minolta 250 mirror

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

Thank you for the replies. I think there is something else besides compaction to justify such a price. I do not understand some aversion to donut bokeh. An important drawback seems to me a possible low resolution. I have a 50/1.2 lens and I'd like a same size tele lens.

Do you have other recommendations besides this Minolta lens with terrifying price? What price would be OK for such a mirror 250-350 lens (I can only use T or M42 mounts on Pentax crop)?

[quote="calvin83"]

calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

For FF camera, the best will be Minolta 250, Tamron 350/Rubinar 300. Or you could read through the following thread
http://forum.mflenses.com/whats-the-second-best-tiny-mirror-lens-t66119.html

TrueLoveOne · Expire: 2013-12-24

I don't think the 250 has any resolution issues.

Just went outside and took a photo of the first cat i could see, Sony A3000 20.1MP, straight jpg from cam, nothing altered, and a crop of the same shot. They're large, so if you click on them you can see what it can do!
Always remember: they do not have an aperture, so it's always f/5.6 and according depth of field. This can be a challenge when focussing!

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

Thanks for the link. I noted Spiratone. For now there is nothing on ebay. Shocked

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

You're right. I think of some cheap 500/8 lenses.

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

In this moment the best priced offers are Osawa and Ohnar 300 / 5.6 mirror lenses.
Do you know something about this lenses?

calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

There are three types of Japanese 300 / 5.6 mirror lenses. The Spiratone type is 72mm and the others two types are 67mm. The Makinon type has MC coating and can focus down to 1:4 but shorter focus throw. The Osawa/Ohnar and the others does not have MC coating, they can only focus to 2.5M but with a longer focus throw. The Makinon type seems have better flare resistant than the other two type. There is also a Soligor CD 300/5.6 Mirror Click here to see on Ebay I forget to mention. It seems the Soligor has MC coating at the front and it may be just the same lens as the Spiratone 72mm(I am not sure).

ManualFocus-G · Expire: 2014-11-24

I found the Makinon 400mm mirror lens awful and the Ohnar 300mm lens slightly better, although low resolution. All types I've tried have been low contrast other than the Tamron SP 350/5.6 (very good) and the Rubinar 300/4.5 (outstanding).

Nordentro · Expire: 2015-01-29

calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

So in conclusion, 72mm diameter lenses are better optically than 67mm diameter lenses? But losing the advantage of compactness?

hoanpham · Expire: 2015-01-18

I won't draw a conclusion by filter size like that.

I have a few mirror lenses: this minolta, tamron 55BB and canon fd.
They all good but with different properties:
minolta: very compact and light, last to go. no problem to use with sony a7r 36Mpix.
tamron: 500/8 is very good for close range, but focus throw is too short in long range that makes it hard to use (adaptall2)
canon fd: 500/8 better focus throw in mid-long range, biggest and heaviest of the mirror lenses i have.

tamron with TCx2 like 01F or 200F becomes 1000mm still usable; resolution is a bit washed out with TC.

calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

For that design matters.

paulhofseth · Expire: 2018-06-28

This is a similar effect as with lots of glass in front of a digital sensor. Light rays crossing from one medium to another get bent. So a design made to correct for a glass mounted at the rear of the lens will have a different performance when those two transitions -in and out of the filter- are absent. The size of the effect will depend on the entry angles concerned and the refraction and dispersion qualities of the glass, even if the surfaces to be crossed are perfectly plane parallell.

I have not tried the Minolta without the rear filter, so I do not know how significant it is. I do not have the original documentation to hand right now, but a paraphase from memory is that "the filters that came with it should be used at all times to avoid image deterioration".

p.

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

Thanks for posting. A lens that I do not enjoy using it starts to become a new favorite Smile

calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

My experience is that all the mirror lens I tried have no negative impact without the rear filter and many of them does work better without the the rear filter. If you want to know more, read through the first page of this thread http://forum.mflenses.com/sensor-stack-size-interesting-reading-for-legacy-lens-users-t66629.html .

edri · Joined: 26 Oct 2014 Posts: 315 Location: walking in the air

Maybe for expensive lenses as you have this effect is not obvious and it is observable for ordinary lenses.

Anything else about mirror lenses from the same "The lens book" :

"... typically the effective aperture of a mirror lens is a stop less than the marked aperture: f/11 for f/8; f16 for f11."

calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

TrueLoveOne · Expire: 2013-12-24

I only have the ND filter.
As far as i recall i used it without, you're right about the filter. I just checked on this site: http://www.minoltaflashback.com/rf-lens.html They say the lens cannot be focussed correctly without a rear element, be it a normal filter or any other.

But i dont think it matters that much though, at least not on digital, look at this shot:

Red (RF Rokkor 250) by Ren� Maly, on Flickr

To be absolutely sure i would have to test it again, without any element in it. The cat pic in this topic was shot with the ND filter.

VLR · Joined: 05 Mar 2015 Posts: 86

I had a Makinon 300 mm f/5.6 Reflex Mirror for MC/MD with 67 mm filter thread and it was the worst lens I've seen so far. Sharpness was incredibly low and focus peaking on the NEX never showed anything.

Using a RF Rokkor 250 mm, now. Worlds apart! Sharpness is close to a Tele Rokkor 200 f/4, low distortion and zero CAs (after all, it's a mirror lens). Actual T-stop isn't that bad, either: Should be around T7.0 according to my calculations. But as it has been said before: hard to focus because of the shallow DOF.

For comparison:
Test of the RF 250 mm f/5.6
Test of the MD 200 mm f/4

TrueLoveOne · Expire: 2013-12-24

VLR: nice website!

Pontus · Expire: 2016-08-25

I just tested my Minolta 250/5.6

Basic adjustments made in Aperture. Shot handheld with Sony NEX-7 in RAW. ISO 400 and 1/640.

No donuts when used properly or lots of donuts if you like that sort of thing. Incredible reach and sharpness for a lens so small. No CA.

100% crop