Exposure Control With Finite Objective

Deanimator · Post by **Deanimator** » Tue Apr 10, 2018 3:09 pm

Macrero wrote:On the topic, I am guessing you shoot in Live View which acts basically as EFSC, how the "shutter shock" impacts image then?

Actually, I can't shoot in live view, since use of non-Canon flashes in live view on the T4i is problematic at best. I compose in live view, then shoot on manual.

Macrero · Post by **Macrero** » Tue Apr 10, 2018 4:36 pm

Deanimator wrote:Actually, I can't shoot in live view, since use of non-Canon flashes in live view on the T4i is problematic at best. I compose in live view, then shoot on manual.

Missed the flash part. Cant help with that, I use continuous light since I started working in studio.

RobertOToole · Post by **RobertOToole** » Tue Apr 10, 2018 8:18 pm

Macrero wrote: .........Though Nikon finite objectives are tough optics, you'd have to have a very bad luck to get a bad/damaged one.

- Macrero

FYI, this all depends on the seller, last year I made a couple of purchases from a China and all went well.

Late last year I received two bad Nikon Objectives, a 5X LU Plan Fluor and a 5x TU Plan Fluor. The main drawback when buying from China is that the sellers I have used, offer the product but no warranty or return for overseas shipments. Luckily the other 3 objectives in that shipment were okay so I can recover my costs.

No more Chinese shipments for me.

We need a thread on this subject. So far all my South Korean lenses, and lenses from Japan, have been in perfect shape.

Robert

P.s. Anyone need a soft LU and TU plan Fluor? Guess I can pull them apart for a post maybe? The TU Plan looks really hard to disassemble.

Deanimator · Post by **Deanimator** » Wed Apr 11, 2018 12:30 am

RobertOToole wrote:
Macrero wrote: .........Though Nikon finite objectives are tough optics, you'd have to have a very bad luck to get a bad/damaged one.

- Macrero
FYI, this all depends on the seller, last year I made a couple of purchases from a China and all went well.

Late last year I received two bad Nikon Objectives, a 5X LU Plan Fluor and a 5x TU Plan Fluor. The main drawback when buying from China is that the sellers I have used, offer the product but no warranty or return for overseas shipments. Luckily the other 3 objectives in that shipment were okay so I can recover my costs.

No more Chinese shipments for me.

We need a thread on this subject. So far all my South Korean lenses, and lenses from Japan, have been in perfect shape.

Robert

P.s. Anyone need a soft LU and TU plan Fluor? Guess I can pull them apart for a post maybe? The TU Plan looks really hard to disassemble.

Yours is an apt cautionary tale. I consider myself far too much of a neophyte to buy objectives via eBay.

Macrero · Post by **Macrero** » Wed Apr 11, 2018 3:15 am

RobertOToole wrote:
Macrero wrote: .........Though Nikon finite objectives are tough optics, you'd have to have a very bad luck to get a bad/damaged one.

- Macrero
FYI, this all depends on the seller, last year I made a couple of purchases from a China and all went well.

Late last year I received two bad Nikon Objectives, a 5X LU Plan Fluor and a 5x TU Plan Fluor. The main drawback when buying from China is that the sellers I have used, offer the product but no warranty or return for overseas shipments. Luckily the other 3 objectives in that shipment were okay so I can recover my costs.

No more Chinese shipments for me.

We need a thread on this subject. So far all my South Korean lenses, and lenses from Japan, have been in perfect shape.

Robert

P.s. Anyone need a soft LU and TU plan Fluor? Guess I can pull them apart for a post maybe? The TU Plan looks really hard to disassemble.

LU/TU Plan Fluor are not finite objectives as far as I know

I was referring to the old finite CF series M, BD, CF N Plans... I dropped accidentally a M Plan 10 from one meter high (or more) on a tiled floor, there was a serious bent on the mounting rim, but after testing performance had not changed at all. If that were a Mitutoyo objective it would have ended up as a nice paperweight.

I agree though that one have to be careful with buying cheap objectives from China since most of those sellers are just liquidators who have little or no idea about what they are selling. But that's the price of deal-hunting, we want a high grade, expensive objectives with perfect, tested optics at a fraction of their actual price... but that's not easy to find and there is always a risk, especially if you buy from an unprofessional seller who is selling the objective AS-IS with no returns accepted...

