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14x Mutar image quality


Active Member
I currently have a CF 250mm Sonar f5.6 lens which I find is both a very useful focal length and that it produces superb images.

For the sake of convenience (eg weight in my bag etc), I have considered buying a 1.4x Mutar to give me extra reach.

However, putting relative cost aside, I wonder if I should just get a 350mm lens for reasons of overall image quality and have the benefit of 1 stop faster aperture.

If the image quality from the 1.4x Mutar is not too degrading then convenience would win the argument.

However, while IMHO an extender cannot be expected to provide 100% the same level of imaging performance, what is the real visible difference?

All such things are relative, so I suppose my decision is not so much about what will give the better result; rather, to what real degree is a CF 250mm Sonar + 1.4x Mutar a lesser quality image than a 350mm Sonar on its own?

I am not deciding on costs difference and widest aperture - just image quality.

I shoot trannies and film. I shoot mostly with a tripod using a 501cm and 503cw. I would shoot 350mm for landscapes and buildings. I print a maximum image size of say 40"x40".

The only reason converters exist is convenience.

A Superachromat 350 mm will beat a 250 mm Sonnar with converter with one hand tied behind its back.

What is the real difference?
Well, all things being relative, the 'bottom line' may well be that the gain in convenience is well worth the loss in quality. It depends on how much you like to give.

But have you considered cropping? 1.4x isn't that much after all.
Thanks Qnu. It is that issue of convenience that might appeal to me. Have you used the 1.4x? What are the optical disadvantages - level of "softness" etc.?

No, i must admit i haven't used the 1.4x converter.

As a general rule, a converter can not improve the prime lens' performance (i thought i'd begin with stating the obvious
), but 'blows up' the faults of the prime lens, and brings along a few of its own.
The better the converter, the less it will do the last bit.

What converters usually do is indeed lower contrast, and resolution. Some produce a quite distinct level of distortion, and colour fringing too.

The difficulty however is not in comparing a lens to that same lens with converter, but a lens with converter to another lens of a focal length similar to the combination's effective focal length.
As it happens, as focal lengths grow, performance usually (not always) drops. But by how much?

However, it really boils down to this "convenience" thing. You carry a converter because it is smaller and lighter than carrying an extra lens.
I have a converter too: a Vivitar 2x. It certainly isn't great. But since i expect convenience, not top-notch optical performance, i get what i expect, and that is no disappointment.

(I must keep putting smilies in, because of the way they contrast with the murky background. If only the text too would show a bigger contrast. But light grey on a little darker grey... There are books, ancient and new, condemning such typographical niceties as ergonomical lunacy. And how right they are...
Thanks Qnu. Your "relative" perspective is helpful!

I understand the issues of image degredation, but would be interested to see how the 1.4x in use shows up its own degree of degreation.

I suppose in my case the issue is a bit accademic and one would expect that Zeiss would not be inclined to release an extender that does not "match" the primes to a good level of image quality tollerance. A 1.4x is far far more convenient than adding the rather large 350mm lens itself to my kit.

By the way, while white text on the dark grey background is not ideal ergonomically (or whatever the optical version of ergonomics is), for me it is a nice relief from black text on white background. Yes, your smiles do come up well.

Keep smiling.
I've been using both the 1.4XE and PC Mutar 1.4x extenders. You don't lose much with the 1.4 extenders optically; it's the 2x extenders that are killers. My use for the 1.4XE is to extend my 100mm planar to almost 150mm and to get extra magnification with the 120mm Makro. I haven't been able to see much (if any) loss on the optical front, but I do shoot primarily digital so that edge softness is not an issue.

The PC Mutar 1.4x is great for panorama stitching and makes a killer combination with the 50mm CF FLE.
Thanks Larry, that is very helpful information. I'm especially interested in your comments about the PC Mutar 1.4x. Do you think this is worth getting if I'm in the market for a 1.4x anyway - gain the perspectice control as a bonus anyway?

I do have a CF 50mm FLE lens which I love using, so the PC may give me an added use for my 50mm.
Are you shooting with wide-angle lenses frequently? The PC Mutar works from 40mm to 100mm; the 1.4XE is designed to work from 100mm upwards (i.e., telephoto). The two converters complement each other. If you shoot film it is important to check the specs on the PC Mutar since there is not a lot of shift at 40mm; since I shoot digital the shift limitations do not apply due to the smaller frame size.

The PC Mutar is ideal for panorama stitching of digital frames. I use it for up/down shift of 10-15mm, which along with a panorama tripod head allows generation of 6-frame panoramas of about 150 MB (8-bit TIFF). Printing these at 20x30 gives a superb result.
Thanks Larry. I was aware of the 1.4x extender focal length compatability; but, not of the PC Mutar's limits.

My 1.4x purpose is for use with 120mm upwards.

The only wide angle I own is the 50mm FLE (I'm not a 6x6 wide angle fan, or else I would have added an SWC by now.

So, since I shoot LF field camera (Linhof Technika) I suppose the PC Mutar may be too limiting in my Hassy kit. When I do very wide stuff I either shoot with the Linhof or my Hassy XPan II (itching for a 30mm lens one of these days).

I thought the PC Mutar might have had broader use opportunities, but alas no.