take advantage of it, which goes against your depth of field requirement.

JerryPH · May 11, 2009

Yes it is the same amount of light... *without* the flash. With the flash at different powers you will have that difference in terms of shutter speeds that are not available on the other cameras that cannot sync higher than 1/250th. What Garbz said becomes pertinent when you are talking lightly lighter conditions where you do not want to raise ISO but still have a dark background while most effectively using your flash power settings.

IE: You have a nice shot at ISO 100, 1/250th and F/8... but though your subject is well lit, your background is a touch too bright. If you riase ISO to 200, EVERYTHING rises, so you will need to now lower flash power 1 full stop to get the same results. Now... your background is still a little too obtrusive... raise shutter speed to 1/500th, background drops a full stop and things are the same as before... but now, take it one step further... set shutter speed to 1/1000th... suddenly things are just right plus your flash is putting out 1/2 the amount of light to accomplish the same subject lighting. Yes, th D70s can do that too (sync above 1/500th).

See the interaction?

tsaraleksi · May 11, 2009

Yes, you're right. 1/500, f/8, ISO200 = 1/250, f/8, ISO100, so the benefit of a faster sync speed is lost in that respect.

NateS · May 11, 2009

Easy solve to your problem which I just did myself.

If I understand correctly, you are wanting to let less light in during the day (i.e. faster shutter or lower iso) but still be able to use your flash sync. Also possibly to use a lower aperture outside and with flash than what you can currently do.

Pick up a 3 stop (0.9) ND filter. I just picked up a Hoya HMC 3 stop ND filter to use outdoors. My reasoning is that I wanted to be able to darken the background (in broad daylight) and lighten the subject with the flash....can't be done with 1/200th. Throwing my 3 stop ND filter on and now my 1/200th is about the equivalent light as 1/1000 (May not be exact). This will let me 1....block enough light to not have a washed out background at 1/200 and 2....keep me from having to shoot outdoor portraits at f/16 to block enough light for shooting 1/200.

Now I should be able to shoot f/8 or even larger in the sun without overexposing my background....light the subject with flash.

I have only done some simple tests so far, but plan to get out and do some real shooting with the setup soon.

epp_b · May 11, 2009

Yes, you're right. 1/500, f/8, ISO200 = 1/250, f/8, ISO100, so the benefit of a faster sync speed is lost in that respect.

The calculations are correct, but your conclusion is wrong. The benefit is that the flash uses less power (recycles faster, batteries last longer, etc.)

tsaraleksi · May 11, 2009

epp_b said:
The calculations are correct, but your conclusion is wrong. The benefit is that the flash uses less power (recycles faster, batteries last longer, etc.)

But that is the only benefit, versus the usual benefits of higher sync speed, namely, the ability to drown the ambient with a faster shutter instead of a smaller f/stop.

goodoneian · May 11, 2009

okay i think i understand now. basically my only benefits would be that assuming with that hypothetical situation, at iso 100 and 1/250th i would be using full power, but with iso 200 and 1/500th i would be able to use half power? both apertures being f/8

goodoneian · May 11, 2009

NateS said:
Easy solve to your problem which I just did myself.

If I understand correctly, you are wanting to let less light in during the day (i.e. faster shutter or lower iso) but still be able to use your flash sync. Also possibly to use a lower aperture outside and with flash than what you can currently do.

Pick up a 3 stop (0.9) ND filter. I just picked up a Hoya HMC 3 stop ND filter to use outdoors. My reasoning is that I wanted to be able to darken the background (in broad daylight) and lighten the subject with the flash....can't be done with 1/200th. Throwing my 3 stop ND filter on and now my 1/200th is about the equivalent light as 1/1000 (May not be exact). This will let me 1....block enough light to not have a washed out background at 1/200 and 2....keep me from having to shoot outdoor portraits at f/16 to block enough light for shooting 1/200.

Now I should be able to shoot f/8 or even larger in the sun without overexposing my background....light the subject with flash.

I have only done some simple tests so far, but plan to get out and do some real shooting with the setup soon.

you pose an interesting point. a neutral density filter doesn't effect the power of the flash? this may be an obvious answer but i never though of that idea

Garbz · May 12, 2009

No the ND filter DOES affect the flash power but doesn't affect the depth of field, which I thought is what the point of the topic is.

1/250th ISO100 f/8 is the same as 1/250th ISO200 f/8 with a ND1 filter. Thus allowing you to up the shutter speed to 1/500th with all other variables staying the same effectively reducing the darkness of the scene compared to the flash.

So the ND1 filter directly counters the 1 stop increase in ISO, all other variables staying the same you WOULD benefit from the higher sync speed of the camera.

goodoneian · May 12, 2009

Garbz said:
No the ND filter DOES affect the flash power but doesn't affect the depth of field, which I thought is what the point of the topic is.

1/250th ISO100 f/8 is the same as 1/250th ISO200 f/8 with a ND1 filter. Thus allowing you to up the shutter speed to 1/500th with all other variables staying the same effectively reducing the darkness of the scene compared to the flash.

So the ND1 filter directly counters the 1 stop increase in ISO, all other variables staying the same you WOULD benefit from the higher sync speed of the camera.

the point of the topic was about depth of field, i was just asking about the flash being effected by the ND filter.

so another hypothetical situation:

i'm using my d300 at iso 100, 1/250th, and f/8, my flash at half power. i put the 1 stop ND filter on and lower my aperture to 5.6. i would then have to raise my flash to 1 full power to for the exposure, correct?

if so that's a pretty even trade for me, since it's less depth of field and that's what i would like to achieve the vast majority of the time

JerryPH · May 12, 2009

Well if you are using CLS, what is stopping you from using F/2.8 and a higher shutter speed to *both* decrease background light and DOF? Look up High Speed FP flash in the D300 manual.

This lets you use up to 1/8000th of a second shutter times, as long as your Nikon flash is close enough and powerful to properly expose the subject you can do anything to the background in terms of darkening or blurring it.