Lens-to-Camera adapters with glass? Test yours!

I've been using an adapter with my digital SLR cameras for a long time -- to allow the use of my many manual-focusing lenses.

The adapter has glass in it to allow for infinity focus, and I haven't had any problems with it. It does magnify the focal length of the lens by 1.25X, however, so a 50mm lens becomes a 62.5mm lens.

I keep running across comments (not just on this Forum) that "POO-POO" adapters with glass as "degrading the image", and so forth. So I decided to run some simple tests on my gear. Like I said, I've never had a problem.

I realize that there are many different adapters and their optics won't be the same, but I'm only interested in my adapter -- an inexpensive Spiratone adapter to put Minolta-mount MF lenses on my Sony full-frame a-mount AF cameras.

Adapters may vary in quality. The same is true with lenses. I realize that my tests are comparing the results from different lenses -- one AF, the other MF. For example, I might be comparing a Sigma AF 24mm lens to a Vivitar MF 19mm lens (with adapter producing a 24mm optic).

I took pictures at f8, with the camera on a tripod using mirror lock-up and a cable release -- of high quality resolution charts at high magnification (cropping), and viewed them "unlabe;led". In other words, even though I took the pictures, I did know which was which.

In all of my comparisons, I could not pick out any of the images as better than the other -- sharper, clearer, better, etc.

So I'm convinced that using my MF-to-AF "Glassy" adapter has no quality limitation with my MF lenses -- other than the increase in focal length, lack of an auto-diaphragm, and lack of AF. None of those are big problems for me.

I realize that results may be different with the aperture wide open -- as with any tele-converter -- but normally, I try to set my aperture as close to f8 as possible.

If you've shied away from adapters with glass due to other people comments, you may want to reconsider -- and run some simple tests. Sure, there will be some limitations, but they may or may not be significant to you. You might be pleasantly surprised -- like me!

Even if I were able to compare a Sigma 24mm AF to a Sigma 24mm MF that does not mean it's a apples-to-apples comparison. Sigma made three different MF 24mm f2.8 lenses -- 7/7, 8/7, and 10/8.

And as I point out, there are differences between Glassy adapters and between lenses. I'm merely pointing out that shutterbugs should consider trying out, and testing, Glassy adapters to see if they meet their needs -- despite what they might hear on the WEB.

There's no point in posting my results for my adapter and my lenses and my cameras. That's apples to oranges for anyone else. People need to do their own tests with their own gear, and decide for themselves, instead of simply taking someone else's word for it.

Edited by XKAES - 13 January 2024 at 20:15

I was thinking of the AF and MF Sigma Superwide II, you used the AF 24/2.8, that is the SuperWide II and that is available in MF as well. I own them. I did not think of some older ones.

Still don't know if you looked at the whole frame or the centre. Also, the camera you used is relevant. Was it full-frame or APS-C? Was it 6mpx or 42mpx?

Much, much better is not an exact definition, if you consider modern lenses just better, be my guest. I won't die on that hill. But do you disagree that one uses these old manual focus lenses for their character and the fun of it?

Still would have liked the pictures....

XKAES wrote: As I mentioned, I used my Sony full-frame a-mount AF cameras

We're almost there: A850, A900, A99 or A99m2? I don't know what full-frame Sony DSLR/DSLT you own.

I've had several adapters over the years with glass in and wasn't happy with any .
The first I got in the 90's to use SR mount lenses on my Minolta 7000AF .
Results weren't that good so don't use it .

Tried another when I got my first digital camera , a Sony a100 around 2007 .
Again , wasn't impressed .
I then smashed out the glass to use my Minolta MD macro lens , and was happy !
I used several telephoto lenses on the adapter without glass with a reduced MFD with good results .

I also had an M42 to Nikon F adapter with the corrective lens in that also gave poor results .

It should also be noted some lenses have a larger rear element than the one in the adapter which also reduces the effective aperture and alters the rendering of the image .
It's not just sharpness I found to suffer , but colour and contrast .
With some lenses they also seemed to give a hazy appearance that isn't present with adapters without glass or on their native film bodies .
Further degrading what you got from the lens without an adapter .

I still use SR lenses on film and now my Sony E mount a6600 and a7Riv as they were intended ( no glass between the lens and film/sensor ) with very nice results .
Not all lenses should be expected to be as sharp as modern lenses , but I use them because I like their character in an overall image , without pixel peeping .

I think I tried an SR to EF adapter too , with poor results .

YMMV, adapters vary as does standards .

Personally, with cheap mirrorless cameras , both full frame and crop , readily available used , I see no point using glass containing adapters just to make the lens focus to infinity .

Likewise with the price of native A mount lenses dropping , you might as well buy A mount lenses to fill any gaps rather than adapting .

Using lenses like Tamron adaptall, M42 etc are still worth having as on A mount these don't need corrective lenses .
The SLT cameras make focussing much easier and as some cameras allow you to set focal length for image stabilisation, that's another bonus .

XKAES wrote: I certainly appreciate so many shutterbugs assuming (blindly believing) that "newer glass is better glass". I'm able to get all sorts of great manual-focus and auto-focus lenses for about the cost of postage. Thanks so much!!!

The biggest advantage of the rise of mirrorless cameras are people dumping their DSLRs and lenses on eBay , loads of stuff are selling for a fraction of what they used to .

Recent deals are such as my Minolta AF 300mm F/2.8 and 400mm F/4.5 and a 28mm F/2 , I paid a bit more than the postage (!) but got them for a out 1/3 of what they went for not long ago .

Picked up some more Minolta SR mount lenses as well , 58mm f/1.2 MD , 85mm F/2 , again about a third of the usual price .

Just picked up an all black SRT 101 with a 28mm for less than £30 as well .

Good time to buy , bad time to sell ..

Everyone wants the latest mirrorless gear .

Edited by neilt3 - 02 September 2024 at 17:07

XKAES wrote: I wonder what they'll want NEXT year? Built-in AI would be my first guess.

Most likely, they'll not need more than one lens then as it just generates an image that you ask for .
Sunny sky on an overcast day , no problem.
Dramatic stormy sky ? No problem.
Litter and PITA tourist removal ? No problem.

Look at mobile phones for what's on the cards for cameras .