More DF.65
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More DF.65
Mosquito wing.
Easily available.
1mm slide. Cover slip. Canada balsam.
40x .65 Watson para from around 1965.
Microsystem 70 stand.
DIY DF patch in an abbe condenser filter holder
No oil.
Lumix G3 with NDPL2X eyepiece mounted.
No photo shop or processing.
AWB, can be improved by selecting incandescent.
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Re: More DF.65
Thin aluminium. Based roughly on the DF element in Nikon phase condenser.
Fixed to 32mm X 1mm watch glass for 32mm holder.
Outside ring is measured to the inside of the condenser,all held together with industrial super glue, satin black paint. Thin strips cut with scissors to hold it together,got repaired a few times so stuck to glass before it all gets too blobby with glue.
Cut out with a DIY blade in the compass, takes a few passes but it's a good way to worry through up to 0.5mm without too much trouble.
Light gap is about 1mm.
Probably not fair to expect anything above n/a .65 dry.
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Re: More DF.65
Radiolarian using a dry Achro condenser.
Same Watson x40 .65.
Only using Lumix G3 onboard processor for monochrome.
I didn't make the slide, came from a junk shop.
Not cropped so f.o.v is around 0.3mm.
Re: More DF.65
It is interesting that the dry achro is more colourful than the Abbe condenser .
I dont think that darkfield plays too well with deep refractive objects because of the flair from the out of focus but refractive parts.....sometimes they are better stacked in brightfield and then the colours inverted.
Polycistina are a really enjoyable and rewarding things to focus stack (if you are after something bomb proof to try; have a go with Zerene Stacker .. it 30 days free, and then I think it just watermarks ).
What I dont understand is why some setups work ok with stops but then others dont seem to work (?)
I dont think that darkfield plays too well with deep refractive objects because of the flair from the out of focus but refractive parts.....sometimes they are better stacked in brightfield and then the colours inverted.
Polycistina are a really enjoyable and rewarding things to focus stack (if you are after something bomb proof to try; have a go with Zerene Stacker .. it 30 days free, and then I think it just watermarks ).
What I dont understand is why some setups work ok with stops but then others dont seem to work (?)
Last edited by Chas on Sun Apr 09, 2023 6:54 pm, edited 1 time in total.
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Re: More DF.65
For a dry condenser the n/a is likely to be 0.9 or less, that would make 0.65 near the limit with the top lens being flat against the bottom of the slide.
A condenser with 1.25 for oil is a better bet dry up to 0.8.
Low power condenser with an air gap is the least likely to work.
Stacking and a DG oil condenser would be preferable for sure.
A condenser with 1.25 for oil is a better bet dry up to 0.8.
Low power condenser with an air gap is the least likely to work.
Stacking and a DG oil condenser would be preferable for sure.
Re: More DF.65
I dont know how many iterations there are of Watson Universal condensers, but the rear lens element of the No.1 and No.3 that I have are quite a bit smaller than the ordinary condenser's rear element... this is was the cause of my problems:
Anything as large as 1 pence coin (~20mm) will completely block the light to one side or another of the rear lens. Using an 18mm stop in the swing-out filter holder was still a bit difficult to get right.
Putting the stop right behind the rear lens of the condenser made everything much easier and (perhaps because I am using a diffuse light source) closing down the iris makes the background blacker without diminishing the brightness of the objects.
I am trying out a Dry Zonal darkfield condenser .. it looks quite promising even though I cant get it through the hole in the middle of the stage! ( I have it on a Bausch & Lomb stand which looks as if it has spent some period of its life on a rubbish dump ).
There seems to enough of a gap between the condenser head and the condenser holder to allow the stop to held on with a push-on cap type arrangement.
Anything as large as 1 pence coin (~20mm) will completely block the light to one side or another of the rear lens. Using an 18mm stop in the swing-out filter holder was still a bit difficult to get right.
Putting the stop right behind the rear lens of the condenser made everything much easier and (perhaps because I am using a diffuse light source) closing down the iris makes the background blacker without diminishing the brightness of the objects.
I am trying out a Dry Zonal darkfield condenser .. it looks quite promising even though I cant get it through the hole in the middle of the stage! ( I have it on a Bausch & Lomb stand which looks as if it has spent some period of its life on a rubbish dump ).
There seems to enough of a gap between the condenser head and the condenser holder to allow the stop to held on with a push-on cap type arrangement.
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Re: More DF.65
I think the universal dry Achro is a 6 element condenser with a n/a of 0.9.
The abbe 1.25 with the flat top lens is by far the easiest.
The abbe 1.25 with the flat top lens is by far the easiest.
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Re: More DF.65
I find that an inexpensive photographic lens polarizer placed over the field lens does a good job of cutting down glare around the brightest elements of a subject and helps darken the background. It works especially well when used in tandem with an analyzer placed between the objective and the eyepiece.Phill Brown wrote: ↑Sun Apr 09, 2023 10:41 am
More challenging.
Radiolarian using a dry Achro condenser.
Same Watson x40 .65.
BTW that DIY darkfield patch is absolutely killer!
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Re: More DF.65
CPL
DF polarised thread.
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Re: More DF.65
In my defense these are 60 year old optics.
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Re: More DF.65
The oil darkfield photographs dont look so different to the those taken using your home made stop.
What was your impression when you were looking through the microscope?
(Was the oil darkfield condenser a Watson Zonal or some other?).
What was your impression when you were looking through the microscope?
(Was the oil darkfield condenser a Watson Zonal or some other?).
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- Posts: 608
- Joined: Mon May 24, 2021 1:19 pm
- Location: Devon UK.
Re: More DF.65
Yes it's a Watson zonal. The edges don't have the same aberrations.
Only good for na .5 to.95, just a bright centre for
Lower na.
Only good for na .5 to.95, just a bright centre for
Lower na.
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- Posts: 608
- Joined: Mon May 24, 2021 1:19 pm
- Location: Devon UK.
Re: More DF.65
New project.
Same subject, mosquito wing.
Using a Watson abbe with a minor mod. Might look similar to patch but
first image is filament projected from the Kohler a 4x .30.
Second image 20x .50, it's a better example of old objective than the 40x used.
Third image is 40x .65
Resolution is better, enough light for 1/80th second at 800 iso on the little Lumix G3.
Will add a mirror next to test the idea it can work at faster shutter without a flash.
Edit. The G3 suffers from shutter shock badly.
I have a Canon 50D which does a better job of it with live view.
This part of the project has added another £1.50 so trying to keep a lid on the spend.
Same subject, mosquito wing.
Using a Watson abbe with a minor mod. Might look similar to patch but
first image is filament projected from the Kohler a 4x .30.
Second image 20x .50, it's a better example of old objective than the 40x used.
Third image is 40x .65
Resolution is better, enough light for 1/80th second at 800 iso on the little Lumix G3.
Will add a mirror next to test the idea it can work at faster shutter without a flash.
Edit. The G3 suffers from shutter shock badly.
I have a Canon 50D which does a better job of it with live view.
This part of the project has added another £1.50 so trying to keep a lid on the spend.