stacking with FF sensor.

Started 5 months ago | Discussions thread
mawyatt2002
mawyatt2002 Contributing Member • Posts: 502
Re: stacking with FF sensor.

RobinHsherwood wrote:

Donald B wrote:

RobinHsherwood wrote:

Donald B wrote:

RobinHsherwood wrote:

Donald B wrote:

RobinHsherwood wrote:

Donald B wrote:

Montanawildlives wrote:

Incredible shot. What lens?

4x amscope microscope objective lens.

Don

Finite or infinity corrected?

dont know what that refers to.

Don

Finite microscope objectives project an image at a certain distance away,and can be used directly on extension tubes of an appropriate length, ( normally 160 mm).

Infinity corrected microscopes require an additional 'tube lens' to produce the image. (normally a 200 mm focal length), Amscope supplies both kinds.

so far i can change the tube length to any size from 50mm to 160mm havnt tried longer yet.

Don

Then you have the finite objective. You may find some vignetting at 50 mm on FF.

I have used mine out to about 235 mm on bellows (about 6X mag).

I also use the Amscope 4X and 10X infinity corrected objectives on a Minolta 100-300 mm Apo lens. Very nice and a little more versatile in mag.

,Im going to buy one of those Helicon tubes ,saves screwing lengths on and off ,but unsure of internal reflections as i have lined my tubes with a fine black matt velvet sort of fabric.

Don

Can't speak to the Helicon tubes, but I know many people have to add flocking to narrow extension tubes. Mine are Kenko and are reflection free up to joining 2 sets. They are very well baffled. For longer lengths I add Minolta bellows, again internally baffled.

I did get reflections with a conical RMS adapter, but the flat adapters are reflection free.

You may want to consider using bellows instead of adding or subtracting tubes.

Yes the conical adapters are noted for having severe reflections, however the flat adapters are not completely reflection free either. Black anodized aluminum is reflective, so it's best to flock the back of these flat adapters.

Another source of reflections that's not obvious is the exit ring on some microscope objectives. Some have an exposed metal ring around the back of the lens, usually part of the mounting thread disc, and some without any coating or paint.

Here's an example on a couple popular Mitutoyo objectives, as you can see the outer section has the brass exposed. When you mount these to the adapter this ring is exposed and if you can see the ring when looking at the back of the adapter, so can the sensor 

The simple solution is to extend the flocking on the back of the adapter plate to cover these rings, just make sure it doesn't cause vignetting.

Best,

Mitutoyo objectives

Flocking adapter plate back

Front adapter view of flocking

20X Mitutoyo installed

10X Mitutoyo installed

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