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Lighting for macro photography of fern gametophytes
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ChrisR
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Joined: 14 Mar 2009
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Location: Near London, UK

PostPosted: Fri Dec 04, 2015 10:51 am    Post subject: Reply with quote

Quote:
I have friends at my local plant science department who deal with vibration by fixing the camera very hard to a strong inflexible plate, and the sample too, but they have more cash than I do, so that option is not open to me.

There's a lot you can do. First is rigidly "connect" your camera to you subject - in other words put them on the same stiff thing. EG a lump of kitchen worktop material. Granite or marble if you have some in the shed, but chipboard will do.
Then isolate your rigid thing from the floor. Think "soft". A slightly-inflated bin liner tied to hold air in, helps a lot. A tyre inner tube, or kids' beach float/pillow, is a posher way.
Doing something like that I get to 5x OK.
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jsp



Joined: 28 Mar 2015
Posts: 354
Location: United Kingdom

PostPosted: Fri Dec 04, 2015 10:52 am    Post subject: Reply with quote

Thank you that's very helpful indeed.

In that case I think I might have a go at either of

1) the 2pcs YONGNUO YN560 IV 2.4GHZ Flash Speedlite + 1pc Yongnuo YN560-TX Wireless Flash Controller:

http://www.amazon.co.uk/YONGNUO-Speedlite-YN560-TX-Controller-Commander/dp/B010D2Y2U8/ref=sr_1_3?ie=UTF8&qid=1449250681&sr=8-3&keywords=yongnuo+speedlite+yn-560+iv

or

2) A Canon speedlite 90ex as master with a speedlite 430ex II as slave, second hand from ebay.

I understand that some Yongnuo flashes fail suddenly after small amounts of use, which concerns me a bit, which is why I also considered the Canon flashes secondhand. It's great to have confirmation that one of these options is the way to go.

About the step size - thanks for pointing that out. I may be mis-remembering the step sizes, because we calculated that quite carefully and bought a scanner with a dpi that seemed high enough, having checked the EOS magazine article on the MP-E to find the DOF at different magnifications. I'll look at that again though. It's clearly important to get that right. :-) If the steps are too long then I just need to use a scanner with a higher dpi (the one that the camera is sitting on in the photo.) I will take a look at that. Thanks!


Thanks also for mentioning about diffraction blurring. I'll read up about that. I've worked with diffraction gratings, so I understand the concept, but diffraction blurring is new to me.

Thanks so much for taking the time to look at my project and give me your thoughts. I appreciate it.

JSP
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jsp



Joined: 28 Mar 2015
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Location: United Kingdom

PostPosted: Fri Dec 04, 2015 10:53 am    Post subject: Reply with quote

ChrisR - Thanks I hadn't thought of that. I'll have a go.
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ChrisR
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PostPosted: Fri Dec 04, 2015 11:00 am    Post subject: Reply with quote

Steps - See table 2A in the middle of this page

Flash- "we " all use manual. I started a small collection of used Nikon SB27s. They all cost less than £20, bought slowly.
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jsp



Joined: 28 Mar 2015
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Location: United Kingdom

PostPosted: Fri Dec 04, 2015 11:22 am    Post subject: Reply with quote

The scanner I'm using Plustek OpticPro U12 which is a 600 x 1200 dpi. We assume 1200 steps per inch which is 0.0211mm long steps.

The other scanner I have is a CanonScan Lide 220 which is a 4800 x 4800 dpi scanner with much shorter steps.

We're not sure whether the Plustek is doing larger steps and then scanning ten lines at a time, or doing one step and then measuring one line at a time. We may need to program it to move 1000 steps and then measure how far it has gone in order to be sure of step size.

Either way, you've given me plenty to get on and do, which is great, as I was really quite stumped before. I'll get measuring the scanner, and look out for a chunk of worktop. :-)

Thanks!
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jsp



Joined: 28 Mar 2015
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Location: United Kingdom

PostPosted: Fri Dec 04, 2015 11:41 am    Post subject: Reply with quote

Thanks for that table. :-)

Would you mind if I ask another question as you're being so kind in thinking about all this?

I understand that for the best focus stacking I ought to have the stepper motor moving the focusing ring on the camera lens so that the distance between the sensor and the fern stay the same. However, I'm actually moving the sample gradually towards the camera, while the focus rings stays still. Do you think that this will be an issue? Theoretically I could hook up the motor to the focus ring, if it would really help.

Thanks!
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jsp



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PostPosted: Fri Dec 04, 2015 11:52 am    Post subject: Reply with quote

ChrisR, how do you trigger your several nikon flashes? That's the part I'm finding costs the money. One flash is easy, but several fired at once seems more expensive to set up. Thanks!

I figure everything will be manual in my project. :-)
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rjlittlefield
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PostPosted: Fri Dec 04, 2015 11:53 am    Post subject: Reply with quote

jsp wrote:
I understand that for the best focus stacking I ought to have the stepper motor moving the focusing ring on the camera lens so that the distance between the sensor and the fern stay the same. However, I'm actually moving the sample gradually towards the camera, while the focus rings stays still. Do you think that this will be an issue? Theoretically I could hook up the motor to the focus ring, if it would really help.

The criterion for "perfect" is actually that the subject stays fixed with respect to the entrance pupil of the lens (the effective aperture position). The sensor position doesn't matter, and perhaps counterintuitively one way to do perfect stacking is to use a bellows, lock the lens in one place, and focus by changing the rear bellows extension to move the camera body.

