Combining short and long barrel objectives.

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Javier
Posts: 806
Joined: Tue May 09, 2017 11:19 am
Location: Buenos Aires, Argentina.

Combining short and long barrel objectives.

#1 Post by Javier » Wed Nov 04, 2020 6:07 pm

Hi,

I have a microscope with short barrel objectives, and I want to add a 20 x to it. I'm pretty sure the 20 x objective is a long barrel one, and it is the only one available around here. All objectives are DIN standard. I understand that the 20x will work fine in my scope, and that the major drawback will be the need for 10 mm refocus prior to using this objective, right?

Do you consider this a deal-breaker or can it be done?

TIA.

deBult
Posts: 402
Joined: Tue Jul 16, 2019 3:20 pm
Location: Continental Europe

Re: Combining short and long barrel objectives.

#2 Post by deBult » Wed Nov 04, 2020 6:42 pm

Sooner or sooner (not later) you will crash the 20* into the slide (don’t ask how I known).

Bets, deBult.

Javier
Posts: 806
Joined: Tue May 09, 2017 11:19 am
Location: Buenos Aires, Argentina.

Re: Combining short and long barrel objectives.

#3 Post by Javier » Wed Nov 04, 2020 7:46 pm

deBult wrote:
Wed Nov 04, 2020 6:42 pm
Sooner or sooner (not later) you will crash the 20* into the slide (don’t ask how I known).

Bets, deBult.
:lol: :lol: :lol:

Greg Howald
Posts: 1185
Joined: Tue Oct 20, 2020 6:44 am

Re: Combining short and long barrel objectives.

#4 Post by Greg Howald » Wed Nov 04, 2020 7:53 pm

It will work. It will be awkward. Focal length is beyond thinking about being even close to other objectives and that's right, no matter how careful you try to be the moment is coming, but usually nothing terribly bad happens.
Greg

DonSchaeffer
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Joined: Sun Mar 22, 2020 10:06 am
Location: Winnipeg, Manitoba, Canada

Re: Combining short and long barrel objectives.

#5 Post by DonSchaeffer » Wed Nov 04, 2020 10:30 pm

I don't think it's a deal breaker. I'm focusing and refocusing all the time.

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Rossf
Posts: 363
Joined: Mon Jan 20, 2020 12:39 am
Location: Victoria Australia

Re: Combining short and long barrel objectives.

#6 Post by Rossf » Wed Nov 04, 2020 11:39 pm

I’m with you DonSchaeffer -whether it’s for economic necessity or it just an objective you really like but just happens to be a bit long or short-it’s still workable once you get the dropping the stage between changing nose turrets down. Keep on breaking the rules! And I’ve done cosmetic damage before but luckily no optical damage.
Regards Ross

apochronaut
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Joined: Fri May 15, 2015 12:15 am

Re: Combining short and long barrel objectives.

#7 Post by apochronaut » Thu Nov 05, 2020 1:06 pm

Of course one can make do but it is a pita. There are always short barrelled 20's around.
Here's a Tiyoda. https://www.ebay.com/itm/Tiyoda-Tokyo-M ... ect=mobile

and if you don't like that one. There are a couple of Lomos and Jenas and even some J.I.S. on right now.

Even any of those European 37mm parfocal objectives would be better. Leitz, Wild, C.B.S., Seibert. English, Baker, C.T.S..

Javier
Posts: 806
Joined: Tue May 09, 2017 11:19 am
Location: Buenos Aires, Argentina.

Re: Combining short and long barrel objectives.

#8 Post by Javier » Thu Nov 05, 2020 2:21 pm

Thanks to everyone for your inputs.

I think I will take my chances with the available long barrel objective. International shipping and taxes are very expensive for me. Besides, I think I will take the binocular path sooner than I thought, and the standard options are all long barrel from what I have seen. I'm having a lot of trouble with floaters in my eyes and other artifacts when using high magnifications. In my experience, those problems are minimized when both eyes are used at the same time.

Javier
Posts: 806
Joined: Tue May 09, 2017 11:19 am
Location: Buenos Aires, Argentina.

Re: Combining short and long barrel objectives.

#9 Post by Javier » Mon Nov 09, 2020 7:05 pm

Before purchasing the 20 x long barrel objective, I tested the available extra focus on my scope. It seems I will have an issue with the mechanical stage, as I won't be able to go through the entire specimen under the coverslip. One of the first things I did on my scope a few months ago was removing the focus stop nob since it limited the movement of the stage and I couldn't examine the entire sample either. I wonder if there is something wrong with the mechanical stage or if I'm doing something wrong.

Thanks in advance for your help.
Attachments
Maximum inside movement with the 45 mm need or with the standard 35 mm and the focus nob stop in its place.
Maximum inside movement with the 45 mm need or with the standard 35 mm and the focus nob stop in its place.
WhatsApp Image 2020-11-09 at 15.46.00.jpeg (61.37 KiB) Viewed 3562 times
Maximum outside movement
Maximum outside movement
WhatsApp Image 2020-11-09 at 15.47.17.jpeg (69.24 KiB) Viewed 3562 times

PeteM
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Joined: Tue Dec 06, 2016 6:22 am
Location: N. California

Re: Combining short and long barrel objectives.

#10 Post by PeteM » Mon Nov 09, 2020 7:52 pm

Is buying a new short barrel 20x from China not an option? The new prices of a "185" objective are very low and China subsidizes the shipping cost to most countries.

Javier
Posts: 806
Joined: Tue May 09, 2017 11:19 am
Location: Buenos Aires, Argentina.

Re: Combining short and long barrel objectives.

#11 Post by Javier » Mon Nov 09, 2020 8:19 pm

Importing is not an option right now for me, thank you for your input though.

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