(LSA || DCR150 || ITL200) ? FF : CROP

Have questions about the equipment used for macro- or micro- photography? Post those questions in this forum.

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Adalbert
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Post by Adalbert »

Hello everybody,
Has anybody tested the tube-lenses 360mm / 300mm / 240mm ?
What abut the CANON 300mm or 100-300
or something from Tokina, Tamron, Sigma, etc?
BR, ADi

ChrisR
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Post by ChrisR »

A long time ago I tried the Canon 70-300L . It wasn't bad on APS with a Nikon 10x objective, appearing to be better at 300 than 200, though it wasn't a repeated/rigoous test. Perhaps I did something wrong at 200.
At 300mm in normal photography it's a "very good" lens compared with many. I tried a couple of lesser 300mms, which also didn't do as well as tube lenses.

I found a 240mm f/9 G-Claron in a flea market for £5. Sorry, it's just sitting on a shelf at the moment!
Chris R

Adalbert
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Post by Adalbert »

Hi Chris,
not bad :-)
What about this one (OK, is expensive but APO)
https://www.ebay.de/itm/Rodenstock-Apo- ... Sw5cNYg1lT
BR, ADi

mawyatt
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Post by mawyatt »

RobertOToole wrote:Hi Mike,
mawyatt wrote:Using a longer or shorter FL as a tube lens makes sense per your explanation, same image projected smaller (higher res with smaller image circle) or larger (lower res with larger image circle), kind of like the resolution times image circle is a constant (within reason) for a given objective.

However Robert's short focus doesn't seem to follow this line of thinking. All I can come up with is the focus beyond infinity somehow compensates for a particular lens behavior. This is why I asked the question to Robert if this applied to other tube lenses,
I did try almost all the longer tube lenses and they worked the same way as the DCR-150 with much more detail and sharpness. This worked very well with the Century, and the Sigma, off the top of my head.

Also I did not think to try the Mity 10x or 20x, but I did throw on a Nikon S Fluor with the ITL200 with shorter focus and the results were very much improved without any side-effects.

mawyatt wrote:even the other Mitty's like the 10 and 20X. Also the Raynox 250 evidently didn't respond to the short focus concept, like the 150??

Interesting indeed!!

Best,
The Raynox 208mm (DCR-150), 170mm both worked very well with short focus but I did not think to try the 125mm Raynox (DCR-250) since I normally don't push objectives down that far. I would guess that the R125mm would also benefit from short focus.

Hope that clears things up a little.

Robert
Robert,

Your short focus concept seems to benefit from some sort of "optical correction" that's taking place between the Mitutoyo 5X and the tube lens, and as you say seems to not depend on the tube lens.

My simple thinking (I'm not an optics guru like others here) is the tube lens is acting like another complex element(s) in the overall lens (objective & tube) optical transfer function and you've discovered a setup that produces a slightly better overall transfer function that's "outside" the general use recommendations (like what've done with the ThorLabs ITL200 setup). This is intriguing indeed!!

Thus my question about does it work for the Mitty 10 & 20X.

Agree, the Raynox 250 (125mm) is already pushing down quite a bit, but others (Beats I think) have shown the Mitutoyo 5X working well on APC with a 100mm tube lens, thus my question about the possible use of the Raynox 250 for short focus.

So all the "fogginess" is with me not with your superb tests or explainations :roll:

Anyway, thanks so much for all the work and tests you've done for us.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

mawyatt
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Post by mawyatt »

ChrisR wrote:A long time ago I tried the Canon 70-300L . It wasn't bad on APS with a Nikon 10x objective, appearing to be better at 300 than 200, though it wasn't a repeated/rigoous test. Perhaps I did something wrong at 200.
At 300mm in normal photography it's a "very good" lens compared with many. I tried a couple of lesser 300mms, which also didn't do as well as tube lenses.

