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Minolta MD 75-200 4,5
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PostPosted: Sat Jan 20, 2024 3:28 pm    Post subject: Minolta MD 75-200 4,5 Reply with quote
This is the second copy I bought since the first one was ill calibrated and did not reach infinity at short focal length.

Definition is very good but this lens seems to be less contrasty than the Minolta 75-150 f4. It is hence less easy to achieve perfect focus but there is a lot of finesse once you get there. Bokeh looks nice. I do not own anymore the MD 70-210 f4. My souvenir on a not so well shimmed adapter was less even sharpness in the corners.

This lens requires some post processing since there are some chromatic aberrations, both lateral and longitudinal. But these are only a problem in difficult situations. Software correction works well for lateral CA, less so for longitudinal.

The photo below was an extreme case of longitudinal CA. But you could always convert to black and white...

Embâcle | Freeze by lumens pixel, sur Flickr


PostPosted: Sat Jan 20, 2024 10:30 pm    Post subject: Re: Minolta MD 75-200 4,5 Reply with quote
lumens pixel wrote:
This is the second copy I bought since the first one was ill calibrated and did not reach infinity at short focal length.

Definition is very good but this lens seems to be less contrasty than the Minolta 75-150 f4.


The MD 4.5/75-200mm seems to be prone to hazing, and that could well be the effects of slight hazing. I just another copy of the MD-III 4.5/75-200mm along with the recently acquired MD 8/100-500, and the 75-200 had some fungus inside the front group. Cleaning was pretty easy as it was sufficient to unscrew the inner metal ring on the front assembly, thus freeing the front lens.

On closer inspection it is clear that also this lens has some minor haze, probably reduncing contrast in some situations.

S


PostPosted: Sat Jan 20, 2024 10:34 pm    Post subject: Re: Minolta MD 75-200 4,5 Reply with quote
stevemark wrote:
lumens pixel wrote:
This is the second copy I bought since the first one was ill calibrated and did not reach infinity at short focal length.

Definition is very good but this lens seems to be less contrasty than the Minolta 75-150 f4.


The MD 4.5/75-200mm seems to be prone to hazing, and that could well be the effects of slight hazing. I just another copy of the MD-III 4.5/75-200mm along with the recently acquired MD 8/100-500, and the 75-200 had some fungus inside the front group. Cleaning was pretty easy as it was sufficient to unscrew the inner metal ring on the front assembly, thus freeing the front lens.

On closer inspection it is clear that also this lens has some minor haze, probably reduncing contrast in some situations.

S


I am lucky enough to have received from the postman a copy that is really like new, in its box, with the guarantee certificate. None of these prevent fungus or haze of course, these mostly depend upon storage conditions. But my glass is clear.

When I write that this lens has less contrast than the 75 150 it is also because the small zoom is exceptionally contrasty to my eyes.

Edit: Well upon further inspection there is a hint of maybe not haze but cleaning marks on what seems to be the second element. Really difficult to see so I am not sure this can affect contrast. The lens will spend the night under an Ikea UV light, just to check whether it could change something and reduce the probability of any subsequent fungus infection.


PostPosted: Sun Jan 21, 2024 12:26 am    Post subject: Re: Minolta MD 75-200 4,5 Reply with quote
lumens pixel wrote:
But my glass is clear.


Good to know.

Nevertheless I have three samples of the MD-III 4.5/75-20mm, plus two samples of the MD-II, and all of them have some fungus in the front (focusing) group. Two of them (one MD-II and one MD-III) in addition have some fungus on the outer surfacs of the variator group, and one sample also in the rear part. This is indicating that either dust or (more probably) some grease has been migrating inside the lens.

BTW the MinAF 4.5-5.6/75-300mm (I) lens, the "big beercan", is prone to hazing, too. No fungus observed until now, though.

S


PostPosted: Sun Jan 21, 2024 9:59 am    Post subject: Re: Minolta MD 75-200 4,5 Reply with quote
stevemark wrote:
lumens pixel wrote:
But my glass is clear.


Good to know.

Nevertheless I have three samples of the MD-III 4.5/75-20mm, plus two samples of the MD-II, and all of them have some fungus in the front (focusing) group. Two of them (one MD-II and one MD-III) in addition have some fungus on the outer surfacs of the variator group, and one sample also in the rear part. This is indicating that either dust or (more probably) some grease has been migrating inside the lens.

