Nikon CF 50x/0.55 BD ELWD

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 12:33 am

Hi all

I just bought this lens but it does not have a WD marking on it. It has a blue ring near the thread. I am aware of similar Nikon CF 50x objs with a 8.2 and 8.7mm WD.

1. Does anyone know what the working distance of this lens is?

2. I have some experience with the Nikon and Mitutoyo 20x but last night I tried this 50x on a 70-200mm , lens set at 200mm, infinity, f2.8, iso200 but when I when to focus via liveview for the start position, the camera screen looked blur/opaque , like looking thru a frosted clear glass. Wondering if anyone has some suggestion of what I am doing wrong

cheers
Denis

liuto · Post by **liuto** » Mon Dec 15, 2014 1:18 am

This is a BD lens designed for coaxial lighting. Did you block the rear light openings? This is necessary otherwise you have strong straylight in the optical path.

regards
Hermann

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 1:58 am

Thanks Herman. I am new to this. I paid $75USD for this.

"Did you block the rear light openings? "

I am just using standard adapters in front of the 70-200 tube lens and connected the 50x.

I am not sure what you mean or how to block rear light openings? Can you please suggest how I achieve this?

cheers
Denis

BTW, is this lens any good?

ChrisR · Post by **ChrisR** » Mon Dec 15, 2014 3:00 am

1) 75 anything, is cheap

2) yes it should be good - it's like the objective Rik used for his fly mouthparts

It's similar to this objective - designed to be used with an illumination system which shines light down an annulus around the outside of the glass. In your case it's likely that light is coming the other way and fogging your image. You need to close that off.
In this particular objective it's the ring I've tinted red, yours will look a little different:

You may find you can unscrew parts from the front of the objective, which would give you more access. This particular one I happened to snap
recently - yours will be somewhat different and maybe not so obliging.

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 3:08 am

Thanks so much Chris

So I need to get rubber ring/flat washer. I will check it out tonight

I will take some pics and post it here

cheers
Denis

ChrisR · Post by **ChrisR** » Mon Dec 15, 2014 3:10 am

Exactly - squishy O rings work a treat. Bemuse a plumber while rooting through his selection box

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 5:51 am

Hahahah, thanks Chris

I will get some this week.

Much appreciated.

Denis & big hugs for your awesome help as usual

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 7:22 pm

Hi CHris

I have attached some images of the rear of the lens.

The ring I need to get : diameter is 24mm and about .5 to 1mm thick, width is 3mm.

cheers
Denis

ChrisR · Post by **ChrisR** » Tue Dec 16, 2014 2:22 am

I'll PM you one...

Clintonwake · Post by **Clintonwake** » Tue Dec 16, 2014 6:33 am

Thanks Chris

Much appreciated

cheers
Denis

Clintonwake · Post by **Clintonwake** » Tue Dec 23, 2014 6:29 am

Chris

I did as you suggested and covered the rear with a rubber ring and it resolved the haze/glow. I then took 200 skots of the eye of a horsefly. using a canon 70-200, @200mm @ infinity, stachshot 1um, f2.8, iso 200, 1 sec, 4 leds & diffuser, settle time of 5 seconds but the image was blur & not sharp

Any ideas or suggestion?

cheers
Denis

ChrisR · Post by **ChrisR** » Tue Dec 23, 2014 7:17 am

Nothing else shiny in there?
Find a suitable subject and see if a single image is sharp.
Suitable subject can be hard. Butterfly wings are ok but not flat, though I have one stuck to a slide with double sided tape to stop it curling up. Laser printed lable on something plastic rather than fibrous paper? Nothing too shiny.
Have to say try flash, diffused, to eliminate movement. Tube of paper should do as a diffuser.

Blur is relative - it won't be tack sharp near pixel level, you're using effective aperture
50/(2 x 0.55) = ~f/45
so - it should look sharp enough at screen (~1000 pixels wide) view.

Hope you're using your Stackshot in high res mode, and you've got the backlash sorted out. That threw me at first.

rjlittlefield · Post by **rjlittlefield** » Tue Dec 23, 2014 12:49 pm

Clintonwake wrote:1 sec, 4 leds & diffuser

1 second exposure time with continuous illumination is very vulnerable to motion blur at 50X. Try flash illumination, using a consumer flash set on low power, to freeze out any motion.

--Rik

Clintonwake · Post by **Clintonwake** » Tue Dec 23, 2014 2:45 pm

Thanks Chris & Rik

I am using a 100mm polysytrene tube around the insect as the diffuser, perhaps thats too shiny & should try paper. I will also use 3 flashes, 1 on top and 2 on the side instead of LEDs and increase the speed to 1/100 or 1/160 to reduce the vulnerability to motion blur at 50X as stated by Rik.

I will check if I am using Stackshot in high res mode as I was not aware of that. I am using sorbothane under the block of wood base, and also some sorbothane under the long lens , 5 sec settle time etc to mitigate some vibrations.

Thanks once again for such prompt and expert advice.

Wishing you both and families ( INCLUDING YOUR MEMBERS) a VERY MERRY CHRISTMAS AND HAPPY NEW YEAR.

CHEERS from Australia.
Denis

ChrisR · Post by **ChrisR** » Tue Dec 23, 2014 2:54 pm

Single flash should work. Let it bounce off the "far" inside edge of the cup a bit but not hit the subject directly.
As here: Simple Diffuse Lighting
Last stack I did at 40x NA 0.55 was at 1/8th power so about 1/8000th second flash. If the ambient light is normal low level, it'll do little or nothing in 1/160th at base ISO. Turn off your focus lights!

I haven't sorted out the backlash thing fully, but when you set start and end positions, you have to do both from one direction.
Otherwise it'll do a whole stack with nothing in focus!
IE assuming you want to stack from 2mm to 3mm, go "back" to 1mm, forward to 2mm and set "start", then forward to 3mm and set "end".
When it runs it should go back to just before 2mm, then forwards to 2mm, then step to 3mm.

It still seems to do an odd frame but at least it "works".
I use mirror lockup even with flash, so that's 2 "exposures" as far as the Stackshot is concerned.