I found a 240mm f/9 G-Claron in a flea market for £5. Sorry, it's just sitting on a shelf at the moment!
Chris,

Wonder how the Nikon 300mm F4 would behave? This has the Fresnel lens, so not a typical 300 tho. I recall my old Nikon 70-200 VR1 worked well at 200.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

dmillard
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Post by dmillard »

Adalbert wrote: What about this one (OK, is expensive but APO)
https://www.ebay.de/itm/Rodenstock-Apo- ... Sw5cNYg1lT
BR, ADi
I previously found the Apo-Ronar 240mm f/9 to be very free of chromatic aberration, but my copy was one that may have been tweaked for infinity focus. If you can wait, I'll run some comparison tests before this weekend, using an ITL200 and a Nikkor M 200mm f/8 on an APS-C format Sony NEX 7, and the Apo Ronar 240mm and a Nikkor M 300mm f/9 on a full frame Sony A7rii.
A few concrete examples will be more informative for both of us than anecdotal accounts that rely on my often rosy memories! :)

Edit: 200mm f/8, not f/9
Last edited by dmillard on Wed Aug 29, 2018 7:28 am, edited 1 time in total.

Lou Jost
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Post by Lou Jost »

I use the Nikon 300mm f/4.5 ED-IF and 400mm f/5.6 ED-IF as tube lenses, and they are very good.

I have accumulated a accumulated a bunch of long tube lenses: Canon 300mm f/2.8 fluorite, plus these:
270mm 6.3 Nikkor-T ED
304.9mm Lenzar and AG
311mm Raynox 5320
360mm 9 Apo-Ronar
486 Raynox 5320
500mm Nikkor-T ED
I'll be testing them on full frame one of these days; I had to leave most in the US because of unexpected airline weight restrictions on travel to Ecuador.

Adalbert
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Post by Adalbert »

Hi David, hi Lou,
I'm looking forward to seeing the results of your tests!
BR, ADi

RobertOToole
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Post by RobertOToole »

FYI This is an interesting chart from Qioptiq, where you can see the effect of a longer tube lens on a Mag.x. (250mm is the normal standard tube FL).

Field size goes up as resolution drops.

(Cutoff resolution is usually just the frequency at which the contrast of an image is reduced to zero. In other words, it is frequency at which the MTF drops to zero)

Image

I would be mostly concerned with getting a long lens set-up rigid. I tried a Sigma 100-400 once and even with a QR long lens brace at the front it was far from what I would call solid compared to a higher mag objective with a ITL200 on my normal studio set-up.
Last edited by RobertOToole on Wed Aug 29, 2018 8:54 am, edited 1 time in total.

RobertOToole
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Post by RobertOToole »

FWIW I tried about a dozen 250mm+ lenses at least with the Mag.x and I found only one that gave me the image quality I was looking for and that was the Century +4 Achromat Diopter. (Turns out the Century is really good at infinity focus but its really excellent at short focus.)

The Mag.x is a special case since it was designed to cover a large (for line-scan and inspection, not a consumer market camera) sensor and was designed with a XL size exit pupil according to Qioptiq.

Robert

JH
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Post by JH »

enricosavazzi wrote: The glass window of the sensor and the additional UV+IR cut filter, and if present the anti-aliasing filter, have some effect in adding some spherical aberration, but this is visible only with fast lenses (usually f/1 to f/2) of relatively short focal lengths. It can safely be ignored when effective aperture is f/8 or slower. This is principally a problem when adapting fast legacy lenses designed for use with film on digital cameras.
Thank you!
Best regards
Jörgen Hellberg
Jörgen Hellberg, my webbsite www.hellberg.photo

JH
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Post by JH »

Here is some butterfly scales with my apo ronar 360 mm.

http://www.photomacrography.net/forum/v ... hp?t=31211

Best regards
Jörgen Hellberg
Jörgen Hellberg, my webbsite www.hellberg.photo

mawyatt
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Post by mawyatt »

RobertOToole wrote:FYI This is an interesting chart from Qioptiq, where you can see the effect of a longer tube lens on a Mag.x. (250mm is the normal standard tube FL).

