Reflex lenses

gus

I see these in manufacturers cattledogs but no-one appears to be using them. They are dirt cheap relative to prime/zooms which shows a problem straight up like sigma 600mm f8 $380 usd.

Anyone know why they still sell them if they are that bad ? Not much to search on as ive had a look & wondered if anyone may have 1st hand experience.

patch29

Humungus wrote:

I see these in manufacturers cattledogs but no-one appears to be using them. They are dirt cheap relative to prime/zooms which shows a problem straight up like sigma 600mm f8 $380 usd.

Anyone know why they still sell them if they are that bad ? Not much to search on as ive had a look & wondered if anyone may have 1st hand experience.

I think you are locked in at f8 only, you get donuts in your highlight and the quality is usually lacking. I almost bought one, but read so many poor reviews I decided it was not worth spending the money. I am sure if you google for some reviews on specific lenses you will find the same findings repeated.

luckyrwe

I had the old Nikon 500.8 but it would not work on the F4 because the built in tripod adapter got in the way. Same with other models of lens and camera, such as those with pop up flash.

The quality of these lenses is acceptable, but for the price it is not bad. If you want the 500/4 prime lens you will pay 30 times the price of the catadioptric lens. But is it 30 times better?

GREAPER

I had a 600mm mirror lense for my first camera, a Pentax ME Super. They are capable of making sharp images and are a poor man's chance to get some reach but they do have some disadvantages.

They are slow lenses, typically f/8 (Nikon has made one that is f/5,6). Usually a person uses long glass like 600mm to photograph wildlife or sports, which means you are looking for faster shutterspeeds f/8 is pretty slow in all but the brightest light.

I have never seen one of these lenses that was autofocus. Even though they work on autofocus cameras, I think you may have to focus manually.

The bokeh (sp) produced by these lenses tends to be doughnut shaped with a bright circle that is darker in the center. some people dont like this, others do, up to you.

Most lenses are at the widest aperature when you are focusing and composing through the viewfinder. They stop down to the aperature you have selected just before the shutter operates. This allows you to see the most light possible through the viewfinder for focusing and composing. The mirror lenses have no other aperature than the one you are looking through which often means you have less light to focus with. That may sound confusing so I will give an example. My slow 170-500mm zoom has a min aperature of 5,x If I shoot at f/8 I still get the light at f/5.x to use for autofocus etc. When I take that shot the camera changes it to f/8, releases the shutter and changes back to f/5.x. With a reflex lens it is stuck at f/8 and that is all the light I get for focusing.

In my opinion it may be fun to have one of these lenses to play with, but I would still want the best prime or zoom I could afford as a primary wildlife lens.

gus

Thanks all...good info. Interesting to read.

luckyrwe

I was in Panama in 1983 when the Pope was there. I was about a mle away on a hill to get the overal view. For grins I took my Nikon F2 and Sigma 600mm f/8 CAT lens and added teleconverters. I had two 2x and one 3x, all Vivitar. This gave me a 7,200mm f/90 lens! While it sounds like an awesome depth of field I did get one picture (30th sec, tripod and tree) of a blur. The blur is his face, honest!

The CAT lens is the easiest, cheapest way for anyone to get into supertelephoto for under $200. Go for it!