Need suggestion on lightening, output yellowish (pic inside)

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leekekhuan
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Need suggestion on lightening, output yellowish (pic inside)

Post by leekekhuan »

Hi,

First i would like to thanks everyone who posted their rig and suggestions to keep newbie like us going in right direction.
So after spending weeks and collecting my all necessary items i was able to take my first micro shot.

Image

I try diffusing light with all different DIY items available at home but i can get yellowish output rather white. Should i go shop and buy diffuser like
http://www.bhphotovideo.com/c/product/7 ... m/alsVwDtl?

BTW here is my setup (inspired by one of the rig i saw here)
Image.

Any advice will be appreciated.

Thanks in advance.
LEE.
Last edited by leekekhuan on Mon Jul 13, 2015 7:18 am, edited 1 time in total.

rjlittlefield
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Post by rjlittlefield »

Lee,

1. The simplest way to fix your yellow cast is to set a custom white balance on your camera to compensate for whatever the diffuser is doing to the spectrum. Just stick a piece of white card in front of your subject so that its front surface is illuminated by the flash, take a picture of that, and set white balance from the completely out-of-focus image that you'll get. You'll probably have to dial the exposure down to compensate for the card's being white instead of gray, but with flash that will not significantly affect the color balance. Be sure that no light is coming through the white card, or you'll end up with weird colors again because then your color balance will incorporate whatever the transmission spectrum of the white card is.

2. I notice that you have pretty severe "focus banding", with several bands of obvious blur between the bases of the antennae, on the front panel of the face, and in the mandibles. Looking at your setup, it's not obvious to me how you are stepping focus. As you probably know already, the depth of field of a 10X objective is only about 8 microns (0.008 mm), so very precise control of stepping is required. If you don't have a way to reliably make such small steps between the subject and lens, then consider stepping focus by moving the rear standard of the bellows while keeping the subject and objective in one place. Movements of the rear standard are about magnification-squared less sensitive than changes in subject-to-lens distance, so your depth of focus back at the sensor is more like 10*10*0.008 = 0.8 mm. It is much easier to make such a large movement reliably. You won't be able to make as deep a stack that way, but for what depth you can cover, the quality should be much better.

I hope this helps...

--Rik

leekekhuan
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Post by leekekhuan »

Rik,

Thank for quick reply and helpful answer.
1- Dully noted.

2- I am using "Nikon PB-6" knob to move my entire camera setup (which is not giving me precise movement), but i am planning to buy StackShot. This was just rough test and want to see if everything works.

BTW looking at my setup, what is macro range i am getting 10x? And how to find if it not 10x (that was a stupid question, i am using NIKON M PLAN 10 0.25 210/0 MICROSCOPE OBJECTIVE :lol: ).

Thanks again,
LEE.

rjlittlefield
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Post by rjlittlefield »

leekekhuan wrote:BTW looking at my setup, what is macro range i am getting 10x? And how to find if it not 10x (that was a stupid question, i am using NIKON M PLAN 10 0.25 210/0 MICROSCOPE OBJECTIVE. :lol:
Ah, but that's not a stupid question, and in fact you're probably not getting 10X from the setup that you show. :idea:

A 10X finite objective like you're using will give pretty accurately 10X if -- and only if -- it's positioned at the correct distance away from the sensor plane.

That distance depends on the objective's designed "tube length". For your objective, that's probably 150 mm, as discussed at FAQ: How can I hook a microscope objective to my camera?.

But in your setup, the distance appears to be a lot more than 150 mm, in which case you're getting more than 10X. How much more is essentially impossible to calculate exactly. It's much more practical to just measure it, by taking a picture of something with known size and then measuring the image.

For small things, the best something with known size is called a "stage micrometer", which consists of a tiny ruler printed on a microscope slide. A typical unit is 100 tick marks in 1 mm, so 0.01 mm per tick mark. These days they can be conveniently purchased on eBay, new, for as little as $7 USD including shipping to the U.S.

But at only 10X (or a little higher), you're seeing at least a 1 mm field of view, so it works OK to use an ordinary mm scale. Just be sure to measure between the centers or corresponding edges of the marks. It is surprisingly easy to measure from the edge of one tick mark to the opposite edge of another tick mark, which gives a number that is way too large or too small depending on which way you've gone.

--Rik

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Post by rjlittlefield »

By the way, when you post images larger than the recommended 1024 pixels wide, you end up changing the forum page format so that users with small screens have to scroll back and forth, back and forth, just to read a paragraph. Either that, or they have to shrink their browser's display scale so that the text becomes very small and hard to read.

This is occurring for me right now, because your image of the ant face is displayed at 1280 pixels wide.

I recommend to follow the guideline in the future -- images no larger than 1024 pixels wide, please.

--Rik

leekekhuan
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Post by leekekhuan »

rjlittlefield wrote:By the way, when you post images larger than the recommended 1024 pixels wide, you end up changing the forum page format so that users with small screens have to scroll back and forth, back and forth, just to read a paragraph. Either that, or they have to shrink their browser's display scale so that the text becomes very small and hard to read.

This is occurring for me right now, because your image of the ant face is displayed at 1280 pixels wide.

I recommend to follow the guideline in the future -- images no larger than 1024 pixels wide, please.

--Rik
My apologies, will change to 1024 right away.