- Macrero

RobertOToole · Post by **RobertOToole** » Wed Apr 11, 2018 5:35 pm

Macrero wrote:
LU/TU Plan Fluor are not finite objectives as far as I know I was referring to the old finite CF series M, BD, CF N Plans... I dropped accidentally a M Plan 10 from one meter high (or more) on a tiled floor, there was a serious bent on the mounting rim, but after testing performance had not changed at all. If that were a Mitutoyo objective it would have ended up as a nice paperweight.

Yes, correct, good point. I read and answered too quickly

Macrero wrote: I agree though that one have to be careful with buying cheap objectives from China since most of those sellers are just liquidators who have little or no idea about what they are selling.

True and sometimes its worse than that. Some of the Ebay sellers in China do not even have the product in their hands, they are selling another sellers item for 2X the price and they even use the same auction photos of the other sellers. One printing Nikkor last year was being sold by 3-4 different Chinese Ebay sellers all using the same auction photos, and the best part? I know the true seller of the item so none of the 3 sellers ever touched the product since this other person still had it.

Macrero wrote: But that's the price of deal-hunting, we want a high grade, expensive objectives with perfect, tested optics at a fraction of their actual price... but that's not easy to find and there is always a risk, especially if you buy from an unprofessional seller who is selling the objective AS-IS with no returns accepted...

If you are smart and patient you can even find new and never used objectives for very low prices. A lot of Ebay lens prices today are higher than NEW from the official distributor. This is the case with some Mitutoyos.

I think we should start a vendor rating thread!

All the best,

Robert

RobertOToole · Post by **RobertOToole** » Wed Apr 11, 2018 5:37 pm

Deanimator wrote:
Yours is an apt cautionary tale. I consider myself far too much of a neophyte to buy objectives via eBay.

Feel free to send me an email if you are ever looking for something I can probably help.

Robert

ChrisR · Post by **ChrisR** » Wed Apr 11, 2018 6:09 pm

5X LU Plan Fluor
I have one of those - mine's "ok". Would make an interesting comparison!

BTW - reminder of Mitutoyo 7.5x tale.
It went to Ohio from Taiwan, and was found to have "knocked" image type.
It went back to Taiwan and was sold again on ebay.

Macrero · Post by **Macrero** » Thu Apr 12, 2018 3:45 am

Robert,

I am aware of those chinese sellers, I have never bought from them, of course... True, I have seen many Mitus (and other) objectives priced higher that the current retail price and the funny thing is that there were buyers watching the item

You must be smart, patient and lucky as well

to get a new (or in good condition) expensive objetive at a low price. There are millions of buyers on eBay and those will most likely be sold minutes after listing.

If it's enough to be smart and patient, please get me your new 4X favorite, the S FLuor 4/0.20 at a low price, I'd love to test it, but it seems that I am not smart and patient enough to find it

thanks in advance

Best,

- Macrero

enricosavazzi · Post by **enricosavazzi** » Thu Apr 12, 2018 4:23 am

There is actually an additional way to control exposure with a microscope objective, but:

- It is just a variation on changing the illumination intensity.
- It works better with infinity objectives than finite ones.

This additional way is reducing the illumination intensity with a neutral density filter mounted at the rear of the objective. Adding a filter in this position slightly shortens the optical path length and (in finite objectives) introduces some aberrations, but this can be kept under control by increasing the physical path length by adding a washer between objective and turret and by using a thin and AR-coated filter.

Some Olympus infinity objectives come with a built-in ND filter (which should be removable but may require some tools, e.g. in objectives with a model denomination ending with CY). Some other objectives have a more easily removable ND filter mounted in a sleeve at the rear of the objective.

The idea behind this ND filter is to provide the same illumination intensity to the eyepieces when switching among objectives of different NA and magnification, to make it more comfortable for users who spend many hours a day using a scope. So the 5x and 10x objectives have strong ND filters, the 20x a weaker one, and 40x and above typically no ND filter. This is practical in modern high-end Olympus microscopes that provide a very bright illumination (most of the BX models come standard with 100W halogen, for example). It may be a problem on scopes with weaker illumination and with some illumination methods that "eat up" a lot of light.