In your case, the MP-E 65 focuses mostly by extension, so even by turning the ring you would be changing the subject-to-entrance-pupil distance.

Bottom line, what you're doing is fine and is the most common practice at higher magnifications. Needing to focus "by ring" becomes an issue at low magnifications, significantly below 1:1, for example when shooting an entire flower. See http://www.zerenesystems.com/cms/stacker/docs/troubleshooting/ringversusrail for some further discussion.

--Rik
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Lou Jost



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PostPosted: Fri Dec 04, 2015 12:01 pm    Post subject: Reply with quote

I'd like to put in a plug for the Yongnuo 560 series flashes. They go down to 1/180 power, and this seems to eliminate vibration problems almost completely at 10x or below. They also have numerous triggering options, including slave from an on-camera flash and radio control. Best thing you can do to improve your shooting is to get two of these.

Also a plug for blocks of granite or marble, on cork pads.
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ChrisR
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PostPosted: Fri Dec 04, 2015 12:12 pm    Post subject: Reply with quote

Quote:
ChrisR, how do you trigger your several nikon flashes?

These work - ebay 201368540090.

I usually use a "proper" lead from the camera for the main light, but (depending on the camera) if you set the pop-up to a very low power, that''ll do. There are radio triggers etc, of course.

Usually for me "main" and "Fill" are plenty, as macro backgrounds are often absent or uncritical. It's so easy to burn out highlights, a "key" or highlight isn't practical, or can be arranged with a hole through a tissue diffuser.

See Ploum's approach where he needs careful highlights, and uses a number of continuous sources.
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jsp



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PostPosted: Fri Dec 04, 2015 12:38 pm    Post subject: Reply with quote

Thanks, that's great to know that I'm heading in the right direction with stepping the sample towards the camera. :-)

Good to hear that Yongnuo is well regarded, and also about the alternative trigger. This great to have your thoughts on these options.

Ploum's work:

http://www.photomacrography.net/forum/viewtopic.php?t=25241

OMG! Shocked Very Happy
I think my ferns would explode. :-)
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rjlittlefield
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PostPosted: Fri Dec 04, 2015 12:49 pm    Post subject: Reply with quote

ChrisR wrote:
See Ploum's approach where he needs careful highlights, and uses a number of continuous sources.

Results are shown in his gallery thread, http://www.photomacrography.net/forum/viewtopic.php?t=25139. That lighting technique is very effective, particularly because with continuous illumination you can just fly the lights around until you see the right effect. Flashes are both larger and take longer to visualize, typically requiring numerous test shots.

From where you are now, the quickest path to getting sharp photos is to go with flash. But you'll give up some control by going that route, and I don't know how you'll feel about that tradeoff.

--Rik
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Charles Krebs



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PostPosted: Fri Dec 04, 2015 2:04 pm    Post subject: Reply with quote

If you need to purchase the flash components, I really like your first suggestion above. The Yongnuo YN560-TX with a couple of 560 III or IV is an extremely versatile arrangement. The ability to easily set manual power levels and trigger the flashes from the on-camera YN560-TX is extremely nice. (And you will only be using manual flash for image stacking). Between my son (also a photographer) and myself we've used a pretty fair amount of Yongnuo (flashes, transmitters and receivers) over the past few years. Initially I was leery of the reliability (based on web comments), but it has all worked well. (Naturally I can't guarantee what your experience would be Wink ).

IMO your set-up (based on the picture you recently posted) really needs to be improved as far as maintaining a constant, rigid relationship of camera to subject (as long as there is nothing causing vibration in the scanner component). It seems this could be accomplished very inexpensively. Perhaps a solid piece of wood running under the scanner and extending enough to attach the camera to one end.

A Canon body like yours, with effective EFSC (be sure camera is set to use Silent Mode 1 or 2 when in live-view!) really will provide images with continuous light that are comparable to electronic flash provided there is no external, or "environmental" vibration source. Perhaps I am spoiled since this is not an issue for me... as long as I pay close attention to some potential problems... no loud music, no washer/dryer running upstairs, no family members with "heavy feet" running around. I do realize that some people live in environments where it might not be possible to avoid all external vibration. Flash is then the best option. But I have moved from electronic flash to continuous light because it is so much easier to set up attractive lighting since you can actually see the lighting effect as you adjust the light positions.

Plant materials (especially cut sections) are extremely hard to keep from moving or wilting during the acquisition of an image stack. If the entire piece in the picture moves "together" then turning on the x/y/and rotation settings in the stacking software will help immensely. But very commonly, parts of the plant specimen that are in the picture will move relative to other parts that are in the picture. This is a big problem, so mounting and bracing the subject carefully can help a great deal.
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Lou Jost



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PostPosted: Fri Dec 04, 2015 5:38 pm    Post subject: Reply with quote

It might be quite cheap to buy a couple of big ceramic or marble tiles to serve as a solid base. I didn't spend much on mine. They give great stability. I drilled mine so I can either attach the camera directly (very sturdy) or attach a Stackshot (less sturdy).
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jsp



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PostPosted: Sat Dec 05, 2015 1:15 am    Post subject: Reply with quote

Hi,

We've got a carpenter in and by pure luck, he's left a hefty chunk of worktop in my front garden. I've been out and appropriated it. Very Happy

Ploum's photos are amazing, I see what you mean. I think I'll be better with flash though, because fern gametophytes wilt like bits of lettuce would if cut at the same size. I think even those LEDs would be too much for them.

I'll have another look at those Yongnuo flashes. They seem like a good plan.

Thanks for all this feedback.
Very Happy
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