Kohler illumination

[henryr]

I'm still wondering what members think of AO 735 versus ortho illuminator. Any preferences or are both considered passe? I've read out the slick lighting systems, in some Zeiss scopes, but plan on staying with my old AO Spencer.

[75RR]

I agree with Charles. Both illuminators provide Köhler, as long as you can get the bulbs you are good to go with either one.

I would guess that the ortho illuminator once set up will require less fiddling about.
While the spencer 735 will probably be a little more fiddly, it is black and has a cool shape.

Hi Henry,

Here is Kurt Maurer's site which shows the AO 735 in use with a Spencer 13 as well as the Ortho Illuminator with a AO Model 2 for comparison. It depends on which foot print you want.
http://ngc704.home.comcast.net/~ngc704/otherstuff/

[KurtM]

Pretty well put, 75RR. Bottom line is, both do the same thing, but the O-I does it easier. It is limited to orthogonal placement of the scope, however, while the #735 is more flexible but requires more knowledge/futzing to set up. If you're asking about other options, then might say so, although I'm not so sure there are a lot of other options except other "research lamps" under other brand names? Nice thing about either the O-I or #735, they're pleasantly in keeping with the vintage look, feel, and utility of the Model 15.

Might get whichever presents a good deal first...?

As for "passe" ... I would rather tend to believe that either provides illumination far superior to what most modern microscopes on the market today come with. Not that I would know, but that's the kind of general drift I hear (paging Mr. Phil...).

[apochronaut]

Both the ortho illuminator and the # 735 research illuminator provide a remote source of 100 watt illumination. The # 370 illuminator does as well. If one is involved in critical research using apochromatic objectives and making photographs, the ortho illuminator has a great deal of latitude for adding or mixing filters, all of which are integral to the illuminator. It is kind of an early version of the rear mounted 100 watt illuminator that were integral components on the 20.120 and 420 microscopes, except it has a specialized tungsten bulb. It is situated , so as to project the beam up from under the stage. The microscope clamps to the illuminator and maintains a preset distance from the filament, similar to an integrated iluminator. 110v. and not variable.

The 735 has a similar capability but the unit itself has no preset distance from the microscope. It also uses the mirror as a deviator, so the mirror needs to be good. Filtering is not integrated and requires an auxiliary filter carrier mounted on the front. You would have to purchase interchangeable large glass filters to fit in the filter carrier. They are about 4 inch. I have never tried cheaper gelatine filters but some theatrical heat resistant types might work. It is definitely a more cumbersome illuminator, if you want to use it to full capacity. It is 110v. so not variable.
The bulbs can be expensive for both of these but a 110 volt halogen conversion is a likliehood. Those bulbs are cheap.

Both work well for oil immersion high resolution dark field.

Alternately, if you do not need the 100 watt illumination or aren't trying to do pristine photomicrographs an understage simpler illuminator of lower wattage might suffice or a 20 or so watt remote illuminator, refelecting off the mirror also might do. AO made an 18 watt you can drop filters into as did B&L . They have a 6 v. trafo , so are variable , too.

[apochronaut]

I forgot about the 370. It is an older design, going back to the 20's. It generally has similar features as the 735 but , filtering is a little more difficult. There may have been forward add on filter carriers( it would make sense) but I have never seen one . It was made at a time when the premium research grade illuminators from Spencer # 360, 374 and 394 were arc or gas filled 150 and 400 watts, so the 370 , which persisted until later was definitely an amateur kind of unit. It's ace in the hole though, is that it can be elevated on a pole , enough to be used for incident illumination ... so that is a definite plus.

[henryr]

I really appreciate all the responses, but, have one last question. It seems the ortho illuminator (I O) requires the tube body to be vertical or, in other words, the objective and O I light sources axes need to be parallel. The 735 seems to have some flexibility, in that, it and scope mirror can be adjusted when the tube body is tilted for ease of viewing. Are those reasonable assumptions?

[KurtM]

Yes.

[apochronaut]

second to , Kurt but with qualifications. The ortho illuminator was made after they had evolved inclined heads, and therefore flat stages. Those had become preferred by almost all professional microscopists. For microscopes with an inclination joint and therefore the necessity to tilt the stage in order to bring the eyepiece to a more comfortable viewing angle , it might seem like the # 735 illuminator is a better option but it has a fairly limited movement. It is really designed , also to be used with a similar microscope fittted with an inclined head and a flat stage.