Charles Krebs
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Post by Charles Krebs »

Lee,

I don't think Rik noticed your exact objective, but it has a 210mm tube length. That means there should be a physical 200mm between the sensor and the back shoulder of the objective to achieve a magnification of 10X. Your Canon body "depth" (mount to sensor) is 44mm so you should have 156mm in the range shown in red below to be at 10X.
Image

With a 10/0.25 this exact distance is not extremely critical. A larger extension will give a greater magnification, a shorter extension a lower magnification. Since you are using a full-frame sensor (24x36mm) you are already beyond the image circle that the objective was designed to "cover", but if I am not mistaken, others have used that objective on full-frame with good results. (And for shots like the one you posted here, where there is really no critical details in the corners, it is even less of a concern). However, it wold probably be good to not use a smaller extension than mentioned above. With a smaller extension your magnification decreases, but so does the quality image circle. Since you are already "pushing it" with the full-frame sensor, you may well start to see poorer edge/corner quality if you go for magnifications lower than 10X.

Conversely, if you go for higher magnifications with more extension you will not experience a smaller image circle, but overall image quality will begin to degrade due to diffraction.

I like the cone adapters like you are using, but if you haven't seen previous discussions in the forum, you should know that it is pretty important to line the interior with a low reflectance flocking material, and/or add a flare-reduction diaphragm inside. (Easy to do... it can be as simple as a black piece of card-stock with a hole cut in it just large enough to let the image pass through without vignetting).

rjlittlefield
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Post by rjlittlefield »

Charles Krebs wrote:I don't think Rik noticed your exact objective, but it has a 210mm tube length.
I did look at the objective, but I did not recognize it as being a 210. Instead I triggered on what appeared to be RMS threads and a fairly short working distance, so I figured probably 160. Thanks for the catch.

--Rik

leekekhuan
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Post by leekekhuan »

Thank you Charles and RIK for so helpful tips.
Charles, do you have that article handy which shows where to put "flocking material". I remember seeing that article but didn't bookmark for future reference.

Also need advice on this
http://www.ebay.com/itm/X-axis-60X60mm- ... 3a8cd32686.

This goes in Resolution=0.01mm, but i am not sure about weight capacity Load capacity=4kgf (39.2N). Looking at my setup will this be suitable to purchase?[/url]

rjlittlefield
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Post by rjlittlefield »

I see in earlier post that you are planning to buy a StackShot. For what purpose are you considering the linear stage?

--Rik

leekekhuan
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Post by leekekhuan »

rjlittlefield wrote:I see in earlier post that you are planning to buy a StackShot. For what purpose are you considering the linear stage?

--Rik
Rik sometime i go out of home to shoot flower/insect. I don't think i can use StackShot while outside.

BTW here is another stage
http://www.alibaba.com/product-detail/0 ... 8Q2Q%3D%3D
:shock:

Charles Krebs
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Post by Charles Krebs »

This is the flocking material I like:
http://www.fpi-protostar.com/hitack.htm
A 20x28 sheet will typically last a long, long time.

A quick search didn't find a specific posting about the cone adapters. But here are a few talking about such flare issues. It really is important to address this issue, especially with the cone adapters.

http://www.photomacrography.net/forum/v ... php?t=9725
http://www.photomacrography.net/forum/v ... php?t=8249
http://www.photomacrography.net/forum/v ... hp?t=17428
http://www.photomacrography.net/forum/v ... php?t=9758


What types of subjects and magnifications do you envision doing outdoors?

The small "micrometer driven" stages are usually quite precise (as long as the step size you need is easy to set). But they really need to be used in conjunction with a coarser geared (or smooth sliding) platform or you'll go crazy turning the little micrometer dial trying to set up the shot. (You also need to be sure the one you select has sufficient travel for your needs).

leekekhuan
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Post by leekekhuan »

Thank you Charles again for pointers.
Just ordered mine tape.

I was planning to use this for quick subject search
Image

Once subject locked then use the micrometer driven stage.

Normally for outside how you guys photograph?

rjlittlefield
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Post by rjlittlefield »

leekekhuan wrote:Normally for outside how you guys photograph?
Mostly I avoid high magnification stacking outdoors because for me the added value does not justify the added effort and much higher frustration. Even in the studio, I find it quite challenging enough to get the subject positioned and illuminated the way I want, and that's with micrometer control on all axes and without wind, water, unstable ground, and so on. I hugely admire people who regularly do deep stacks in the field, but I do not want to join their ranks.
I don't think i can use StackShot while outside.
The StackShot can be used outdoors, but then you need a battery too, and it's a lot of stuff to pack around in any case. See the discussion at Lichen on wooden fence, and be sure to read the whole thread.

The most prolific field stacker I know is John Hallmén, username morfa on the forum, web site http://www.johnhallmen.se/. If I recall correctly, the last I saw he was using a micrometer driven linear stage with 25mm travel, mounted on a ballhead, mounted on a low-profile macro tripod. But my memory is sometimes faulty, I don't have any links at hand, and he may have moved on to something better in any case. I suggest searching the forum for his postings and studying his website, then possibly sending him a personal message asking for pointers.

--Rik

leekekhuan
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Post by leekekhuan »

Thanks RIK for more tip.
I do follow John Hallmén from 2-3 years in Flickr.
I ordered StackShot yesterday but disappointed despite fedex international priority booking i am only getting it on Monday. We have long weekend here in Singapore and i was planning to play a bit but hey what can you do.
Will update thread with new pictures when i have my toy with me.

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