teleconverters?

[daine]

hi just wondering if it would be worth buying a 2x teleconverter or not, i really cant afford a super zoom lense, i have a tamron 70-300mm lense. would i be better off using the sky watcher ED80 telescope its extremely sharp but a little too heavy and the focus would be a little bit of a pain to work with, id like to do a bit of bird watching

[WooD]

That would probably be the worst lens you could put a TC on.

Going 2X on a pro lens will degrade your image quality some, I'd not go with over a 1.4X TC on any lens.

I use one on a 300 f/4, and I cant tell any difference in image quality.

[scootermcq]

Tamron 1.4tc on 80-200 f2.8





There is a slight trade off in IC, but I am OK with the amount. I agree whole heartedly with Woods comments

[daine]

so what about the ed80 scope? its got a 600mm focal length at f7,5 ive done a little bit of astro work with my d90 mounted to it but the thing weighs 2.5 kilos heres one of the astro images think it was a 10 min exposure i haven't edited this image it has a little distortion around the edges has anyone ever worked with a telescope for bird images?

[windrider86]

I purchased one and never ever used it. It will also decrease the light in your photos so you'll have to adjust for that

[Aegea]

Having used both, I think you'd be better off with the 'scope. The Tamron is f/5.6 at the long end IIRC, so with even a 1.4x TC you will be at f/8. Based on my experience with a 1.4x TC, D90, and Nikon 70-300, autofocus will be slow and erratic in anything but the best light. IQ will also be degraded. Scooter's 80-200 f/2.8 is a whole other beast, and can take TCs much better than the slower 70-300s.

Focus is a pain with a scope, and it's cumbersome and requires support, but the IQ is very good indeed, even with a teleconverter added for 840mm FL. Here's a Cardinal taken with that setup (the EXIF says 1000mm, but it's garbled)

[daine]

might just have to save up for a little while and buy a decent lense, not really keen on dragging the scopes tripod around

[daine]

how would a 500mm mirror lense go? i found one on ebay its f8 but only 90mm long

[OsmosisStudios]

Originally Posted by daine

how would a 500mm mirror lense go? i found one on ebay its f8 but only 90mm long

A mirror lens may only be 90mm in total length, but it has a 500mm focal length. Dont get the two confused.

You'd be better off just saving your money, or renting if you need it right away.

[wildbird]

I use a 2x teleconverter a fair bit (used to at least, not so much since I relocated, but I digress). I used it in very bright conditions usually, shooting mostly birds and outdoors sport such as cricket in temps around 40 degreees celsius, so was always bright. Never really had a ny issue, but i was using a 70-200 2.8 nikon on both a D90 and D3s. Used to use 70-300 on D90 till it got broken, and had good success with that, light weight, easier to carry to get to the shots than the heavier option.