Thursday, December 29, 2016

American stuff

These lenses came from people who had a home in Curaçao besides their Dutch home; the equipment probably was bought in Curaçao, but the seller couldn't confirm that. Anyway, the total set was imported in America, as both lenses and the accompanying SR-T 200 camera bore American type designations; I don't think Celtic lenses were sold in Europe, except maybe in the UK.

This was the budget version of the MC W.Rokkor-X version with the usual cosmetic differences: a sunken instead of raised red dot and a finely ribbed focus ring instead of the Rokkor-X's waffle-type. As far as I know the most important difference between Celtic and Rokkor(-X) lenses may be their coatings: this lens as well as a MC Celtic Macro 3.5/50mm have a golden color rendition instead of the much more neutral color balance of the corresponding Rokkor lenses. It's well known that Minolta went to great lengths to provide equal and accurate color balance and contrast between the lenses in the Rokkor line-up. The more expensive coatings to provide that are most probably replaced by simpler and cheaper ones for the Celtic equivalents. Apart from the cosmetic differences mentioned this lens looks very similar to the Rokkor counterpart in mechanics and optics. Sharpness and contrast are very similar too.

The American equivalent of the MC Rokkor-PF 50mm 1:2 came as an unexpected and welcomed bonus. It's one of the very few MC lenses with a plastic aperture ring; its image quality is average, even stopped down to f/8 the corners aren't perfectly sharp.

Thursday, October 6, 2016

Minolta RF Rokkor 250mm 1:5.6

Every Minolta collector knows about this lens and will probably own or want it; at least I did, but the exorbitant prices for this thing always put me off: there's no way I'm going to splurge a thousand euros for it.

This one came as part of a rather large setup that I had to buy as a whole, only to acquire a slide copier unit and macro stand for my Minolta Auto Bellows III. Meanwhile I sold most of the setup, putting me at the breakeven point so now it doesn't feel so bad to have an expensive thing like this mirror lens sitting in my drawer. Might still sell it though.

Some image samples made with my A7R2. You can find full-resolution images here.

In actual use this lens is of course very light and small considering it's a 250mm telephoto. Peaking on the A7R2 is quite effective, allowing me to get critically sharp pictures, but the use of magnification is more reliable; the lowest magnification is still useable without undue jumping of the viewfinder image. The in-body image stabilization is also fairly effective, shutter speeds of 1/125 s yielded good results, didn't try longer shutter times.

Image quality is very good, I'd say. It's just about sharp enough on the very demanding A7R2, which is a feat in itself, but I think I'd get better results from the Sony FE 4/70-200mm with a little cropping to get to the same coverage. To be honest, the doughnet-shaped out-of-focus blur is mostly disturbing and even the slightest misfocus makes for an ugly picture. Combined with the inability to stop down the lens isn't very useful in my book. A fixed 250mm field-of-view is also very limiting, I consider a telephoto zoom an essential part of my arsenal.

Saturday, September 17, 2016

Minolta 500mm mirror lens

Though I had serious doubts about its usefulness I didn't want to pass up on the opportunity to get the Minolta RF Rokkor 500mm 1:8 mirror lens.

It came with almost all of its accessories, including the (tattered) leather case, 4 extra filters but unfortunately the filter wrench is missing. Upon closer inspection it looks like the main mirror is a little weathered but that doesn't seem to affect imagery too much.

Image quality is surprisingly good, provided you manage to nail focus and hold the camera still c.q. use a sturdy tripod and head. I used it hand-held on a camera with image stabilization, the Sony A7R2, and could get away with 1/250s shutter speeds most of the time. Click on the pictures to get a full-res version.

That last picture was one of the very few of a series that came out alright, most of the others were out of focus. I've found it extremely difficult to focus. I got best result by using the low magnification of the A7R2 and even while the image should be stabilized, the travel of the sensor isn't adequate to cover for the image motion of my not to shaky hands so that the image jumps up and down in the viewfinder despite the image stabilization. Maybe you could put this lens to use after a lot of practice but I don't think I'll use it for actual shooting. And if you want smooth bokeh: looks elsewhere, this mirror lens provides the typical doughnut features in the out-of-focus regions.

Some more reading, including comments of others, can be found in this thread on TalkEmount.

Friday, April 1, 2016

The Minolta macro heavyweight champion

The most prominent feature of this lens is its weight indeed: with 600g it is the heaviest Minolta macro lens you can find. It is a chubby, hefty lens and it oozes mechanical quality. The matching life-size adapter is aptly provided with a tripod mount, while the adapter for the MD Macro 100/4 successor hasn't one.

Matching extension tube
You can safely pick one up if you come across one for a nice price, but if you're really after a macro lens you'd be better off with the Minolta MD Macro 100mm 1:4 or its Rokkor equivalent, one of Minolta's finest lenses in SR-mount in my opinion. Its image quality is almost beyond criticism and it's lighter and smaller to boot. The 1/3 slower maximum aperture is hardly relevant because both lenses vignet a lot wide-open, the MC 100/3.5 even more so than the MD 100/4. The MC lens is generally less contrasty and a little less sharp than the MD 100/4, the latter has real bite and punch in its images.

