AO 40X plan objective comparison.

[apochronaut]

This resulted from a query from Einman. Here is a small comparison. AO made 4, 40X infinity corrected plan objectives. 3, were planachro .66 N.A. and 1 was planapo .80 N.A., without a correction collar.
The first to be released was cat. # 1023 around 1967. The next was cat.# 1309 about 10 years later, then cat.# 1323 around 1985 followed by cat. # 1128 shortly after, which I think only bore the Reichert and later Leica, brand.
Here are 4 pictures, taken 1 through each, of a large pleurosira diatom, which filled about 2/3 of the 20mm f.o.v.There are pores on it's surface, surrounded by reticulations. Attention to those and as well, borders and the background, show considerable differences in the resolving power as well as chromatic aberration level of the 4.
Pictures are in order of the date of release.
Cat.# 1023 was an excellent plan lens for it's time but the release of # 1309, clearly was an attempt to catch back up to B & L. The planachromats made for the B & L Balplan, are optically superior to the earliest AO planachro series 1017(4X),1019(10X),1022(20X),1023(40X) and 1024(100X), with the exception of the #1022 20X .50 but notably so, in the case of the cat.# 1023 40X .66. The development of the cat.# 1309 brought AO a long way towards equaling the field and then of course the #1323, planapo arrived which was another thing altogether. The # 1128 seems to be a bit of a budget objective, probably pitched at the school/university, small lab and veterinary clinic market, where the cost of the 1309 and 1323, could easily have been seen as prohibitive. It's design and performance are very similar to that of the #1023, even though it is classed as an advanced planachro.

[btschumy]

Thanks so much for posting these. I've been wondering what the visual difference would be between Achro and Apo objectives. The difference is quite noticeable when viewed side by side. However, it is not a "knock your socks off" kind of difference. A bit more detail and less purple fringing.

These comparisons must be somewhat hard to do because it is next to impossible to get the focus exactly the same between them. I do see some areas in the Acho slides that show more detail than the Apo. I would assume this is due to a slight difference in focus. Otherwise you'd think the Apo would win over the whole image.

[apochronaut]

thanks. yes, for sure, getting absolute focus control is difficult. in this case , i zeroed in on a specific detail and focused on that. in the upper left, you can see where the shallower depth of field of the planapo( due to .80) comes into play, giving the illusion that the planachros might have better resolution, there. it is surprising, how good the 1309 is.

[rnabholz]

Really interesting comparison.

Seeing the effect of the difference in N.A. side by side is rare and of real value I think. To my eye, the APO does perform better resolving fine detail, but I agree, first impressions might be that the 1309 is sharper simply due to depth of focus.

Well done and thanks.

Rod

[apochronaut]

I didn't mic the sample until now but it is .015 : thinner than optimal. This would have a slight disproportionate effect on the planapo over the others.

[einman]

Thanks APO for this comparison. Just what I needed.

[billben74]

Thanks apo.
Its really nice to see these comparisons that you do, especially when combined some of your extensive knowledge to put it all in context.

(and a nice image too)

[apochronaut]

Thanks; Glad they are of value.

[kit1980]

Thanks for this comparison - it's hard to find apo vs achro comparison on the Internet.
Also it's interesting to see such a significant difference between different achromatic objectives with the same nominal NA.

[cpsTN]

APOCHRONAUT:

Although most of my objectives are Plans, my AO 110 currently has a 45x #1116 Achro where the "traditional" 40x would be. If I were to replace this with a 40x Plan #1128, would it be worth the trouble? I am also going to replace the 4-port turret with a 5-port turret for more expandibility, probably ending up with 4x, 10x, 20x, 40x, 100x.

[charlie g]

For me there is so much structure we need agreement on concise area to all look at in these series of images, in order to make comparisons.

I suggest the cribiform lattices between the upper left horizontal dark spines of material. Please look at the middle section of these lattice works between the second and third horizontal spines or struts of dark material. Thats the second and third horizontal strut from top of the imaged object.

I can not sense the apo performs better than the others in this series...I sense subtle differences in focus between the different images. There is too much structure to sense which image is 'better', to my eyes!

Thanks for this shoot-out, apo. charlie guevara

[apochronaut]

APOCHRONAUT:

Although most of my objectives are Plans, my AO 110 currently has a 45x #1116 Achro where the "traditional" 40x would be. If I were to replace this with a 40x Plan #1128, would it be worth the trouble? I am also going to replace the 4-port turret with a 5-port turret for more expandibility, probably ending up with 4x, 10x, 20x, 40x, 100x.

Both the # 1024 and the 1128 show considerably more chromatic aberration than the 1309 or obviously, the 1323. The latter two , also have superior resolution, which can be seen in numerous details, around the frame. Although the 1128 was made later in production, it was more of a budget objective, than the 1309, probably geared to the educational market, somewhat. The 1309, would be my choice. You can find one of those for very little, these days. If you wanted to lay out, close to 200.00, you can get the planapo.

[apochronaut]

For me there is so much structure we need agreement on concise area to all look at in these series of images, in order to make comparisons.

I suggest the cribiform lattices between the upper left horizontal dark spines of material. Please look at the middle section of these lattice works between the second and third horizontal spines or struts of dark material. Thats the second and third horizontal strut from top of the imaged object.

I can not sense the apo performs better than the others in this series...I sense subtle differences in focus between the different images. There is too much structure to sense which image is 'better', to my eyes!

Thanks for this shoot-out, apo. charlie guevara

The difference in chromatic aberration levels is pretty obvious and if you zero in on any one of dozens of fine details, you can see that the 1309 and 1323 do have superior resolution. Those little radial striations around some of the pores are useful. Focus differences are probably there but also somewhat reduced depth of focus, with the 1323.