Some people prefer a rather large amount of tilt and in this case the # 735 has some difficulty achieving an appropriate angle to the mirror.

The 370, can accomodate this by allowing for a vertical height adjustment on it's pole, For all around versatility, when used with an average microscope with an inclination joint, it is the winner. Same output as the 735, same optics, same iris, a little more difficult filtering( but overcomeable), + vertical movement, which allows for a better ilumination angle and above stage illumination.

[KurtM]

I agree with Phil, the #370 is more versatile than the #735 by virtue of its elevation capability. I use mine for illuminating other things around the lab quite a lot, including stereomicroscope subjects and micro aquariums for macro photography.

I have a Spencer #370, but also this "clone":



Phil, have you ever seen or heard of this, a Burton Mfg. Co. Model 1100? Very similar to the #370, but more nicely made. I already ran it past Charles, who says he never heard of it. This is the only one I've ever seen or heard of, I feel very lucky to have it.

[henryr]

Is the only difference pole mounting versus resting on a bench? I would have thought a later model (the 375) would have some improvements...maybe AO thought that was an improvement. I don't wouldn't consider it that.

I posted this and then read apochronauts post. Mine is unnecessary but I wasn't allowed to delete it.

[apochronaut]

I agree with Phil, the #370 is more versatile than the #735 by virtue of its elevation capability. I use mine for illuminating other things around the lab quite a lot, including stereomicroscope subjects and micro aquariums for macro photography.

I have a Spencer #370, but also this "clone":



Phil, have you ever seen or heard of this, a Burton Mfg. Co. Model 1100? Very similar to the #370, but more nicely made. I already ran it past Charles, who says he never heard of it. This is the only one I've ever seen or heard of, I feel very lucky to have it.

On ebay, once or twice . Perhaps this very one. I'm curious what the " more nicely made " means? I think there were others too. B & L had some very similar lamps . It is as though, these lamp styles evolved and a number of maker's had their versions of them. In the 70's and 80's we had many different gooseneck lamps, various versions of "luxo" lamps, etc.

To answer the question of the evolution of the 370 into the 735. Although, they seem related due to the 100 watt output, the general size etc., the 735 was considered a research illuminator, whereas the model 370, introduced in the late 20's was considered a general purpose laboratory illuminator of moderate size. The tungsten lamps of the time were not as good as gas filled Mazda lamps, so the research illuminators of 150 watts and 400 watts( model 374 and 394) used gas filled bulbs. The very concentrated high wattage was valuable for dark field.

Those illuminators disappeared during W.W. 2 for obvious reasons and were never brought back. The 370 persisted as the main high wattage lamp and the 735 was introduced , not so much as a replacement for it but as a replacement for the 394. Both the 370 and 735 had a period of parallel production. All of the adjustments are external on the 735 , tilt and focus are by virtue of turning knobs and the bulb is of a different design than the 370. One can also use it as an incident illuminator by making a suitable support on which to elevate it if necessary. The 370 continued to be a good general purpose lamp into the late 50's, when the need for a lamp that elevated the way it does became more and more unnecessary, it's use as a 100 watt diascopic illuminator was duplicated by the more convenient to use 735, the ortho illuminator, in base illumination and mounted incident illuminators for stereo microscopes came along and it's slightly cumbersome adjustments no longer fit in with a smoothly operating lab where time was of the essence. .

[KurtM]

I'm curious what the " more nicely made " means?

Like I said, I have one of each so it's easy to compare them directly. The Spencer 370 is very nicely made, no doubt, but the Burton has a bit nicer fit and finish. Some of the parts are castings instead of sheet metal, everything is rounded instead of left squared off, nicer crinkle finish paint job, that sort of thing. As a result, it's just a bit more user friendly all around.

[apochronaut]

Does it have the capacity to accept filters?

[charlie g]

Regards to the Ortho-Illuminator...I have one and no use for it. My circa 1960's Reichert/Austria Biozets substage field illuminator cobbles well to any stand I have which lacks a field illuminator...it's compact, tiny bench footprint...nests right under most stands I would use it with.

Anyone con-US who'd like it for the cost of shipping...well contact me offlist by pm. charlie guevara

[KurtM]

Does it have the capacity to accept filters?

Yes, arranged similar to the 370, only wider (full 1/4"), and with springs clips to hold the filter(s) securely.