Re: Help with multiple strobe hit calculations
Quote:
Originally Posted by
Brian K
... it's better to darken the studio, open the shutter and block the lens in between pops with a black card ...
Never had to use a black card - maybe because I close down beyond f32. Right on to leave the shutter open though. Reciprocity should be no problem - a slow (1/1000sec) flash multiplied by, say, 20 is about 1/50sec. The head and tail of the flash count for about 1/4 intensity (try pouring peas from a packet to see that).
Re: Help with multiple strobe hit calculations
Quote:
Originally Posted by
Christopher Broadbent
Never had to use a black card - maybe because I close down beyond f32. Right on to leave the shutter open though. Reciprocity should be no problem - a slow (1/1000sec) flash multiplied by, say, 20 is about 1/50sec. The head and tail of the flash count for about 1/4 intensity (try pouring peas from a packet to see that).
Most of the electronic studio flash units, of the type commonly used for still life are closer to a 1/250th of a second in flash duration. There are some exceptions but not many that supply high watt output and high speed. This is why I used to use Ascor Sunlights for freezing splashes and pours. They were one of the few that supplied high speed and high wattage. Your figure of 1/1000th as being a "slow" flash is not accurate. That would be a low powered flash and even if the manufacturer rated it's speed as such, most often that speed is grossly overstated.
When I spoke of afterglow I was not referring to the head and tail falloff of the flash but the fact that when a flash is fired in a multiple pop type situation the tube gets hot and can glow. This glow can be sufficient to cause a color tinge depending on the aperture, film speed and film reciprocity characteristics.
Re: Help with multiple strobe hit calculations
aphexafx,
I'm also new to this forum (my first post..)and I just didn't have enough patience to read all to responses to your problem.From what I read, didn't see the suggestion I'll make, that I use myself to gain DOF in some my photos. Or you maybe have already did so by default (again, didn't read all responses) But...
Have you tried focusing the lens further past the subject? To explain myself , in front of the subject you have 1/3 distance DOF and behind you got 2/3s of the DOF.
Am I making sense?
That means that if you focus past your subject you gain 1/3 of the DOF that otherwise would get "wasted" the subject would seem out of focus but when stopped down it will gain the 0.10 (?) circle of confusion proprieties you need do define as "in focus"
Thanks and good luck with this endeavor
Arpi
Re: Help with multiple strobe hit calculations
Hi arpipap, welcome.
You make a good point. Yes I do take this into account, and in fact my 4x5 has an exposure calculator that helps define the DOF for the working aperture, and using this feature I always back my focus appropriately into the scene so that the DOF is split, as you suggest.
Re: Help with multiple strobe hit calculations
"in front of the subject you have 1/3 distance DOF and behind you got 2/3s of the DOF. "
This is true for infinity but at this setup he is at about 1:3 which start to go more in the direction of 2/5 in front and 3/5 back if I remember correctly at 1:1 its 50:50 to the front and back.
I would take the shoot with my 120 mm Macro Sironar gets lesser DOF problems, with shorter lenses!
Cheers Armin
Re: Help with multiple strobe hit calculations
Quote:
Originally Posted by
Armin Seeholzer
"in front of the subject you have 1/3 distance DOF and behind you got 2/3s of the DOF. "
This is true for infinity but at this setup he is at about 1:3 which start to go more in the direction of 2/5 in front and 3/5 back if I remember correctly at 1:1 its 50:50 to the front and back.
I would take the shoot with my 120 mm Macro Sironar gets lesser DOF problems, with shorter lenses!
Cheers Armin
I have a 120mm Nikkor-AM, however the DOF issue would be similar: I would have to move in thus reducing the lens to subject distance. This would also increase perspective distortion, which I definitely don't want to do.
I've learned tons since I started this thread; so after I get my studio back together I guess I'll set this up again and mess around with it!
Thanks, Armin.
