[Yael]

Im looking into options for a telephoto in the 800-1000mm range and came up with two options. From all of my Googling it seems like a choice between the lesser of two evils. Either a mirror lens in the 800-1000mm focal length range or I could pair up a 300mm telephoto with a 3x teleconverter for a 900mm focal length. Anyone have any input?

If it matters, I already have a 300mm telephoto and a 3x teleconverter so if there isnt much difference is it worth it to get a mirror lens?

[jatrax]

What is the minimum aperture of your 300? Add a 3x and you lose 3 stops of light, I think. So an f/4 becomes an f/11. Difficult to see through to focus.

I am not a big fan of mirror lenses, mostly because of a poor experience with one. In hind sight it was probably a poor example so a good quality one might be better.

Getting to 1,000mm is going to be difficult and image quality will not be very good. Best IQ solution I can think of would the Sigma 500mm f/4.5 and the Sigma 2x TC. But that would be very expensive. I guess if you really need to get there on a reasonable budget I would opt for the 1000mm mirror, but I would not be expecting much in the way of image quality.

Also be prepared to use a substantial tripod. At 1000mm a butterflies wings will be enough to cause to vibration.

[Yael]

What is the minimum aperture of your 300? Add a 3x and you lose 3 stops of light, I think. So an f/4 becomes an f/11. Difficult to see through to focus.

I am not a big fan of mirror lenses, mostly because of a poor experience with one. In hind sight it was probably a poor example so a good quality one might be better.

Getting to 1,000mm is going to be difficult and image quality will not be very good. Best IQ solution I can think of would the Sigma 500mm f/4.5 and the Sigma 2x TC. But that would be very expensive. I guess if you really need to get there on a reasonable budget I would opt for the 1000mm mirror, but I would not be expecting much in the way of image quality.

Also be prepared to use a substantial tripod. At 1000mm a butterflies wings will be enough to cause to vibration.

How expensive is "very expensive"?

[kiwi_jono]

I would test the combo you have now with a fixed subject and tripod - to see what you think of the IQ. As jatrax says you should not expect great IQ. In fact, unless the 300mm has particularly good IQ, you might find you can crop as good a image without the 3x converter as with.

Also with mirror, quality can be iffy. There are some good mirror lenses out there but generally expensive and still have donut bokeh (which can be ugly depending on your point of view). The biggest advantage with a mirror lens is their relatively compact size.

[fgaudet]

How expensive is "very expensive"?

About $5000 for the lens alone.

[boriscleto]

How expensive is "very expensive"?

The Sigma 500/4.5 sells for $5000 new, somewhat less used if you can find one. The TC is cheap, just $250.

Digiscoping might be a better option than a mirror or 3x tele converter.

A Pentax Q with a K mount adapter would be a very inexpensive solution. A 300mm lens becomes a 1600mm+ lens.

[Yael]

About $5000 for the lens alone.

Jeeze... I dont think I will be adding that to my shopping list any time soon.

[SpecialK]

Post a shot of the 300/TC combo for us to evaluate. Also, there is the "mirror lens club" that will have samples you can compare.

You are fighting an uphill battle, either way.

[fgaudet]

Depending on what you are planning to do, at this focal range, you may also consider getting a telescope and a mount adapter for you camera.

Also, if your 300mm is any good and your camera has a decent sensor, you will get better results shooting at 300mm and cropping down to 900mm than you will get with inexpensive mirror lenses or a 3x TC. Sure you will lose MP but the end result will still be better.

If your 300 is so-so, results will vary.

[jatrax]

Jeeze... I dont think I will be adding that to my shopping list any time soon.

That's why I said "very expensive", LOL.

Here is what you are getting into if you are serious about long telephotos: Nikon 800mm f/5.6E FL ED VR Lens 2205 B&H Photo

Makes the Sigma 500mm + TC look cheap.

Digiscoping might be a better option than a mirror or 3x tele converter.

If ultimate image quality is not needed this might be the best suggestion price wise. You just need to determine what quality you want and what your budget is.

[Yael]

If this helps anyone the 300 I have is a 1:5.5 300mm Bushnell in an M42 mount, and the TC is an EMC 3x TC also in an M42 mount. So not the highest quality or modern glass by any stretch of the imagination...

...Sounds like I should stick with the 300/TC combo at the moment and put my money into a good tripod though.

[jatrax]

You should at least try that combination. Looks like it will be about f/13, and I'm not even sure you can see anything through it much less focus. But do give it a try and let us know, I've never tried such a combination.

[JinDesu]

How critical is the IQ for you? How soft are you willing to accept things? Any images for example from your side?

[Imageman]

Get a couple of long telephoto lenses in m42, a 400mm and a 600mm, they will cost around 100 dollars each or even less.


You will be astounded by their quality.

[RobA_Oz]

Mirror lenses are a bit of a compromise in a number of ways. I have a Tamron 500mm f8 and the Pentax 400-600mm f8-12 zoom. Frankly, the IQ of the Tamron is as good as (maybe better than) the Pentax and it didn't cost an arm and a leg. However, the zoom on the Pentax is something of an attraction, but the small and fixed aperture on a mirror lens means you lose one element of control and for dark or low contrast subjects, you're really best off using Live View for focussing. They are, nonetheless light and comparatively easy to use otherwise.