There's a gallery with full-resolution test pictures, where you can see for yourself if you agree with my statement that the 100/4 is the more desireable lens.

A Minolta MC 135mm lens

My first Minolta MC 135mm lens, this is the oldest of the two MC versions with a rubber-clad focus ring. According to Dennis Lohmann's lens index it is the optical design with 6 elements in 5 groups; the later version has the 4/4 design in common with the early MD Tele Rokkor 135/2.8 lenses.

As usual with MC lenses this feels like a solid piece of equipment. Focus is smooth and without play and the metal aperture ring adds to the impression of quality. In common with all later 135/2.8 models it features a built-in lens hood.

In general the Minolta 135/2.8 lenses with 4 elements in 4 groups are most highly regarded, so let's see how this lens compares to the Minolta MD Tele Rokkor 135/2.8 with a 4/4 design as well as the last 135/2.8 in the Minolta line-up, the plain MD 135/2.8 with a 5/5 design. All test shots have been made with the Sony A7 and processed in Lightroom/Photoshop.
MC Tele Rokkor-PF @ f/2.8, center crop
MD Tele Rokkor @ f/2.8, center crop
MD @ f/2.8, center crop
The interesting part here is the difference in purple fringing: the MC lens is less affected by it than the other two. Sharpness is about equivalent in all crops. The MD Tele Rokkor is slightly sharper and contrastier in the corners, difficult to show in small crops so you'll have to evaluate that in the full-res samples.

MC Tele Rokkor-PG @ f/2.8, center crop
MD Tele Rokkor @ f/2.8, center crop
MD @ f/2.8, center crop

Again there's little between the lenses in terms of sharpness. The MC is less contrasty and has a cooler color rendition than the other two.

All lenses improve of course on stopping down, although the MC remains the less contrasty one. Is the highly-praised 4/4 design better than the others? Maybe, just maybe, differences are small in my opinion and the older MC lens acquits itself quite well, I'd have no hesitation in using it. You can evaluate the lenses at all apertures in the gallery with the full-resolution samples. 

Wednesday, March 16, 2016

The Minolta Rokkor-TC 135mm 1:4

Found this lens last Sunday on the Dutch Fotografica fair. It was priced at € 20, I offered € 15 but the English seller didn't understand me and said I could have it for 10. Deal struck.

It's my second sample; my first one's diaphragm broke down later, the leaves got messed up in each other. It's one of the few SR-mount lenses without an automatic diaphragm, it features a black ring to set the aperture and a chrome ring to open up for focussing or close down to the preset value for taking the picture. It was meant as a budget lens at the time, together with some other preset lenses like the Tele Rokkor-QE 200mm 1:5. You'd think it's not heavy given its f/4 speed but it's still 375g, filter thread is 46mm and closest focus is 1.5m.

The test pictures show that it's a bit flary and not really pin-sharp wide-open in the center, corners aren't sharp and the whole image shows purple fringing. Stopping down to f/5.6 improves the center but the corners need f/11 to get really sharp. A rather unspectacular performance but useful nevertheless. You might like the general moderate-contrast rendering which is much unlike modern lenses, it lends an atmosphere of yesteryear to the pictures.
The total scene
Center at f/4
Center at f/5.6

And now for some trees against the sky, a demanding test for any lens.
Center at f/4
Center at f/5.6
Upper left corner at f/4
Upper left corner at f/11
The full set of test pictures is here.

Tuesday, March 15, 2016

The slowest Minolta 200mm lens

This is a somewhat rare find: a Minolta Tele Rokkor-QE 200mm 1:5. The lens doesn't have an automatic diaphragm and wide-open it's only f/5, thus keeping the price lower. It was introduced in 1964 and so it wasn't Minolta's first 200mm: in 1960 Minolta brought the more expensive Auto Tele Rokkor-QF 200mm 1:3.5. In the price list shown at Dennis Lohmann's site the 200/5 is listed for $119.50 vs. $199.50 for the Auto 200/3.5.

Unfortunately my sample has suffered from non-expert repair attempts. Most screws are damaged and the little ball providing for the aperture click-stops is missing. Even though it's a budget lens the mechanics feel quite solid and the optical formula is more elaborate, 5 elements in 4 groups, than that of its shorter 100mm and 135mm sister models which only contain 3 elements in 3 groups. It's relatively light at 430g due its limited max. aperture and the minimum focussing distance is a reasonable 2.5m.

It's not really a lens most people will go after for actual picture-taking, but of course having it I can show something of its performance on the Sony A7. And to be honest, it's better than I expected from a budget lens introduced in 1964.

Full scene
Center at f/5
Center at f/8
Sharpness wide-open is already good in the center. Contrast is only moderate even on stopping down.

The next scene is eminently suitable for showing corner performance, there's hardly anything more demanding of a lens than tree branches and twigs against the sky.

Full scene

Center at f/5
Center at f/8
Upper right corner at f/5
Upper right corner at f/8
Vignetting at f/5 and also f/5.6 is apparent and is reduced significantly at f/8. Sharpness is already very good wide-open and improves only slightly by f/8, contrast remains moderate. Purple fringing and CA is quite low for such a lens. All-in-all a surprisingly good performance. Set of full-res test pictures here.