Field size goes up as resolution drops.

(Cutoff resolution is usually just the frequency at which the contrast of an image is reduced to zero. In other words, it is frequency at which the MTF drops to zero)

Image

I would be mostly concerned with getting a long lens set-up rigid. I tried a Sigma 100-400 once and even with a QR long lens brace at the front it was far from what I would call solid compared to a higher mag objective with a ITL200 on my normal studio set-up.
Robert, Lou,

This follows what I mentioned about the product of the image circle diameter and resolution being a constant for a given objective & tube lens within a reasonable magnification range.

The Mag X is constant for all three tube lens cases if you multiply 2y' (image diameter) times R'O (Cut off frequency).

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

rjlittlefield
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Post by rjlittlefield »

RobertOToole wrote:Hi Mike,
mawyatt wrote:Using a longer or shorter FL as a tube lens makes sense per your explanation, same image projected smaller (higher res with smaller image circle) or larger (lower res with larger image circle), kind of like the resolution times image circle is a constant (within reason) for a given objective.

However Robert's short focus doesn't seem to follow this line of thinking. All I can come up with is the focus beyond infinity somehow compensates for a particular lens behavior. This is why I asked the question to Robert if this applied to other tube lenses,
I did try almost all the longer tube lenses and they worked the same way as the DCR-150 with much more detail and sharpness. This worked very well with the Century, and the Sigma, off the top of my head.
I've added some emphasis to the quote, and I'd like to question/challenge the part that is now bold.

When I look at http://www.photomacrography.net/forum/v ... 556#236556 , I see the summary statement that
In most cases compared to a down-sized normal focus image, the short focus image is sharper, clean and more detailed.
But when I look at the actual images in that same post, it seems to me that the short focus images do not show more detail on subject; they just show the same detail spread across fewer pixels. No doubt that makes the images appear sharper, and the total amount of detail per frame probably goes up, but those are different things.

Studying Robert's words carefully, I'm now noticing the part about "compared to a down-sized normal focus image". I'm also thinking that the amount of downsizing to match magnifications would be only about 0.8X, and I'm very aware that resampling at ratios close to 1 always ends up creating large areas of the image where each output pixel is some weighted average of several input pixels, essentially guaranteeing some loss of detail.

So, while I don't question the statement exactly as worded, I'm wondering if it's misleading about what's actually happening. My interpretation of the images is that the short focus configuration just makes the optical image smaller, without affecting its intrinsic quality. Assuming that's correct, then the experiments certainly validate the approach of adjusting magnification by changing rear focus distance, but they do not suggest that you should routinely shorten the rear focus distance in search of better IQ.

Robert, what are your thoughts about this?

--Rik

RobertOToole
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Post by RobertOToole »

Hi Rik,

Thanks for getting involved in the conversation, I know I do and I am sure lots of others here are interested in your view on this.

So when I came across the short focus IQ vs infinity image difference I was surprised and of course my first thought was the question, are the details and aberrations just reduced since the image is smaller?

To see the results side by side I made some test images with the ITL200 tube lens and the Mitutoyo 5x in two configurations, one at infinity and one with short focus past infinity.

Then I processed both files with the same settings and as a last step I downsized the infinity image to the same size as the short focus image using the normal default PS CS bicubic sharper (reduction) command as I would normally to reduce an image in size.

When I compared these at 100% view in PS, I do see more detail in the short focus image when compared with the infinity focus image.

I checked a second time with the Century +4 and the results were the same in this case also.

There is some kind of detail loss due the image detail being manipulated by PS bicubic smoother I am sure, but I have no idea exactly how much, but I can see a difference comparing the two. So my personal preference would be to go with a short focus past infinity image for the maximum amount of details and sharpness.

I can post the normal vs downsized image test results if anyone is interested, I am sure I saved these.


Robert

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