BTW the MinAF 4.5-5.6/75-300mm (I) lens, the "big beercan", is prone to hazing, too. No fungus observed until now, though.

S


Well... This lens will then have a special place in the rotation under the UV lamp to try to avoid fungus formation. Too bad.


PostPosted: Sun Jan 21, 2024 2:38 pm    Post subject: Re: Minolta MD 75-200 4,5 Reply with quote
lumens pixel wrote:

Well... This lens will then have a special place in the rotation under the UV lamp to try to avoid fungus formation. Too bad.


That may help for fungus just behind the first (front) lens. Not sure whether that'll help further inside, since photographic glass (and especially the highly refractive glass used in most "modern" lenses) is blocking UV rays pretty well. In addition you'll suck in spores whenever you focus, and distribute them inside the lens whenever you're zooming ...!

I'll dismantle the worst sample of my MD-II 4.5/75-200mm and publish the procedure later on.

Cleaning the front section was pretty straightforward - however some solvent (acetone) was necessary to loosen the small metal ring which holds the front lens. It's best to remove that one first (and clean the space between front lens and second group) before revoming the remaining front assembly (=focusing group). The latter can be taken out easily by first loosening the three small screws just below the name ring ("MD ZOOM 75-200mm 1:4.5 ...") and then unscewing the remaining front assembly (=focusing group). Some solvent may be necessary for the screws as well.

S


PostPosted: Sun Jan 21, 2024 3:36 pm    Post subject: Reply with quote
Same lens and color now. No chromatic aberration on this pic which I found surprising.

Marcher sur l'eau | Walking on water by lumens pixel, sur Flickr


PostPosted: Sun Jan 21, 2024 6:58 pm    Post subject: Reply with quote
lumens pixel wrote:
Same lens and color now. No chromatic aberration on this pic which I found surprising.


Most of the well known vintage MF tele zooms are pretty well color corrected around f=100mm. Some a bit further up, others more around 80mm, but you get it. Was this image taken at a shorter focal length, e. g. around 135mm?

S


PostPosted: Sun Jan 21, 2024 9:08 pm    Post subject: Reply with quote
As much as I recall it should have been a little bit above 135, maybe 170mm.

The black and white shot on top of the thread had significant longitudinal CA and I am not sure it was a longer focal length.

Lateral CA are not much of a problem, even if I prefer them absent.


PostPosted: Sun Jan 21, 2024 10:57 pm    Post subject: Reply with quote
lumens pixel wrote:
As much as I recall it should have been a little bit above 135, maybe 170mm.

The black and white shot on top of the thread had significant longitudinal CA and I am not sure it was a longer focal length.

Lateral CA are not much of a problem, even if I prefer them absent.


Sorry, my misunderstanding. Ithought you were talking about lateral CAs (difficult to judge on a b/w image).
Longitudinal CAs usually disappear when stopping down a bit - so probably the duck wasn't shot wide open, I guess?

S


PostPosted: Sun Jan 21, 2024 11:43 pm    Post subject: Reply with quote
You can see small hexagons in the bokeh


PostPosted: Mon Jan 22, 2024 12:28 am    Post subject: Reply with quote
stevemark wrote:
lumens pixel wrote:
As much as I recall it should have been a little bit above 135, maybe 170mm.

The black and white shot on top of the thread had significant longitudinal CA and I am not sure it was a longer focal length.

Lateral CA are not much of a problem, even if I prefer them absent.


Sorry, my misunderstanding. Ithought you were talking about lateral CAs (difficult to judge on a b/w image).
Longitudinal CAs usually disappear when stopping down a bit - so probably the duck wasn't shot wide open, I guess?

S


It was either f5,6 or f6,7.

Note that on this lens the wide open f4,5 stop seems conservative. My other zoom lenses display at f4 the same shutter speed value. But I am not taking into account vignetting (or lack of).


PostPosted: Tue Sep 17, 2024 2:53 pm    Post subject: Reply with quote
I have solved my focusing problems with this lens while shimming my adapter as indicated in my post regarding the Minolta MD 45 2,0.

I can reach infinity at all focal lengths which is good news.

This lens has a lot of resolution but lacks a little bit in contrast compared to the 75 150 f4,0 and of course compared to primes.

However if you tweak a little bit in post you can reach interesting results.

This shot has been taken on a dull day and I played with contrast and white and black points for a moment.

Paris la Défense by lumens pixel, sur Flickr
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