Re: Help with multiple strobe hit calculations
If you have the patience to do the post-processing work, you can make multiple exposures using focus bracketing (changing the focus point for each sheet of film), then combining the images in Photoshop.
Folks like Gregory Crewdson have been doing this to get greater apparent depth of field (for him with his 8x10.) He is shooting at wider aperatures on multiple sheets of film. He then scans each sheet of film and combines them using layers in Photoshop, using just the in focus part from each sheet of film.
Personally, I don't think I have the commitment necessary to any single image to do the work required. Put another way - I get bored spending that much time on any one image! :D
I like to make images, and I love the "pop" of the strobes in the studio. But after that I hate finishing the image and doing output. I just want to make new images. Unfortunately, I can't afford teh assistants required to just hand off the "rough draft." :)
It still would be a great experiment, and a great tool to have in your kit for when it is really needed. Ket us know how it goes if you try it.
Best,
Michael
Re: Help with multiple strobe hit calculations
Hi Michael - somehow I didn't notice your response until now, sorry about that...
With Crewdson being the extreme, I am a believer in multi-exposure techniques for studio work for everything from wire removal to focus composites to extended DR and even noise removal.
However, I am also interested in perfecting my pure 4x5 technique! Thanks for the suggestions.
I am the opposite of you, then. I love spending all day on a shot and all night editing it! If there is something I can't master, I have no problem taking the set down and committing to studying what I need to know, and going back later to do it right!
I think that most of the members here are of the fine-art alliance, but I love commercial and product work, I'm totally passionate about it and learning more every day. Studio work invites absolute perfectionism and I love it. :)
Re: Help with multiple strobe hit calculations
Aphexafx: What is the actual depth of your set-up from the front edge of the first glass to the background card? There are several DOF calculators linked on the homepage of this forum. Work through some examples and figure out what it will take.
Consider usingdifferent subject elements. I think you might look at two different strategies:Both involve changing the size of the glasses.
Smaller glasses and a smaller overall set-up may fit into the DOF that your current equipment will provide in a macro configuation.
Using larger glasses and a larger set-up will allow you to back away from the macro configuration and shoot with less extension (fewer Pops) and larger DOF.
Re: Help with multiple strobe hit calculations
Quote:
Originally Posted by
Drew Bedo
Aphexafx: What is the actual depth of your set-up from the front edge of the first glass to the background card? There are several DOF calculators linked on the homepage of this forum. Work through some examples and figure out what it will take.
Consider usingdifferent subject elements. I think you might look at two different strategies:Both involve changing the size of the glasses.
Smaller glasses and a smaller overall set-up may fit into the DOF that your current equipment will provide in a macro configuation.
Using larger glasses and a larger set-up will allow you to back away from the macro configuration and shoot with less extension (fewer Pops) and larger DOF.
Hey there, Drew. Well if I remember correctly, there was perhaps one or two feet between the front of the glasses and the background, mostly due to the fact that I was trying to light it evenly without any spill onto the glasses, and soft boxes are awkward...
I really do want to play with larger glasses, but I have yet to go looking for them. I will keep that in mind this week, though. It is a great solution, and large stemmed glasses would make great props for future still life anyway use, I am sure.
Another solution I have thought of is to use translucent plexiglas sheets (red/yellow) with an opaque black paper center for the background and light it from behind - I could then get as close as I needed. Plexiglas is pretty cheap, and I'm going to order some for my scanner anyway... It might be just the ticket. I would probably be able to control the hotspots much more easily as well? Not to mention, the contrast would be automatic. The entire back end would need to be masked off from the front end in order to avoid any edge diffraction on the glasses..sounds like great fun actually!
I am forever grateful for all the suggestions here. Tonight I shot another scene to 4x5, and it was also prototyped with a digital (shown below), so I look forward to seeing how I've managed to translate the exposure this time.
http://farm4.static.flickr.com/3409/...8594948aab.jpg
Obviously I am no Broadbent lol. :D But I'm having fun.