Help with lens,

[chiltonstar]

I find it strange that the lens behaves differently in MF and AF especially if focus is achieved by moving different elements between MF and AF this isn't something I have come across with any of the kit I have used...

Another theory dashed - you are quite right. I was confusing the manual and auto lenses.Chris

[MooMoo]

You want a FAST light capture (low F number) and prime (single focal length) and Aspherical (reduces coma on edges - star bloat).

Suggestions are the Canon 50mm f/1.4 USM (great lens but FOV of 80mm on a 1.6x crop sensor APS-C) and Samyang 14mm f/2.8 Aspherical ED lens (quality consistency issues and Moustache distortion - some are soft focusing and some are sharp, manual focus but if you get a good one its good - except you have to correct the M distortion).

[MooMoo]

Cable releases for canons are useful

Without interalometer - http://www.amazon.co...mote cord canon

With intervalometer - http://www.amazon.co...er remote canon

Samyang 14mm lens http://www.amazon.co...g aspherical 14

Canon 50mm lens - http://www.amazon.co...=canon 50mm 1.4

[Aenima]

Thank you Moo Moo,

I have one of those remotes for my 300D but have yet to receive the one I ordered from ebay for the Nikon. I like the idea of the decent prime lens but something like 50mm doesn't sound like it has much magnification to it. I have bought a cheap 135mm prime soligor but dont expect too much from it as it was very cheap, but worth a try.

Probably the shorter focal lengths would work for capturing the milky way or whole constellations but I want to aim for a closer shot at the larger deep sky objects and stuff that my reflector is too powerful to frame nicely. Although its hard to judge the FOV even in a scope, which i'm used to so lenses give me extra trouble trying to figure it out.

For the time being Im happy with my 18-55mm AF-S and 55-200mm AF-S as the camera works well with the CPU lenses, otherwise I'm just gonna experiment with some cheap n cheerful primes or old m42 lenses until I got a better idea of what I'm doing with this whole widefield thing..

Much appreciative for the advice btw.

Regards

Aenima

[Psychobilly]

The only thing to watch is that lenses for "digital" cameras have additional coatings on the rear elements to reduce artefacts from reflections back off the camera sensor...Older manual lenses didn't need this but they are still worth a go as for the vast majority of targets your unlikely to have any problems...

You can setup FOV indicators in apps like Stellarium that will show you what the sensor/scope/lens will cover...

I don't use Stellarium myself but if you shout I am sure someone who does will be able to help you set it up or I can work out the FOV in degrees and arcmins for them for you...

Peter...

[Aenima]

Cheers Peter, appreciate the info and suggestions, I have used stellarium FOV but mostly to work out the 200p / canon 300D sensor fov, not sure how accurate it is as I dont recall specifying primefocus but its still quite a close match using the sensor specs and focal length (1000mm) but with the lenses - yet again - i'm much less familiar with the numbers involved.

I keep reading that the d3100 - DX ? - has a smaller than normal chip, but the specsheet gives the size as bigger than the 300D sensor, maybe the canon has a smaller chip too?

But yeah I now have the AF-S 55-200mm nikkor to go with the 18-55 AF-S (VR) kit lens that came with the d3100 so its quite a range covered with those two, when I figure out using a mini-bahtinov or focus mask for cameras the modded 300D can be used for nebulous areas.

Thanks for the tips,

Regards

Aenima

[knobby]

The 55- 200 vr is a nice lens, very reasonable price and gets good reviews.

Probably at its best around the 150 mm which will also mean you can use the lower f number (the f changes as you zoom)

Don't forget to turn the vr off... It does weird things to images when on a tripod

[Aenima]

The VR option is only on the 18-55mm which was part of the kit - the 55-200mm is the pre-VR version but still pretty similar, fast auto-focus sharp and lightweight I like it already.

Cheers for the heads-up on the VR switch on tripods (mine will be used piggybacked on the EQ5),

Regards

Aenima

[Aenima]

The non-vr model is slightly different in construction but not much, it came up at a good price at a good time, in great condition so I can live without VR

Regards

Aenima

[knobby]

Ooops .. must learn to read and not jump to conclusions, read back and yes you clearly have the non vr version which is still a nice lens.

its late and hot and sticky and it must be slowing the brain cells down

[Psychobilly]

Canon APS-C is 1, 6x crop and the Nikon DX is 1.5x crop...

Sent from my GT-I9100 using Tapatalk 4 Beta

[Aenima]

Canon APS-C is 1, 6x crop and the Nikon DX is 1.5x crop...

Sent from my GT-I9100 using Tapatalk 4 Beta

Ah, slight size difference by look of it but not sure what the crop # factor means in terms of comparison to average chip size, I take it the 'crop' is related to the FOV and the edges of the image rather than the sensor itself (being cropped )).

The full frame ones would be the more expensive types I'd imagine, as both the 300D and d3100 are budget models really - just quite a difference in age.

HOT yes, very very very very. O.o

Regards

Aenima