6 replies to this topic

[Jonas]

There are so many things to ask about from this summers photographs, lets start with this.

 

I got a cheap 500 mm F/8 Hansa mirror tele, which is both smaller and lighter than an ordinary tele lens. I was hoping to exceed the quality that I got from my AF-s 55-300 on far away subjects. I cleaned the mirror lens externally and also removed and cleaned the filter threaded in the back. Performance with or without this filter seems very similar, so I put it back. Then I did this test. These pictures are taken with a D5500 at about 600 m range on a clear day. Tripod and remote release was used, 300 mm F/8 was used on the AF-s. Both images are cropped to view the same area, not resized. The exposure is different (1/100 vs 1/400). The mirror tele was on manual exposure, histogram was checked (though this part seems to be close to overexposed).

AF-S 55-300:

Hansa 500:

All photos gets blurred when zoomed too far, but this was not really what I was expecting from a 500mm lens. It is far better to crop from the 55-300mm. And that has not been cleaned so there is room for improvement.

(1) Is this the image quality that I can expect from a 500mm mirror tele?

(2) Is there any point of using a mirror tele in 2021 except for getting artistic with the rings?

(3) If you think it should look better than this, would it be worth taking the lens apart for internal cleaning (I can see dust) or do you have tips on a better mirror tele lens? Should I be looking for an old Nikon or a new from ebay?

[Bengan]

IQ differs a lot between different mirror lenses. I have no experience with the one you're using here. I have used Tamron Adaptall lenses and they definitely perform a lot better than this. There is also a variance between copies and you can find good and bad with all brands. 

The shot here could also suffer from motion blur. It's hard to tell from only one shot.

I don't think that you could clean away the problem here. Some dust doesn't affect the shots.

Bottom line, mirror lenses can be fun but don't expect them to outperform normal lenses. With a good quality 300 mm you should be able to get netter results cropping.

[Jerry_]

Mirror lenses can be fun/artistic lenses and offer unexpensive solutions for long focal lengths (just by how light is channeled/mirrored in such lenses).

A sideeffect of the unexpensive solution with little correction by glass, especially in the narrow lens tube, is that imagequality suffers. As Bengan however mentioned there are different qualities on the market, each going with their own pricetag.

Another aspect to consider is the small max aperture (f8) which is at the absolute limit for getting enough light to autofocus.

In general don’t expect a mirrorlens to outperform an average glass based lens.

Mirror based lenses *might* be interesting for astronomy due to the long focal lenghts, but then again it will not be a single capture to take, but multiple ones which are then processed and combined (allowing to correct for some bluriness)

As for the example capture given here, have a look at the top of the writing « Kabel » or the top of the smaller pole/stick. You will identify a shadowzone, larger than the thickness of the writing. A clear indication that the lens moved vertically during the shot.

[g4aaw pete]

Everything that Bengt & Jerry_ wrote.

Also, I find mine difficult to focus in poor light.

 

My best moon shot with my Tamron mirror 500 + x2 teleconverter is only just about ok.

 

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[Jonas]

Thank you all.

 

I looked at some other photos (including both more of the same island and some (poor) photos of the moon) this effect is actually visible in all of them. I did use the moon for testing when I cleaned the lens but I wanted to do a comparative test on something more realistic. On the moon photos the top side is smooth, suggesting that the camera is moving down. This sounds like there could be a tripod issue. I should investigate this and also try to take some photos in portrait mode.

 

Also, I don't expect a mirror lens to outperform a glass lens in general, however I thought that the 500/300 mm difference would show. Otherwise we could all do like the phone photographers, shoot everything in wide and crop...

[Merco_61]

If I remember correctly, the best 500 cat in F-mount was the Tokina, closely followed by the Nikon with the Tamron SP and Vivitar series one trailing a bit behind. Then there were the cats from Panagor etc and the lowest quality from the Exakta. I think the Hansa is at about the same level as the Panagor.

 

The best overall were the Minoltas, Pentaxes and Olympus catadioptric lenses.